JP3360328B2 - Method and apparatus for driving permanent magnet motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for driving a permanent magnet motor, and more particularly, to a method and an apparatus for driving a permanent magnet motor without providing a sensor for detecting the position of a rotor. About.

[0002]

2. Description of the Related Art Conventionally, in response to a strong demand for higher efficiency and higher accuracy of an AC motor, for example, a rotor is constituted by a permanent magnet, and a phase of a voltage and a current applied to a coil wound around a stator is adjusted. Attention has been paid to a permanent magnet motor controlled to obtain a rotating field. This permanent magnet motor is theoretically 2
Since there is no secondary copper loss and good controllability, it is expected that the above requirements can be sufficiently satisfied. However, in order to drive the permanent magnet motor, it is necessary to detect the position of the rotor. Therefore, if a position detection sensor is added, the size of the permanent magnet motor itself increases, and regular maintenance is performed. Is required, which leads to an increase in cost.

Focusing on this point, the position of the rotor is detected based on the terminal voltage of the permanent magnet motor, and the inverter is controlled based on the position detection result, without specially providing a position detection sensor. To control the phase of the voltage and current applied to the permanent magnet motor by means of a computer ("IEICE National Convention, 1992," Position sensorless drive of PM motor by current-source inverter ", Takehisa Koganezawa, Isao Takahashi, Kazunobu Oyama) ,reference).

FIG. 10 is an electric circuit diagram showing a configuration of a position sensorless driving device for a permanent magnet motor, which includes a three-phase diode bridge rectifier circuit 2 having a three-phase AC power supply 1 as an input, and
A step-down chopper circuit 3 using a DC voltage obtained by the three-phase diode bridge rectifier circuit 2 as a power supply, and a brushless DC representing a permanent magnet motor as a load by performing a predetermined switching operation with an output of the step-down chopper circuit 3 as an input. A voltage-type three-phase full-bridge inverter 4 comprising three pairs of switching elements 4a for supplying three-phase power to the motor 6 and a diode 4b connected in parallel with each of the switching elements 4a, and is inversely connected in parallel to the step-down chopper circuit 3. A regenerative power bypass diode 5 connected thereto, an inverter control circuit 8 that receives a voltage induced by the brushless DC motor 6 and supplies a switching command to control the brushless DC motor 6 to have a power factor of approximately 1,
It has a small-capacity capacitor 9 provided between the output terminals of the step-down chopper circuit 3.

The step-down chopper circuit 3 includes a reactor 3
b, a switching element 3a that is switching-controlled to control the current of the reactor 3b to DC, and a diode 3c connected in parallel with the electrolytic capacitor 2b via the switching element 3a. The chopper control circuit for switching the switching element 3a includes a subtractor 3d for calculating a difference between the current command value and the reactor current, a PI control unit 3e to which the subtraction result of the subtractor 3d is input, and a predetermined It has a comparator 3f that compares the magnitude of a frequency reference signal (for example, a triangular wave signal) with an output signal from the PI control unit 3e and supplies a comparison result signal to the switching element 3a as a switching command.

In the permanent magnet motor sensorless driving device having the above-described configuration, the output current of the step-down chopper circuit 3 becomes almost DC when the regenerative power bypass diode 5 is not conducting, but the regenerative power bypass diode 5 is not driven. In the conductive state, the output current of the step-down chopper circuit 3 is not constant, and the input voltage and the output voltage of the step-down chopper circuit 3 become substantially equal. Therefore, if the period during which the regenerative power bypass diode 5 conducts is short, the output current of the step-down chopper circuit 3 becomes substantially direct current, and the load current and voltage have the waveform of the current source inverter device. vice versa,
If the period during which the regenerative power bypass diode 5 conducts is long, the period during which the output voltage of the step-down chopper circuit 3 becomes constant increases, and becomes almost DC, and the load current and voltage have waveforms similar to those of the voltage type inverter device.

When performing this operation,
The switching command is supplied to the voltage-type three-phase full-bridge inverter 4 by the inverter control circuit 8 using the induced voltage of the brushless DC motor 6 as an input, so that the power factor of the brushless DC motor 6 becomes almost 1, so that the regenerative power bypass diode 5 can be shortened and can be made closer to the waveform of the current source inverter, so that harmonic components are reduced and the voltage waveform becomes closer to a sine wave, so that the brushless DC has higher efficiency and lower noise. Motor 6
Driving can be achieved.

