JP2021005996A - Controller for electric motor - Google Patents

Abstract

To provide a controller for an electric motor which can suppress an operational load while suppressing a variation in the torque of an electric motor associated with change in the output of the electric motor.SOLUTION: In a first interval of a control cycle of an electric motor M having the first interval to a third interval, the first interval including the peak of a first AC voltage Vv, a V-phase modulation wave Vv* according to the output of the electric motor M is output as well as the smallest or the largest value of a triangular wave is output as a U-phase modulation wave Vu* and a W-phase modulation wave Vw*. In the second interval including the peak of a second AC voltage Vu, a U-phase modulation wave Vu according to the output of the electric motor M is output as well as the smallest or the largest value of a triangular wave is output as a V-phase modulation wave Vv* and the W-phase modulation wave Vw*. In the third interval including the peak of a third AC voltage Vw, a W-phase modulation wave Vw* according to the output of the electric motor M is output as well as the smallest or the largest value of a triangular wave is output as a V-phase modulation wave Vv* and the W-phase modulation wave Vw.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for an electric motor.

As a control device for an electric motor, there is a device that shifts from three-phase modulation control or field weakening control (two-phase modulation control, third-order harmonic superimposition control, etc.) to square wave control as the output of the electric motor increases. Patent Document 1 is a related technique.

However, in the above control device, when transitioning from three-phase modulation control or field weakening control to square wave control, the on-time of the switching element of the inverter circuit that drives the motor suddenly becomes long, so that the current flowing through the motor is distorted. The torque may change suddenly and give a shock to the load connected to the motor.

Therefore, as another control device for the electric motor, the drive signal corresponding to the target torque and the target rotation speed is obtained by referring to the map showing the correspondence relationship between the torque and the rotation speed of the electric motor and the drive signal for driving the switching element. There is a device that drives the electric motor by the obtained drive signal. Patent Document 2 is a related technique.

JP-A-2018-64313 Japanese Unexamined Patent Publication No. 2013-215041

However, in the above other control devices, it is necessary to interpolate the map values so that the torque does not change suddenly even if the output of the electric motor becomes high, so that the calculation load may increase.

An object of one aspect of the present invention is to suppress a calculation load while suppressing fluctuations in the torque of the electric motor due to a change in the output of the electric motor in the control device of the electric motor.

The electric motor control device according to the present invention includes an inverter circuit and a control circuit.

When the first modulated wave is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the inverter circuit repeatedly turns on and off at a duty ratio according to the first modulated wave, and the first modulated wave becomes When the minimum or maximum value of the carrier wave, the first switching element which is always on or off, and when the second modulated wave is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the second When the second modulated wave is the minimum or maximum value of the carrier wave, the second switching element that is always on or off and the third modulated wave are repeatedly turned on and off at a duty ratio according to the modulated wave. When it is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, it is repeatedly turned on and off at a duty ratio according to the third modulated wave, and when the third modulated wave is the minimum value or the maximum value of the carrier wave. A third switching element that is always on or off is provided, and a first to third AC voltage having different phases is applied to the three phases of the electric machine by turning the first to third switching elements on and off. To drive the electric motor.

The control circuit outputs a first modulated wave corresponding to the output of the electric motor in the first section in which the peak of the first AC voltage exists in the control cycle of the electric motor including the first to third sections. At the same time, the minimum or maximum value of the carrier wave is output as the second and third modulated waves, and the second modulated wave corresponding to the output of the electric motor is output in the second section where the peak of the second AC voltage exists. At the same time, the minimum or maximum value of the carrier wave is output as the first and third modulated waves, and in the third section where the peak of the third AC voltage exists, the third modulated wave corresponding to the output of the electric motor is output. At the same time, the minimum or maximum value of the carrier wave is output as the first and second modulated waves.

As a result, in the control cycle of the motor (first to third sections), when the first to third modulated waves corresponding to the output of the motor are smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, One-phase switching element of the three-phase switching elements can be repeatedly turned on and off, that is, one-phase modulation control can be performed. Further, in the control cycle of the motor, when the first to third modulated waves corresponding to the output of the motor are the minimum value or the maximum value of the carrier wave, the three-phase switching elements are always turned on or off, that is, that is, they are always turned off. , Square wave control can be performed. Further, in the control cycle of the electric motor, the switching element can be turned on and off at a duty ratio corresponding to the first to third modulated waves, so that the on time of the switching element is gradually changed according to the output of the electric motor. be able to. Therefore, even if the output of the motor becomes high and the transition from one-phase modulation control to square wave control can be performed, the on-time of the switching element can be seamlessly changed, so that the distortion of the current flowing through the motor can be suppressed and the torque can be suppressed. Fluctuations can be suppressed. Further, since it is only necessary to switch the phase for switching the switching element for each of the first to third sections and complicated calculation is not required, the calculation load of the control device can be suppressed.

