JP2010011687A - Electric driving controller, electric vehicle, and overvoltage prevention method - Google Patents

Abstract

An electric drive control device capable of preventing an overvoltage from occurring in an electronic device connected to an output of a power supply source.
An electric drive control apparatus according to the present invention includes:
AC motor 1 for traveling, power conversion device 2 for driving AC motor 1, power supply source 4 for supplying power to power conversion device 2, and smoothing means for smoothing the output of power supply source 4 5, an electric drive control device used for a vehicle equipped with a DC voltage detecting means 51 for detecting a DC voltage V _dc applied to the smoothing means 5, and a DC voltage V detected by the DC voltage detecting means 51. _{When dc} becomes equal to or higher than a predetermined voltage, the motor control unit 11 corrects the input characteristics of the power conversion device 2 so that the DC voltage V _dc decreases. As a result, it is possible to prevent the occurrence of overvoltage application to the electronic device connected to the output of the power supply source.
[Selection] Figure 1

Description

  The present invention relates to an electric drive control device, an electric vehicle, and an overvoltage prevention method for a vehicle that travels by supplying power from a power supply source to an AC motor via a power converter.

  2. Description of the Related Art There is known a vehicle electric drive control device that supplies power from a power supply source to an AC motor via a power converter and drives the vehicle. In this vehicle electric drive control device, for example, electric power from an AC motor connected to the internal combustion engine of the vehicle for power generation is transferred to the other drive AC motor via a power converter such as a rectifier, a buck-boost converter, or an inverter. Supply. In such an electric drive control device for a vehicle, a smoothing capacitor is used to suppress fluctuations in the DC voltage, but a small capacitor is used to avoid an increase in size and cost of the device.

  If a power imbalance occurs between the power supply source and the AC motor due to changes in the vehicle status, etc., excessive power generated cannot be absorbed by the small smoothing capacitor, and voltage fluctuations may occur. Techniques for achieving stabilization have been conventionally proposed (see, for example, Patent Document 1).

JP 2007-252181 A

  However, in the conventional technology described above, if the voltage fluctuation due to the decrease in the capacity of the smoothing capacitor becomes too large, the voltage cannot be sufficiently suppressed and an excessive voltage fluctuation occurs, and the electronic device connected to the output of the power supply source There was a risk of overvoltage application.

The invention of claim 1 is an AC motor for driving, a power converter for driving the AC motor, a power supply source for supplying power to the power converter, and a smoothing for smoothing the output of the power supply source. An electric drive control device used for a vehicle provided with a means. Then, the DC voltage applied to the smoothing means is detected by the DC voltage detecting means, and when the detected DC voltage becomes equal to or higher than a predetermined voltage, the input characteristics of the power converter is converted to DC voltage by the input characteristic correcting means. Correct the input characteristics to decrease. As a result, overvoltage application can be prevented from occurring in the electronic device connected to the output of the power supply source. Further, according to the invention of claim 5, overvoltage application can be reliably prevented.
An electric vehicle according to a seventh aspect of the invention includes an AC motor for driving, a power converter for driving the AC motor, a power supply source that supplies power to the power converter, and a smooth output from the power supply source. Smoothing means, DC voltage detecting means for detecting a DC voltage applied to the smoothing means, and control means for controlling the power converter. The control means corrects the voltage phase of the AC motor when the DC voltage detected by the DC voltage detection means exceeds a predetermined voltage, and converts the power so that the voltage phase is such that the DC voltage decreases. Control the device.
The invention of claim 8 is an engine for driving front wheels of a vehicle, an alternator driven by the engine to generate DC power, a smoothing means for smoothing the output of the alternator, and a power converter for converting DC power to AC power. And an overvoltage prevention method used in a vehicle comprising an AC motor that drives the rear wheels of the vehicle with converted AC power, wherein the DC voltage applied to the smoothing means is detected and detected by the DC voltage detection means. When the direct current voltage becomes equal to or higher than a predetermined voltage, the input characteristics of the power converter are corrected to input characteristics that reduce the direct current voltage.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that an overvoltage application generate | occur | produces in the electronic device connected to the output of the electric power supply source.

Hereinafter, the best mode for carrying out the invention will be described with reference to the drawings.
-First embodiment-
FIG. 1 is a block diagram showing a first embodiment of an electric drive control device according to the present invention. The electric drive control device supplies power to the AC converter 1 used for driving the vehicle, the power converter 2 for driving the AC motor 1, the controller 3 for controlling the power converter 2, and the power converter 2. The power supply source 4 and the smoothing means 5 for smoothing the output of the power supply source 4 are provided.

    FIG. 1 shows a case where the electric drive control device is applied to an electric four-wheel drive vehicle. The power supply source 4 includes a generator 41, a field control unit 42 that controls the field of the generator 41, and a rectifier 43 that rectifies the output of the generator 41. The generator 41 is rotationally driven by an engine (not shown) that drives the front wheels. The power conversion device 2 constitutes an inverter and will be referred to as an inverter 2 below. The smoothing means 5 is provided with a DC voltage detecting means (voltage sensor) 51 for detecting a DC voltage applied to the smoothing means 5 and a smoothing capacitor 52 for smoothing the output of the power supply source 4 in parallel. Yes.