Further, since the small-capacity capacitor 9 is connected between the output terminals of the step-down chopper circuit 3, the load current ripple can be reduced. As a result, higher harmonic components are reduced, and higher efficiency and lower noise operation can be performed.
Furthermore, leakage current, which is particularly problematic when a compressor is used as a load, can be reduced. Furthermore, since the load current ripple can be reduced by the capacitor 9,
The switching frequency of the switching element 3b of the step-down chopper circuit 3 can be reduced, and the switching loss can be reduced.

At the start, the brushless DC motor 6
Cannot be controlled by the inverter control circuit 8 because the induced voltage is zero, but the brushless DC motor 6 can be started by forcibly supplying a switching command to the voltage-type three-phase full-bridge inverter 4. After a certain amount of induced voltage is generated, a switching command is supplied by the inverter control circuit 8 to perform the above operation. In addition, when the forced operation at the time of starting is performed, an overcurrent may flow, but the overcurrent can be reliably prevented by the step-down chopper circuit 3 and a stable starting can be performed.

In addition, when the brushless DC motor 6 is used, the rotational position sensor, which has been essential, becomes unnecessary, and the main circuit functions as a current source inverter at low speed rotation which is difficult to detect with the conventional sensorless control circuit. The voltage waveform is close to a sine wave. Therefore, a low-speed region in which closed-loop control is possible can be extended, and stable operation can be achieved over a wide range. Further, the configuration of the integrator 8b, the comparator 8c and the like included in the inverter control circuit 8 can be simplified.

The inverter control circuit 8 includes a resistor voltage dividing circuit 8 for detecting a phase voltage of the brushless DC motor 6.
a, an integrator 8b receiving the phase voltage detected by the resistor voltage dividing circuit 8a as an input, a comparator 8c determining whether the output of the integrator 8b is positive or negative, and a photocoupler 8d receiving the determination result of the comparator 8c as an input. And a logic operation circuit 8e that receives a signal from the photocoupler 8d as an input and obtains and outputs a switching command. However, the integrator 8b, the comparator 8c, and the photocoupler 8d are provided for three phases. Therefore, each phase voltage is integrated by the integrator 8b, the comparator 8c determines whether the phase voltage is positive or negative, and is supplied to the logical operation circuit 8e through the photocoupler 8d. The logic operation circuit 8e obtains and outputs a switching command to the voltage-type three-phase full-bridge inverter 4 based on the positive / negative determination result of each phase so that the phase voltage and the line current become the same phase. As a result, the power factor of the brushless DC motor 6 becomes substantially 1, so that the conduction period of the regenerative power bypass diode 5 can be shortened, harmonic components can be reduced, and the load voltage waveform can be made closer to a sine wave. Therefore, high efficiency and low noise of the operation of the brushless DC motor 6 can be achieved.

[0012]

In the case where the permanent magnet motor sensorless driving device having the above structure is employed, the voltage of the element increases during the current overlapping period, the regenerative power bypass diode 5 conducts, and the electrolytic capacitor 2b Is bypassed. This bypassed voltage is superimposed on the terminal voltage of the brushless DC motor 6 as a spike voltage as shown in FIG. Particularly, at the time of high-speed operation, the overlap angle becomes large and the width of the spike voltage becomes wide. Therefore, as shown by A and B in FIG. 12, the terminal of the brushless DC motor 6 is shifted with respect to the actual rotational position of the rotor. The voltage will shift significantly. FIG. 12 also shows the position detection signal. As a result, when the rotation position of the rotor is detected based on the terminal voltage of the brushless DC motor 6, a phase error that cannot be ignored is generated, and as a result,
The phase of the motor current is shifted, the power factor is deteriorated, and the motor efficiency is reduced.