Further, the control device of the electric motor includes an electric angle detection unit that detects the electric angle of the rotor of the electric motor, and the control circuit has a voltage command value according to the output of the electric motor and an electric angle detected by the electric angle detection unit. The target electric angle calculation unit that calculates the target electric angle by the above, and when the target electric angle is in the first section, the modulation factor obtained by using the input voltage and the voltage command value of the inverter circuit is first modulated. When the target electric angle is in the second section, the input voltage of the inverter circuit and the voltage command value are used to obtain the wave and the minimum or maximum value of the carrier as the second and third modulated waves. When the modulation factor to be obtained is the second modulation wave and the minimum or maximum value of the carrier is the first and third modulation waves, and the target electric angle is in the third section, the input voltage of the inverter circuit is used. It is configured to include a modulation wave generator in which the modulation factor obtained by using the voltage command value is the third modulation wave and the minimum or maximum value of the carrier is the first and second modulation waves. May be good.

Further, the control device of the electric motor includes an electric angle detection unit that detects the electric angle of the rotor of the electric motor, and the control circuit has a voltage command value according to the output of the electric motor and an electric angle detected by the electric angle detection unit. To calculate the first voltage command value corresponding to the first AC voltage, the second voltage command value corresponding to the second AC voltage, and the third voltage command value corresponding to the third AC voltage. When the absolute value of the voltage command value calculation unit and the first voltage command value is larger than the absolute value of the second and third voltage command values, it is obtained by using the input voltage of the inverter circuit and the voltage command value. The modulation factor is the first modulation wave, the minimum or maximum value of the carrier is the second and third modulation waves, and the absolute value of the second voltage command value is the absolute value of the first and third voltage command values. When it is larger than the value, the modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value is set as the second modulation wave, and the minimum or maximum value of the carrier is set as the first and third modulation waves. , When the absolute value of the third voltage command value is larger than the absolute value of the first and second voltage command values, the modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value is set to the third. It may be configured to include a modulation wave generation unit which uses the minimum value or the maximum value of the carrier as the first and second modulation waves as well as the modulation wave.

Further, in the next calculation cycle, the control circuit may switch from the first section to the second section, switch from the second section to the third section, or from the third section to the first section. If there is a switching timing to, the switching timing may be configured to match the start timing of the next calculation cycle.

As a result, in the switching timing from the 1st section to the 2nd section, the switching timing from the 2nd section to the 3rd section, or the switching timing from the 3rd section to the 1st section, the first to first sections are used. Since each value of the modulated wave of 3 can be switched, the switching element can be turned on when the switching element does not need to be turned on, or the switching element can be turned off when the switching element needs to be turned on. It is possible to further suppress the distortion generated in the current flowing through the electric motor, and further suppress the fluctuation of the torque.

Further, the control circuit has a switching timing from the first section to the second section, a switching timing from the second section to the third section, or a switching timing from the third section to the first section. The switching timing of the respective values of the first to third modulated waves may be staggered so that the switching timings of the respective values of the first to third modulated waves do not overlap each other.

As a result, it is possible to prevent switching elements different from each other from being turned on at the same time, so that it is possible to suppress the occurrence of a reverse polarity pulse (surge voltage) and suppress electromagnetic noise. Therefore, the distortion generated in the current flowing through the electric motor can be further suppressed, and the fluctuation of the torque can be further suppressed.

Further, in the next calculation cycle, the control circuit may switch from the first section to the second section, switch from the second section to the third section, or from the third section to the first section. If there is a switching timing to, the switching time from the start timing of the next calculation cycle to the switching timing is obtained, and the frequency, which is the reciprocal of the switching time, is set until the switching time elapses from the start timing of the next calculation cycle. It may be configured to be set to the frequency of the carrier wave in the period of.

As a result, the error between the duty ratio of the drive signal and the desired duty ratio can be reduced, so that low-order harmonics can be suppressed from being applied to the current flowing through the electric motor, and torque ripple and noise vibration increase. Can be suppressed.

According to the present invention, in the control device of the electric motor, it is possible to suppress the calculation load while suppressing the fluctuation of the torque of the electric motor due to the change of the output of the electric motor.

