JP2009077506A - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller with the operation performance improved. <P>SOLUTION: This motor controller has a DC-AC converting means which converts DC voltage into AC voltage and supplies it to a three-phase brushless DC motor; an induced voltage detecting means which detects the induced voltage of the brushless DC motor, a magnetic pole position detecting means which detects the magnetic pole position of the brushless DC motor from the induced voltage; a first voltage control means which outputs voltage waveform, based on the magnetic pole position outputted by the magnetic pole detecting means; a PWM control means which converts the voltage waveform into a PWM signal; and a regeneration voltage detecting means which detects the regeneration voltage, contained in the induced voltage wherein the regeneration voltage factor is set, on the basis of physical quantity relating to the motor current. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device that controls the frequency of a brushless DC motor.

  Conventional motor control devices for controlling the rotational speed of a brushless DC motor include a 120 ° energization control system and a sine wave 180 ° energization control. Patent documents of the 120 ° energization control method include, for example, Patent Literature 1, and patent documents of the 180 ° energization control method include, for example, Patent Literature 2 and Patent Literature 3.

  The 120 ° energization method is a method of directly detecting the zero-cross signal of the induced voltage, and is obtained by comparing the inverter phase voltage with the reference voltage in order to detect it. The commutation signal is changed based on this zero cross signal. This zero cross signal is generated 12 times during one rotation of the motor, and is generated every mechanical angle 30 °, that is, every electrical angle 60 °.

  The 180 ° energization method amplifies the differential voltage between the neutral point potential of the motor winding and the neutral point potential of the three-phase Y-connected resistor to the three-phase inverter output voltage, and inputs it to the integration circuit The position detection signal corresponding to the induced voltage is obtained by comparing the output signal of the integration circuit with the low-pass signal obtained by processing the output signal with a filter circuit and cutting the direct current.

This position detection signal is generated 12 times during one rotation of the motor, and is generated every 30 ° mechanical angle, that is, every 60 ° electrical angle. In this method, phase correction control is required because the integration circuit is passed.
Japanese Patent No. 2642357 JP 7-245982 A Japanese Patent Laid-Open No. 7-337079

  Problems in the conventional configuration will be described. FIG. 6 is a control block diagram of a conventional motor control device.

  Since this 120 ° energization method compares the zero crossing of the induced voltage part, if the motor load sudden change or the power supply voltage sudden change occurs, the induced voltage zero crossing signal will be hidden in the inverter output voltage region and detected. It may not be possible. In such a state, first, a step-out phenomenon occurs and the inverter system stops.

  In addition, at 120 ° energization, the induced voltage per phase can be confirmed continuously for 60 ° electrical angle, but in order to reduce the noise and vibration during motor operation, the energization angle is set to about 150 ° for operation. If this is the case, the induced voltage per phase can only be confirmed continuously for an electrical angle of 30 °, and the risk of step-out increases due to the effect of the inverter regenerative voltage even during normal operation, and unstable phenomena such as turbulence occur. There was a tendency to occur easily.

  Further, this configuration has a problem that an operation close to 180 ° energization is impossible. FIG. 7A is a relationship diagram between the phase current waveform and the induced voltage waveform of 120 ° energization control. During normal operation, the phase current 20 is set to the position of the induced voltage 10 and when the maximum rotation speed is increased, the phase current 20 needs to be advanced, but the limit is fast and the high-speed rotation performance is inferior.

  FIG. 7B is a relationship diagram between the phase current waveform and the induced voltage waveform in the 180 ° energization control. Since the 180 ° energization method passes through the integration circuit, the zero-cross position of the induced voltage cannot be accurately grasped with an absolute value, and the phase difference between the zero-cross position and the position detection signal varies greatly depending on the operating state. Complicated control such as phase correction is required, which makes it difficult to adjust the phase correction and makes the control calculation complicated.

  Further, the motor requires a neutral point output terminal, and uses the third harmonic component of the induced voltage waveform, and therefore has a problem that it cannot be used in a motor using a sine wave magnetized magnet.