[0013] Further, in the permanent magnet motor sensorless drive device having the above-described configuration, the closed-loop control (brushless DC) is performed.
Control the switching position of the rotor based on the terminal voltage of the motor and control the switching timing of the voltage-type three-phase full-bridge inverter based on the detection result of the rotation position). It is preferable to set the gain of the integrator 8b included in the circuit 8 high, and it is possible to suppress a stall, an increase in current, and the like due to the forced operation. In addition, it is easily affected by the spike voltage and the power supply frequency component caused by the step-down chopper circuit 3. As a result, when the rotation position of the rotor is detected based on the terminal voltage of the brushless DC motor 6, it is almost ignored. Unacceptable phase errors may occur, resulting in motor current phase shift, poor power factor, and reduced motor efficiency. To become. Incidentally, the latter inconvenience may also occur in a brushless DC motor drive device that does not have the step-down chopper circuit 3 and the regenerative power bypass diode 5.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and performs an accurate rotation position detection by drastically reducing the influence of spike voltage and the like. It is an object of the present invention to provide a permanent magnet motor driving method and device capable of achieving accurate driving.

[0015]

According to a first aspect of the present invention, there is provided a method of driving a permanent magnet motor, comprising the steps of: In this method, a predetermined voltage is supplied to the switching command generating means in place of the terminal voltage of the permanent magnet motor in accordance with the detected superimposed period.

According to the method of driving a permanent magnet motor of the present invention, the terminal voltage of the permanent magnet motor in the initial stage of conduction of the regenerative power bypass means is replaced with the terminal voltage of the permanent magnet motor in response to the detected superimposition period. This is a method of supplying a voltage to the switching command generating means. A permanent magnet motor driving device according to a third aspect of the present invention includes an energization state detection unit that detects an energization state of the regenerative power bypass unit, and a permanent state in response to the energization state detection unit detecting the energization state of the regenerative power bypass unit. Switching means for supplying a predetermined voltage to the switching command generating means in place of the terminal voltage of the magnet motor.

According to a fourth aspect of the present invention, there is provided a permanent magnet motor driving device for holding a terminal voltage of a permanent magnet motor at a corresponding point in time in response to a detection of an energized state of a regenerative power bypass unit by an energized state detection unit. Means, further comprising, as switching means, in response to the energized state of the regenerative power bypass means being detected by the energized state detecting means,
In this case, a voltage corresponding to the terminal voltage held by the holding means is supplied to the switching command generating means instead of the terminal voltage of the permanent magnet motor.

[0018]

[0019]

[0020]

According to the method for driving a permanent magnet motor of the first aspect,
The rectified output of the rectifying means having an AC power supply as input is stepped down by the step-down chopper means, and a switching command is generated by the switching command generating means in accordance with the rotor position detection signal obtained based on the terminal voltage of the permanent magnet motor. In addition, the permanent magnet motor is driven by inverter means which is controlled based on the generated switching command and receives a stepped-down DC power supply, and a regenerative power bypass means is provided in parallel with the step-down chopper means to overlap the current. In the case of coping with the rise of the voltage of the switching element in the above, the superposition period of the voltage bypassed by the regenerative power bypass means and the terminal voltage of the permanent magnet motor is detected, and the permanent magnet motor is Since a predetermined voltage is supplied to the switching command generation means instead of the terminal voltage of Therefore, the phase error can be greatly reduced compared to the case where the terminal position of the permanent magnet, which generates a large phase error due to the influence of the spike voltage, is used as it is to detect the rotational position of the rotor. The detection of the rotational position of the child can be performed with high accuracy, and thus the permanent magnet motor can be driven with high efficiency and high accuracy.

According to the permanent magnet motor driving method of the present invention, the terminal voltage of the permanent magnet motor in the initial stage of conduction of the regenerative power bypass means is replaced with the terminal voltage of the permanent magnet motor in accordance with the detected superimposition period. Since the corresponding voltage is supplied to the switching command generating means, the voltage supplied to the switching command generating means instead of the terminal voltage of the permanent magnet motor becomes the voltage corresponding to the voltage immediately before the spike voltage generation, and the phase error is reduced. Thus, the rotational position of the rotor can be detected with higher accuracy, and the permanent magnet motor can be driven with higher efficiency and higher accuracy.

