JP5370769B2 - Control device for motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a motor drive unit which can suppress overshooting of a current flowing in a coil of a motor or vibration of torque generated by the motor when shifting to a state of performing square wave control and stronger field control for strengthening a field magnetic flux of an AC motor. <P>SOLUTION: The device includes a mode control part which performs stronger field shift control going through a stronger field and pulse width modulation control mode A2 which performs stronger field control and pulse width modulation control, during shifting from a normal field and pulse width modulation control mode A1 which performs normal field control and pulse width modulation control to a stronger field and square wave control mode A3 which performs stronger field control and square wave control. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a control device that controls a motor drive device including a DC / AC converter that converts a DC voltage into an AC voltage and supplies the AC voltage to an AC motor.

  2. Description of the Related Art Generally, an electric motor driving device that drives an AC motor by converting a DC voltage from a DC power source into an AC voltage by an inverter is generally used. In such an electric motor drive device, sinusoidal PWM (pulse width modulation) control based on vector control and maximum frequency are used to efficiently generate torque by supplying sinusoidal AC voltage to the coils of each phase of the AC motor. A lot of torque control is performed. By the way, the induced voltage of the electric motor increases as the rotational speed increases, and the AC voltage (hereinafter referred to as “required voltage”) required to drive the electric motor also increases. When this necessary voltage exceeds the maximum AC voltage that can be output from the inverter (hereinafter referred to as “maximum output voltage”), the necessary current cannot be passed through the coil, and the motor can be controlled appropriately. Can not. In order to reduce the induced voltage, field weakening control is performed to weaken the field magnetic flux of the electric motor. However, when the field weakening control is performed, the maximum torque control cannot be performed, so that the maximum torque that can be output decreases and the efficiency also decreases. With respect to such a problem, the following Patent Document 1 discloses an electric motor that shifts from sinusoidal PWM control to overmodulation PWM control and further to rectangular wave control as the rotational speed of the motor increases and the induced voltage increases. The technology of the control device of the drive device is described.

  Here, regarding the modulation rate which is the ratio of the effective value of the fundamental wave component of the AC voltage waveform to the DC power supply voltage (system voltage), the upper limit of the modulation rate is 0.61 in the sinusoidal PWM control. On the other hand, in the overmodulation PWM control, the modulation rate can be increased to a range of 0.61 to 0.78, and in the rectangular wave control, the modulation rate becomes a maximum of 0.78. Therefore, according to the control device described in Patent Document 1, by increasing the amplitude of the fundamental wave component of the AC voltage waveform supplied to the AC motor by overmodulation PWM control or rectangular wave control (increasing the modulation factor). Compared with a configuration in which only the sine wave PWM control is performed, the rotation speed region in which the maximum torque control can be performed by effectively using the DC voltage is expanded. When the required voltage of the motor is lower than the maximum output voltage, maximum torque control is performed together with sine wave PWM control or overmodulation PWM control, and when the required voltage of the motor reaches the maximum output voltage, field weakening control is performed together with rectangular wave control.

JP 2006-31770 A

  In the above control device, PWM control is performed in an operation region where maximum torque control can be performed. However, since such PWM control has a large number of on / off switching elements constituting the inverter, switching loss tends to increase. . In order to further improve the efficiency of the electric motor, it is effective to suppress such switching loss. On the other hand, according to the rectangular wave control, the number of on / off times of the switching element can be significantly reduced as compared with the PWM control, so that switching loss can be suppressed. However, as described above, since the modulation factor is fixed in the rectangular wave control, when the DC voltage is constant, the output torque is determined according to the rotation speed of the motor. Therefore, the torque corresponding to the target torque can be output to the motor. Can not.

  Therefore, the inventors of the present application determine the modulation rate by determining the field adjustment command value so as to perform the strong field control that strengthens the field magnetic flux of the AC motor even in the operation region where the maximum torque control can be performed. A maximum of 0.78 was devised to perform rectangular wave control. As a result, it is possible to expand the operating range of the electric motor in which the rectangular wave control is performed, to reduce the switching loss in the inverter, and to increase the efficiency. However, when a transition is made from a state in which PWM control is performed together with maximum torque control to a state in which rectangular wave control is performed together with field strengthening control, the current command value, which is the command value of the current flowing through the motor coil, changes abruptly. There is a case. Therefore, the current flowing through the coil of the electric motor may overshoot and vibrate, and further, the torque generated by the electric motor may vibrate.

  Therefore, when shifting to a state in which the rectangular wave control is executed together with the strong field control that strengthens the field magnetic flux of the AC motor, the electric motor that can suppress the overshoot of the current flowing in the coil of the motor and the vibration of the torque generated by the motor. It is desirable to realize a control device for a driving device.

  In order to achieve the above object, according to the present invention, a characteristic configuration of a control device that controls a motor driving device including a DC / AC converter that converts a DC voltage into an AC voltage and supplies the AC voltage to the AC motor is the AC motor. A current command determining unit that determines a current command value that is a command value of a current supplied from the DC / AC converter to the AC motor based on a target torque of the AC motor, and the current so as to increase a field flux of the AC motor. A field adjustment unit for determining a field adjustment command value for executing a strong field control for adjusting the command value and a normal field control for not adjusting the current command value; a rotational speed of the AC motor; and the current command A voltage command determination unit that determines a voltage command value that is a command value of a voltage supplied from the DC / AC conversion unit to the AC motor based on the value and the field adjustment command value A voltage waveform controller that controls the DC-AC converter based on the voltage command value, and executes pulse width modulation control and rectangular wave control, respectively, and a normal field that executes the pulse width modulation control together with the normal field control A strong field / pulse that executes the pulse width modulation control together with the strong field control during the transition from the pulse width modulation control mode to the strong field / rectangular wave control mode that executes the rectangular wave control together with the strong field control. And a mode control unit that executes strong field transfer control through the width modulation control mode.

  According to this characteristic configuration, by executing the strong field / rectangular wave control mode in which the rectangular wave control is executed together with the strong field control, the operating range in which the rectangular wave control in the motor is performed can be expanded, and the DC / AC conversion unit The switching loss can be reduced and the efficiency can be increased. At this time, by appropriately determining the field adjustment command value by the field adjustment unit and changing the degree of the strong field, the torque corresponding to the target torque is appropriately output to the motor regardless of the rotation speed of the motor. Can be made. Then, during the transition from the normal field / pulse width modulation control mode to the strong field / square wave control mode, the strong field through the strong field / pulse width modulation control mode that executes the pulse width modulation control together with the strong field control. By executing the transition control, it is possible to suppress a sudden change in the current command value, which is the command value of the current flowing through the coil of the electric motor. Accordingly, it is possible to suppress overshoot of the current flowing through the coil of the motor and vibration of torque generated by the motor.

  Here, the pulse width modulation control includes overmodulation pulse width modulation control in which the amplitude of the AC voltage waveform based on the voltage command value exceeds the amplitude of the carrier waveform, and the amplitude of the AC voltage waveform is less than the amplitude of the carrier waveform. A configuration including certain normal pulse width modulation control is preferable. In this case, the mode control unit executes at least a strong field / overmodulation pulse width modulation control mode for executing the overmodulation pulse width modulation control together with the strong field control as the strong field / pulse width modulation control mode. It is preferable to adopt a configuration to do so. At this time, the mode control unit, as the strong field / pulse width modulation control mode, increases the voltage index indicating the magnitude of the voltage command value with respect to the DC voltage, and the normal pulse width together with the strong field control. It is also preferable to execute the strong field / normal pulse width modulation control mode after executing the strong field / normal pulse width modulation control mode for executing the modulation control. Alternatively, the mode control unit may execute only the strong field / overmodulation pulse width modulation control mode as the strong field / pulse width modulation control mode.

  Thereby, even when the pulse width modulation control includes the overmodulation pulse width modulation control and the normal pulse width modulation control, the strong field transfer control can be appropriately executed.

  The mode control unit causes the voltage waveform control unit to execute the rectangular wave control in a state where a voltage index representing the magnitude of the voltage command value with respect to the DC voltage is equal to or greater than a predetermined rectangular wave switching threshold value. In a state where the voltage index is less than the rectangular wave switching threshold value, it is preferable that the voltage waveform control unit execute the pulse width modulation control. In this case, when the field adjustment command value is equal to or greater than a predetermined end threshold value in the direction of increasing the field magnetic flux of the AC motor, the mode control unit ends the strong field control and ends the field control. It is preferable that the voltage index is set to be less than the rectangular wave switching threshold value by determining the field adjustment command value so as to execute normal field control, and the voltage waveform control unit performs the pulse width modulation control. It is.

  According to this configuration, regardless of the voltage index that is forcibly set to the rectangular wave switching threshold by performing the strong field control, the strong field control and the rectangular wave control are appropriately terminated and the normal field control and the pulse width modulation control are performed. Can be restored. At this time, since the end of the strong field control is determined based on the value of the field adjustment command value, it is possible to suppress an increase in efficiency reduction due to an increase in the degree of the strong field. Note that the end threshold value, which is the threshold value of the field adjustment command value for ending the strong field control, is an efficiency improvement due to the increase in the degree of the strong field due to the improvement in efficiency accompanying the reduction of switching loss by the rectangular wave control. It is preferable to set within a range exceeding the decrease.

  The mode control unit determines the field adjustment command value so as not to execute the strong field control when the target torque of the AC motor is out of a predetermined strong field allowable torque range. It is preferable.

  Here, in the rectangular wave control, harmonic components other than the fundamental component included in the current flowing through the coil are likely to be large. Therefore, depending on the value of the target torque of the AC motor, it may not be appropriate to shift to rectangular wave control by performing strong field control. According to this configuration, by restricting the torque range that allows the strong field control to be performed, the strong field is performed only when it is appropriate to shift to the rectangular wave control, and thus the rectangular wave control is appropriately performed. be able to.

  Here, the voltage command determination unit further includes a change rate regulating unit that regulates the change rate of the voltage index representing the magnitude of the voltage command value with respect to the DC voltage to be equal to or lower than a predetermined regulation rate, The mode control unit increases the voltage command value as the field adjustment command value changes from a reference value for executing the normal field control in a direction in which the field magnetic flux is strengthened. The voltage waveform control unit executes the rectangular wave control when the voltage threshold is equal to or higher than the switching threshold, and the voltage waveform control unit executes the pulse width modulation control when the voltage index is less than the rectangular wave switching threshold. Further, the mode control unit regulates the change rate of the voltage index by the change rate regulation unit after the start of the strong field control in the strong field transition control, and the voltage index is When configured to perform the strong field pulse width modulation control mode in time to reach the serial square wave switching threshold is suitable.

  According to this configuration, when the strong field transition control is performed, the change speed of the voltage index is regulated by the change speed regulating unit after the start of the strong field control. It can be secured for a relatively long time. Thus, the strong field / pulse width modulation control mode can be appropriately executed during the time until the voltage index reaches the rectangular wave switching threshold and the strong field / rectangular wave control mode is executed. . Therefore, it is possible to suppress a sudden change in the current command value, and it is possible to suppress overshoot of the current flowing in the coil of the motor and vibration of torque generated by the motor.

  The change rate regulating unit includes a command voltage index setting unit that sets a command voltage index that is a command value of the voltage index, and the field adjustment unit is a difference obtained by subtracting the command voltage index from the voltage index. When the voltage index deviation is not less than a predetermined strong field threshold value and less than zero, the field adjustment command value is changed in a direction in which the field magnetic flux is strengthened. The field adjustment command value is changed in the direction of weakening the magnetic flux so that the field magnetic flux is not changed when the voltage index deviation is less than the strong field threshold and when the voltage index deviation is zero. The field control command value is determined, and the mode control unit sends the command voltage index setting unit to the command voltage index setting unit based on a relationship between a command voltage index initial value that is an initial value of the command voltage index and the voltage index. Above the indicator It was started, the command voltage indicator setting section, it is preferable that a configuration of increasing the command voltage indicator at a predetermined rate of change until reaching the square wave switching threshold from the command voltage indicator initial value.

  According to this configuration, in the configuration in which the field adjustment unit determines the field adjustment command value for adjusting the field magnetic flux of the AC motor according to the difference between the voltage index and the command voltage index, the command voltage index setting Increases the command voltage index at a predetermined change rate from the command voltage index initial value to the rectangular wave switching threshold value, so that the actual voltage index following the command voltage index also increases at the predetermined change rate Will do. At this time, since the increase of the command voltage index is started based on the relationship between the command voltage index initial value and the voltage index, it is possible to always set a command voltage index appropriate for the actual voltage index. By regulating the rising speed of the voltage index in this way, it is possible to ensure a relatively long time until the voltage index reaches the rectangular wave switching threshold value. As a result, the strong field / pulse width modulation control mode can be appropriately executed during the time until the voltage index reaches the rectangular wave switching threshold and the strong field / rectangular wave control mode is executed. it can. Therefore, it is possible to suppress a sudden change in the current command value, and it is possible to suppress overshoot of the current flowing in the coil of the motor and vibration of torque generated by the motor.

  The command voltage index initial value is preferably set to be larger than the voltage index when the normal field control is executed according to at least one of the rotational speed and the target torque of the AC motor.

  According to this configuration, when the strong field transfer control is executed, it is possible to prevent the field adjustment command value from changing in a direction in which the voltage index deviation is greater than zero and weaken the field magnetic flux. The command voltage index initial value can be set so that the strong field control is started.

  Further, the command voltage index setting unit is configured so that the time until the command voltage index reaches the rectangular wave switching threshold value from the command voltage index initial value is constant regardless of the command voltage index initial value. It is preferable to set the change speed of the command voltage index.

  According to this configuration, even when the command voltage index initial value is varied according to at least one of the rotational speed and the target torque of the AC motor, the command voltage index is switched to the rectangular wave regardless of the command voltage index initial value. A certain amount of time can be secured before reaching the value. As a result, a certain time can be ensured until the voltage index reaches the rectangular wave switching threshold, and the strong field / pulse width modulation control mode can be appropriately executed at that time.

  Alternatively, instead of the configuration in which the change speed regulation unit includes the above-described command voltage index setting unit, the change speed regulation unit has a target field adjustment command value such that the voltage index becomes the rectangular wave switching threshold value. A target field adjustment command value determining unit for determining the transition control field adjusting unit for determining the field adjustment command value that changes at a predetermined change rate until the target field adjustment command value is reached. The field adjustment unit strengthens the field magnetic flux in a state where a voltage index deviation, which is a difference obtained by subtracting the rectangular wave switching threshold value from the voltage index, is equal to or greater than a predetermined strong field threshold value and less than zero. The field adjustment command value is changed in the direction, and in the state where the voltage index deviation is greater than zero, the field adjustment command value is changed in the direction to weaken the field magnetic flux, and the voltage index deviation becomes the stronger field. The condition below the threshold and the voltage finger The field adjustment command value is determined so as not to change the field magnetic flux in a state where the deviation is zero, and the mode control unit, when the voltage index is equal to or higher than a predetermined strong field start voltage index, The target field adjustment command value determining unit determines the target field adjustment command value, and after the target field adjustment command value is determined until the voltage index becomes the rectangular wave switching threshold value, It is also preferable that the field adjustment command value determined by the transition control field adjustment unit is input to the voltage command determination unit instead of the field adjustment command value determined by the field adjustment unit.

  According to this configuration, in the configuration in which the field adjustment unit determines the field adjustment command value for adjusting the field magnetic flux of the AC motor according to the difference between the voltage index and the command voltage index, the voltage index is rectangular. The target field adjustment command value that becomes the wave switching threshold value is determined, and until the voltage index reaches the rectangular wave switching threshold value, the field adjustment command value determined by the normal field adjustment unit is set. Instead, the field adjustment command value determined by the transition control field adjustment unit is input to the voltage command determination unit. At this time, the field adjustment command value determined by the transition control field adjustment unit changes at a predetermined rate of change until the target field adjustment command value is reached. Accordingly, it is possible to secure a relatively long time until the voltage index reaches the rectangular wave switching threshold by regulating the rising speed of the voltage command value reflecting such a field adjustment command value. As a result, the strong field / pulse width modulation control mode can be appropriately executed during the time until the voltage index reaches the rectangular wave switching threshold and the strong field / rectangular wave control mode is executed. it can. Therefore, it is possible to suppress a sudden change in the current command value, and it is possible to suppress overshoot of the current flowing in the coil of the motor and vibration of torque generated by the motor.