  In addition, in the sensorless sine wave 180 ° energization drive control by the current feedback method, the motor magnetic pole position is estimated and calculated by the motor current and the motor electrical constant, so the calculation error becomes large, and the limit point of the motor current advance control is There was a problem that the maximum number of rotations was not far from control with a position sensor.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to provide a 180 ° sine wave with a position sensor by applying a new method of induced voltage feedback control that does not require a mechanical electromagnetic pickup sensor. An object of the present invention is to provide a motor control device that achieves a high speed performance of the same level, further improves the step-out limit torque in any operating load region, and is inexpensive and highly reliable.

  The present invention includes a plurality of switching elements, a DC / AC conversion means for converting a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching element and supplying the AC voltage to a three-phase brushless DC motor, Inductive voltage detection means for detecting, magnetic pole position detection means for detecting the magnetic pole position of the brushless DC motor from the induced voltage, and voltage control means for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means And a PWM control means for converting the voltage waveform into the PWM signal, a regenerative voltage detection means for detecting a regenerative voltage included in the induced voltage, and the detected regenerative voltage and the induced voltage. Magnetic pole position detecting means for determining the magnetic pole position based on the reference voltage, and the regenerative voltage detecting means The regenerative voltage is determined by comparing the reference voltage with the induced voltage, and the reference voltage is the above (DC voltage value) × (regenerative voltage coefficient) or (DC voltage value) × (1-regenerative voltage). Voltage coefficient), and the regenerative voltage coefficient is set based on a physical quantity related to the motor current.

  The regenerative voltage coefficient is increased when the motor current effective value is large, and is decreased when the motor current effective value is small.

  The regenerative voltage coefficient is a linear function expression of the effective motor current value.

  The regenerative voltage coefficient is increased when the motor current amplitude is large, and is decreased when the motor current amplitude is small.

  The regenerative voltage coefficient is a linear function equation of motor current amplitude.

According to the motor control device of the present invention, it is possible to provide a motor control device that avoids the step-out phenomenon due to the regenerative voltage, and it is possible to construct an inverter system corresponding to a wide range of operation loads at a low cost and the motor current fluctuation is extremely large. However, since the regenerative voltage can be accurately determined and erroneous detection of the induced voltage can be prevented, it is possible to provide a motor control device that is highly responsive, stable, and reliable with respect to current changes.

  Embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, a motor control device according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a control block diagram of the motor control device of the present embodiment. The motor control device of the present embodiment is a motor control device that controls the rotation speed of the three-phase brushless DC motor 7.

  In this figure, the motor control device converts a DC voltage 4 into an AC voltage and outputs it to a three-phase brushless DC motor (hereinafter abbreviated as BLM) 7 and an induction for detecting an induced voltage of the BLM 7. A voltage detection means 1; a magnetic pole position detection means 2 for detecting the magnetic pole position of the brushless DC motor from the induced voltage; a voltage control means 3 for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means 2; PWM control means 5 for converting a voltage waveform into a PWM signal, regenerative voltage detection means 8 for detecting a regenerative voltage included in the induced voltage, and a magnetic pole position for determining a magnetic pole position based on the detected regenerative voltage and the induced voltage And detecting means 2.

  FIG. 2A is a configuration diagram of the DC / AC converting means according to the present embodiment, and FIG. 2B is a field induced voltage waveform relationship diagram of the three-phase brushless DC motor.

  As shown in FIG. 2A, the PWM control means 5 outputs a PWM signal for controlling the applied voltage, frequency, and phase for controlling the rotation speed of the BLM 7. The DC / AC converting means 6 comprises six switching elements that open and close at high speed.

  First, the roles of the induced voltage detection means 1, the magnetic pole position detection means 2, the voltage control means 3, and the PWM control means 5 will be described sequentially in FIG. This portion is the same as the operation of the control block diagram of the conventional motor control device in FIG.

  In FIG. 1, the induced voltage detection means 1 lowers the induced voltage of the BLM 7, the magnetic pole position detection means 2 detects the induced voltage zero cross signal, and outputs the induced voltage zero cross signal to the voltage control means 3 as the magnetic pole position. Based on the magnetic pole position, the voltage control means 3 calculates a voltage waveform for driving the BLM 7 and outputs it to the PWM control means 5.