According to a third aspect of the present invention, the rectification output of the rectification unit to which the AC power is input is reduced by the step-down chopper unit, and the rotor position obtained based on the terminal voltage of the permanent magnet motor is obtained. A switching command is generated by the switching command generating means in response to the detection signal, and is controlled based on the generated switching command.
In addition, the permanent magnet motor is driven by inverter means having a stepped-down DC power source as input, and a regenerative power bypass means is provided in parallel with the step-down chopper means to drive the permanent magnet motor by bypassing the voltage rise of the switching element. In this case, the energized state of the regenerative power bypass means is detected by the energized state detecting means, and in response to the energized state of the regenerative power bypass means being detected by the energized state detecting means, the terminal voltage of the permanent magnet motor is changed by the switching means. Since the predetermined voltage is supplied to the switching command generating means in place of the above, the rotational position of the rotor is detected by directly using the terminal voltage of the permanent magnet having a large phase error under the influence of the spike voltage. Compared with the case, the phase error can be greatly reduced, and the detection of the rotational position of the rotor can be performed with high accuracy. Information, highly efficient permanent magnet motor, the drive precision can be achieved.

According to the permanent magnet motor driving device of the present invention, the terminal voltage of the permanent magnet motor at the corresponding time is held in response to the detection of the energized state of the regenerative electric power bypass means by the energized state detecting means. A terminal held by the holding means in place of the terminal voltage of the permanent magnet motor in response to the energized state of the regenerative power bypass means being detected by the energized state detecting means. Since the voltage corresponding to the voltage is supplied to the switching command generation means, the voltage supplied to the switching command generation means instead of the terminal voltage of the permanent magnet motor becomes the voltage corresponding to the voltage immediately before the spike voltage generation, and the phase The error can be further reduced significantly, and the detection of the rotational position of the rotor can be made even more accurate, and the permanent magnet motor can be made even more efficient and accurate. The dynamic can be achieved.

[0024]

[0025]

[0026]

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is an electric circuit diagram showing an embodiment of a permanent magnet motor driving apparatus according to the present invention, which is obtained by a three-phase diode bridge rectifier circuit 2 having a three-phase AC power supply 1 as an input, and a three-phase diode bridge rectifier circuit 2. Step-down chopper circuit 3 using a DC voltage as a power source, and step-down chopper circuit 3
A brushless D representing a permanent magnet motor as a load by performing a predetermined switching operation with the output of
A voltage-type three-phase full-bridge inverter 4 comprising three pairs of switching elements 4a for supplying three-phase power to the C motor 6 and a diode 4b connected in parallel with each switching element 4a, and the step-down chopper circuit 3 in parallel. A brushless DC is input to the reverse-connected regenerative power bypass diode 5 and the induced voltage of the brushless DC motor 6 as inputs.
It has an inverter control circuit 8 for supplying a switching command to control the motor 6 so that the power factor becomes substantially 1, and a small-capacity capacitor 9 provided between output terminals of the step-down chopper circuit 3.

As shown in FIG. 2, the inverter control circuit 8 includes a photocoupler 7a connected in anti-parallel with the regenerative power bypass diode 5, and an inversion circuit 7b for inverting the level of an output signal from the photocoupler 7a. And a switch control circuit 7c which receives an inversion signal output from the inversion circuit 7b as an input, and a switch control circuit 7c,
An inverter control circuit of the conventional permanent magnet motor driving device shown in FIG. 10 further includes a changeover switch 7d for selectively supplying the phase voltage or the ground voltage detected by the resistance voltage dividing circuit 8a to the integrating circuit 8b. And different.