It is a circuit diagram showing the composition of the electric motor drive concerning a first embodiment of the present invention. It is a functional block diagram of a control device concerning a first embodiment. It is a figure which shows the example of the control mode map which concerns on 1st embodiment. It is a figure which shows the example of the basic d-axis electric current command value map which concerns on 1st embodiment. It is a figure which shows the example of the q-axis current command value map which concerns on 1st embodiment. It is a figure which shows the example of the conversion map used in the integral input adjustment part which concerns on 1st embodiment. It is a figure which shows the example of the command modulation factor map used in the command modulation factor setting part which concerns on 1st embodiment. It is a flowchart which shows the flow of operation | movement of the control apparatus which concerns on 1st embodiment. It is a figure which shows an example of the change of d-axis current command value and q-axis current command value accompanying the change of the target torque and rotation speed in the control apparatus which concerns on 1st embodiment. It is a functional block diagram of the control apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows the example of the d-axis current adjustment command value map used in the target d-axis current adjustment command value determination part which concerns on 2nd embodiment. It is a flowchart which shows the flow of operation | movement of the control apparatus which concerns on 2nd embodiment.

1. First Embodiment First, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, in the present embodiment, the motor drive device 1 is a synchronous motor 4 (IPMSM, hereinafter simply referred to as “motor 4”) having an embedded magnet structure as an AC motor that operates by three-phase AC. The case where it is comprised as an apparatus to drive is demonstrated as an example. The electric motor 4 is configured to operate as a generator as required. The electric motor 4 is used as a driving force source for an electric vehicle or a hybrid vehicle, for example. The electric motor drive device 1 includes an inverter 6 that converts a direct current voltage Vdc into alternating current and supplies it to the electric motor 4. And in this embodiment, as shown in FIG. 2, the control apparatus 2 controls the electric motor drive apparatus 1, and performs the current feedback control of the electric motor 4 using a vector control method. At this time, the controller 2 is configured to execute pulse width modulation (hereinafter referred to as “PWM”) control and rectangular wave control as voltage waveform control. Further, the control device 2 performs, as field adjustment control, normal field control in which the current command values Idb and Iqb determined based on the target torque TM are not adjusted, and the current command value Idb so as to weaken the field flux of the motor 4. The field weakening control for adjusting Iqb and the field strengthening control for adjusting current command values Idb and Iqb so as to increase the field magnetic flux can be executed. As shown in FIG. 3, the control device 2 starts from the normal field / PWM control mode A1 that executes PWM control together with normal field control, and the strong field / rectangular wave control mode that executes rectangular wave control together with strong field control. It is characterized in that the strong field transfer control through the strong field / PWM control mode A2 for executing the PWM control together with the strong field control can be executed during the shift to A3. Hereinafter, the electric motor drive device 1 and its control device 2 according to the present embodiment will be described in detail.

1-1. Configuration of Electric Motor Drive Device First, the configuration of an electric motor drive device 1 according to the present embodiment will be described with reference to FIG. The electric motor drive device 1 includes an inverter 6 that converts a DC voltage Vdc into an AC voltage and supplies the AC voltage to the electric motor 4. In addition, the electric motor drive device 1 includes a DC power source 3 that generates a DC voltage Vdc, and a smoothing capacitor C1 that smoothes the DC voltage Vdc from the DC power source 3. As the DC power source 3, for example, various secondary batteries such as a nickel hydride secondary battery and a lithium ion secondary battery, a capacitor, or a combination thereof is used. The DC voltage Vdc, which is the voltage of the DC power supply 3, is detected by the voltage sensor 41 and output to the control device 2.

  The inverter 6 is a device for converting a direct current direct current voltage Vdc into an alternating current voltage and supplying the alternating current voltage to the electric motor 4, and corresponds to a direct current to alternating current converter in the present invention. The inverter 6 includes a plurality of sets of switching elements E1 to E6 and diodes D1 to D6. Here, the inverter 6 is a pair of switching elements for each of the phases (U phase, V phase, W phase) of the electric motor 4, specifically, a U-phase upper arm element E1 and a U-phase lower phase. The arm element E2, the V-phase upper arm element E3, the V-phase lower arm element E4, the W-phase upper arm element E5, and the W-phase lower arm element E6 are provided. In these examples, IGBTs (insulated gate bipolar transistors) are used as the switching elements E1 to E6. The emitters of the upper arm elements E 1, E 3, E 5 for each phase and the collectors of the lower arm elements E 2, E 4, E 6 are connected to the coils of the respective phases of the electric motor 4. The collectors of the upper arm elements E 1, E 3, E 5 for each phase are connected to the system voltage line 51, and the emitters of the lower arm elements E 2, E 4, E 6 for each phase are connected to the negative line 52. In addition, diodes D1 to D6 that function as freewheeling diodes are connected in parallel to the switching elements E1 to E6, respectively. As the switching elements E1 to E6, power transistors having various structures such as a bipolar type, a field effect type, and a MOS type can be used in addition to the IGBT.

  Each of the switching elements E <b> 1 to E <b> 6 performs an on / off operation according to the switching control signals S <b> 1 to S <b> 6 output from the control device 2. Thereby, the inverter 6 converts the DC voltage Vdc into an AC voltage and supplies it to the electric motor 4 to cause the electric motor 4 to output a torque corresponding to the target torque TM. At this time, each of the switching elements E1 to E6 performs a switching operation according to PWM control or rectangular wave control described later in accordance with the switching control signals S1 to S6. In the present embodiment, the switching control signals S1 to S6 are gate drive signals that drive the gates of the switching elements E1 to E6. On the other hand, when the electric motor 4 functions as a generator, the inverter 6 converts the generated AC voltage into a DC voltage and supplies it to the system voltage line 51. Each phase current flowing through the coils of each phase of the electric motor 4, specifically, the U-phase current Iur, the V-phase current Ivr, and the W-phase current Iwr is detected by the current sensor 42 and output to the control device 2.

  Further, the magnetic pole position θ at each time point of the rotor of the electric motor 4 is detected by the rotation sensor 43 and output to the control device 2. The rotation sensor 43 is configured by, for example, a resolver. Here, the magnetic pole position θ represents the rotation angle of the rotor on the electrical angle. The target torque TM of the electric motor 4 is input to the control device 2 as a request signal from another control device such as a vehicle control device (not shown).

1-2. Configuration of Control Device Next, functions of the control device 2 shown in FIG. 1 will be described in detail with reference to FIGS. Each functional unit of the control device 2 described below is based on hardware and / or software (program) or both for performing various processes on input data using a logic circuit such as a microcomputer as a core member. It is configured. As described above, the target torque TM and the magnetic pole position θ are input to the control device 2. Furthermore, the control device 2 also receives a U-phase current Iur, a V-phase current Ivr, and a W-phase current Iwr. Therefore, as shown in FIG. 2, the control device 2 is based on the target torque TM, the magnetic pole position θ, the rotational speed ω of the motor 4 derived from the magnetic pole position θ, and the phase currents Iur, Ivr, and Iwr. Then, current feedback control using a vector control method is performed, and voltage command values Vd and Vq which are command values of voltages supplied to the motor 4 are determined. Then, based on the voltage command values Vd and Vq, switching control signals S1 to S6 for driving the inverter 6 are generated and output, and drive control of the electric motor 4 is performed via the inverter 6. At this time, the control device 2 is configured to execute PWM control and rectangular wave control with respect to voltage waveform control performed by controlling the inverter 6 based on the voltage command values Vd and Vq, and for the current command values Idb and Iqb. With respect to the field control performed by determining the field adjustment command value so as to adjust the field magnetic flux of the electric motor 4, normal field control, strong field control, and field weakening control can be executed. And the control apparatus 2 switches and performs either of several control modes combining these voltage waveform control and field control.

  In the PWM control, on / off of each of the switching elements E1 to E6 of the inverter 6 is controlled based on AC voltage waveforms Vu, Vv, Vw (see FIG. 2) based on the voltage command values Vd, Vq. Specifically, the output voltage waveform (PWM waveform) of the inverter 6 of each phase of U, V, and W is a high level period during which the upper arm elements E1, E3, and E5 are turned on, and the lower arm elements E2 and E4. The duty ratio of each pulse is controlled so that the fundamental wave component is substantially sinusoidal in a certain period, and is composed of a set of pulses composed of a low level period in which E6 is in the ON state. In the present embodiment, the PWM control includes two control methods of normal PWM control and overmodulation PWM control.

  The normal PWM control is PWM control in which the AC voltage waveforms Vu, Vv, and Vw are less than or equal to the amplitude of the carrier waveform. As such normal PWM control, sine wave PWM control is typical, but in this embodiment, a space vector PWM (applying a neutral point bias voltage to the fundamental wave of each phase of sine wave PWM control. Space Vector PWM (hereinafter referred to as “SVPWM”) control is used. In the SVPWM control, the PWM waveform is directly generated by digital calculation without being compared with the carrier, but even in this case, the AC voltage waveforms Vu, Vv, and Vw are less than the amplitude of the virtual carrier waveform. In the present invention, such a method of generating a PWM waveform without using a carrier is also included in normal PWM control or overmodulation PWM control in comparison with the amplitude of a virtual carrier waveform. Assuming that the ratio of the effective value of the fundamental wave component of the output voltage waveform of the inverter 6 to the DC voltage Vdc is the modulation factor M (see formula (4) described later), in the SVPWM control as the normal PWM control, the modulation factor M is “0”. It can be changed in the range of “˜0.71”.

  The overmodulation PWM control is PWM control in which the amplitude of the AC voltage waveforms Vu, Vv, and Vw exceeds the amplitude of the carrier waveform. In the overmodulation PWM control, the waveform of the fundamental wave component of the output voltage waveform of the inverter 6 is distorted by making the duty ratio of each pulse large on the peak side of the fundamental wave component and smaller on the valley side than in the normal PWM control, Control is performed so that the amplitude is larger than that of the normal PWM control. As such overmodulation PWM control, for example, each of the switching elements E1 to E6 is turned on and off M times per cycle of the electric angle of the motor 4 (M is an integer of 2 or more), and the electric angle for each phase. There is M pulse control (for example, 3-pulse control or 5-pulse control) in which M pulses are output per half cycle. The M pulse control is a control in which M pulses are output per electrical angle half cycle, and the width of each pulse is predetermined according to the phase of the electrical angle. At this time, the output voltage waveforms of the respective phases are outputted with a phase shift of 120 °. In the overmodulation PWM control, the modulation factor M can be changed in the range of “0.71 to 0.78”.

  In the rectangular wave control, the switching elements E1 to E6 are turned on and off once per electrical angle cycle of the motor 4, and one pulse is output per electrical angle half cycle for each phase. That is, the output voltage waveform of the inverter 6 of each phase of U, V, and W appears alternately in the high level period and the low level period once per cycle, and these high level period and low level period Is controlled so as to be a rectangular wave of 1: 1. At this time, the output voltage waveforms of the respective phases are outputted with a phase shift of 120 °. Thus, the rectangular wave control causes the inverter 6 to output a rectangular wave voltage. In the rectangular wave control, the modulation factor M is fixed at “0.78” which is the maximum modulation factor Mmax. That is, when the modulation factor M reaches the maximum modulation factor Mmax, rectangular wave control is executed. For this reason, in the present embodiment, the rectangular wave switching threshold value Mb that is the threshold value of the modulation factor M for executing the rectangular wave control is set to the maximum modulation factor Mmax.

  As described above, the field control in the present embodiment includes normal field control, strong field control, and weak field control. As will be described later, the current command determination unit 7 determines current command values Idb and Iqb, which are command values of the current supplied from the inverter 6 to the motor 4 based on the target torque TM of the motor 4. The field control is control for appropriately adjusting the field magnetic flux of the electric motor 4 by determining the field adjustment command value so as to appropriately adjust the current command values Idb and Iqb thus determined. Specifically, the current command determination unit 7 determines a basic d-axis current command value Idb and a basic q-axis current command value Iqb as current command values based on the target torque TM. Here, in the current vector control method, the d-axis is set in the field magnetic flux direction, and the q-axis is set in a direction advanced by π / 2 in electrical angle with respect to the field direction. Therefore, the field magnetic flux of the electric motor 4 can be adjusted by appropriately determining the d-axis current adjustment command value ΔId for adjusting the basic d-axis current command value Idb as the field adjustment command value.

  As will be described later, the current command determination unit 7 determines current command values (basic d-axis current command value Idb and basic q-axis current command value Iqb) so as to perform maximum torque control. Here, the maximum torque control is control for adjusting the current phase so that the output torque of the electric motor 4 becomes maximum with respect to the same current. In this maximum torque control, torque can be generated most efficiently with respect to the current flowing through the armature coil of the electric motor 4. The current phase is the q-axis of the combined vector of the d-axis current command value Id (including the basic d-axis current command value Idb) and the q-axis current command value Iq (including the basic q-axis current command value Iqb). Is the phase for. The normal field control is field control that does not adjust the current command values Idb and Iqb determined by the current command determination unit 7. That is, in the normal field control, the d-axis current adjustment command value ΔId is set to zero (ΔId = 0) so as not to adjust the basic d-axis current command value Idb. Therefore, in the present embodiment, the control device 2 performs the maximum torque control during the execution of the normal field control. In other words, the normal field control according to the present embodiment is maximum torque control.

  The strong field control is field control that adjusts the current command values Idb and Iqb so as to increase the field magnetic flux of the electric motor 4 as compared with the normal field control (maximum torque control). That is, the strong field control is a control that adjusts the current phase so that a magnetic flux in a direction that strengthens the field magnetic flux of the electric motor 4 is generated from the armature coil. Here, in the strong field control, the d-axis current adjustment command value ΔId is set so as to delay the current phase compared to the normal field control. Specifically, in the strong field control, the d-axis current adjustment command value ΔId is set to a positive value (ΔId> 0) so as to change (increase) the basic d-axis current command value Idb in the positive direction.

  The field weakening control is field control that adjusts the current command values Idb and Iqb so as to weaken the field magnetic flux of the electric motor 4 as compared with the normal field control (maximum torque control). That is, the field weakening control is a control for adjusting the current phase so that the magnetic flux in the direction of weakening the field magnetic flux of the electric motor 4 is generated from the armature coil. Here, in the field weakening control, the d-axis current adjustment command value ΔId is set so that the current phase is advanced as compared with the normal field control. Specifically, in the field weakening control, the d-axis current adjustment command value ΔId is set to a negative value (ΔId <0) so as to change (decrease) the basic d-axis current command value Idb in the negative direction.

  FIG. 3 is a diagram showing an example of a control mode map that defines areas in which each control mode is executed in the operable area of the electric motor 4 defined by the rotational speed ω and the target torque TM. As shown in this figure, in the present embodiment, the control device 2 includes a normal field / PWM control mode A1 that executes PWM control together with normal field control, and a strong field / PWM control mode that executes PWM control together with strong field control. A2, a strong field / rectangular wave control mode A3 that executes rectangular wave control together with strong field control, and a field weakening / rectangular wave control mode A5 that executes rectangular wave control together with weak field control are configured to be executable. Further, when the control device 2 shifts to the weak field / rectangular wave control mode A5 without going through the strong field / PWM control mode A2 and the strong field / rectangular wave control mode A3, the normal field / Between the PWM control mode A1 and the field weakening / rectangular wave control mode A5, a field weakening / PWM control mode A4 that executes PWM control together with field weakening control is configured to be executable. A region F shown in the map of FIG. 3 is a strong field control region in which characteristic control in the present invention is performed. In this strong field control region F, the strong field / PWM control mode A2 is first executed, and then the strong field. Strong field transfer control for shifting to the magnetic / rectangular wave control mode A3 is performed.