  Based on the voltage waveform, the PWM control means 5 outputs a PWM signal to the DC / AC conversion means 6. In the motor control apparatus configured as described above, the rotation speed of the BLM 7 is controlled by changing the frequency and phase (hereinafter referred to as “inverter frequency”) of the AC voltage output from the DC / AC conversion means 6. .

  In the case of 120 ° energization control, the PWM control means 5 outputs six kinds of PWM signals for opening and closing the switching elements of the direct current to alternating current conversion means 6, and the switching elements are opened and closed by the six kinds of PWM signals. The inverter frequency output from the AC conversion means 6 is controlled.

  Six kinds of PWM signals will be described. The six types of PWM signals are pulse signals for driving the switching elements of the DC / AC converter 6. The PWM signal has six basic patterns PTN1 to PTN6 in one cycle of the inverter electrical angle, and the reciprocal of one cycle of the PWM signal is the inverter frequency.

  Actually, the method for changing the rotation speed of the BLM 7 is that the PWM control means 5 controls the rotation speed of the BLM 7 while changing the inverter frequency of the DC / AC conversion means 6.

  As shown in FIG. 2 (a), the DC / AC converting means 6 has six switching elements. For the U-phase, V-phase, and W-phase, one switching element is provided in the upper arm and the lower arm is switched. One element is provided.

  In PTN1, the U-phase upper arm switching element Tu and the V-phase lower arm switching element Ty are energized. In PTN2, the U-phase upper arm switching element Tu and the W-phase lower arm switching element Tz are energized. In PTN3, the V-phase upper arm switching element Tv and the W-phase lower arm switching element Tz are energized.

  In PTN4, the V-phase upper arm switching element Tv and the U-phase lower arm switching element Tx are energized. In PTN5, the W-phase upper arm switching element Tw and the U-phase lower arm switching element Tx are energized. In PTN6, the W-phase upper arm switching element Tw and the V-phase lower arm switching element Ty are energized.

  The commutation switching of the PWM signal is performed based on the voltage waveform output of the voltage control means 3.

  The detailed operation of the magnetic pole position detecting means 2 will be described with reference to FIG. 2B and FIGS. 3 and 4 are explanatory diagrams of the operation of the regenerative voltage detecting means according to this embodiment.

  The induced voltage zero cross signal of the BLM 7 is generated six times during one electrical angle cycle. FIG. 3A shows the induced voltage zero-cross signal per phase. FIG. 3A is a relationship diagram of the phase current waveform and the phase induced voltage waveform, and shows the induced voltage 10, the phase current 9, the positive zero cross signal 11 and the reverse zero cross signal 12.

  The positive zero cross signal 11 is generated at an electrical angle of 0 °, and the reverse zero cross signal 12 is generated at an electrical angle of 180 °. The induced voltage that can be actually observed by the magnetic pole position detecting means 2 is the induced voltage 10a in FIG. 3B and the induced voltage 10b in FIG. 4B if the negative side of the DC voltage 4 is the GND potential N. This means that the line voltage of the BLM 7 is observed. If the induced voltage near the zero cross signal is considered, the waveform of the induced voltage 10 is superimposed on the PWM voltage component. .

  Basically, the intersection of the half of the DC voltage VDC (= VDC / 2) and the induced voltage 10a (10b), and further the conduction point of each of the upper and lower arm elements of the DC / AC converting means 6 is one. The positive zero cross signal 11 (reverse zero cross signal 12) can be detected during the arcing period (TON portion in FIGS. 3 and 4).

  The magnetic pole position detection means 2 detects the positive zero cross signal 11 and the reverse zero cross signal 12 in the figure, and outputs them to the voltage control means 3 as the magnetic pole position. Based on the zero cross signal, the voltage control means 3 calculates a voltage waveform substantially similar to the phase current 9, and the PWM control means 5 creates a PWM signal base PTN corresponding to each electrical angle based on the voltage waveform. To do.