The structure and operation of the other parts are the same as those of the conventional permanent magnet motor driving device shown in FIG.
Detailed description is omitted, and only the operation related to the difference will be described below. The photocoupler 7a turns on in response to the non-conducting state of the regenerative power bypass diode 5, and turns off in response to the conducting state. Therefore, when the regenerative power bypass diode 5 conducts during the overlap period, the photocoupler 7a is turned off, and the overlap period can be detected. Since the OFF signal of the photocoupler 7a is inverted by the inverting circuit 7b and supplied to the switch control circuit 7c, the changeover switch 7d is switched to supply the ground voltage to the integrating circuit 8b. As a result, the terminal voltage of the brushless DC motor 6 on which the spike voltage is superimposed is prevented from being supplied to the integration circuit 8b, and the integration output of the integration circuit 8b can be kept constant. In this case, both the terminal voltage on which the spike voltage is superimposed and the ground voltage are different from the terminal voltage corresponding to the rotational position of the rotor.
In general, the spike voltage is extremely large, so that the rotational position of the rotor can be detected with high accuracy by supplying the ground voltage to the integration circuit 8b. As a result, the phase error can be significantly reduced, the phase shift of the current of the brushless DC motor 6 can be greatly reduced, and the power factor can be improved and the brushless DC motor 6 can be driven efficiently.

In this embodiment, the ground voltage is supplied to the integrating circuit 8b instead of the terminal voltage on which the spike voltage is superimposed, but a predetermined voltage may be supplied instead of the ground voltage. The good thing is, of course.

[0031]

Embodiment 2 FIG. 3 is an electric circuit diagram showing a main part of another embodiment of the permanent magnet motor driving device according to the present invention. The difference from the electric circuit diagram of FIG. Is sampled and held at a predetermined timing, and a sample / hold circuit (hereinafter abbreviated as S / H circuit) 7e for holding the sampling voltage is provided instead of the ground voltage, and the S / H circuit 7e is sampled by the switch control circuit 7c. It is only a point to be controlled as needed.

In this embodiment, instead of directly supplying the terminal voltage of the brushless DC motor 6 on which the spike voltage is superimposed to the integration circuit 8b, the terminal voltage of the brushless DC motor 6 immediately before the spike voltage is generated is used. The data can be held by the S / H circuit 7e and continuously supplied to the integration circuit 8b. Therefore, compared to the case where a ground voltage that may be different from the actual terminal voltage is supplied to the integration circuit 8b, a voltage that is significantly smaller than the terminal voltage corresponding to the rotational position of the rotor is supplied to the integration circuit 8b. Thus, the rotational position of the rotor can be detected with higher accuracy. As a result, the phase error can be further reduced, and the phase shift of the current of the brushless DC motor 6 can be further greatly reduced. As a result, the power factor can be significantly improved and the brushless DC motor 6 can be driven more efficiently.

The hold of the terminal voltage in the S / H circuit 7e may be a zero-order hold,
The primary hold is preferable, and the accuracy of detecting the rotational position of the rotor can be further improved.

[0034]

Embodiment 3 FIG. 4 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving apparatus according to the present invention. Integral gain setting resistors R1 and R2 are provided in parallel with the integrating circuit 8b. ,..., Rn and corresponding switch SW
, SW2,..., And SWn, and a frequency / voltage conversion circuit (hereinafter referred to as F / F) that receives as input an output from a comparator 8c that determines whether the integration output from the integration circuit 8b is positive or negative. / V conversion circuit) 7
f, and furthermore, each switch SW1,
Comparator CMP1, CMP2,..., CMPn that outputs a switching instruction signal for SW2,.
, The output voltage from the F / V conversion circuit 7f is supplied to one input terminal, and the reference voltage corresponding to the switching frequency for each of the switches SW1, SW2,. Is supplied.

However, the integral gain setting resistors R1 and R
, Rn are preferably set to satisfy the following equation. ω> 10 · ωc ωc = ｛R0 · R1 · R2 ···· Rn · C / (R0
+ R1 + R2 +... + Rn)｝-1 Here, ω is the real angle rotation frequency of the brushless DC motor 6, and ωc is the cutoff frequency of the integration circuit 8b.

Immediately after the start of the brushless DC motor 6, that is, when the rotation frequency is extremely low, all the switches SW
Since SW1, SW2,..., And SWn are OFF, the integration process is performed with a sufficiently high integration gain determined based on the resistor R0 and the capacitor C. As a result, the operating frequency at which the brushless DC motor 6 can be driven by the closed loop control can be made sufficiently low, and the control can be shifted to the closed loop control in a short time after starting. When the operating frequency increases, the switches are sequentially turned on in response to the increase in the operating frequency.
Therefore, the resistance value that defines the integral gain decreases, and the integral gain can be reduced (see the Bode diagrams of the integrating circuits shown in FIGS. 5A and 5B). Therefore, the detection error of the rotational position due to the low frequency component can be reduced. As a result, the phase error can be significantly reduced, the phase shift of the current of the brushless DC motor 6 can be greatly reduced, and the power factor can be improved and the brushless DC motor 6 can be driven efficiently.