  Further, as described above, in the present embodiment, two voltage waveform controls of normal PWM control and overmodulation PWM control are executed as PWM control. Therefore, the normal field / PWM control mode A1 includes a normal field / normal PWM control mode A1a that executes normal PWM control together with normal field control, and a normal field / overmodulation PWM control that executes overmodulation PWM control together with normal field control. Mode A1b. The strong field / PWM control mode A2 includes the strong field / normal PWM control mode A2a for executing normal PWM control together with the strong field control, and the strong field / overmodulation PWM control for executing overmodulation PWM control together with the strong field control. Mode A2b. Further, here, the field weakening / PWM modulation mode A4 is a field weakening / overmodulation PWM control mode A4a in which the overmodulation PWM control is executed together with the field weakening control.

  In the example of the control mode map shown in FIG. 3, the curves L1 to L4 all depend on the rotational speed ω and the target torque TM of the electric motor 4 when the modulation factor M becomes a certain value during normal field control (maximum torque control). It is a fixed line. A curve L1 is a line at which the modulation factor M during normal field control becomes the maximum modulation factor Mmax (= 0.78). A curve L2 is a line in which the modulation factor M during the normal field control becomes the overmodulation switching modulation factor Mo (= 0.71) set to the boundary value between the normal PWM control and the overmodulation PWM control. A curve L3 indicates a strong field start modulation factor Ms (for example, Ms = 0.64) in which the modulation factor M during normal field control is set to a value lower than the overmodulation switching modulation factor Mo (= 0.71). Is a line. The strong field start modulation factor Ms is determined by setting both a command modulation factor initial value MTs and a strong field threshold value ΔMs, which will be described later. A curve L4 is a line in which the modulation factor M during the normal field control becomes a value (for example, 0.76) set between the overmodulation switching modulation factor Mo and the maximum modulation factor Mmax.

  Incidentally, the induced voltage of the electric motor 4 increases as the rotational speed ω increases, and the AC voltage (hereinafter referred to as “necessary voltage”) required to drive the electric motor 4 also increases. When the necessary voltage exceeds the maximum AC voltage that can be output from the inverter 6 by converting the DC voltage Vdc at that time (hereinafter referred to as “maximum output voltage”), a necessary current flows through the coil. As a result, the electric motor 4 cannot be appropriately controlled. Therefore, the field weakening / rectangular wave control mode A5 is executed in the region on the higher rotation side than the curve L1 where the modulation factor M representing the required voltage of the motor 4 with respect to the maximum output voltage based on the DC voltage Vdc reaches the maximum modulation factor Mmax. Is done. The necessary voltage and the maximum output voltage can be compared with each other as the effective value of the AC voltage.

  Further, in the present embodiment, when a predetermined condition is satisfied even when the modulation factor M is lower than the maximum modulation factor Mmax, the strong field / rectangular wave control mode A3 for executing the rectangular wave control together with the strong field control is executed. To do. At this time, the current command values Id and Iq after the adjustment based on the d-axis current adjustment command value ΔId suddenly change, thereby causing overshoot of the current flowing in the coil and vibration of the torque generated by the motor 4. In order to suppress this, strong field transfer control is executed in which the strong field / rectangular wave control mode A3 is shifted to the strong field / PWM control mode A2. If the normal field control is performed, the strong field control is executed to perform the rectangular wave control while causing the electric motor 4 to output a torque corresponding to the target torque TM in a state where the modulation factor M is lower than the maximum modulation factor Mmax.

  As shown in FIG. 3, the strong field control region F is set within the strong field allowable torque range TMR defined for the target torque TM. In other words, the strong field control region F is within the strong field allowable torque range TMR, and the modulation rate M during the normal field control is from the strong field start modulation rate Ms to the maximum modulation rate Mmax (Ms ≦ M <Mmax). ) Is set. When the operating point determined by the rotational speed ω and the target torque TM of the electric motor 4 enters the region F from the region of the normal field / PWM control mode A1, the control device 2 uses the method described later to After the PWM control mode A2 is executed for a predetermined time, the strong field transfer control for shifting to the strong field / rectangular wave control mode A3 is performed. If the rotational speed ω and the target torque TM of the electric motor 4 remain within this region F even after the transition to the strong field / rectangular wave control mode A3, the execution state of the strong field / rectangular wave control mode A3 Will continue. By setting such a strong field control region F, rectangular wave control in the operable region of the electric motor 4 is executed as compared with the conventional case of having only the weak field / rectangular wave control mode A5. The area to be expanded is enlarged. In FIG. 3, a broken line that divides the strong field control region F is a region in which the strong field / PWM control mode A2 is executed when the rotation speed ω or the target torque TM of the motor 4 changes at a predetermined change speed. 2 shows an example of a boundary where the strong field / rectangular wave control mode A3 is switched. The position of this boundary differs depending on the rotational speed ω or the change speed of the target torque TM. Therefore, as the control mode map, the entire strong field control region F performs the strong field transfer control in which the strong field / PWM control mode A2 is executed for a predetermined time and then the strong field / rectangular wave control mode A3 is entered. It is set as an area.

  In the strong field control region F, at least the strong field / overmodulation PWM control mode A2b is executed as the strong field / PWM control mode A2. Further, as the strong field / PWM control mode A2, as the modulation factor M increases, after the strong field / normal PWM control mode A2a is executed, the strong field / overmodulation PWM control mode A2b is executed. Is also suitable. Here, as the strong field / PWM control mode A2, only the strong field / overmodulation PWM control mode A2b is executed, or the strong field / normal PWM control mode A2a and the strong field / overmodulation PWM control mode A2b Whether to execute both of these in order depends on the setting of a command modulation rate initial value MTs described later. That is, when the command modulation factor initial value MTs is set to a value equal to or greater than the overmodulation switching modulation factor Mo (= 0.71), basically only the strong field / overmodulation PWM control mode A2b is executed. The In this case as well, the strong field / normal PWM control mode A2a may be executed for a very short time until the modulation factor M reaches the overmodulation switching modulation factor Mo. Execution of the control mode for a very short time is not considered to be actively executed, and is considered to be excluded. On the other hand, when the command modulation factor initial value MTs is set to a value less than the overmodulation switching modulation factor Mo (= 0.71), the command modulation factor initial value MTs becomes stronger as the command modulation factor MT increases at a predetermined change speed. After the field / normal PWM control mode A2a is executed, the strong field / overmodulation PWM control mode A2b is executed. In the present embodiment, the command modulation rate initial value MTs is set to a value equal to or greater than the overmodulation switching modulation rate Mo (= 0.71). Therefore, basically only the strong field / overmodulation PWM control mode A2b is executed. This will be described as an example.

  The normal field / normal PWM control mode A1a is executed in a region on the lower rotation side than the curve L2 except in the strong field allowable torque range TMR, and in a region on the lower rotation side than the curve L3 in the strong field allowable torque range TMR. . In addition, outside the strong field allowable torque range TMR, the normal field / overmodulation PWM control mode A1b is executed in a region on the higher rotation side than the curve L2 and on the lower rotation side than the curve L4. Further, except for the strong field allowable torque range TMR, the field weakening / overmodulation PWM control mode A4a (field weakening / PWM control mode A4) is higher in the region higher than the curve L4 and lower than the curve L1. Is executed. In the weak field / overmodulation PWM control mode A4a, the normal field / overmodulation PWM control mode A1b is suddenly shifted to the state in which the field weakening control and the rectangular wave control are performed, thereby adjusting by the d-axis current adjustment command value ΔId. This is executed to prevent the subsequent current command values Id and Iq from changing rapidly. Thereby, it is possible to suppress the occurrence of overshoot of the current flowing in the coil and vibration of the torque generated by the electric motor 4.

Next, functions of the control device 2 will be described based on a functional block diagram of the control device 2 shown in FIG. As shown in FIG. 2, the target torque TM is input to the d-axis current command value deriving unit 21. The d-axis current command value deriving unit 21 derives a basic d-axis current command value Idb based on the input target torque TM. Here, the basic d-axis current command value Idb corresponds to a command value for the d-axis current when maximum torque control is performed. In the present embodiment, the d-axis current command value deriving unit 21 derives a basic d-axis current command value Idb corresponding to the value of the target torque TM using the basic d-axis current command value map shown in FIG. In the illustrated example, when a value of “TM1” is input as the target torque TM, the d-axis current command value deriving unit 21 derives “Id1” as the basic d-axis current command value Idb accordingly. To do. Similarly, when the values “TM3” and “TM5” are input as the target torque TM, the d-axis current command value deriving unit 21 sets “Id3” and “Id5” as the basic d-axis current command value Idb. Derived respectively. The basic d-axis current command value Idb derived in this way is input to the adder 23. The adder 23 is further supplied with a d-axis current adjustment command value ΔId derived by an integrator 32 described later. The adder 23 adds the d-axis current adjustment command value ΔId to the basic d-axis current command value Idb and derives the adjusted d-axis current command value Id as shown in the following formula (1).
Id = Idb + ΔId (1)

  The target torque TM and the d-axis current adjustment command value ΔId are input to the q-axis current command value deriving unit 22. The q-axis current command value deriving unit 22 derives the q-axis current command value Iq based on the input target torque TM and the d-axis current adjustment command value ΔId. In the present embodiment, the q-axis current command value deriving unit 22 uses the q-axis current command value map shown in FIG. 5 to determine the q-axis current command value according to the target torque TM and the d-axis current adjustment command value ΔId. Iq is derived. In FIG. 5, the thin solid line is an equal torque line 61 indicating the values of the d-axis current and the q-axis current for outputting the torques TM1 to TM5, and the thick solid line is the d-axis current for performing maximum torque control. And a maximum torque control line 62 indicating the value of the q-axis current. In FIG. 5, a thick one-dot chain line is a voltage limiting ellipse 63 that indicates a range of values that can be taken by the d-axis current and the q-axis current that are limited by the rotational speed ω of the electric motor 4 and the DC voltage Vdc. The diameter of the voltage limiting ellipse 63 is inversely proportional to the rotational speed ω of the electric motor 4 and proportional to the DC voltage Vdc. When the d-axis current command value Id and the q-axis current command value Iq take values on the voltage limit ellipse 63, the modulation factor M becomes the maximum modulation factor Mmax (= 0.78). At this time, the control device 2 causes the voltage waveform control unit 10 to perform rectangular wave control.

  Further, a strong field control region F shown by hatching in FIG. 5 indicates a region where the strong field / PWM control mode A2 and the strong field / rectangular wave control mode A3 are executed. The upper limit of the strong field control region F is defined by the point where the maximum torque control line 62 intersects the voltage limit ellipse 63. Further, the lower limit of the strong field control region F is defined by the magnitude of the positive d-axis current adjustment command value ΔId, and here, for shifting from the maximum torque control line 62 shown in FIG. It is defined as a region where the d-axis current adjustment command value ΔId is less than a predetermined end threshold value ΔIds. In other words, the strong field control region F is defined as a region where the d-axis current adjustment command value ΔId is greater than zero and less than the end threshold value ΔIds (0 <ΔId <ΔIds). Here, the end threshold value ΔIds is a threshold value of the d-axis current adjustment command value ΔId for ending the strong field control, and the efficiency improvement accompanying the reduction of the switching loss by the rectangular wave control is the increase of the strong field current. It is preferable to set it within a range that exceeds the efficiency drop due to (increase in the degree of strong field).

  In the illustrated example, when a value of “TM1” is input as the target torque TM, the q-axis current command value deriving unit 22 determines whether the equal torque line 61 and the maximum torque control line 62 of the target torque TM = TM1. “Iq1” that is the value of the q-axis current at the intersection is derived as the basic q-axis current command value Iqb. In this case, both the weak field control and the strong field control are not performed, and the d-axis current adjustment command value ΔId input from the integrator 32 described later is zero (ΔId = 0). Therefore, the q-axis current command value Iq is the same value as the basic q-axis current command value Iqb. At this time, the control device 2 executes the normal field / PWM control mode A1.

  When a value of “TM3” is input as the target torque TM, the q-axis current command value deriving unit 22 determines the q at the intersection of the equal torque line 61 and the maximum torque control line 62 of the target torque TM = TM3. The value of the axis current “Iq3” is derived as the basic q-axis current command value Iqb. Here, the basic q-axis current command value corresponds to the command value of the d-axis current when maximum torque control is performed. At this time, since the basic d-axis current command value Idb and the basic q-axis current command value Iqb are within the strong field control region F, the strong field control is performed. In this case, a positive value as the d-axis current adjustment command value ΔId, here “ΔId1” (ΔId1> 0), is input from the integrator 32 described later. Therefore, the q-axis current command value deriving unit 22 is the value of the q-axis current on the voltage limiting ellipse 63 moved by “ΔId1” in the positive direction of the d-axis along the equal torque line 61 of the target torque TM = TM3. “Iq4” is derived as the q-axis current command value Iq. However, as will be described later, the mode control unit 5 causes the command modulation rate setting unit 33 to change the command modulation rate from the command modulation rate initial value MTs to the rectangular wave switching threshold value Mb set to the maximum modulation rate Mmax. The command modulation rate MT is increased at the speed. Thereby, since the changing speed of the d-axis current adjustment command value ΔId is restricted, the changing speed when the q-axis current command value Iq also changes from “Iq3” to “Iq4” is restricted.

  When a value of “TM5” is input as the target torque TM, the q-axis current command value deriving unit 22 determines the q at the intersection of the equal torque line 61 and the maximum torque control line 62 of the target torque TM = TM5. The value of the axis current “Iq5” is derived as the basic q-axis current command value Iqb. At this time, since the basic d-axis current command value Idb and the basic q-axis current command value Iqb are outside the voltage limit ellipse 63, field weakening control is performed. In this case, a negative value as the d-axis current adjustment command value ΔId, here, “−ΔId2” (−ΔId2 <0) is input from the integrator 32 described later. Therefore, the q-axis current command value deriving unit 22 is the value of the q-axis current on the voltage limiting ellipse 63 moved by “−ΔId2” in the negative direction of the d-axis along the equal torque line 61 of the target torque TM = TM5. A certain “Iq6” is derived as the q-axis current command value Iq. At this time, the control device 2 executes the field weakening / rectangular wave control mode A5.

  The d-axis current values (Id1, Id3, Id5) corresponding to the basic q-axis current command values Iqb (Iq1, Iq3, Iq5) obtained from the q-axis current command value map of FIG. 5 are the basic values shown in FIG. This coincides with the basic d-axis current command value Idb obtained using the d-axis current command value map. Therefore, the basic d-axis current command value Idb can be obtained from the map shown in FIG. In the present embodiment, a d-axis current command value deriving unit 21 and a q-axis current command value deriving unit 22 that determine the basic d-axis current command value Idb and the basic q-axis current command value Iqb based on the target torque TM of the electric motor 4. However, this constitutes the current command determination unit 7 in the present invention. The basic d-axis current command value Idb and the basic q-axis current command value Iqb are current command values in the present invention, which are command values for the current supplied from the inverter 6 to the motor 4.

  The d-axis current command value Id and the q-axis current command value Iq derived as described above are input to the current control unit 24. Further, the current control unit 24 receives the actual d-axis current Idr and the actual q-axis current Iqr from the three-phase to two-phase conversion unit 27, and receives the rotation speed ω of the electric motor 4 from the rotation speed deriving unit 28. The actual d-axis current Idr and the actual q-axis current Iqr are obtained by the U-phase current Iur, the V-phase current Ivr, the W-phase current Iwr detected by the current sensor 42 (see FIG. 1), and the rotation sensor 43 (see FIG. 1). Based on the detected magnetic pole position θ, the three-phase to two-phase conversion unit 27 performs three-phase to two-phase conversion and is derived. The rotational speed ω of the electric motor 4 is derived by the rotational speed deriving unit 28 based on the magnetic pole position θ detected by the rotation sensor 43 (see FIG. 1).