  The electrical angles X1 to X2 in FIG. 3 and the electrical angles X3 to X4 in FIG. 4 are current cut sections. Further, the voltage control means 3 can create a voltage waveform of a 120 ° to 180 ° energization waveform. However, in order to observe the induced voltage, it is necessary to make the conduction angle less than 180 °.

When the conduction angle> 120 °, in addition to the six PWM signals described in the 120 ° conduction control, a three-phase sine wave drive PWM signal is added. Basically, a PWM signal for 120 ° energization control is used in a section where the current is OFF in any one of the three phases (≡current cut section). In the section where the phase current flows in all three phases, the PWM signal for three-phase sine wave drive is used. Since this PWM signal is already known as three-phase sine wave PWM control, detailed description thereof is omitted here.

  The voltage waveform output by the voltage control means 3 is almost similar to that of the phase current 9, but the phase difference is somewhat advanced with respect to the phase current 9. In the present embodiment, for simplification, the phase difference is described as zero. That is, voltage waveform ≡phase current 9 is defined.

  FIG. 8 is an equivalent circuit diagram of the BLM7. R1 is the primary resistance of the winding, Lu · Lv · Lw is the inductance of each phase, and Eu · Ev · Ew is the field induced voltage of each phase. Here, the field induced voltage means an induced voltage generated only by a magnet (field) when the BLM 7 rotates in a non-energized state.

  FIG. 2B is a field induced voltage waveform relationship diagram of the three-phase brushless DC motor. In the figure, U1 represents the positive zero cross position of Eu, and U2 represents the reverse zero cross position. Similarly, the other phases are also shown, and the interval between the zero cross positions is ideally generated 6 times every 60 ° and one cycle of the electrical angle. These zero-cross positions are named as the true magnetic pole positions of the BLM7.

  The true magnetic pole position of the BLM 7 cannot be determined directly from the zero cross signal of the induced voltage 10 due to the influence of the armature reaction, and a phase difference occurs between the two. Further, since this phase difference depends on the operating load, it is difficult to specify the true magnetic pole position from the induced voltage zero cross signal.

However, even if the true magnetic pole position cannot be specified, it is sufficiently possible to control the rotation speed of the BLM 7 only by the induced voltage zero cross signal, and it may be preferable to control by the induced voltage. In the present embodiment, description will be made assuming that the phase difference between the two is zero. That is,
True magnetic pole position ≡ induced voltage zero cross position. That is, if the induced voltage 10 in FIG. 3A corresponds to the U phase,
Zero cross U1 = positive zero cross signal 11
Zero cross U2 = Reverse zero cross signal 12
It is. In addition,
Eu ≠ induced voltage 10
It is. The above equation is generated because the voltage waveform amplitudes of both are different due to the influence of the armature reaction.

  Next, the detailed operation of the regenerative voltage detection means 8 will be described with reference to FIGS.

  Generally, as a condition for generating the regenerative voltage, the regenerative voltage is generated continuously for a predetermined time from the moment when the phase current of the BLM 7 is cut, and then the original induced voltage is generated. The output of the induced voltage detection means 1 includes both the regenerative voltage and the induced voltage, and both need to be distinguished. If this determination is wrong, the regenerative voltage portion is erroneously detected as a zero-cross signal of the induced voltage, and abnormal phenomena such as turbulence and step-out occur.

  FIG. 3B and FIG. 4B show the relationship between the regenerative voltage and the induced voltage. FIG. 3 shows a case where the time differential value is positive as the induced voltage 10, and FIG. 4 shows a case where the time differential value is negative as the induced voltage 10.

In the figure, the regenerative voltage 13 and the regenerative voltage 14 are generated from the moment when the phase current 9 is cut and continue to the regenerative voltage end point 19 and the regenerative voltage end point 22. As one of the necessary conditions for determining the positive zero cross signal 11,
Induced voltage 10a ≧ VDC / 2
As one of the necessary conditions for determining the reverse zero cross signal 12,
Induced voltage 10b ≦ VDC / 2
There is. However, since the voltage value of the regenerative voltage 13 is VDC before the positive zero cross signal 11 is detected, the relationship of the above equation is already satisfied and erroneous detection occurs.