[0037]

Embodiment 4 FIG. 6 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving apparatus according to the present invention. The difference from the embodiment of FIG. 4 is that a plurality of resistors R1 and R2 are provided. ,
.., Rn by switches SW1, SW2,..., SWn
The only difference is that a voltage-controlled variable resistor Rv is provided instead of being connected in parallel via the DC / DC converter, and the voltage-controlled variable resistor Rv is controlled based on the output voltage from the F / V conversion circuit 7f.

Therefore, in this embodiment, instead of changing the integral gain stepwise, a brushless DC
It can be changed continuously according to the operating frequency of the motor 6, and low frequency components can be more reliably eliminated.

[0039]

Embodiment 5 FIG. 7 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving apparatus according to the present invention. The difference from the embodiment of FIG. 4 is that a plurality of resistors R1 and R2 are provided. ,
.., Rn by switches SW1, SW2,..., SWn
, A high-pass filter HPF that can be inserted through a switch SWf is provided between the resistance voltage dividing circuit 8a and the integrating circuit 8b, and the switch SWf is switched by the output voltage from the F / V conversion circuit 7f. And the point where the output of the integrating circuit 8b is located at the comparator 8c via the position correcting circuit 7g.

Therefore, in the case of this embodiment, while the operating frequency of the brushless DC motor 6 is low, this is equivalent to a reduction in the integral gain of the integrating circuit 8b. A state in which a large integral gain is obtained. Further, in a state where a sufficient integral gain is obtained, the low-frequency component can be effectively cut off by the high-pass filter HPF, so that the rotational position detection error caused by the low-frequency component can be reduced. As a result, the phase error can be significantly reduced, the phase shift of the current of the brushless DC motor 6 can be greatly reduced, and the power factor can be improved and the brushless DC motor 6 can be driven efficiently.

[0041]

Embodiment 6 FIG. 8 is a block diagram showing a main part of still another embodiment of the permanent magnet motor driving apparatus according to the present invention. The phase voltage detected by the resistance voltage dividing circuit 8a is compared with the phase comparator 10a. A phase-locked loop circuit (hereinafter abbreviated as a PLL circuit) 10 including a low-pass filter 10b and a voltage-controlled oscillation circuit (hereinafter abbreviated as a VCO circuit) 10c.
And the PLL circuit 10 detects the fundamental frequency of the phase voltage. Then, the detected fundamental frequency is set to F / V
The terminal of the brushless DC motor 6 is supplied to the conversion circuit 10d, the detected fundamental frequency is used as a frequency command value, and the voltage obtained by the F / V conversion circuit 10d is supplied to the amplitude variable circuit 10e as an amplitude command value. A signal (terminal voltage simulation signal) having the same phase and the same amplitude as the voltage is obtained, and the terminal voltage simulation signal is supplied to the integration circuit 8b.

In the case of this embodiment, even if the terminal voltage of the brushless DC motor 6 includes a spike voltage, low frequency noise, and the like, a fundamental frequency free from these effects is obtained. A terminal voltage simulation signal having the same phase and the same amplitude as the terminal voltage is obtained and integrated, so that a rotational position detection error caused by a spike voltage, a low frequency component, or the like can be reduced. As a result, the phase error can be significantly reduced, the phase shift of the current of the brushless DC motor 6 can be greatly reduced, and the power factor can be improved and the brushless DC motor 6 can be driven efficiently.

This embodiment can be applied to a permanent magnet motor driving device including the step-down chopper circuit 3 and the regenerative power bypass diode 5 as shown in FIG. The same can be applied to

[0044]

Embodiment 7 FIG. 9 is a block diagram showing a main part of an embodiment of a permanent magnet motor driving apparatus according to the present invention, wherein a phase voltage detected by a resistance voltage dividing circuit 8a is applied to a variable notch filter 1.
1a and the F / V conversion circuit 11b, and the cut-off frequency is set by supplying the output voltage from the F / V conversion circuit 11b to the variable notch filter 11a. Then, the output signal from the variable notch filter 11a is supplied to the phase correction circuit 11c to
Correct the phase so that it is in phase with the terminal voltage of the motor 6,
It is supplied to the integration circuit 8b.