  The current control unit 24 includes a d-axis current deviation δId that is a deviation between the d-axis current command value Id and the actual d-axis current Idr, and a q-axis current that is a deviation between the q-axis current command value Iq and the actual q-axis current Iqr. The deviation δIq is derived. The current control unit 24 performs a proportional-integral control calculation (PI control calculation) based on the d-axis current deviation δId to derive a d-axis voltage drop Vzd that is a d-axis component of the voltage drop, and a q-axis current deviation. A proportional-integral control calculation is performed based on δIq to derive a q-axis voltage drop Vzq that is a q-axis component of the voltage drop. Note that it is also preferable to perform a proportional integral derivative control calculation (PID control calculation) instead of these proportional integral control calculations.

Then, the current control unit 24 derives the d-axis voltage command value Vd by subtracting the q-axis armature reaction Eq from the d-axis voltage drop Vzd as shown in the following equation (2).
Vd = Vzd-Eq
= Vzd-ω · Lq · Iqr (2)
As shown in this equation (2), the q-axis armature reaction Eq is derived based on the rotational speed ω of the electric motor 4, the actual q-axis current Iqr, and the q-axis inductance Lq.

Further, the current control unit 24 adds the induced voltage Em caused by the d-axis armature reaction Ed and the armature interlinkage flux of the permanent magnet to the q-axis voltage drop Vzq, as shown in the following formula (3). A voltage command value Vq is derived.
Vq = Vzq + Ed + Em
= Vzq + ω · Ld · Idr + ω · Mif (3)
As shown in this equation (3), the d-axis armature reaction Ed is derived based on the rotational speed ω of the electric motor 4, the actual d-axis current Idr, and the d-axis inductance Ld. The induced voltage Em is derived based on the induced voltage constant MIf determined by the effective value of the armature linkage flux of the permanent magnet and the rotational speed ω of the motor 4.

  In the present embodiment, the d-axis voltage command value Vd and the q-axis voltage command value Vq are set as voltage command values that are command values of voltages supplied from the inverter 6 to the electric motor 4. The basic d-axis current command value Idb and the basic q-axis current command value Iqb determined by the d-axis current command value deriving unit 21 and the q-axis current command value deriving unit 22 are the adder 23 and the q-axis current command value derivation. The unit 22 sets the d-axis current command value Id and the q-axis current command value Iq after adjustment by the d-axis current adjustment command value ΔId. The voltage command values Vd and Vq are determined based on the adjusted d-axis current command value Id and q-axis current command value Iq and the rotational speed ω of the electric motor 4. Therefore, the adder 23, the q-axis current command value deriving unit 22, and the current control unit 24 use the voltage based on the rotation speed ω, the current command values Idb and Iqb, and the d-axis current adjustment command value ΔId of the motor 4. A voltage command determining unit 9 is configured to determine the command values Vd and Vq.

The modulation factor deriving unit 29 receives the d-axis voltage command value Vd and the q-axis voltage command value Vq derived by the current control unit 24. Further, the value of the DC voltage Vdc detected by the voltage sensor 41 is input to the modulation factor deriving unit 29. The modulation rate deriving unit 29 derives the modulation rate M based on these values according to the following equation (4).
M = √ (Vd ² + Vq ² ) / Vdc (4)
In the present embodiment, the modulation factor M is the ratio of the effective value of the fundamental wave component of the output voltage waveform of the inverter 6 to the DC voltage Vdc. Here, the effective value of the three-phase line voltage is the value of the DC voltage Vdc. Derived as a divided value. In the present embodiment, the modulation factor M corresponds to a voltage index representing the magnitudes of the voltage command values Vd and Vq with respect to the DC voltage Vdc at that time. As described above, the maximum value of the modulation factor M (maximum modulation factor Mmax) is “0.78” corresponding to the modulation factor M when the rectangular wave control is executed.

The subtractor 30 receives the modulation factor M derived by the modulation factor deriving unit 29 and the command modulation factor MT set by the command modulation factor setting unit 33. The subtracter 30 derives a modulation factor deviation ΔM obtained by subtracting the command modulation factor MT from the modulation factor M as shown in the following equation (5).
ΔM = M−MT (5)
In the present embodiment, the modulation factor deviation ΔM represents the degree to which the voltage command values Vd and Vq exceed the maximum AC voltage value that can be output by the DC voltage Vdc at that time. Therefore, the modulation factor deviation ΔM substantially functions as a voltage shortage index that represents the degree of shortage of the DC voltage Vdc. A method of setting the command modulation rate MT by the command modulation rate setting unit 33 will be described later.

  A modulation factor deviation ΔM derived by the subtracter 30 is input to the integral input adjustment unit 31. The integral input adjustment unit 31 performs a predetermined adjustment on the value of the modulation factor deviation ΔM, and outputs an adjustment value Y that is the adjusted value to the integrator 32. FIG. 6 is a diagram showing an example of a conversion map used by the integral input adjustment unit 31. As shown in FIG. As shown in this figure, in this embodiment, the integral input adjusting unit 31 is in a state where the modulation factor deviation ΔM is equal to or greater than a predetermined strong field threshold value ΔMs (ΔMs <0) and less than zero (ΔMs ≦ ΔM <0). ) Outputs a positive adjustment value Y (Y> 0), and outputs a negative adjustment value Y (Y <0) when the modulation factor deviation ΔM is greater than zero (0 <ΔM). Zero (Y = 0) is output as the adjustment value Y when the state is less than the strong field threshold value ΔMs (ΔM <ΔMs) and when the modulation factor deviation ΔM is zero (ΔM = 0). More specifically, the integral input adjustment unit 31 increases the modulation factor deviation ΔM when the modulation factor deviation ΔM is greater than the strong field threshold value ΔMs and less than the intermediate threshold value ΔMsm (ΔMs ≦ ΔM <ΔMsm). The adjustment value Y that increases as the output is output. In this range, the relationship between the modulation factor deviation ΔM and the adjustment value Y can be expressed by a linear function. Thus, by setting the conversion map region in which the adjustment value Y increases as the modulation factor deviation ΔM increases, it is possible to suppress the d-axis current adjustment command value ΔId from rapidly increasing immediately after the strong field control is started. Therefore, it is possible to suppress the current command values Id and Iq after the adjustment based on the d-axis current adjustment command value ΔId from suddenly changing and overshooting the current flowing in the coil or the vibration of the torque generated by the motor 4. .

  Further, the integral input adjustment unit 31 outputs an adjustment value Y that decreases as the modulation factor deviation ΔM increases in a state where the modulation factor deviation ΔM is equal to or greater than the intermediate threshold value ΔMsm (ΔMsm ≦ ΔM). In this range, the adjustment value Y is proportional to the modulation factor deviation ΔM, and the proportionality constant is a negative value. Here, the strong field threshold value ΔMs is a threshold value of the modulation factor deviation ΔM for starting the strong field control, and is set to a value less than zero. This strong field threshold value ΔMs has a strong field start modulation factor Ms determined in combination with the command modulation factor initial value MTs, which increases the efficiency accompanying reduction of switching loss by rectangular wave control and increases the field current ( It is preferable to set so as to exceed the efficiency drop due to the fact that the strength field is large. The intermediate threshold value ΔMsm is set to a value greater than the strong field threshold value ΔMs and less than zero. For example, the strong field threshold value ΔMs can be set to “−0.07”, and the intermediate threshold value ΔMsm can be set to “−0.03”. This strong field threshold value ΔMs, together with the command modulation factor initial value MTs, constitutes a start condition for the strong field control.

  The adjustment value Y derived by the integral input adjustment unit 31 is input to the integrator 32. The integrator 32 integrates the adjustment value Y using a predetermined gain, and derives the integration value as a d-axis current adjustment command value ΔId. In the present embodiment, this d-axis current adjustment command value ΔId corresponds to a field adjustment command value for adjusting the field magnetic flux of the electric motor 4. The d-axis current adjustment command value ΔId is determined by the modulation factor deriving unit 29, the command modulation factor setting unit 33, the subtractor 30, the integral input adjusting unit 31, and the integrator 32. Therefore, in the present embodiment, the field adjustment unit 8 is configured by the modulation rate deriving unit 29, the command modulation rate setting unit 33, the subtracter 30, the integral input adjustment unit 31, and the integrator 32. Then, normal field control (maximum torque control), strong field control, and weak field control are selectively executed in accordance with the d-axis current adjustment command value ΔId. Here, when the d-axis current adjustment command value ΔId is zero (ΔId = 0), normal field control (maximum torque control) is performed. When the d-axis current adjustment command value ΔId takes a positive value (ΔId> 0), the current command values Idb and Iqb are adjusted so as to increase the field magnetic flux of the electric motor 4. That is, when a strong field current that is a positive d-axis current adjustment command value ΔId flows, the field flux of the electric motor 4 is strengthened compared to the normal field control, and the strong field control is performed. When the d-axis current adjustment command value ΔId takes a negative value (ΔId <0), the current command values Idb and Iqb are adjusted so as to weaken the field magnetic flux of the motor 4. That is, when a field weakening current that is a negative d-axis current adjustment command value ΔId flows, the field magnetic flux of the electric motor 4 is weakened compared to the normal field control, and the field weakening control is performed.

  As described above, when the modulation factor deviation ΔM is greater than the strong field threshold value ΔMs and less than zero (ΔMs ≦ ΔM <0), a positive value (Y> 0) is output as the adjustment value Y. The d-axis current adjustment command value ΔId derived by the controller 32 increases (changes in the positive direction), and the d-axis current adjustment command value ΔId changes in the direction of increasing the field magnetic flux of the motor 4. In the state where the modulation factor deviation ΔM is greater than zero (0 <ΔM), a negative value (Y <0) is output as the adjustment value Y. Therefore, the d-axis current adjustment command value ΔId derived by the integrator 32 is output. Decreases (changes in the negative direction), and the d-axis current adjustment command value ΔId changes in the direction of weakening the field magnetic flux of the electric motor 4. When the modulation factor deviation ΔM is less than the strong field threshold value ΔMs (ΔM <ΔMs) and the modulation factor deviation ΔM is zero (ΔM = 0), zero (Y = 0) is output as the adjustment value Y. The d-axis current adjustment command value ΔId derived by the integrator 32 is not changed, and the d-axis current adjustment command value ΔId is determined so as not to change the field magnetic flux of the electric motor 4.

  As described above, in the normal field control according to the present embodiment, the maximum torque control is performed to adjust the current phase so that the output torque of the motor 4 is maximized with respect to the same current. Therefore, as the d-axis current adjustment command value ΔId changes from the reference value (ΔId = 0) of the d-axis current adjustment command value ΔId for executing the normal field control in the direction in which the field magnetic flux of the motor 4 is increased, the same torque The adjusted current command values Id and Iq required for outputting the voltage increase, and the voltage command values Vd and Vq and the modulation factor M derived based on the current command values Id and Iq increase. In other words, the voltage command determination unit 9 increases the voltage command values Vd and Vq as the d-axis current adjustment command value ΔId increases (changes in the positive direction) from the reference value (ΔId = 0). The modulation factor deriving unit 29 increases the modulation factor M as the d-axis current adjustment command value ΔId increases from the reference value (ΔId = 0) (changes in the positive direction).

  The command modulation rate setting unit 33 sets a command modulation rate MT that is a command value of the modulation rate M. In this embodiment, the command modulation rate MT is a variable value, and the command modulation rate setting unit 33 outputs the command modulation rate MT that changes with time T according to the command modulation rate map to the subtractor 30. FIG. 7 is a diagram showing an example of the command modulation rate map. As shown in this figure, the command modulation rate setting unit 33 performs command modulation at a predetermined change rate from the command modulation rate initial value MTs, which is the initial value of the command modulation rate MT, until the rectangular wave switching threshold value Mb is reached. Increase rate MT. Here, the command modulation factor initial value MTs is set by the mode control unit 5 in accordance with the rotational speed ω of the electric motor 4 and the target torque TM. At this time, it is set to be larger than the modulation rate M at the rotational speed ω and the target torque TM when the normal field control is executed. That is, the command modulation factor initial value MTs is the modulation factor M derived by the modulation factor deriving unit 29 according to the rotational speed ω and the target torque TM when the field magnetic flux is not adjusted by the d-axis current adjustment command value ΔId. Set to a larger value. In other words, the command modulation rate initial value MTs is determined based on the rotational speed ω and the target torque when it is assumed that the normal field control (maximum torque control) is performed without performing the strong field control in the entire region where the normal field control can be performed. It is set to a value larger than the modulation factor M in TM. FIG. 7 illustrates a plurality of values (MTs1 to MTs4) of the command modulation factor initial value MTs that change in this way. The command modulation factor initial value MTs may be set so as to change stepwise according to the rotational speed ω and the target torque TM as shown, or continuously changed according to the rotational speed ω and the target torque TM. It may be set to do. Thus, by variably setting the command modulation factor initial value MTs, when the operating point defined by the rotational speed ω and the target torque TM of the motor 4 enters the strong field control region F from any region shown in FIG. In addition, it is possible to secure time until the modulation factor M reaches the rectangular wave switching threshold value Mb. Therefore, the strong field transfer control can be appropriately performed regardless of the operating point of the electric motor 4 before entering the strong field control region F. Therefore, for example, even when the operating point of the electric motor 4 enters the strong field control region F from a state where the operating point is in the normal field / overmodulation PWM control mode A1b, the strong field transfer control can be appropriately performed. On the other hand, the rectangular wave switching threshold Mb is set to the maximum modulation rate Mmax (= 0.78) as described above.

  Then, the command modulation rate setting unit 33 changes the command modulation rate so as to gradually increase (increase) with the passage of time T from the command modulation rate initial value MTs set as described above until the rectangular wave switching threshold value Mb is reached. The modulation rate MT is output. Here, the change rate of the command modulation rate MT is constant. Further, in the present embodiment, the command modulation factor setting unit 33 is changing the time until the command modulation factor MT reaches the rectangular wave switching threshold value Mb from the command modulation factor initial value MTs, that is, the command modulation factor MT is changing. The change rate of the command modulation rate MT is set so that the time (hereinafter referred to as “command modulation rate change time ΔT”) is constant regardless of the command modulation rate initial value MTs. As a result, different command modulation rate MT changing speeds are set in accordance with the command modulation rate initial value MTs. However, for each command modulation rate initial value MTs, the command modulation rate MT change rate is determined by the command modulation rate. It is set constant over the entire area of the rate change time ΔT. This command modulation rate change time ΔT is preferably set according to the response characteristics of the electric motor 4. As the response characteristics of the motor 4 used here, it is preferable to use the electrical time constant of the motor 4. This command modulation rate change time ΔT executes the strong field / PWM control mode A2 in the strong field transfer control when shifting from the normal field / PWM control mode A1 to the strong field / rectangular wave control mode A3. Corresponds to time. That is, as the command modulation rate change time ΔT becomes longer, the time during which the strong field / PWM control mode A2 is executed becomes longer before the strong field / rectangular wave control mode A3 is entered. The command modulation factor setting unit 33 increases the command modulation factor MT to the rectangular wave switching threshold value Mb, and then waits until the mode control unit 5 ends the strong field control or the weak field control and returns to the normal field control. The modulation rate MT is maintained in a state where it matches the rectangular wave switching threshold value Mb.