  Details of the above-described units will be described. In the controller 3, the torque command deriving unit 6 displays a torque command T * necessary for controlling the AC motor 1 based on vehicle information from a host control device (not shown) mounted on the vehicle in a table, map, Etc. and output. The vehicle information includes accelerator opening, wheel speed, engine speed, and the like. The position detector 14 (for example, a resolver) detects the motor rotation position θ. Instead of using the position detecting means 14, the rotational position may be estimated from the AC current of the AC motor 1 or the like. The speed deriving unit 16 derives the motor rotation speed ω based on the motor rotation position θ from the position detection unit 14.

The motor control current command deriving unit 7 is based on the torque command T ^* from the torque command deriving unit 6 and the motor rotational speed ω from the speed deriving unit 16, that is, according to the driving state of the AC motor 1. I ^* _d and I ^* _q are derived from a table, map, mathematical expression, or the like. On the other hand, the DC voltage command deriving unit 8 is based on the torque command T ^* from the torque command deriving unit 6 and the motor rotational speed ω from the speed deriving unit 16, and the DC voltage command V ^* _dc corresponding to the driving state of the AC motor 1. Is derived from a table, a map, a mathematical formula or the like.

Further, the rotation coordinate conversion unit 15 is based on the three-phase AC currents I _u , I _V , I _W detected by the AC current detection unit 13 and the motor rotation position θ detected by the position detection unit 14. The d-axis current I _d and the q-axis current I _q are derived from a table, a map, a mathematical expression, or the like. Here, the d axis and the q axis are axes of a rotating coordinate system that rotates together with the rotor magnetic flux of the AC motor 1, the d axis indicates the direction of the magnetic pole position (magnetic flux), and the q axis is electrically with respect to the d axis. The direction orthogonal to is shown.

  Here, although the current values of the u-phase, the v-phase, and the w-phase are detected by the AC current detection means 13, respectively, one or two of the u-phase, the v-phase, and the w-phase are detected as the AC current detection means. 13 may be used to estimate the current value of the other phase. Further, if the alternating current feedback control is not used, the alternating current detecting means 13 can be omitted.

The DC voltage V _dc detected by the DC voltage detection means 51 of the smoothing means 5 is input to the subtraction unit 9 of the controller 3. The subtracting unit 9 subtracts the detected DC voltage V _dc from the DC voltage command V ^* _dc output from the DC voltage command deriving unit 8, and outputs a deviation ΔV _dc . In the present embodiment, a voltage phase correction value deriving unit 10 is further provided in the controller 3 in order to prevent overvoltage application. The voltage phase correction value deriving unit 10 derives a voltage phase correction value θ _hlmt described later based on the deviation ΔV _dc output from the subtraction unit 9.

The motor control unit 11, the motor control current command I ^* _d, I ^* _q, the motor control current I _d, I _q, the motor rotational position theta, of the AC motor 1 based on the motor rotation speed ω and the voltage phase correction value theta _Hlmt Take control. The motor control unit 11 generates a gate signal (UP signal to WN signal) for controlling a switching element (power element such as IGBT) provided in the inverter 2. The gate signal (UP signal to WN signal) is input to the gate driver 12. The gate driver 12 drives the inverter 2 with a gate signal.

  In the present embodiment, the motor control unit 11 switches the motor control method according to the motor rotation speed ω. When the motor rotation speed ω is equal to or less than the predetermined motor rotation speed, it is driven by the pulse width modulation control method or the modulation rate fixed control method. When the motor rotation speed ω is higher than the predetermined motor rotation speed, it is driven by the rectangular wave control method. To do.

The deviation ΔV _dc output from the subtraction unit 9 is also input to the field control unit 42 of the power supply source 4. The field control unit 42 feedback-controls the field of the generator 41 so that the output voltage V _dc of the power supply source 4 matches the DC voltage command V ^* _dc , so that the field control unit 42 is connected between the power supply source 4 and the AC motor 1. Power coordination control is performed. By this power cooperative control, the vehicle electric drive control device can be reduced in size and cost without taking a countermeasure to increase the capacity of the smoothing capacitor 52.

  However, if a power imbalance is transiently generated between the power supply source 4 and the AC motor 1 due to a change in the driving state of the vehicle, and the excessively generated power cannot be absorbed by the smoothing capacitor 52, the DC Voltage fluctuations will occur. For example, when the required power of the inverter 2 changes suddenly in response to a change in the required torque, the field current response on the generator side is slower than the change in the inverter side output power, so the power supply source 4 and the AC motor 1 A power imbalance transiently occurs between As a result, there is a possibility that an overvoltage exceeding the voltage allowable value is applied to the electronic device connected to the output of the power supply source 4.

<Description of overvoltage application mechanism>
The output characteristics of the power supply source 4 will be described. Output characteristic of the power supply source 4 will vary depending on the size of the supplied field current I _f to rotation speed ωg and rotor windings of the generator 41. When the rotational speed ωg of the generator 41 is low, the output characteristics are as shown in FIG. 2, and when the rotational speed ωg of the generator 41 is high, the output characteristics are as shown in FIG. In both cases of FIGS. 2 and 3, the characteristic curve has a tendency that the voltage increases as the current decreases, and the field current _If is independent of the rotational speed ωg of the generator 41. It can be seen that the DC current that can be output increases as it rises.