  In order to prevent this, in the position detection in the figure, if the position detection result is ignored before the regenerative voltage end point 19 and the position detection determination is started after the regenerative voltage end point 19, the regenerative voltage 13 is supplied to the positive zero cross signal 11. As a false positive.

  Similarly, in the case of the reverse zero cross signal 12, the voltage value of the regenerative voltage 14 is 0 V, which already satisfies the relationship of the above equation and erroneously detects. In order to prevent this, the determination of the position detection section in the figure is started after the regenerative voltage end point 22.

  Thus, the regenerative voltage detecting means 8 outputs the regenerative voltage end point 19 and the regenerative voltage end point 22 to the magnetic pole position detecting means 2 as a regeneration end signal, and the magnetic pole position detecting means 2 receives the regenerative voltage until receiving the signal. 13. Ignore position detection of regenerative voltage 14. If the signal is received, determination of position detection is started, so that the original positive zero cross signal 11 and reverse zero cross signal 12 can be determined.

The regenerative voltage detection means 8 has a VTH1 regenerative determination reference voltage 17 and a VTH2 regenerative determination reference voltage 18 inside, and makes a determination by comparing the value with the regenerative voltage 13 and the regenerative voltage 14. Specifically, VTH 1 regeneration determination reference voltage 17 = (1−regenerative voltage coefficient) * VDC
VTH2 regeneration judgment reference voltage 18 = regenerative voltage coefficient * VDC
It is. The regenerative voltage coefficient may be set appropriately. The regenerative voltage detection means 8 samples the regenerative voltage 13 and the regenerative voltage 14. That is, the regeneration detection point 15 and the regeneration detection point 16.

  The regenerative voltage detection means 8 performs voltage sampling from the electrical angles X1 and X3, which are current cut start points, and obtains the voltage Vij between the regenerative detection point 15 and the regenerative detection point 16. This voltage Vij will be described with reference to FIG.

  FIG. 5 illustrates the voltage sampling operation of the regenerative voltage detection means 8. T = 0 in the figure corresponds to the electrical angles X1 and X3 of the current cut start point. From T = 0, the regenerative voltage detection means 8 starts sampling the induced voltage of the induced voltage detection means 1 (which is still the regenerative voltage at this time), and the regenerative voltage end point 19 and the regenerative voltage end point 22 at which the regenerative voltage ends. Thus, a regeneration end signal is generated for the magnetic pole position detecting means 2.

From T = 0, a Vij regeneration detection point 30 that is a regenerative voltage acquisition at time Tij31 intervals is acquired,
V0j, V1j, V2j, ..., Vij
The regenerative voltage is determined every time. Here, i and j are arbitrary natural numbers.

When judging the regenerative voltage,
Vi = Σ (Vip) / (j + 1); p = 0 → j
And the regenerative voltage is determined by comparing Vi with VTH1 or VTH2. That is, in the case of FIG.
Vi ≧ VTH1
In the case of FIG.
Vi ≦ VTH2
If so, Vi is regarded as a regenerative voltage.

  While the above condition is satisfied, the magnetic pole position detecting means 2 ignores all the position detection results. When the above condition is not satisfied, the regenerative voltage detecting means 8 sends a regeneration end signal to the magnetic pole position detecting means 2, and the magnetic pole position detecting means 2 receives the signal to detect the position. Start judgment.

  The magnetic pole position detection means 2 obtains the positive zero cross signal 11 and the reverse zero cross signal 12 according to the conventional determination criterion described above when the regeneration end signal is received. When the position determination is finished, the current cut is finished at the electrical angle X2 after the elapse of the wait time in FIGS. 3 and 4, and phase commutation (switching of the base PTN) is performed.

  When the regenerative voltage coefficient is changed in accordance with the change of the motor current effective value IRMS / motor current amplitude IAMP of the motor current, which is the output of the motor current detecting means 41, the control responsiveness is greatly improved.