  The timing at which the command modulation rate setting unit 33 starts to change the command modulation rate MT is determined by the mode control unit 5. That is, the mode control unit 5 sets the command modulation rate initial value MTs according to the rotational speed ω of the electric motor 4 and the target torque TM, and the command modulation rate initial value MTs and the modulation rate derived by the modulation rate deriving unit 29. Based on the relationship with M, the command modulation factor setting unit 33 starts to increase the command modulation factor MT. In the present embodiment, the mode control unit 5 causes the command modulation rate setting unit 33 to start increasing the command modulation rate MT when the modulation rate M matches the command modulation rate initial value MTs. Note that, based on the relationship between the command modulation rate initial value MTs and the modulation rate M, for example, when the difference between the command modulation rate initial value MTs and the modulation rate M is equal to or less than a predetermined threshold value, the command modulation rate MT It is also suitable as a configuration for starting the increase of the.

  As described above, the command modulation rate initial value MTs is set to be larger than the modulation rate M when the field magnetic flux is not adjusted by the d-axis current adjustment command value ΔId. Then, by gradually increasing the command modulation rate MT at a constant change rate from when the modulation rate M matches the command modulation rate initial value MTs, the modulation rate M after the start of the strong field control also gradually increases at a constant change rate. Can be made. That is, in a situation where the modulation factor M gradually increases as the rotational speed ω and the target torque TM of the electric motor 4 gradually increase, when the modulation factor deviation ΔM is greater than the field threshold value ΔMs, the d-axis The current adjustment command value ΔId increases (changes in the positive direction) to execute the strong field control. By this strong field control, the d-axis current adjustment command value ΔId increases until the modulation factor M coincides with the command modulation factor MT. Therefore, the modulation factor M changes following the command modulation factor MT and finally becomes a rectangular wave. It coincides with the switching threshold value Mb. Since the command modulation rate MT becomes a control target for the modulation rate M in this way, the modulation rate M can be changed in the same manner by changing the command modulation rate MT at a constant change rate. In an ideal state where the basic d-axis current command value Idb (current command value) and the basic q-axis current command value Iqb do not vary, the modulation factor M changes at the same rate of change as the command modulation factor MT. Therefore, in the present embodiment, the command modulation rate setting unit 33 and the mode control unit 5 that controls the command modulation rate setting unit 33 configure the change rate regulation unit 11 that regulates the change rate of the modulation rate M to be equal to or lower than a predetermined regulation rate. Has been. At this time, since the d-axis current adjustment command value ΔId is derived as an integral value of the adjustment value Y of the modulation factor deviation ΔM, the d-axis current is gradually increased by increasing the command modulation factor MT at a constant change rate. The adjustment command value ΔId also changes at a predetermined change speed.

  As described above, by regulating the rate of change of the modulation factor M when the modulation factor M increases, the time until the modulation factor M reaches the rectangular wave switching threshold Mb (maximum modulation factor Mmax) is constant. Time can be secured. In this embodiment, it is possible to secure at least a time equal to or longer than the command modulation rate change time ΔT until the modulation rate M reaches the rectangular wave switching threshold value Mb. The control device 2 executes the strong field / PWM control mode A2 during the time until the modulation factor M reaches the rectangular wave switching threshold value Mb. Thereafter, when the modulation factor M reaches the rectangular wave switching threshold value Mb, the strong field / rectangular wave control mode A3 is executed. As a result, it is possible to suppress abrupt changes in the current command values Id and Iq after adjustment by the d-axis current adjustment command value ΔId, and to suppress overshoot of the current flowing in the coil of the motor and vibration of the torque generated by the motor. be able to.

  The mode control unit 5 determines a control mode to be executed from among a plurality of control modes based on the operation state of the electric motor 4 including the rotation speed ω and the target torque TM, and each unit of the control device 2 according to the control mode. Control the operating state. Here, as shown in FIG. 2, the rotational speed ω, the target torque TM, the modulation factor M, and the d-axis current adjustment command value ΔId are input to the mode control unit 5, and based on these, the mode control unit 5 Control action is performed. In the present embodiment, the mode control unit 5 determines the control mode according to the control mode map shown in FIG. Therefore, the mode controller 5 excludes the strong field control region F, and the normal field / normal PWM control mode A1a, the normal field / overmodulation PWM control mode is increased as the rotational speed ω and the target torque TM of the motor 4 are increased. The control mode is shifted in the order of A1b, field weakening / overmodulation PWM control mode A4a, field weakening / rectangular wave control mode A5. As described above, the boundaries (curves L1, L2, L4) between these control modes are set at positions where the modulation factor M is constant during normal field control (maximum torque control). In this, the curve L1 is set at a position where the modulation factor M during the normal field control becomes the maximum modulation factor Mmax (= 0.78), and the normal field control should be performed based on the rotational speed ω and the target torque TM. In the state where the derived modulation factor M exceeds the maximum modulation factor Mmax, the control device 2 executes the field weakening / rectangular wave control mode A5.

It is assumed that the strong field control region F is within the strong field allowable torque range TMR defined for the target torque TM, and the normal field control is performed without performing the strong field control in the entire region where the normal field control can be performed. In this case, the modulation factor M is set in a region (Ms ≦ M <Mmax) from the strong field start modulation factor Ms (curve L3) to the maximum modulation factor Mmax (curve L1). Here, the strong field start modulation factor Ms is determined by setting both the command modulation factor initial value MTs and the strong field threshold value ΔMs. That is, in a situation where the modulation factor M gradually increases and approaches the command modulation factor MT, the integral input adjustment unit 31 increases the modulation factor deviation ΔM to a field threshold value ΔMs (ΔMs <0) or more and less than zero as described above. In this state (ΔMs ≦ ΔM <0), a positive adjustment value Y (Y> 0) is output. The modulation factor deviation ΔM is obtained by subtracting the command modulation factor MT from the modulation factor M, as shown in the above equation (5). Therefore, the strong field start modulation factor Ms, which is the value of the modulation factor M when starting the strong field control, is obtained by adding the strong field threshold value ΔMs to the command modulation factor MT as shown in the following equation (6). Is required.
Ms = MTs + ΔMs (6)
Therefore, for example, when the command modulation factor initial value MTs is set to “0.71” and the strong field threshold value ΔMs is set to “−0.07”, the strong field start modulation factor Ms is “0. 64 ". In the example shown in FIG. 3, the strong field start modulation rate Ms is the overmodulation switching modulation rate set to the boundary value between the normal field / normal PWM control mode A1a and the normal field / overmodulation PWM control mode A1b. Since it is set smaller than Mo (= 0.71), within the strong field allowable torque range TMR, the mode controller 5 starts the strong field control in the strong field control region F from the normal field / normal PWM control mode A1a. To do.

  Further, the mode control unit 5 causes the voltage waveform control unit 10 to execute rectangular wave control when the modulation factor M is equal to or higher than the rectangular wave switching threshold Mb (maximum modulation factor Mmax), and the modulation factor M switches the rectangular wave. In the state below the threshold value Mb, the voltage waveform control unit 10 is caused to execute PWM control. Furthermore, in the present embodiment, the PWM control includes two types of normal PWM control and overmodulation PWM control. Therefore, the mode control unit 5 is in a state where the modulation factor M is less than the rectangular wave switching threshold Mb, In a state where the modulation switching modulation rate Mo is equal to or less than Mo (= 0.71), the voltage waveform control unit 10 executes normal PWM control, and in a state where the modulation factor is larger than the overmodulation switching modulation rate Mo (= 0.71), the voltage waveform control unit 10 Overmodulation PWM control is executed. Here, the voltage waveform controller 10 includes a three-phase / two-phase converter 25 and a control signal generator 26. The operations of the three-phase / two-phase converter 25 and the control signal generator 26 will be described later.

  When the operating point of the motor 4 determined by the rotational speed ω and the target torque TM enters the strong field control region F, the integral input is performed by setting the command modulation factor initial value MTs and the strong field threshold value ΔMs as described above. The adjustment unit 31 outputs a positive adjustment value Y, and the integrator 32 outputs a positive d-axis current adjustment command value ΔId. Thereby, the strong field control is started. Here, the strong field start modulation rate Ms (curve L3) that defines the strong field control region F is determined by the command modulation rate initial value MTs and the strong field threshold value ΔMs. The mode control unit 5 controls the start of the strong field control by variably setting the command modulation rate initial value MTs among them according to the rotational speed ω of the electric motor 4 and the target torque TM. Further, the mode control unit 5 causes the command modulation rate setting unit 33 to start increasing the command modulation rate MT based on the relationship between the command modulation rate initial value MTs and the modulation rate M. In the present embodiment, the mode control unit 5 causes the command modulation rate setting unit 33 to start increasing the command modulation rate MT when the modulation rate M matches the command modulation rate initial value MTs.

  The command modulation rate setting unit 33 receives the command modulation rate MT increase start command from the mode control unit 5 and then reaches the rectangular wave switching threshold value Mb (maximum modulation rate Mmax) from the command modulation rate initial value MTs. The command modulation rate MT is increased at a predetermined change speed. Thereby, the rate of change (rising speed) of the modulation factor M is regulated, and a predetermined time is secured until the modulation factor M reaches the rectangular wave switching threshold value Mb. The mode control unit 5 causes the voltage waveform control unit 10 to perform PWM control until the modulation factor M reaches the rectangular wave switching threshold value Mb. In this embodiment, since the command modulation rate initial value MTs is set to a value equal to or greater than the overmodulation switching modulation rate Mo (= 0.71), the mode control unit 5 basically increases the overload in the strong field control region F. Modulation PWM control is executed. That is, the mode control unit 5 executes the strong field / overmodulation PWM control mode A2b until the modulation rate M reaches the rectangular wave switching threshold value Mb. Thereafter, the command modulation factor setting unit 33 gradually increases the command modulation factor MT, so that the modulation factor M also gradually increases and finally reaches the rectangular wave switching threshold value Mb. When the modulation factor M is equal to or greater than the rectangular wave switching threshold value Mb, the mode control unit 5 causes the voltage waveform control unit 10 to execute rectangular wave control. Thereby, the strong field / rectangular wave control mode A3 is executed.

  As described above, the mode control unit 5 shifts from the normal field / PWM control mode A1 to the strong field / rectangular wave control mode A3 by regulating the rate of change of the modulation factor M after the start of the strong field control. In the meantime, the strong field / PWM control mode A2 is executed to execute the strong field transfer control.

  As described above, the command modulation rate MT is maintained in a state that matches the rectangular wave switching threshold value Mb after rising to the rectangular wave switching threshold value Mb (maximum modulation rate Mmax). Therefore, the modulation factor M during the strong field control finally converges to the maximum modulation factor Mmax (= 0.78). From this state, when the modulation factor M changes as the target torque TM or the rotational speed ω of the electric motor 4 changes, the modulation factor deviation ΔM also changes according to the change of the modulation factor M, and the field The d-axis current adjustment command value ΔId is appropriately changed in the direction of increasing or decreasing the magnetic flux. As a result, the d-axis current adjustment command value ΔId appropriately changes from a positive value at which the strong field control is performed to a negative value at which the weak field control is performed. In the state where the d-axis current adjustment command value ΔId is a negative value, field weakening control is executed. Regardless of whether the strong field control or the weak field control is performed, the modulation factor M converges to the rectangular wave switching threshold value Mb set as the command modulation factor MT, and the mode control unit 5 sends a rectangular wave to the voltage waveform control unit 10. The state for executing the control is maintained.

  Here, since the field weakening control is executed in a state where the DC voltage Vdc is insufficient with respect to the voltage command values Vd and Vq, a negative d-axis current adjustment command value ΔId (value of field weakening current) is set. Must be executed regardless of size. However, the strong field control executed to forcibly perform the rectangular wave control in a state where the DC voltage Vdc is sufficient with respect to the voltage command values Vd and Vq is a positive d-axis current adjustment command value ΔId (strong field magnet). It is desirable that the efficiency decrease due to the increase in the current) be completed before the efficiency improvement associated with the reduction of the switching loss by the rectangular wave control exceeds the normal field control (maximum torque control) and the PWM control. However, as described above, since the modulation factor deviation ΔM is fixed to zero (modulation factor M = 0.78) during the strong field control, once the strong field control is entered, the target torque TM and the rotational speed ω of the electric motor 4 are reduced. Even if the d-axis current adjustment command value ΔId increases in the positive direction, the normal field / PWM control mode A1 cannot be restored. Therefore, in the present embodiment, the mode control unit 5 is configured to execute the strong field end control for forcibly ending the strong field control. In this embodiment, the strong field end control is used to control the strong field control outside the strong field allowable torque range TMR.

That is, the mode control unit 5 determines the strong field end condition, which is a condition for ending the strong field control, based on the target torque TM and the d-axis current adjustment command value ΔId, and when the strong field end condition is satisfied Then, the d-axis current adjustment command value ΔId is determined so as to end the strong field control. Specifically, the mode control unit 5 performs control to set the d-axis current adjustment command value ΔId to zero when the strong field termination condition is satisfied. In the present embodiment, the strong field end condition satisfies one of the following two conditions (a) and (b).
(A) d-axis current adjustment command value ΔId ≧ end threshold value ΔIds (b) target torque TM is outside strong field allowable torque range TMR Here, strong field allowable torque range TMR is, for example, When rectangular wave control is performed in which harmonic components other than the fundamental wave component of the alternating current flowing through the motor 4 are likely to be large, near the upper limit value of the target torque TM so that the current flowing through the motor 4 does not exceed the limit value. Is the upper limit of the range. The lower limit of the strong field allowable torque range TMR is preferably set so as to exclude a torque range that is not suitable for performing rectangular wave control because the output torque is too small.

  When the strong field termination condition is satisfied, the mode control unit 5 outputs a command for setting the d-axis current adjustment command value ΔId to zero to the integrator 32, and the d-axis current adjustment command output by the integrator 32. The value ΔId is set to zero. At this time, the mode control unit 5 controls the d-axis current adjustment command value ΔId so that the d-axis current adjustment command value ΔId changes to zero at a constant change rate. As a result, it is possible to suppress abrupt changes in the current command values Id and Iq after adjustment by the d-axis current adjustment command value ΔId, and to suppress overshoot of the current flowing in the coil of the motor and vibration of the torque generated by the motor. be able to. Then, by setting the d-axis current adjustment command value ΔId to zero, the modulation factor M becomes less than the rectangular wave switching threshold value Mb (maximum modulation factor Mmax). Accordingly, the strong field / rectangular wave control mode A3 is terminated and the normal field / PWM control mode A1 is executed. The mode control unit 5 stops the control for forcibly terminating the strong field control when both of the strong field termination conditions (a) and (b) are not satisfied. Thereby, the control in which the integrator 32 integrates the adjustment value Y to derive the d-axis current adjustment command value ΔId is resumed.

  The voltage waveform control unit 10 controls the inverter 6 based on the voltage command values Vd and Vq, and selectively executes PWM control and rectangular wave control, respectively. As described above, the voltage waveform controller 10 includes the three-phase / two-phase converter 25 and the control signal generator 26. The d-axis voltage command value Vd and the q-axis voltage command value Vq are input to the two-phase / three-phase conversion unit 25. Also, the magnetic pole position θ detected by the rotation sensor 43 (see FIG. 1) is input to the two-phase / three-phase converter 25. The two-phase / three-phase conversion unit 25 performs two-phase / three-phase conversion on the d-axis voltage command value Vd and the q-axis voltage command value Vq using the magnetic pole position θ to obtain a three-phase AC voltage command value, that is, a U-phase. A voltage command value Vu, a V-phase voltage command value Vv, and a W-phase voltage command value Vw are derived. However, since the waveforms of these AC voltage command values Vu, Vv, and Vw are different for each control mode, the two-phase / three-phase conversion unit 25 has AC voltage command values Vu, Vv, and Vw having different voltage waveforms for each control mode. Is output to the control signal generator 26. Specifically, when the two-phase / three-phase conversion unit 25 receives a normal PWM control execution command from the mode control unit 5, the AC voltage command values Vu and Vv of the AC voltage waveform according to the normal PWM control. , Vw is output. Here, since the normal PWM control is SVPWM control, AC voltage command values Vu, Vv, and Vw are output according to the AC voltage waveform for the SVPWM control. In addition, when the two-phase / three-phase conversion unit 25 receives an overmodulation PWM control execution command from the mode control unit 5, the AC voltage command values Vu, Vv, Vw is output. In addition, when the two-phase / three-phase conversion unit 25 receives a rectangular wave control execution command from the mode control unit 5, the two-phase / three-phase conversion unit 25 converts the AC voltage command values Vu, Vv, and Vw of the AC voltage waveform according to the rectangular wave control. Output. Here, the AC voltage command values Vu, Vv, and Vw when executing the rectangular wave control can be set as command values for the on / off switching phases of the switching elements E1 to E6 of the inverter 6. This command value corresponds to the on / off control signal of each of the switching elements E1 to E6, and is a command value that represents the phase of the magnetic pole position θ that represents the timing for switching on or off of each of the switching elements E1 to E6.