When the rotational speed ωg of the generator 41 is low (FIG. 2), the DC voltage rises due to the influence of magnetic saturation as the field current _If increases. On the other hand, when the rotational speed ωg is high (FIG. 3), even if the field current _If increases, it is not affected by magnetic saturation and the DC voltage rise does not reach its peak. In FIG. 3, the intervals between the characteristic curves of the power supply source 4 are equal intervals, and the inclination is large. It can be seen that the output characteristics of the power supply source 4 change greatly due to changes in the rotational speed ωg of the generator 41 and the field current _If .

  On the other hand, the input characteristics of the inverter 2 differ depending on the motor control method as shown in FIG. When the output torque T of the AC motor 1 and the motor rotational speed ω are constant, the pulse width modulation control method changes the input DC current by changing the modulation factor even if the input DC voltage changes. The AC motor is controlled after always obtaining a constant input power. Therefore, the input characteristics of the pulse width modulation control type inverter 2 show equal power characteristics. The modulation rate indicates a ratio between the amplitude of the carrier wave and the amplitude of the modulation wave.

  Since the modulation factor is constant in the rectangular wave control method, when the input DC voltage changes, the input DC current also changes, and the value is uniquely determined from the relationship between the DC voltage and the impedance. Therefore, the input characteristic of the inverter 2 in the rectangular wave control system shows an equiimpedance characteristic. Further, in the pulse width modulation control method, the modulation rate fixed control method that operates with the modulation rate fixed exhibits the same impedance characteristic as the rectangular wave control method.

  The overvoltage application is likely to occur when the input characteristics of the inverter 2 have an equal impedance characteristic regardless of the rotational speed ωg of the generator 41. In the following, the explanation will focus on the isoimpedance characteristics. However, the electric drive control device of the present embodiment is not limited to the equiimpedance characteristic, and can be applied to the case where the input characteristic of the inverter 2 is the equipower characteristic. In any case, the overvoltage application is prevented. Fully effective.

In the present embodiment, as described above, the field of the generator 41 is feedback-controlled so that the output voltage V _dc of the power supply source 4 matches the DC voltage command V ^* _dc. Power cooperative control with the AC motor 1 is performed. Therefore, the point at which the output characteristics of the power supply source 4 and the input characteristics of the inverter 2 coincide with each other is the system operating point. The overvoltage application occurs because the system operating point changes transiently depending on the driving state of the generator 41 and the inverter 2.

FIG. 5 is a diagram for explaining overvoltage application when the field current If _f fluctuates in an operating state where the rotational speed ωg of the generator 41 is high. Such a situation may occur due to the influence of vehicle noise. Before the field current _If changes, the output characteristic of the power supply source 4 is a characteristic curve indicated by “small field current value _If ”, and the input characteristic of the inverter 2 is “input characteristic of the initial inverter”. The characteristic curve is shown. Therefore, the system operating point at this time is an intersection “initial operating point” of these characteristic curves.

If the output characteristics of the power supply source 4 the field current I _f is soaring of the generator 41 is changed to the characteristic curve indicated by "field current value I _f large", in "the field current value I _f large" The intersection of the characteristic curve shown and the characteristic curve shown in “Input characteristics of the initial inverter” is the transient operating point after the fluctuation. As a result, even if the output of the AC motor 1 is constant and the input characteristics of the inverter 2 are constant, the output voltage of the power supply source 4 varies and the DC voltage exceeds the allowable voltage value. . That is, overvoltage application occurs.

In particular, when the voltage of the "initial operating point" is close to the allowable voltage value becomes a cause even overvoltage a small increase in the field current I _f of the generator 41. Also, the output characteristics shown in FIG. 2 and 3, when the rotation speed ωg of the generator 41 is high, even a minute fluctuation of the field current I _f of the generator 41, it is understood that the cause of the overvoltage applied .

  FIG. 6 is a diagram for explaining overvoltage application when the number of revolutions ωg of the generator 41 rises rapidly. In the example shown in FIG. 6, the rotational speed ωg of the generator 41 rises rapidly, and the output characteristic of the power supply source 4 changes from a state where the rotational speed ωg shown in FIG. 2 is low to a state where the rotational speed ωg shown in FIG. It shows the case of changing. Such a situation can occur when only the front wheels enter a place with a low μ (such as an snowy road) and run idle, and the output of the AC motor connected to the rear wheels does not change. The system operating point “initial operating point” before the change is the intersection of the characteristic curve indicated by “low generator speed ωg” that is the output characteristic of the power supply source 4 and the characteristic curve indicated by “input characteristic of the initial inverter”. It becomes. The DC voltage at this time is lower than the allowable voltage value.

Thereafter, when the rotational speed ωg of the generator 41 rises rapidly and the output characteristic of the power supply source 4 changes to a characteristic curve indicated by “high generator rotational speed ωg”, a characteristic curve indicated by “high generator rotational speed ωg”. The system operating point is the intersection “operating point after change” of the characteristic curve indicated by “input characteristic of initial inverter”. By a result, even if the output of the AC motor 1, as an input characteristic of the inverter 2, and both the field current I _f of the generator 41 is is constant, the rotational speed ωg of the generator 41 rises abruptly The DC voltage will exceed the allowable voltage value. That is, overvoltage application occurs.