The F / V conversion circuit 11b outputs a voltage corresponding to six times the frequency based on the fundamental frequency of the phase voltage. Here, the setting for outputting the voltage corresponding to the six times frequency is that the spike voltage is 6 times the basic frequency of the terminal voltage of the brushless DC motor 6.
This is because it has twice the frequency component. In the case of this embodiment, the F / V conversion circuit 11b outputs a voltage corresponding to six times the fundamental frequency of the terminal voltage of the brushless DC motor 6, and changes the cutoff frequency of the variable notch filter 11a to the brushless DC motor 6. Is set to be six times the fundamental frequency of the terminal voltage of the variable notch filter 1c by the phase correction circuit 11c.
Since the phase shift caused by 1a can be corrected, the rotational position detection error caused by the spike voltage can be reduced. As a result, the phase error can be significantly reduced, the phase shift of the current of the brushless DC motor 6 can be greatly reduced, and the power factor can be improved and the brushless DC motor 6 can be efficiently driven. Therefore, by combining with any of the above embodiments, the detection accuracy of the rotational position of the rotor can be further improved, and the brushless DC motor 6 can be driven more efficiently.

[0046]

As described above, according to the first aspect of the present invention, the superposition period of the voltage bypassed by the regenerative power bypass means and the terminal voltage of the permanent magnet motor is detected, and the superposition period is detected in accordance with the detected superposition period. Since a predetermined voltage is supplied to the switching command generating means in place of the terminal voltage of the permanent magnet motor, the rotor uses the terminal voltage of the permanent magnet, which generates a large phase error under the influence of the spike voltage, as it is. Phase error can be greatly reduced compared to the case of detecting the rotational position of the rotor, the detection of the rotational position of the rotor can be performed with high accuracy, and the permanent magnet motor can be driven with high efficiency and high precision. Has a unique effect.

According to the second aspect of the present invention, the voltage supplied to the switching command generating means instead of the terminal voltage of the permanent magnet motor becomes a voltage corresponding to the voltage immediately before the generation of the spike voltage, so that the phase error can be further reduced. In addition, it has a unique effect that the detection of the rotational position of the rotor can be made more accurate, and the permanent magnet motor can be driven with higher efficiency and higher accuracy.

According to a third aspect of the present invention, the superimposed period of the voltage bypassed by the regenerative electric power bypass unit and the terminal voltage of the permanent magnet motor is detected by the conduction state detecting unit, and switching is performed in accordance with the detected superimposed period. Since a predetermined voltage is supplied to the switching command generating means in place of the terminal voltage of the permanent magnet motor by the means, the terminal voltage of the permanent magnet which causes a large phase error under the influence of the spike voltage is used as it is. Compared with the case of detecting the rotational position of the rotor, the phase error can be greatly reduced, the detection of the rotational position of the rotor can be performed with high accuracy, and the permanent magnet motor can be driven with high efficiency and high accuracy It has the unique effect of being able to.

According to the fourth aspect of the present invention, the voltage supplied to the switching command generating means instead of the terminal voltage of the permanent magnet motor becomes a voltage corresponding to the voltage immediately before the generation of the spike voltage, so that the phase error can be further reduced. In addition, it has a unique effect that the detection of the rotational position of the rotor can be made more accurate, and the permanent magnet motor can be driven with higher efficiency and higher accuracy.

[0050]

[0051]

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a permanent magnet motor driving device according to the present invention.

FIG. 2 is an electric circuit diagram showing a main part of the inverter control circuit.

FIG. 3 is an electric circuit diagram showing a main part of another embodiment of the permanent magnet motor driving device of the present invention.

FIG. 4 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving device of the present invention.

FIG. 5 is a Bode diagram showing characteristics of an integration circuit.

FIG. 6 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving device of the present invention.