  The control signal generator 26 receives the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw generated by the three-phase / two-phase converter 25. The control signal generator 26 generates switching control signals S1 to S6 for controlling the switching elements E1 to E6 of the inverter 6 shown in FIG. 1 according to the AC voltage command values Vu, Vv, and Vw. The inverter 6 performs on / off operations of the switching elements E1 to E6 according to the switching control signals S1 to S6. Thereby, PWM control (normal PWM control or overmodulation PWM control) or rectangular wave control of the electric motor 4 is performed.

1-3. Operation of Control Device Next, the operation of each part of the control device 2 will be described in detail with reference to FIGS. FIG. 7 is a flowchart showing the flow of operation of each part of the control device 2 according to the present embodiment.

  As shown in FIG. 8, the control device 2 first derives the modulation factor M by the modulation factor deriving unit 29 (step # 01). Next, the mode control unit 5 determines whether or not the d-axis current adjustment command value ΔId is zero (step # 02). When the d-axis current adjustment command value ΔId is zero (step # 02: Yes), the mode control unit 5 determines that the normal field control is being performed. In this case, the control device 2 uses the mode control unit 5 to set the command modulation rate initial value MTs according to the rotational speed ω of the motor 4 and the target torque TM (step # 03). Thereafter, it is determined whether the modulation factor M derived by the modulation factor deriving unit 29 is equal to or greater than the command modulation factor initial value MTs (step # 04). Here, the command modulation rate initial value MTs is larger than the modulation rate M at each rotational speed ω and target torque TM when normal field control (maximum torque control) is performed in the entire region where normal field control can be performed. Set to a large value. Therefore, during the execution of the normal field control, the modulation factor M is less than the command modulation factor initial value MTs (step # 04: No). In this state, the command modulation rate setting unit 33 sets the command modulation rate initial value MTs as the command modulation rate MT (step # 05).

  On the other hand, if the modulation rate deviation ΔM is greater than the field threshold value ΔMs by increasing the rotational speed ω and the target torque TM and increasing the modulation rate M during execution of the normal field control, a positive value is obtained. The d-axis current adjustment command value ΔId is determined, and the strong field control is executed. As a result, the modulation factor M further increases and reaches the command modulation factor initial value MTs. When the modulation factor M becomes equal to or greater than the command modulation factor initial value MTs (step # 04: Yes), the command modulation factor setting unit 33 reaches the rectangular wave switching threshold value Mb from the command modulation factor initial value MTs. The command modulation rate MT is gradually increased until a predetermined change rate (step # 06). In this case, in the subsequent steps, a command modulation rate MT that gradually increases with the passage of time T is used. Therefore, in the state where the strong field control is executed and the modulation factor M increases, the increase in the modulation factor M is regulated according to the change rate of the command modulation factor MT. Therefore, a state where the strong field control is being executed and the modulation factor M does not reach the rectangular wave switching threshold value Mb (maximum modulation factor Mmax) is ensured for a certain period of time, and the strong field / PWM control mode A2 is executed during that time. The

  Further, after the strong field control is started as described above, the d-axis current adjustment command value ΔId becomes a positive value (ΔId> 0), and the d-axis current adjustment command value ΔId is not zero (step # 02: No) Next, the mode control unit 5 determines whether or not the command modulation rate MT increasing at a predetermined change speed as described above has reached the rectangular wave switching threshold value Mb (maximum modulation rate Mmax). (Step # 07). If the command modulation rate MT has not yet reached the rectangular wave switching threshold value Mb (maximum modulation rate Mmax) (step # 07: No), the process proceeds to step # 06, and the command modulation rate MT is changed by a predetermined change. Increase further at speed. When the command modulation rate MT reaches the rectangular wave switching threshold value Mb (maximum modulation rate Mmax) (step # 07: Yes), in the subsequent steps, the rectangular wave switching threshold is set as the command modulation rate MT. The value Mb is used. Therefore, until the d-axis current adjustment command value ΔId is set to zero and returned to the normal field control in step # 15 described later, control such that the modulation factor M becomes the rectangular wave switching threshold value Mb is maintained. Control is executed.

  After the command modulation rate MT is determined as described above, the subtractor 30 derives a modulation rate deviation ΔM (= M−MT) obtained by subtracting the command modulation rate MT from the modulation rate M (step # 08). Thereafter, the control device 2 determines whether or not the d-axis current adjustment command value ΔId is greater than zero (ΔId> 0) (step # 09). This determination is to determine whether or not the control device 2 is performing strong field control at that time. When the d-axis current adjustment command value ΔId is equal to or less than zero (ΔId ≦ 0) (step # 09: No), it can be determined that the control device 2 is in normal field control or field weakening control. Therefore, it is next determined whether or not the modulation factor deviation ΔM is less than zero (ΔM <0) (step # 10). This determination is to determine whether or not the modulation factor M is less than the command modulation factor MT. If the modulation factor deviation ΔM is equal to or greater than zero (ΔM ≧ 0) (step # 10: No), the process proceeds to step # 12, and is output from the integral input adjustment unit 31 based on the modulation factor deviation ΔM. The adjustment value Y below zero (see FIG. 6) is integrated by the integrator 32 to derive a d-axis current adjustment command value ΔId (step # 12). As a result, the d-axis current adjustment command value ΔId changes in the negative direction, that is, in the direction in which the field magnetic flux of the electric motor 4 is weakened. At this time, the field weakening control is started if the normal field control is being performed, and the degree of the field weakening is increased if the field weakening control is being performed.

  If the modulation factor deviation ΔM is less than zero (ΔM <0) (step # 10: Yes), then, whether the modulation factor deviation ΔM is greater than or equal to the strong field threshold value ΔMs (ΔM ≧ ΔMs). Is determined (step # 11). If the modulation factor deviation ΔM is less than the strong field threshold value ΔMs (ΔM <ΔMs) (step # 11: No), the integral input adjustment unit 31 outputs zero as the adjustment value Y (see FIG. 6). ). Therefore, the adjustment value Y is not integrated by the integrator 32, and the process proceeds to step # 16. Therefore, the d-axis current adjustment command value ΔId does not change. At this time, if the normal field control is being performed, the normal field control is continued, and if the weak field control is being performed, the weak field control is continued. When the modulation factor deviation ΔM is equal to or greater than the strong field threshold value ΔMs (ΔM ≧ ΔMs) (step # 11: Yes), the integral input adjustment unit 31 outputs a positive value as the adjustment value Y (FIG. 6). Therefore, the integrator 32 integrates the positive adjustment value Y to derive the d-axis current adjustment command value ΔId (step # 12). As a result, the d-axis current adjustment command value ΔId changes in the positive direction, that is, the direction in which the field magnetic flux of the electric motor 4 is strengthened. At this time, if the normal field control is being performed, the strong field control is started, and if the weak field control is being performed, the degree of the weak field is reduced or the process proceeds to the strong field control.

  On the other hand, when the d-axis current adjustment command value ΔId is larger than zero (ΔId> 0) (step # 09: Yes), it can be determined that the control device 2 is in the strong field control. Then, next, the strong field end condition is determined by the mode control unit 5. Specifically, whether or not the d-axis current adjustment command value ΔId is equal to or greater than the end threshold value ΔIds (ΔId ≧ ΔIds) (step # 13), and whether the target torque TM is outside the strong field allowable torque range TMR. (Step # 14). When either of these conditions is satisfied (step # 13: Yes or step # 14: Yes), the d-axis current adjustment command value ΔId is set at a constant change rate by the mode control unit 5 in order to end the strong field control. Zero (step # 15). Thereby, the strong field control is terminated and the normal field control is executed. If none of the above conditions is satisfied (step # 13: No and step # 14: No), the strong field control is continued, and the process proceeds to step # 12. Accordingly, the adjustment value Y output from the integral input adjustment unit 31 according to the modulation factor deviation ΔM is integrated by the integrator 32 to derive the d-axis current adjustment command value ΔId (step # 12). Thereby, even during the strong field control, the d-axis current adjustment command value ΔId is appropriately adjusted according to the modulation factor deviation ΔM. At this time, the d-axis current adjustment command value ΔId may change in the negative direction and shift from the strong field control to the weak field control.

  Thereafter, the basic d-axis current command value Idb derived by the d-axis current command value deriving unit 21 and the d-axis current adjustment command value ΔId derived by the integrator 32 are added to derive the d-axis current command value Id. (Step # 16). Further, the q-axis current command value deriving unit 22 derives the q-axis current command value Iq (step # 17). Based on the d-axis current command value Id and the q-axis current command value Iq, the voltage control values Vd and Vq are derived by the current control unit 24 (step # 18). The process ends here.

  Next, a specific example of the operation of the control device 2 according to the flowchart shown in FIG. 8 will be described with reference to FIGS. FIG. 9 shows a state in which the operating point of the electric motor 4 is changed sequentially from the point t0 to the point t6 shown in FIG. FIG. 6 is a diagram showing an example of changes in current command values Id and Iq after adjustment based on target torque TM, rotation speed ω, and d-axis current adjustment command value ΔId. Specifically, FIG. 9A shows a change in the target torque TM along the time axis T, FIG. 9B shows a change in the rotational speed ω, and FIG. 9C shows a d-axis current command at that time. Changes in the value Id and the q-axis current command value Iq are shown.

  In this example, at time t0 to t1, the rotational speed ω is increased from zero to ω1 with the target torque TM being zero. At this time, the d-axis current command value Id and the q-axis current command value Iq remain zero. From time t1 to t2, the target torque TM is increased from zero to TM6 with the rotational speed ω kept constant at ω1. At this time, the d-axis current command value Id decreases to Id8 in proportion to the target torque TM, and the q-axis current command value Iq increases to Iq8 in proportion to the target torque TM. From time t2 to t6, the rotational speed ω is increased from ω1 to ω2 while the target torque TM is kept constant at TM6. At this time, the d-axis current command value Id and the q-axis current command value Iq are kept constant at time points t2 to t3 until the operating point of the electric motor 4 enters the strong field control region F. At time points t0 to t3, the normal field / PWM control mode A1 (normal field / normal PWM control mode A1a) is executed. At time points t3 to t4 after the operating point of the motor 4 enters the strong field control region F, the strong field control is executed by increasing the d-axis current adjustment command value ΔId, and the d-axis current command value Id is from Id8 to Id9. The q-axis current command value Iq increases from Iq8 to Iq9. At this time, as described above, the rate of increase of the d-axis current adjustment command value ΔId is restricted by restricting the change speed of the command modulation rate MT to a constant speed. The increasing speed of the d-axis current command value Id and the q-axis current command value Iq is also restricted and increases so as to draw a gentle curve. As a result, the rate of change (rising speed) of the modulation factor M is regulated, and a time until the modulation factor M reaches the rectangular wave switching threshold value Mb is secured. The magnetism / PWM control mode A2 is executed.

  Thereafter, since the diameter of the voltage limit ellipse 63 shown in FIG. 5 is reduced by increasing the rotational speed ω from time t4 to t5, the d-axis current command value set on the voltage limit ellipse 63 during the rectangular wave control. Both Id and q-axis current command value Iq decrease. Specifically, the d-axis current command value Id decreases from Id9 to Id8, and the q-axis current command value Iq decreases from Iq9 to Iq8. At this time, the d-axis current adjustment command value ΔId also decreases. From time t4 to t5, the strong field / rectangular wave control mode A3 is executed. At time t5, the d-axis current adjustment command value ΔId becomes zero, and the strong field control ends. At time points t5 to t6 after exiting the strong field control region F, the d-axis current adjustment command value ΔId is further decreased to become a negative value, whereby field-weakening control is executed. The d-axis current command value Id is changed from Id8 to Id7. Q-axis current command value Iq decreases from Iq8 to Iq7. From time t6 to t7, since both the rotational speed ω and the target torque TM are maintained constant, both the d-axis current command value Id and the q-axis current command value Iq do not change.

  From time t7 to t11, the rotational speed ω is decreased from ω2 to ω1 with the target torque TM being constant at TM6. At this time, at time points t7 to t8 until the operating point of the electric motor 4 enters the strong field control region F, the d-axis current adjustment command value ΔId gradually increases while the field weakening control is executed, and the d-axis current command value Id is increased from Id7. The q-axis current command value Iq increases from Iq7 to Iq8. At time t8, the d-axis current adjustment command value ΔId becomes zero and field weakening control ends. At time points t5 to t8, field weakening / PWM control mode A4 is executed. At the time t8 to t9 after the operating point of the electric motor 4 enters the strong field control region F, the diameter of the voltage limiting ellipse 63 shown in FIG. Both the d-axis current command value Id and the q-axis current command value Iq set on the limit ellipse 63 increase. Specifically, the d-axis current command value Id increases from Id8 to Id9, and the q-axis current command value Iq increases from Iq8 to Iq9. At this time, the d-axis current adjustment command value ΔId also increases. From time t8 to t9, the strong field / rectangular wave control mode A3 is executed. In this example, the d-axis current adjustment command value ΔId reaches the end threshold value ΔIds at time t9, and thereafter, the d-axis current adjustment command value ΔId is zero at a constant change rate (decrease rate) until time t10. To. As a result, the d-axis current command value Id decreases from Id9 to Id8, and the q-axis current command value Iq decreases from Iq9 to Iq8. As described above, since the rate of decrease of the d-axis current adjustment command value ΔId is regulated, the rate of decrease of the d-axis current command value Id and the q-axis current command value Iq after adjustment by the d-axis current adjustment command value ΔId is also regulated. It increases to draw a gentle curve. As a result, the rate of change (lowering rate) of the modulation factor M is regulated, and a predetermined time is ensured until the modulation factor M reaches the strong field start modulation factor Ms (curve L3 in FIG. 3). The strong field / PWM control mode A2 is executed at (time points t9 to t10).

  At time points t10 to t11 after the operating point of the electric motor 4 comes out of the strong field control region F, the d-axis current command value Id and the q-axis current command value Iq are kept constant. From time t11 to t12, the target torque TM is decreased from TM6 to zero with the rotation speed ω kept constant at ω1. At this time, the d-axis current command value Id increases from Id8 to zero in proportion to the target torque TM, and the q-axis current command value Iq decreases from Iq8 to zero in proportion to the target torque TM. From time t12 to t13, the rotational speed ω is decreased from ω1 to zero while the target torque TM is zero. At this time, the d-axis current command value Id and the q-axis current command value Iq remain zero. At time points t10 to t3, the normal field / PWM control mode A1 (normal field / normal PWM control mode A1a) is executed.