FIG. 7 is a diagram for explaining overvoltage application when the input characteristics of the inverter 2 change. In the example shown in FIG. 7, the rotational speed ωg and the field current I _f of the generator 41 is constant, shows the case where the input characteristic of the inverter 2 changes rapidly. Such a situation can occur when only the output torque T of the AC motor 1 and the motor rotational speed ω change suddenly due to the collision of only the rear wheels with the obstacle. In FIG. 7, the output characteristics of the power supply source 4 are shown as being in a state where the rotational speed ωg of the generator 41 is high. As shown in FIG. 7, the operating point after the sudden change “the operating point after change” exceeds the allowable voltage value, even if the field current _If is constant and the output characteristics of the power supply source 4 are constant. As a result of sudden changes in the input characteristics of the inverter 2, overvoltage application occurs.

<Response to overvoltage application>
In the present embodiment, as described below, based on the deviation ΔV _dc between the DC voltage command V ^* _dc by the DC voltage command deriving unit 8 and the DC voltage V _dc detected by the DC voltage detection means 51. The voltage phase correction value θ _hlmt of the AC motor 1 is derived, and the derived voltage phase correction value θ _hlmt is reflected in the motor control, thereby preventing the occurrence of overvoltage application as described above.

FIG. 8 shows the configuration of the voltage phase correction value deriving unit 10 of FIG. The subtraction unit 9 calculates a deviation ΔV _dc between the DC voltage command V ^* _dc and the DC voltage V _dc . The calculated deviation ΔV _dc is input to the voltage phase correction value deriving unit 10. The voltage phase correction value deriving unit 10 derives the voltage phase correction value θ _hlmt corresponding to the input deviation ΔV _dc by _{performing a} table search in the voltage phase correction value determination table 101. The voltage phase correction value determination table 101 gives a voltage phase correction value θ _hlmt so that the deviation ΔV _dc becomes zero when the deviation ΔV _dc becomes large, and when the deviation ΔV _dc is small and does not become an overvoltage. The value θ _hlmt = 0 is set so that correction is not performed unnecessarily.

For example, if the threshold value of the deviation ΔV _dc that becomes an overvoltage is ΔV 0, the voltage phase correction is performed when the DC voltage value V _dc is equal to or greater than “V ^* _dc + ΔV 0”. In the present embodiment, the change rate limiting unit 102 is provided in the _subsequent stage of the voltage phase correction value determination table 101 in order to limit the change rate of the voltage phase correction value θ _hlmt , but the change rate limiting unit 102 is omitted. Also good.

Further, when determining the voltage phase correction value theta _Hlmt, it may be derived voltage phase correction value theta _Hlmt by the feedback control or the like using the map, the mathematical expression or the deviation [Delta] V _dc, instead of using the table. In addition, when performing feedback control, it is used together with feedforward control so as not to lose speediness. Further, although the voltage phase correction value θ _hlmt is derived only in accordance with the voltage deviation ΔV _dc here, either the torque command T ^* or the motor rotational speed ω may be taken into consideration when deriving. good. Further, the estimated torque may be calculated inside the controller 3, and this estimated torque may be used instead of the torque command T ^* . As vehicle information, the torque on the wheel shaft may be used instead of the torque command T ^* , and the wheel speed may be used instead of the motor rotational speed ω.

The motor control unit 11 determines the voltage phase correction value θ _hlmt derived in this way, the motor control current commands I ^* _d and I ^* _q , the motor control currents I _d and I _q , the motor rotation position θ and the motor rotation speed. By generating a gate signal based on ω, the input characteristics of the inverter 2 are changed as shown in FIG. 7 to prevent overvoltage application.

FIG. 9 is a block diagram of the motor control unit 11. As described above, the motor control unit 11 switches between the pulse width modulation control method (including the modulation factor fixed control method) and the rectangular wave control method in accordance with the motor rotation speed ω. The motor control unit 11 is provided with a pulse width modulation control method block 111 and a rectangular wave control method block 112, and the voltage phase correction value θ _hlmt is input to each of the blocks 111 and 112. The gate signal generated in each block 111 and 112 is input to the switching unit 113. The switching unit 113 outputs one of the gate signals generated by the pulse width modulation control method block 111 and the rectangular wave control method block 112 to the gate driver 12 (see FIG. 1) according to the motor rotation speed ω.

FIG. 10 is a diagram showing the pulse width modulation control scheme block 111. As shown in FIG. A pulse width modulation control scheme block 111, the motor control current command I ^* _d, I ^* _q, the motor control current I _d, I _q, the motor rotational position theta and voltage phase correction value theta _Hlmt is input. In the pulse width modulation control scheme, the motor control current command I ^* _d, I ^* _q, the motor control current I _d, I _q and the d-axis voltage based on the proportional-integral control unit 30 commands V ^* _d and q-axis voltage command V ^* _q is derived, and a gate signal is generated based on the derived d-axis voltage command V ^* _d and q-axis voltage command V ^* _q . Therefore, the d-axis voltage ratio ε _d and the q-axis voltage ratio ε _q are derived based on the voltage phase correction value θ _hlmt , and the derived ratios ε _d and ε _q are used as the d-axis voltage command V ^* _d and the q-axis voltage command V. ^* Correct by multiplying by _q .