Regenerative voltage coefficient = K1 · IRMS
Or
Regenerative voltage coefficient = K2 / IAMP
You can use mathematical expressions. here,
K1, K2> 0
It is a real number that satisfies

In addition, for the regenerative voltage coefficient obtained from each formula above, it is better to set the upper limit value / lower limit value,
0 <Regenerative voltage coefficient <0.5
It should be set within a real number that satisfies

  The above expression and the regenerative voltage coefficient mean that the regenerative voltage coefficient is increased when the motor current effective value / motor current amplitude increases. In this case, since the DC voltage is usually reduced, a correction effect of reducing the regeneration determination reference voltage VTH1 in a feed forward manner is produced.

  When the motor current effective value / motor current amplitude decreases, the regenerative voltage coefficient is decreased. In this case, since the DC voltage is normally increased, a correction effect for increasing the regeneration determination reference voltage VTH1 in a feed forward manner is produced.

  As a result, control stability and responsiveness to motor current fluctuation are improved, and erroneous detection of the regenerative voltage can be prevented indirectly, and the induced voltage can be accurately captured.

  The present embodiment has been described by taking a three-phase brushless DC motor as an example. However, the concept of application to a single-phase brushless DC motor is the same, and does not depart from the spirit, concept, and claims of the present invention. The embodiment can be changed, added, or deleted as appropriate within the scope.

  The motor control device according to the present invention can be applied to an inverter device for an air conditioner and the like because a motor control device with high operation reliability can be constructed even when the motor current changes.

Control block diagram of motor control apparatus according to embodiment 1 of the present invention (A) Configuration diagram of DC / AC conversion means according to Embodiment 1 of the present invention (b) Field-induced voltage waveform relationship diagram of three-phase brushless DC motor Operation explanatory diagram of the regenerative voltage detection means according to the first embodiment of the present invention. Operation explanatory diagram of the regenerative voltage detection means according to the first embodiment of the present invention. Operation explanatory diagram of the regenerative voltage detection means according to the first embodiment of the present invention. Control block diagram of a conventional motor control device Relationship diagram between phase current waveform and induced voltage waveform of conventional motor controller Equivalent circuit diagram of three-phase brushless DC motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induced voltage detection means 2 Magnetic pole position detection means 3 Voltage control means 4 DC voltage 5 PWM control means 6 DC alternating current conversion means 7 Brushless DC motor (BLM)
8 regenerative voltage detection means 9 phase current 10 induced voltage 11 positive zero cross signal 12 reverse zero cross signal 13 regenerative voltage 14 regenerative voltage 15 regenerative detection point 16 regenerative detection point 17 regenerative determination reference voltage 18 regenerative determination reference voltage 19 regenerative voltage end point 20 phase Current 21 Phase current 22 Regenerative voltage end point 30 Regeneration detection point 31 Regeneration detection time interval 41 Motor current detection means

Claims (5)

DC-AC conversion means that includes a plurality of switching elements, converts a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching element, and supplies the AC voltage to a three-phase brushless DC motor, and an induced voltage for detecting the induced voltage of the brushless DC motor Detection means; magnetic pole position detection means for detecting the magnetic pole position of the brushless DC motor from the induced voltage; voltage control means for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means; In a motor control device having PWM control means for converting a waveform into the PWM signal,
Regenerative voltage detection means for detecting a regenerative voltage included in the induced voltage, and magnetic pole position detection means for determining the magnetic pole position based on the detected regenerative voltage and the induced voltage, and the regenerative voltage detection The means has a predetermined reference voltage and determines the regenerative voltage by comparing the reference voltage with the induced voltage, and the reference voltage is the (DC voltage value) × (regenerative voltage coefficient) or (DC voltage voltage). Value) × (1−regenerative voltage coefficient), and the regenerative voltage coefficient is set based on a physical quantity related to the motor current. The motor control device according to claim 1, wherein the regenerative voltage coefficient is increased when the motor current effective value is large, and is decreased when the motor current effective value is small. The motor control device according to claim 2, wherein the regenerative voltage coefficient is a linear function expression of a motor current effective value. The motor control device according to claim 1, wherein the regenerative voltage coefficient is increased when the motor current amplitude is large and is decreased when the motor current amplitude is small. The motor control device according to claim 4, wherein the regenerative voltage coefficient is a linear function expression of motor current amplitude.

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