2. Second Embodiment Next, a second embodiment of the present invention will be described. FIG. 10 is a functional block diagram of the control device 2 according to the present embodiment. The control device 2 is different from the first embodiment in the configuration of the change speed regulation unit 11 and the parts related thereto. That is, the control device 2 according to the first embodiment regulates the change rate of the modulation factor M by changing the command modulation factor MT at a predetermined change rate by the command modulation factor setting unit 33, The time for executing the PWM control mode A2 is secured. On the other hand, the control device 2 according to the present embodiment regulates the change rate of the modulation factor M by regulating the change rate of the d-axis current adjustment command value ΔId when starting the strong field control. -It is the structure which ensures the time which performs PWM control mode A2. Therefore, the control device 2 according to the present embodiment includes a target d-axis current adjustment command determination unit (hereinafter referred to as a “target ΔId determination unit”) 35 and a d-axis current adjustment command value change rate limiting unit as the change speed regulation unit 11. (Hereinafter referred to as “ΔId change rate limiting unit”) 36. Below, the control apparatus 2 which concerns on this embodiment is demonstrated centering around difference with said 1st embodiment. Note that points not particularly described are the same as those in the first embodiment.

2-1. Configuration of Control Device First, functions of the control device 2 different from the first embodiment will be described based on a functional block diagram of the control device 2 shown in FIG. In the present embodiment, “0.78”, which is the value of the modulation factor M and the maximum modulation factor Mmax, is input to the subtracter 30. The subtracter 30 is a modulation factor deviation obtained by subtracting a fixed modulation value Mmax (rectangular wave switching threshold Mb) value “0.78” from the modulation factor M, as shown in the following equation (7). ΔM is derived.
ΔM = M−0.78 (7)
In the present embodiment, the modulation factor deviation ΔM represents the degree to which the voltage command values Vd and Vq exceed the maximum AC voltage value that can be output by the DC voltage Vdc at that time. Therefore, the modulation factor deviation ΔM substantially functions as a voltage shortage index that represents the degree of shortage of the DC voltage Vdc.

  A modulation factor deviation ΔM derived by the subtracter 30 is input to the integral input adjustment unit 31. The integral input adjustment unit 31 performs a predetermined adjustment on the value of the modulation factor deviation ΔM, and outputs an adjustment value Y that is the adjusted value to the integrator 32. Also in the present embodiment, as in the first embodiment, the integral input adjustment unit 31 is in a state where the modulation factor deviation ΔM is equal to or greater than a predetermined strong field threshold value ΔMs (ΔMs <0) and less than zero (ΔMs ≦ A positive adjustment value Y (Y> 0) is output when ΔM <0), and a negative adjustment value Y (Y <0) is output when the modulation factor deviation ΔM is greater than zero (0 <ΔM). When the deviation ΔM is less than the strong field threshold value ΔMs (ΔM <ΔMs) and the modulation factor deviation ΔM is zero (ΔM = 0), zero (Y = 0) is output as the adjustment value Y. However, in the present embodiment, the conversion map used by the integral input adjustment unit 31 is different from that in the first embodiment. As shown in FIG. 10, in this conversion map, the adjustment value Y is zero when the modulation factor deviation ΔM is less than the strong field threshold value ΔMs, and the modulation factor is obtained when the modulation factor deviation ΔM is greater than or equal to the strong field threshold value ΔMs. A value obtained by inverting the sign of the deviation ΔM is set as the adjustment value Y. Accordingly, when the input modulation factor deviation ΔM is equal to or greater than the predetermined strong field threshold value ΔMs, the integral input adjustment unit 31 outputs a value obtained by inverting the sign of the modulation factor deviation ΔM as the adjustment value Y. To do. On the other hand, the integral input adjustment unit 31 outputs zero (Y = 0) as the adjustment value Y when the input modulation factor deviation ΔM is less than the strong field threshold value ΔMs. As in the first embodiment, the strong field threshold value ΔMs is a threshold value of the modulation factor deviation ΔM for starting the strong field control, and is a value less than zero (for example, “−0.07”). Is set. It is also preferable that the integral input adjustment unit 31 outputs a value obtained by multiplying the modulation factor deviation ΔM by a predetermined constant (gain) as the adjustment value Y.

  Similarly to the first embodiment, the integrator 32 integrates the adjustment value Y derived by the integral input adjustment unit 31 using a predetermined gain, and derives the integration value as a d-axis current adjustment command value ΔId. To do. In the present embodiment, the field adjustment unit 8 is configured by the modulation factor deriving unit 29, the subtracter 30, the integral input adjusting unit 31, and the integrator 32.

The target ΔId determination unit 35 determines a target d-axis current adjustment command value ΔIdt that is a d-axis current adjustment command value ΔId so that the modulation factor M becomes the rectangular wave switching threshold value Mb. The target ΔId determination unit 35 corresponds to the target field adjustment command value determination unit in the present invention. The target ΔId determination unit 35 receives the rotational speed ω, the target torque TM, and the DC voltage Vdc. Based on these, the target ΔId determination unit 35 determines the target d-axis current adjustment command value ΔIdt. At this time, in this embodiment, the target ΔId determination unit 35 determines the target d-axis current adjustment command value ΔIdt using the target d-axis current adjustment command value map. FIG. 11 is a diagram showing an example of the target d-axis current adjustment command value map. As shown in this figure, the target d-axis current adjustment command value map is the same map as the q-axis current command value map (see FIG. 5) used by the q-axis current command value deriving unit 22. That is, in FIG. 11, the thin solid line is the equal torque line 61, the thick solid line is the maximum torque control line 62 for performing the maximum torque control, and the thick one-dot chain line is limited by the rotational speed ω and the DC voltage Vdc. A voltage limit ellipse 63 indicating a range of values that the d-axis current and the q-axis current can take. The diameter of the voltage limiting ellipse 63 is inversely proportional to the rotational speed ω of the electric motor 4 and proportional to the DC voltage Vdc. FIG. 11 exemplifies voltage limit ellipses 63 in which the rotational speed ω and the DC voltage Vdc are a set of ω1 and Vdc1, a set of ω2 and Vdc2, and a set of ω3 and Vdc3. In this example, the relationship of the following formula (8) is established.
(Vdc1 / ω1) <(Vdc2 / ω2) <(Vdc3 / ω3) (8)
When the d-axis current command value Id and the q-axis voltage command value Vq take values on the voltage limit ellipse 63 under the respective rotational speed ω and DC voltage Vdc conditions, the modulation factor M is a rectangular wave switching threshold value. Mb (maximum modulation factor Mmax). At this time, the control device 2 causes the voltage waveform control unit 10 to perform rectangular wave control.

  The target ΔId determination unit 35 first obtains a maximum torque control d-axis current command value IdM for performing maximum torque control based on the input target torque TM. This is the d-axis current command value Id at the intersection of the equal torque line 61 and the maximum torque control line 62 corresponding to the input target torque TM in the target d-axis current adjustment command value map. Next, the target ΔId determination unit 35 obtains a rectangular wave control d-axis current command value IdN that can output the input target torque TM and the modulation factor M becomes the rectangular wave switching threshold value Mb. This is because, in the target d-axis current adjustment command value map, the intersection d of the equal torque line 61 corresponding to the input target torque TM and the voltage limit ellipse 63 corresponding to the input rotational speed ω and DC voltage Vdc. It becomes the shaft current command value Id. Then, the difference between the d-axis current command value IdN during rectangular wave control and the d-axis current command value IdM during maximum torque control is determined as the target d-axis current adjustment command value ΔIdt. FIG. 11 shows an example in which “TM3” is input as the target torque TM, “ω2” is input as the rotational speed ω, and “Vdc2” is input as the DC voltage Vdc. In this case, the target ΔId determination unit 35 sets “Id11”, which is the d-axis current command value Id at the intersection of the equal torque line 61 and the maximum torque control line 62 of the target torque TM = TM3, to the d-axis current command during the maximum torque control. Obtained as the value IdM. Further, the target ΔId determination unit 35 is a “Id12” which is a d-axis current command value Id at the intersection of the equal torque line 61 of the target torque TM = TM3 and the voltage limiting ellipse 63 of the rotational speed ω = ω2 and the DC voltage Vdc = Vdc2. Is obtained as a d-axis current command value IdN during rectangular wave control. Then, a difference value obtained by subtracting the rectangular wave control d-axis current command value Id12 (IdN) from the maximum torque control d-axis current command value Id11 (IdM) is determined as the target d-axis current adjustment command value ΔIdt.

  The ΔId change rate limiting unit 36 determines a d-axis current adjustment command value ΔId that changes at a predetermined change rate until the target d-axis current adjustment command value ΔIdt is reached. The target d-axis current adjustment command value ΔIdt determined by the target ΔId determination unit 35 is input to the ΔId change rate limiting unit 36. The ΔId change rate limiting unit 36 changes the d-axis current adjustment command value ΔId so as to increase at a predetermined change rate from the predetermined initial value until the target d-axis current adjustment command value ΔIdt is reached. At this time, the ΔId change rate limiting unit 36 regulates the change rate of the d-axis current adjustment command value ΔId to be constant by keeping the change rate of the d-axis current adjustment command value ΔId constant. Here, the initial value is set to the value of the d-axis current adjustment command value ΔId when normal field control (maximum torque control) is performed, here zero. Accordingly, the ΔId change rate limiting unit 36 sets the d-axis current adjustment command value ΔId that changes so as to gradually increase (increase) as time passes from the initial value (zero) until the target d-axis current adjustment command value ΔIdt is reached. Output. At this time, the changing speed of the d-axis current adjustment command value ΔId is constant. In the present embodiment, the ΔId change rate limiting unit 36 corresponds to the field control unit for transition control in the present invention.

  The switching unit 37 includes any one of the d-axis current adjustment command value ΔId determined by the field adjustment unit 8 and the d-axis current adjustment command value ΔId determined by the ΔId change rate limiting unit 36 serving as a transition control field adjustment unit. Is used in the voltage command determination unit 9. The operation of the switching unit 37 is controlled by the mode control unit 5. When the d-axis current adjustment command value ΔId determined by the field adjustment unit 8 is used, the d-axis current adjustment command value ΔId derived by the integrator 32 is used as the q-axis current command value constituting the voltage command determination unit 9. The data is input to the derivation unit 22 and the adder 23. When the d-axis current adjustment command value ΔId determined by the ΔId change rate limiting unit 36 is used, the d-axis current adjustment command value ΔId is added to the q-axis current command value deriving unit 22 and the voltage command determining unit 9. Is input to the device 23.

  The function of the mode control unit 5 is basically the same as that of the first embodiment. However, in the present embodiment, the mode control unit 5 does not have a function related to the control of the command modulation rate setting unit 33, and instead causes the target ΔId determination unit 35 and the ΔId change rate limit unit 36 to function appropriately. It has the function to perform control for. First, the mode control unit 5 causes the target ΔId determination unit 35 to determine the target d-axis current adjustment command value ΔIdt when the modulation factor M becomes equal to or greater than the predetermined strong field start modulation factor Ms. In the present embodiment, the strong field start modulation factor Ms is determined according to the setting of the strong field threshold value ΔMs described above. By the way, the field adjustment unit 8 outputs a positive d-axis current adjustment command value ΔId when the modulation factor deviation ΔM is greater than or equal to the strong field threshold value ΔMs (ΔMs <0), and the strong field control is started. The The ΔId change rate limiting unit 36 as the transition control field adjusting unit outputs a d-axis current adjustment command value ΔId that changes at a constant change rate in accordance with the start of the strong field control by the field adjusting unit 8. . Therefore, the strong field start modulation rate Ms, which is the value of the modulation rate M when starting such strong field control, is set to the modulation rate M at which the modulation rate deviation ΔM becomes the strong field threshold value ΔMs. Specifically, the strong field start modulation factor Ms is obtained by adding the strong field threshold value ΔMs (ΔMs <0) to the rectangular wave switching threshold value Mb (maximum modulation factor Mmax). As described above, when the strong field threshold value ΔMs is set to “−0.07”, the strong field start modulation factor Ms is “0.71”.

  In addition, when the target d-axis current adjustment command value ΔIdt is determined by the target ΔId determination unit 35, the mode control unit 5 determines that the modulation factor M is a rectangular wave after the target d-axis current adjustment command value ΔIdt is determined. Until the switching threshold Mb (maximum modulation factor Mmax) is reached, the d-axis current adjustment command value determined by the ΔId change rate limiting unit 36 instead of the d-axis current adjustment command value ΔId determined by the field adjustment unit 8 ΔId is input to the voltage command determination unit 9. The mode control unit 5 performs such input switching of the d-axis current adjustment command value ΔId by controlling the switching unit 37. That is, the mode control unit 5 causes the target ΔId determination unit 35 to determine the target d-axis current adjustment command value ΔIdt when the modulation rate M becomes equal to or greater than the predetermined strong field start modulation rate Ms, and the switching unit 37 is Control is performed so that the d-axis current adjustment command value ΔId determined by the ΔId change rate limiting unit 36 is input to the voltage command determining unit 9. The mode control unit 5 controls the switching unit 37 when the modulation factor M reaches the rectangular wave switching threshold value Mb, and the d-axis current adjustment command value ΔId determined by the field adjusting unit 8 is the voltage. The state is input to the command determination unit 9. In the present embodiment, the mode control unit 5 directly monitors the modulation factor M, and detects that the modulation factor M has reached the rectangular wave switching threshold Mb (maximum modulation factor Mmax = 0.78). It has become. Naturally, it is also suitable as a configuration that monitors the modulation factor deviation ΔM and detects that the modulation factor M has become the rectangular wave switching threshold Mb when the modulation factor deviation ΔM becomes zero. As described above, since the rectangular wave control is started when the modulation factor M becomes the rectangular wave switching threshold value Mb (maximum modulation factor Mmax), the modulation factor M becomes the rectangular wave switching threshold value Mb (maximum modulation factor Mmax). The configuration for detecting that the rate Mmax) is equal to the configuration for detecting that the rectangular wave control is started. The mode control unit 5 determines the d-axis determined by the field adjustment unit 8 except for the period from when the target d-axis current adjustment command value ΔIdt is determined until the modulation factor M becomes the rectangular wave switching threshold value Mb. The switching unit 37 is controlled to use the current adjustment command value ΔId.

  As described above, in the present embodiment, the change rate of the modulation factor M is equal to or lower than a predetermined regulation rate by the target ΔId determination unit 35, the ΔId change rate limiting unit 36, the switching unit 37, and the mode control unit 5 that controls them. The change speed regulation unit 11 is configured to regulate so that

  According to the control device 2 according to the present embodiment, when the modulation rate M is equal to or greater than the predetermined strong field start modulation rate Ms and the strong field control is started, the rate of change of the d-axis current adjustment command value ΔId is regulated. This regulates the rate of change of the modulation factor M. Thereby, it is possible to secure a certain period of time until the modulation factor M reaches the rectangular wave switching threshold value Mb (maximum modulation factor Mmax). The control device 2 executes the strong field / PWM control mode A2 during the time until the modulation factor M reaches the rectangular wave switching threshold value Mb. Thereafter, when the modulation factor M reaches the rectangular wave switching threshold value Mb, the strong field / rectangular wave control mode A3 is executed. As a result, it is possible to suppress abrupt changes in the current command values Id and Iq after adjustment by the d-axis current adjustment command value ΔId, and to suppress overshoot of the current flowing in the coil of the motor and vibration of the torque generated by the motor. be able to.

2-2. Operation of Control Device Next, the operation of each part of the control device 2 will be described with reference to FIG. FIG. 12 is a flowchart showing an operation flow of each unit of the control device 2 according to the present embodiment. In FIG. 12, “(# 09 to # 15)” and “(# 16 to # 18)” are the same steps as the corresponding steps in FIG. 8 according to the first embodiment. Therefore, in FIG. 12, these steps are omitted.

  As shown in FIG. 12, the control device 2 first derives the modulation factor M by the modulation factor deriving unit 29 (step # 21). Next, the mode control unit 5 determines whether or not the modulation factor M is greater than or equal to the strong field start modulation factor Ms (step # 22). When the modulation factor M is less than the strong field start modulation factor Ms (step # 22: No), the strong field control is not started. Therefore, the process proceeds to step # 16 (see FIG. 8) without changing the d-axis current adjustment command value ΔId. At this time, the normal field / PWM control mode A1 is executed.