First, the proportional integration control unit 30 controls the deviations ΔI ^* _d and ΔI ^* _q between the motor control current commands I ^* _d , I ^* _q and the motor control currents _Id , _Iq, and the d-axis voltage command V ^*. _d and q-axis voltage command V ^* _q is derived. d-axis voltage command V ^* _d and q-axis voltage command V ^* _q are input to the basic angle derivation section 31, where the basic angle theta _b of the pulse width modulation control scheme is derived. This basic angle θ _b is input to the adding unit 32 and the ratio deriving unit 33. In the adding unit 32, the voltage phase correction value θ _hlmt from the voltage phase correction value deriving unit 10 and the basic angle θ _b are added, and the result is input to the ratio deriving unit 33 as the basic angle θ _bh after voltage phase correction. . The ratio deriving unit 33 derives the d-axis voltage ratio ε _d and the q-axis voltage ratio ε _q from a table, a map, a mathematical expression, or the like.

In this embodiment, in order to limit the voltage phase correction value θ _hlmt , the upper and lower limit value setting unit 34 and the upper and lower limit value setting unit 35 increase the d axis voltage ratio ε _d and the q axis voltage ratio ε _q . A lower limit is set but may be omitted. The d-axis voltage ratio ε _dlmt output from the upper / lower limit value setting unit 34 is multiplied by the d-axis voltage command V ^* _d by the multiplication unit 36. On the other hand, the q-axis voltage ratio ε _qlmt output from the upper / lower limit value setting unit 35 is multiplied by the q-axis voltage command V ^* _q by the multiplication unit 37. Thus, by multiplying the d-axis voltage ratio ε _dlmt and the q-axis voltage ratio ε _qlmt , the voltage phase correction value θ _hlmt is reflected in the d-axis voltage command V ^* _d and the q-axis voltage command V ^* _q .

Thereafter, the rotation coordinate conversion unit 38 performs rotation coordinate conversion to derive three-phase AC voltage commands V ^* _U , V ^* _V , and V ^* _W. The gate signal generation unit 39 generates a gate signal based on these three-phase AC voltage commands V ^* _U , V ^* _V , and V ^* _W , and outputs the gate signal to the gate driver 12.

Thus, the deviation [Delta] V _dc is detected between the DC voltage command V ^* _dc and the DC voltage V _dc, the phase of the voltage vector V at the calculated voltage phase correction value theta _Hlmt based on the deviation [Delta] V _dc Susumu To increase the negative d-axis voltage command V _d . As a result, the negative d-axis current increases and the effect of field weakening control is enhanced, the input characteristics of the inverter 2 are changed, and overvoltage application can be prevented. If the phase of the voltage vector V is corrected so as to be delayed, the characteristic curve moves in the opposite direction to that when the angle is advanced, and the voltage at the operating point increases.

In the above example, the d-axis voltage command V ^* _d and the q-axis voltage command V ^* _q are derived from the deviations ΔI ^* _d and ΔI ^* _q by proportional-integral control, but the motor control current commands I ^* _d , I ^* _The d-axis voltage command V ^* _d and the q-axis voltage command V ^* _q may be derived from _{q using a} table, map, mathematical formula, or the like. In addition, the correction was performed by multiplying the d-axis voltage ratio ε _dlmt and the q-axis voltage ratio ε _qlmt by the d-axis voltage command V ^* _d and the q-axis voltage command V ^* _{q. Alternatively} , numerical values may be derived from the basic angle θ _b and the basic angle θ _bh after voltage phase correction instead of the ratio by using a table, a map, a mathematical formula, or the like, and converted into the d-axis voltage command V ^* _d and the q-axis voltage command V ^* _q . Correction may be made by addition or subtraction.

FIG. 11 is a diagram showing the rectangular wave control scheme block 112. As shown in FIG. The rectangular wave control method block 112 is inputted with motor control current commands I ^* _d and I ^* _q , motor rotation speed ω, motor rotation position θ, and voltage phase correction value θ _hlmt . In the rectangular wave control method, motor control is performed by using the motor rotation position θ, the rectangular wave basic angle θ _rec, and the electrical angular velocity ω _re . Therefore, the correction is performed by adding the voltage phase correction value θ _hlmt to the rectangular wave basic angle θ _rec .

The electrical angular velocity deriving unit 60 derives the electrical angular velocity ω _re from the motor rotational speed ω. Based on the motor control current commands I ^* _d and I ^* _q and the electrical angular velocity ω _re , the voltage command deriving unit 61 uses a table, map, formula, or the like to determine the d-axis voltage command V ^* _d and q-axis voltage command V ^* _q. Is derived. The basic angle deriving unit 62 derives the rectangular wave basic angle θ _rec by a table, a map, a mathematical expression, or the like based on the d-axis voltage command V ^* _d and the q-axis voltage command V ^* _q . The derived rectangular wave basic angle θ _rec is added to the voltage phase correction value θ _hlmt from the voltage phase correction value deriving unit 10 in the adding unit 63, and as a result, a corrected rectangular wave basic angle θ _rech is derived. The corrected rectangular wave basic angle θ _rech is limited by the upper / lower limit value setting unit 64, but the upper / lower limit value setting unit 64 may not be provided.