FIG. 7 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving device of the present invention.

FIG. 8 is an electric circuit diagram showing a main part of still another embodiment of the permanent magnet motor driving device of the present invention.

FIG. 9 is an electric circuit diagram showing a main part of a modified example of the permanent magnet motor driving device of the present invention.

FIG. 10 is an electric circuit diagram showing the configuration of a conventional position sensorless drive device for a permanent magnet motor.

FIG. 11 is a waveform diagram showing a state in which a spike voltage is superimposed on a terminal voltage of the brushless DC motor 6.

FIG. 12 is a waveform diagram showing a deviation of a terminal voltage of the brushless DC motor 6 with respect to an actual rotation position of a rotor.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 three-phase AC power supply 2 three-phase diode bridge rectifier circuit 3 step-down chopper circuit 4 voltage type three-phase full-bridge inverter 4 a switching element 5 regenerative power bypass diode 6 brushless DC motor 7 a photocoupler 7 c switch control circuit 7 d switch 7 e S / H Circuit 7f F / V conversion circuit 8 Inverter control circuit 10 PLL circuit R1, R2, ..., Rn, Rv Resistance SW1, SW2, ..., SWn Switch CMP1, CMP2, ..., CMPn Comparator HPF High-pass filter

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-93492 (JP, A) JP-A-61-170291 (JP, A) JP-A-1-103184 (JP, A) JP-A-2- 228701 (JP, A) JP-A-3-27785 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 6/18

Claims (4)

(57) [Claims] A rectifier output from a rectifier (2) having an AC power supply (1) as an input is stepped down by a step-down chopper (3), and a rotor obtained based on a terminal voltage of a permanent magnet motor (6). A switching command is generated by the switching command generating means (8) in response to the position detection signal, and the permanent magnet is controlled by the inverter means (4) which is controlled based on the generated switching command and receives a step-down DC power supply as an input. In a permanent magnet motor drive device for driving a motor (6) and providing a regenerative power bypass means (5) in parallel with a step-down chopper means (3) to bypass a voltage increase of a switching element (4a), A superposition period of the voltage bypassed by (5) and the terminal voltage of the permanent magnet motor (6) is detected, and corresponding to the detected superposition period, Permanent magnet motor switching command generating means a predetermined voltage in place of the terminal voltage of (6) (8)
And a permanent magnet motor driving method. 2. The terminal voltage of the permanent magnet motor (6) in the initial stage of conduction of the regenerative power bypass means (5) instead of the terminal voltage of the permanent magnet motor (6) in accordance with the detected superposition period. Voltage switching command generating means (8)
The method of driving a permanent magnet motor according to claim 1, wherein the motor is supplied to a motor. 3. A rotor obtained by stepping down a rectified output of a rectifying means (2) having an AC power supply (1) as an input by a step-down chopper means (3) and based on a terminal voltage of a permanent magnet motor (6). A switching command is generated by the switching command generating means (8) in response to the position detection signal, and the permanent magnet is controlled by the inverter means (4) which is controlled based on the generated switching command and receives a step-down DC power supply as an input. In a permanent magnet motor drive device for driving a motor (6) and providing a regenerative power bypass means (5) in parallel with a step-down chopper means (3) to bypass a voltage increase of a switching element (4a), The energization state detection means (7a) for detecting the energization state of (5) and the energization state of the regenerative power bypass means (5) are set to the energization state detection means (7a). Switching means (7c) and (7d) for supplying a predetermined voltage to the switching command generating means (8) in place of the terminal voltage of the permanent magnet motor (6) in response to the detection. Permanent magnet motor drive device. 4. A holding device that holds a terminal voltage of a permanent magnet motor (6) at a corresponding point in time in response to a detection of an energized state of a regenerative power bypass unit (5) by an energized state detection unit (7a). Means (7e), wherein the switching means (7c) (7d) comprises a regenerative power bypass means (5)
In response to the detection of the energized state of the motor by the energized state detecting means (7a), a voltage corresponding to the terminal voltage held by the holding means (7e) is replaced with the terminal voltage of the permanent magnet motor (6). 4. The permanent magnet motor drive according to claim 3, wherein the drive is supplied to a switching command generating means.