  On the other hand, when the modulation factor M is equal to or greater than the strong field start modulation factor Ms (step # 22: Yes), the mode control unit 5 sets the modulation factor M to the rectangular wave switching threshold Mb (maximum modulation factor Mmax). It is determined whether it is less than (step # 23). If the modulation factor M is less than the rectangular wave switching threshold Mb (step # 23: Yes), the target ΔId determination unit 35 determines the target d-axis current adjustment command value ΔIdt. As described above, the target d-axis current adjustment command value ΔIdt is the d-axis current adjustment command value ΔId at which the modulation factor M becomes the rectangular wave switching threshold value Mb. Thereafter, the d-axis current adjustment command value ΔId is determined by the ΔId change rate limiting unit 36 (step # 25). The d-axis current adjustment command value ΔId determined here is a value that changes at a predetermined change rate from the initial value (zero) until the target d-axis current adjustment command value ΔIdt determined in step # 25 is reached. . Thereby, the strong field control is started. In subsequent steps, a d-axis current adjustment command value ΔId that gradually increases as time T elapses is used. As described above, the increase rate of the modulation factor M is also restricted by restricting the rising speed of the d-axis current adjustment command value ΔId that defines the size of the strong field. Therefore, a state where the strong field control is being executed and the modulation factor M does not reach the rectangular wave switching threshold value Mb (maximum modulation factor Mmax) is ensured for a certain period of time, and the strong field / PWM control mode A2 is executed during that time. The After step # 25, the process proceeds to step # 16 (see FIG. 8).

  After the d-axis current adjustment command value ΔId determined in step # 25 reaches the target d-axis current adjustment command value ΔIdt, the modulation factor M reaches the rectangular wave switching threshold value Mb. As the torque TM and the rotational speed ω change, the d-axis current adjustment command value ΔId is appropriately changed in the direction of increasing or decreasing the field magnetic flux, and the strong field control or the weak field control is performed. Therefore, when the modulation factor M is equal to or greater than the rectangular wave switching threshold value Mb (step # 23: No), the subtractor 30 causes the modulation factor M to be converted from the rectangular wave switching threshold value Mb (maximum modulation factor Mmax = The modulation factor deviation ΔM (= M−0.78) obtained by subtracting 0.78) is derived (step # 26). Thereafter, the process proceeds to step # 09 (see FIG. 8). Therefore, the subsequent processing is the same as in the first embodiment.

3. Other Embodiments (1) In each of the above embodiments, the case where only the strong field / overmodulation PWM control mode A2b is executed as the strong field / PWM control mode A2 has been described as an example. However, the embodiment of the present invention is not limited to this, and after executing the strong field / normal PWM control mode A2a as the modulation field M increases as the strong field / PWM control mode A2, A configuration in which the strong field / overmodulation PWM control mode A2b is executed is also one preferred embodiment of the present invention. In order to perform such control, in the first embodiment, it is preferable to set the command modulation rate initial value MTs to less than the overmodulation switching modulation rate Mo (= 0.71). In the second embodiment, it is preferable to set the strong field start modulation factor Ms to be less than the overmodulation switching modulation factor Mo (= 0.71).

(2) In the first embodiment, the case where the command modulation rate initial value MTs is set according to the rotational speed ω of the electric motor 4 and the target torque TM has been described as an example. However, the embodiment of the present invention is not limited to this. For example, the command modulation rate initial value MTs may be set in accordance with either the rotational speed ω of the electric motor 4 or the target torque TM, which is one preferred embodiment of the present invention. In any case, the command modulation factor initial value MTs is larger than the modulation factor M derived by the modulation factor deriving unit 29 in a state where the field magnetic flux is not adjusted by the d-axis current adjustment command value ΔId. It is preferable to set so as to be.

(3) In the first embodiment, the case where the change rate of the command modulation rate MT is set so that the command modulation rate change time ΔT is constant regardless of the command modulation rate initial value MTs has been described as an example. However, the embodiment of the present invention is not limited to this. For example, setting the rate of change of the command modulation rate MT to be constant regardless of the command modulation rate initial value MTs is also one preferred embodiment of the present invention. In this case, the command modulation rate change time ΔT during which the command modulation rate MT is changing changes according to the command modulation rate initial value MTs. That is, as the command modulation rate initial value MTs becomes a value close to the rectangular wave switching threshold value Mb (maximum modulation rate Mmax), the command modulation rate change time ΔT becomes shorter. Thereby, the time for executing the strong field / PWM control mode A2 can be adjusted according to the command modulation rate initial value MTs.

(4) In the second embodiment, the case where the ΔId change rate limiting unit 36 as the transition control field adjusting unit changes the d-axis current adjustment command value ΔId at a constant change speed has been described as an example. However, the embodiment of the present invention is not limited to this. For example, the time until the target d-axis current adjustment command value ΔIdt is reached, that is, the change time of the d-axis current adjustment command value ΔId is set to be constant regardless of the target d-axis current adjustment command value ΔIdt. It is one of the preferred embodiments of the present invention. In this case, since the time until the d-axis current adjustment command value ΔId reaches the target d-axis current adjustment command value ΔIdt is constant, the time for executing the strong field / PWM control mode A2 is surely constant. It can be set as the structure ensured.

(5) In the second embodiment, the strong field start modulation factor Ms is obtained by adding the strong field threshold value ΔMs to the rectangular wave switching threshold value Mb (maximum modulation factor Mmax). Was described as an example. However, the embodiment of the present invention is not limited to this, and it is also possible to set the strong field start modulation factor Ms independently of the above-described strong field threshold value ΔMs. one of. However, even in this case, it is preferable that the strong field start modulation factor Ms is set to a value smaller than the value obtained by adding the strong field threshold value ΔMs to the rectangular wave switching threshold value Mb. If the strong field start modulation rate Ms is set in this way, before the positive d-axis current adjustment command value ΔId by the field adjustment unit 8 is input to the adder 23, it is generated by the ΔId change rate limiting unit 36. It becomes easy to adopt a configuration in which the positive d-axis current adjustment command value ΔId is input to the adder 23.

(6) In the above embodiment, the case where the motor driving device 1 is configured to supply the DC voltage Vdc from the DC power source 3 to the inverter 6 has been described as an example. However, the embodiment of the present invention is not limited to this. For example, a voltage conversion unit such as a DC-DC converter that converts a power supply voltage from the DC power supply 3 to generate a system voltage having a desired value is provided, and the system voltage generated by the voltage conversion unit is used as a DC / AC conversion unit. A configuration in which the power is supplied to the inverter 6 is also one of the preferred embodiments of the present invention. In this case, the voltage conversion unit can be a boost converter that boosts the power supply voltage, a step-down converter that steps down the power supply voltage, or a step-up / step-down converter that both boosts and steps down the power supply voltage. it can.

(7) In the above embodiment, the case where the AC motor 4 is a synchronous motor (IPMSM) having an embedded magnet structure that operates by three-phase AC has been described as an example. However, the embodiment of the present invention is not limited to this. For example, a synchronous motor (SPMSM) having a surface magnet structure can be used as the AC motor 4, or other than the synchronous motor, for example, induction An electric motor or the like can also be used. Moreover, as an alternating current supplied to such an alternating current motor, a single-phase other than three phases, a two-phase, or a polyphase alternating current having four or more phases can be used.

(8) In the above embodiment, the case where the electric motor 4 is used as a driving force source for an electric vehicle or a hybrid vehicle has been described as an example. However, the use of the electric motor 4 according to the present embodiment is not limited to this, and the present invention can be applied to electric motors of all uses.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a control device that controls a motor driving device that includes a DC / AC converter that converts a DC voltage into an AC voltage and supplies the AC voltage to an AC motor.

1: Motor drive device 2: Control device 4: AC motor 5: Mode control unit 6: Inverter (DC / AC conversion unit)
7: Current command determination unit 8: Field adjustment unit 9: Voltage command determination unit 10: Voltage waveform control unit 11: Change rate regulation unit 33: Command modulation rate setting unit (command voltage index setting unit)
35: Target ΔId determination unit (target field adjustment command value determination unit)
36: ΔId change rate limiting unit (transition control field adjusting unit)
Vdc: DC voltage TM: target torque ω: rotational speed Idb: basic d-axis current command value (current command value)
Iqb: Basic q-axis current command value (current command value)
Id: d-axis current command value Iq: q-axis current command value Vd: d-axis voltage command value (voltage command value)
Vq: q-axis voltage command value (voltage command value)
ΔId: d-axis current adjustment command value (field adjustment command value)
ΔIds: end threshold value ΔIdt: target d-axis current adjustment command value (target field adjustment command value)
M: Modulation rate (voltage index)
MT: Command modulation rate (command voltage index)
MTs: Command modulation rate initial value Mmax: Maximum modulation rate Mb: Rectangular wave switching threshold Ms: Strong field start modulation rate (strong field start voltage index)
ΔM: Modulation rate deviation (voltage index deviation)
ΔMs: Strong field threshold value TMR: Strong field allowable torque range A1: Normal field / PWM control mode A1a: Normal field / normal PWM control mode A1b: Normal field / overmodulation PWM control mode A2: Strong field Magnetism / PWM control mode A2a: Strong field / normal PWM control mode A2b: Strong field / overmodulation PWM control mode A3: Strong field / rectangular wave control mode

Claims (10)

A control device that controls a motor drive device including a DC / AC converter that converts a DC voltage into an AC voltage and supplies the AC voltage to an AC motor,
Based on the target torque of the AC motor, a current command determination unit that determines a current command value that is a command value of a current supplied from the DC / AC conversion unit to the AC motor;
Field adjustment for determining a field adjustment command value for executing a strong field control for adjusting the current command value so as to increase a field magnetic flux of the AC motor and a normal field control for performing no adjustment for the current command value. And
Voltage command determination that determines a voltage command value that is a command value of a voltage supplied from the DC / AC converter to the AC motor based on the rotational speed of the AC motor, the current command value, and the field adjustment command value And
A voltage waveform controller that controls the DC-AC converter based on the voltage command value, and executes pulse width modulation control and rectangular wave control, respectively;
During the transition from the normal field / pulse width modulation control mode in which the pulse width modulation control is performed together with the normal field control to the strong field / rectangular wave control mode in which the rectangular wave control is performed together with the strong field control. A mode control unit for performing strong field transfer control via the strong field / pulse width modulation control mode for performing the pulse width modulation control together with the field control;
A control device for an electric motor drive device. The pulse width modulation control includes overmodulation pulse width modulation control in which the amplitude of the AC voltage waveform based on the voltage command value exceeds the amplitude of the carrier waveform, and a normal pulse in which the amplitude of the AC voltage waveform is equal to or less than the amplitude of the carrier waveform. Width modulation control,
2. The mode control unit executes at least a strong field / overmodulation pulse width modulation control mode for executing the overmodulation pulse width modulation control together with the strong field control as the strong field / pulse width modulation control mode. The control apparatus of the electric motor drive device of description.   The mode control unit performs the normal pulse width modulation control together with the strong field control as the voltage index indicating the magnitude of the voltage command value with respect to the DC voltage as the strong field / pulse width modulation control mode. 3. The control device for an electric motor driving device according to claim 2, wherein after executing the strong field / normal pulse width modulation control mode to be executed, the strong field / overmodulation pulse width modulation control mode is executed. The mode control unit causes the voltage waveform control unit to execute the rectangular wave control when the voltage index indicating the magnitude of the voltage command value with respect to the DC voltage is equal to or greater than a predetermined rectangular wave switching threshold value, In the state where the index is less than the rectangular wave switching threshold, the voltage waveform control unit is caused to execute the pulse width modulation control,
Further, the mode control unit terminates the strong field control and the normal field control when the field adjustment command value is equal to or greater than a predetermined end threshold value in the direction of increasing the field magnetic flux of the AC motor. 4. The field adjustment command value is determined so as to execute the step, the voltage index is set to be less than the rectangular wave switching threshold value, and the pulse width modulation control is performed by the voltage waveform control unit. The control apparatus of the electric motor drive device as described in any one.   The mode control unit determines the field adjustment command value so that the strong field control is not executed when the target torque of the AC motor is out of a predetermined strong field allowable torque range. The control device for an electric motor drive device according to any one of claims 4 to 5. A change rate regulation unit that regulates the change rate of the voltage index representing the magnitude of the voltage command value with respect to the DC voltage to be equal to or less than a predetermined regulation rate;
The voltage command determination unit increases the voltage command value as the field adjustment command value changes in a direction in which the field magnetic flux is strengthened from a reference value for executing the normal field control,
The mode control unit causes the voltage waveform control unit to execute the rectangular wave control when the voltage index is equal to or greater than a predetermined rectangular wave switching threshold value, and the voltage index is less than the rectangular wave switching threshold value. Then, let the voltage waveform control unit execute the pulse width modulation control,
Further, in the strong field transition control, the mode control unit regulates the change speed of the voltage index by the change speed regulation unit after the start of the strong field control, and the voltage index is the rectangular wave switching threshold value. The motor drive device control device according to any one of claims 1 to 5, wherein the strong field / pulse width modulation control mode is executed in a time period until the motor is reached. The change speed regulation unit includes a command voltage index setting unit that sets a command voltage index that is a command value of the voltage index,
The field adjustment unit is configured to increase the field magnetic flux in a direction in which the field magnetic flux is increased in a state where a voltage index deviation, which is a difference obtained by subtracting the command voltage index from the voltage index, is greater than or equal to a predetermined strong field threshold and less than zero. When the adjustment command value is changed and the voltage index deviation is greater than zero, the field adjustment command value is changed in a direction to weaken the field magnetic flux, and the voltage index deviation is less than the strong field threshold value. And determining the field adjustment command value so as not to change the field magnetic flux when the voltage index deviation is zero,
The mode control unit causes the command voltage index setting unit to start increasing the command voltage index based on a relationship between a command voltage index initial value that is an initial value of the command voltage index and the voltage index,
The control device for an electric motor drive device according to claim 6, wherein the command voltage index setting unit raises the command voltage index at a predetermined change rate from the command voltage index initial value until the rectangular wave switching threshold value is reached. .   The electric motor according to claim 7, wherein the command voltage index initial value is set to be larger than the voltage index when the normal field control is executed according to at least one of a rotational speed and a target torque of the AC motor. Control device for driving device.   The command voltage index setting unit is configured so that the time until the command voltage index reaches the rectangular wave switching threshold value from the command voltage index initial value is constant regardless of the command voltage index initial value. The control device for an electric motor drive device according to claim 8, wherein a change speed of the command voltage index is set. The change speed regulation unit reaches a target field adjustment command value, a target field adjustment command value determination unit that determines a target field adjustment command value such that the voltage index becomes the rectangular wave switching threshold value. A transition control field adjustment unit that determines the field adjustment command value that changes at a predetermined change rate until
The field adjustment unit increases the field magnetic flux in a state where a voltage index deviation, which is a difference obtained by subtracting the rectangular wave switching threshold value from the voltage index, is greater than or equal to a predetermined strong field threshold value and less than zero. The field adjustment command value is changed, and when the voltage index deviation is greater than zero, the field adjustment command value is changed in the direction of weakening the field magnetic flux, and the voltage index deviation is the strong field threshold value. The field adjustment command value is determined so as not to change the field magnetic flux in a state of less than and a state where the voltage index deviation is zero,
The mode control unit causes the target field adjustment command value determination unit to determine the target field adjustment command value when the voltage index is equal to or greater than a predetermined strong field start voltage index, and the target field adjustment After the command value is determined, the transition control field adjustment unit is determined instead of the field adjustment command value determined by the field adjustment unit until the voltage index reaches the rectangular wave switching threshold value. The motor drive device control device according to claim 6, wherein the field adjustment command value is input to the voltage command determination unit.

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