The corrected rectangular wave basic angle θ _rech output from the upper / lower limit value setting unit 64 is added to the motor rotation position θ from the position detecting unit 14 in the adding unit 65, and a rectangular wave control angle θ _v is derived. The gate signal generator 66 electrical angular velocity omega _re from the rectangular wave control angle theta _v and the electrical angular velocity derivation section 60 is inputted, the gate signal is generated based on them. As described above, also in the rectangular wave control method, it is possible to prevent overvoltage application by advancing the phase of the voltage vector V as in the case of the pulse width modulation control method.

12-14 is a figure explaining the operating point before and behind correction | amendment. FIG. 12 is a diagram corresponding to FIG. 5 and shows a situation in which overvoltage application is prevented when the field current If _f fluctuates in an operating state where the rotational speed ωg of the generator 41 is high. Before correction is will move the field pole current value varies from I _f small to I _f Univ from the "initial operating point" to the "uncorrected operating point", the DC voltage value jumps up, i.e. have overvoltage occurs It was. On the other hand, by performing the correction to advance the phase of the voltage vector V described above, the input characteristic of the inverter 2 is changed from a characteristic curve (broken line) indicated by “input characteristic of initial inverter (before correction)” to “after correction”. To a characteristic curve (solid line). As a result, the DC voltage value of the “corrected operating point” that is the intersection of the input characteristic curve and the output characteristic curve becomes lower than the allowable voltage value, and overvoltage application is prevented.

  FIG. 13 is a diagram corresponding to FIG. 6 and shows a situation in which overvoltage application is prevented when the rotational speed ωg of the generator 41 rises rapidly. The “corrected operating point”, which is the intersection of the characteristic curve indicating “after correction” and the characteristic curve indicated by “high generator speed ωg”, is lower than the allowable voltage value, preventing overvoltage application.

  FIG. 14 is a diagram corresponding to FIG. 7 and shows a situation in which overvoltage application is prevented when the input characteristics of the inverter 2 change. The input characteristic of the inverter 2 before correction changes from a characteristic curve (solid line) indicated by “initial inverter input characteristic” to a characteristic curve (dashed line) indicated by “before correction”. However, by advancing the phase of the voltage vector V by the correction described above, the corrected input characteristic changes to a characteristic curve “after correction” (thick line) shown on the right side of the broken line. As a result, the position of the “post-correction operating point” is lower than the allowable voltage value, and overvoltage application is prevented.

In the above-described first embodiment, when the deviation ΔV _dc is large and overvoltage application occurs, the inverter is set so that the voltage value at the operating point becomes smaller than the allowable voltage value as shown in FIGS. 2 input characteristics were changed. As a result, overvoltage application can be prevented without increasing the capacity of the smoothing capacitor 52. Further, even if the smoothing capacitor 52 is deteriorated, the same effect is obtained. One method of changing the input characteristics is to change the voltage phase of the AC motor 1 so as to advance the phase of the voltage vector V as described above.

-Second embodiment-
FIG. 15 is a block diagram illustrating an electric drive control device for a vehicle according to the second embodiment. The second embodiment is different from the vehicle electric drive control device shown in FIG. 1 in that the discharge means 17 is provided in parallel with the smoothing capacitor 52. The discharging means 17 is provided with a discharging resistor.

  The discharging unit 17 is provided with a comparator and a switch, and is configured such that the discharging unit 17 operates at an arbitrary voltage threshold. The comparator in the discharging unit 17 turns on the switch when it is determined that the DC voltage exceeds a predetermined voltage threshold, and the surplus power is consumed by the discharging resistor of the discharging unit 17. As a result, the DC voltage can be lowered. Note that when the DC voltage falls below the voltage threshold, the switch is turned off. The voltage threshold at which the switch is turned on / off may be set to the same value, or may have hysteresis.

  In the second embodiment, the discharging means 17 is provided in parallel with the smoothing capacitor 52 and is used in combination with the voltage phase correction described above. Therefore, even when the DC voltage fluctuates at a speed exceeding the processing speed of voltage phase correction, it is possible to reliably prevent overvoltage application.

As described above, in the embodiment of the electric drive control device according to the present invention, the AC motor 1 used for driving the vehicle, the power conversion device 2 for driving the AC motor 1, and the power conversion device 2 are controlled. It is used in a vehicle including a controller 3, a power supply source 4 that supplies power to the power converter 2, and smoothing means 5 for smoothing the output of the power supply source 4. The electric drive control device, a DC voltage detector 51 for detecting the DC voltage V _dc applied to the smoothing unit 5, when the DC voltage V _dc detected by the DC voltage detection unit 51 becomes a predetermined voltage or higher The motor control unit 11 corrects the input characteristics of the power conversion device 2 so that the DC voltage V _dc decreases. By the operation of the motor control unit 11, it is possible to prevent the occurrence of overvoltage application to the device connected to the output of the power supply source 4.

The motor control unit 11 may correct the input characteristics by correcting the motor voltage phase. Further, the correction of the motor voltage phase, may be performed based on the deviation [Delta] V _dc between the DC voltage command V ^* _dc power source 4 and the DC voltage V _dc, the torque command T ^* and to the AC motor 1 The determination may be performed based on any one of the motor rotation speed ω and the deviation ΔV _dc . Further, the discharge means 17 is connected in parallel with the smoothing capacitor 52, and when the DC voltage V _dc detected by the DC voltage detection means 51 becomes equal to or higher than a predetermined voltage, discharge is performed by the discharge resistor of the discharge means 17. Thus, the occurrence of overvoltage application can be reliably prevented.

  In the above-described conventional technique, if the voltage fluctuation due to the capacity reduction of the smoothing capacitor 52 becomes too large, the voltage cannot be sufficiently suppressed and an excessive voltage fluctuation occurs, and the electronic device connected to the output of the power supply source 4 There was a risk of overvoltage application.

On the other hand, in the electric drive control device of the present embodiment, when a situation in which the deviation ΔV _dc is large and an overvoltage application occurs is detected, the voltage phase correction value θ _hlmt is calculated from the deviation ΔV _dc and the voltage phase correction is performed. Since the jump of the DC voltage is suppressed by correcting the voltage phase of the AC motor 1 based on the value θ _hlmt , the responsiveness is excellent. For this reason, it is possible to cope with a rapid jump in voltage and to reliably prevent the occurrence of overvoltage application. Further, in the second embodiment, the discharge means 17 is provided in parallel with the smoothing capacitor 52, and when the deviation ΔV _dc increases, the voltage phase of the AC motor 1 is corrected and the discharge resistance of the discharge means 17 is corrected. Therefore, it is possible to more reliably prevent the occurrence of overvoltage application.

  The overvoltage prevention method according to the present invention includes an engine that drives the front wheels of a vehicle, an alternator 4 that is driven by the engine to generate DC power, a smoothing means 5 that smoothes the output of the alternator 4, and converts DC power into AC power. Used in a vehicle including the power conversion device 2 that performs this operation and the AC motor 1 that drives the rear wheels of the vehicle using the converted AC power. In this overvoltage prevention method, a DC voltage applied to the smoothing means 5 is detected, and when the detected DC voltage becomes equal to or higher than a predetermined voltage, the input characteristic of the power converter 2 is such that the DC voltage decreases. A step of correcting the characteristic.

The step of correcting the input characteristics of the power conversion device includes the following steps. The step of detecting the rotational speed (ω) of the AC motor 1, the step of calculating the torque command (T ^* ) required by the vehicle from the vehicle information, the detected rotational speed (ω) of the AC motor 1 and the calculated Based on the torque command (T ^* ), the DC voltage command (V ^* _dc ) of the power supply source 4 is calculated, and the calculated DC voltage command (V ^* _dc ) and the DC voltage detection means 51 detect the DC voltage command (V ^* _dc ). A step of calculating a deviation (ΔV _dc ) from the DC voltage (V _dc ), a step of calculating a voltage phase correction value (θ _hlmt ) based on the deviation (ΔV _dc ), and a voltage phase correction value (θ _hlm t) Correcting the voltage phase of AC motor 1 based on

The step of correcting the input characteristics of the power converter further includes the following steps. A step of calculating motor control current commands (I ^* _d ) and (I ^* _q ) based on the detected rotational speed (ω) of the AC motor 1 and the calculated torque command (T ^* ), and a motor control current A step of detecting (I _d ), (I _q ), a step of detecting the motor rotational position (θ), the calculated motor control current commands (I ^* _d ), (I ^* _q ), and the detected motor Based on the control current (I _d ), (I _q ), the detected motor rotational position (θ), the detected rotational speed of the AC motor (ω), and the calculated voltage phase correction value (θ _hlmt ), A step of generating a drive signal for the conversion device (respective gate signals of the U, V, and W phase drive elements).

The step of correcting the input characteristics further includes a step of controlling the field current by inputting the deviation (ΔV _dc ) to the field controller 42 of the alternator 4 so that the output voltage of the alternator 4 matches the calculated DC voltage command. It may be added.

  In the above-described embodiment, the electric four-wheel drive vehicle has been described as an example, but the present invention is not limited to this. For example, the present invention can be applied to a hybrid vehicle (HEV) provided with a DC-DC converter. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

1 is a block diagram showing a first embodiment of an electric drive control device according to the present invention. FIG. It is a figure which shows the output characteristic of the electric power supply source 4 when the rotation speed (omega) g of the generator 41 is low. It is a figure which shows the output characteristic of the electric power supply source 4 when the rotation speed (omega) g of the generator 41 is high. FIG. 4 is a diagram showing input characteristics of an inverter 2. It is a figure explaining the overvoltage application in case the field current If fluctuates in the driving _| running state with the high rotation speed (omega) g of the generator 41. It is a figure explaining the overvoltage application in case the rotation speed (omega) g of the generator 41 rises rapidly. It is a figure explaining the overvoltage application in case the input characteristic of the inverter 2 changes in the driving | running state in which the rotation speed (omega) g of the generator 41 is high. 3 is a diagram illustrating a configuration of a voltage phase correction value deriving unit 10. FIG. 3 is a block diagram of a motor control unit 11. FIG. It is a figure which shows the pulse width modulation control system block. It is a figure which shows the rectangular wave control system block 112. FIG. In the rotation speed ωg of the generator 41 is high operating state is a diagram for explaining the operation point after the voltage phase correction in the case where the field current I _f is varied. It is a figure explaining the operating point after voltage phase correction | amendment when the rotation speed (omega) g of the generator 41 rises rapidly. It is a figure explaining the operating point after voltage phase correction | amendment in case the input characteristic of the inverter 2 changes in the driving | running state where the rotation speed (omega) g of the generator 41 is high. It is a block diagram which shows 2nd Embodiment of the electric drive control apparatus by this invention.

Explanation of symbols

1: AC motor, 2: Power converter (inverter), 3: Controller, 4: Power supply source (alternator), 5: Smoothing means, 6: Torque command deriving unit, 7: Motor control current command deriving unit, 8: DC voltage command derivation unit, 9: subtraction unit, 10: voltage phase correction value derivation unit, 11: motor control unit, 12: gate driver, 13: AC current detection unit, 14: position detection unit, 15, 38: rotational coordinates Conversion unit, 16: Speed deriving unit, 17: Discharging means, 30: Proportional integral control unit, 31, 62: Basic angle deriving unit, 32, 63, 65: Adding unit, 33: Ratio deriving unit, 34, 35, 64 : Upper and lower limit value setting unit, 36, 37: multiplication unit, 39, 66: gate signal generation unit, 41: generator, 42: field control unit, 43: rectification unit, 51: DC voltage detection unit, 52: smoothing capacitor, 60: Electrical angular velocity derivation , 61: voltage command derivation unit, 101: Voltage phase correction value determination table 102: change rate restriction unit, 111: PWM control method block 112: rectangular wave control method block 113: switching unit

Claims (11)

An AC motor for traveling, a power converter for driving the AC motor, a power supply source for supplying power to the power converter, and a smoothing means for smoothing the output of the power supply source An electric drive control device used for a vehicle,
DC voltage detecting means for detecting a DC voltage applied to the smoothing means, and when the DC voltage detected by the DC voltage detecting means is equal to or higher than a predetermined voltage, the input characteristics of the power converter are converted to the DC voltage. An electric drive control device comprising input characteristic correction means for correcting the input characteristic so that the current decreases. The electric drive control device according to claim 1,
The electric drive control device, wherein the input characteristic correction means corrects a motor voltage phase of the AC motor. In the electric drive control device according to claim 2,
The electric drive control device, wherein the input characteristic correction means corrects the motor voltage phase based on a deviation between a DC voltage command of the power supply source and the DC voltage. In the electric drive control device according to claim 3,
The electric drive control device, wherein the input characteristic correction means corrects the motor voltage phase based on any one of a torque command related to the AC motor, a rotational speed of the AC motor, and the deviation. In the electric drive control device according to any one of claims 1 to 4,
It further comprises discharge means connected in parallel with the smoothing means,
An electric drive control device characterized by performing discharge by the discharge means when a DC voltage applied to the smoothing means becomes equal to or higher than a predetermined voltage. In the electric drive control device according to any one of claims 1 to 5,
The electric drive control apparatus, wherein the power supply source includes an alternator. AC motor for traveling,
A power converter for driving the AC motor;
A power supply source for supplying power to the power converter;
Smoothing means for smoothing the output of the power supply source;
DC voltage detection means for detecting a DC voltage applied to the smoothing means;
When the DC voltage detected by the DC voltage detection means becomes a predetermined voltage or higher, the voltage phase of the AC motor is corrected, and the power conversion device is adjusted so that the DC voltage is reduced. An electric vehicle comprising control means for controlling. An engine that drives the front wheels of the vehicle, an alternator that is driven by the engine to generate DC power, a smoothing means for smoothing the output of the alternator, and a power converter that converts the DC power into AC power; An overvoltage prevention method used for a vehicle including an AC motor that drives a rear wheel of the vehicle with the converted AC power,
An overvoltage prevention method for correcting an input characteristic of the power conversion device to an input characteristic that reduces the DC voltage when a DC voltage detected by the DC voltage detection means exceeds a predetermined voltage. . In the overvoltage prevention method of Claim 8,
The step of correcting the input characteristics of the power converter is
Detecting the rotational speed of the AC motor;
Calculating a torque command required by the vehicle from the vehicle information;
Calculating a DC voltage command of the power supply source based on the detected rotational speed of the AC motor and the calculated torque command;
Calculating a deviation between the calculated DC voltage command and the DC voltage detected by the DC voltage detecting means;
Calculating a voltage phase correction value based on the deviation;
An overvoltage prevention method comprising a step of correcting a voltage phase of the AC motor based on the voltage phase correction value. In the overvoltage prevention method according to claim 9,
The step of correcting the input characteristics further includes:
Calculating a motor control current command based on the detected rotational speed of the AC motor and the calculated torque command;
Detecting a motor control current of the AC motor;
Detecting a motor rotation position of the AC motor;
Based on the calculated motor control current command, the detected motor control current, the detected motor rotation position, the detected rotational speed of the AC motor, and the calculated voltage phase correction value, the power conversion An overvoltage prevention method comprising a step of generating a drive signal for a device. The overvoltage prevention method according to any one of claims 8 to 10,
An overvoltage prevention method, wherein a field current is controlled by inputting the deviation into a field controller of the alternator so that an output voltage of the alternator matches the calculated DC voltage command.

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