It is a figure which shows an example of the control device of the electric motor of an embodiment. It is a figure which shows an example of the AC voltage applied to each phase, and the modulation wave corresponding to each phase in one-phase modulation control. It is a figure which shows the comparison of a V-phase modulation wave and a carrier wave, and an example of a drive signal in 1-phase modulation control. It is a figure which shows the comparison of a U-phase modulation wave and a carrier wave, and an example of a drive signal in 1-phase modulation control. It is a figure which shows the comparison of a W phase modulation wave and a carrier wave, and an example of a drive signal in 1-phase modulation control. It is a figure which shows an example of the AC voltage applied to each phase and the modulated wave corresponding to each phase in a rectangular wave control. It is a figure which shows the comparison between a V-phase modulated wave and a carrier wave, and an example of a drive signal in a rectangular wave control. It is a figure which shows the comparison between a U-phase modulated wave and a carrier wave, and an example of a drive signal in a rectangular wave control. It is a figure which shows the comparison of a W phase modulated wave and a carrier wave, and an example of a drive signal in a rectangular wave control. It is a figure which shows an example of the dq / uvw conversion part. It is a figure which shows another example of a dq / uvw conversion part. It is a flowchart which shows an example of the operation of the dq / uvw conversion part in the modification 1. It is a figure for demonstrating the setting of a switching time. It is a flowchart which shows an example of the operation of the dq / uvw conversion part in the modification 2. It is a figure for demonstrating the setting of a switching time. It is a figure which shows an example of a V-phase modulated wave, a carrier wave, and a drive signal in a modification 1. It is a figure which shows an example of the control device of the electric motor in the modification 3. It is a figure which shows an example of the dq / uvw conversion part in the modification 3. It is a flowchart which shows an example of the operation of the dq / uvw conversion part in the modification 3. It is a flowchart which shows the other example of the operation of the dq / uvw conversion part in the modification 3. It is a figure which shows an example of a V-phase modulated wave, a carrier wave, and a drive signal in a modification 3.

Hereinafter, embodiments will be described in detail based on the drawings.
FIG. 1 is a diagram showing an example of a control device for an electric motor according to an embodiment.

The control device 1 shown in FIG. 1 is a control device for driving an electric motor M mounted on a vehicle such as an electric forklift or a plug-in hybrid vehicle, and includes an inverter circuit 2 and a control circuit 3. It is assumed that the electric motor M includes an electric angle detection unit Sp (resolver or the like) that detects the electric angle θ of the rotor and sends the detected electric angle θ to the control circuit 3.

The inverter circuit 2 drives the electric motor M by the DC power supplied from the DC power supply P, and includes a voltage sensor Sv, a capacitor C, and switching elements SW1 to SW6 (IGBT (Insulated Gate Bipolar Transistor) or the like). , The current sensors Si1 and Si2 are provided. That is, one end of the capacitor C is connected to the positive electrode terminal of the DC power supply P and each collector terminal of the switching elements SW1, SW3, SW5, and the other end of the capacitor C is the negative electrode terminal of the DC power supply P and the switching elements SW2, SW4, SW6. It is connected to each emitter terminal of. The connection point between the emitter terminal of the switching element SW1 and the collector terminal of the switching element SW2 is connected to the U-phase input terminal of the motor M via the current sensor Si1. The connection point between the emitter terminal of the switching element SW3 and the collector terminal of the switching element SW4 is connected to the V-phase input terminal of the motor M via the current sensor Si2. The connection point between the emitter terminal of the switching element SW5 and the collector terminal of the switching element SW6 is connected to the input terminal of the W phase of the motor M.

The voltage sensor Sv detects an input voltage Vin output from the DC power supply P and input to the inverter circuit 2, and sends the detected input voltage Vin to the control circuit 3.

The capacitor C smoothes the input voltage Vin.
The switching element SW1 (second switching element) is turned on when the drive signal S1 is at a high level and is turned off when the drive signal S1 is at a low level. Specifically, the switching element SW1 is U-phase when the U-phase modulated wave Vu * (second modulated wave) corresponding to the output of the electric motor M is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave. When the U-phase modulated wave Vu * is the maximum value of the carrier wave, the duty ratio of the drive signal S1 becomes 100 [%] when the U-phase modulated wave Vu * is repeatedly turned on and off based on the drive signal S1 having a duty ratio corresponding to the modulated wave Vu *. , Always on, and when the U-phase modulated wave Vu * is the minimum value of the carrier wave, the duty ratio of the drive signal S1 becomes 0 [%] and is always off. When the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the U-phase modulated wave Vu * approaches the maximum value of the carrier wave as the output of the electric motor M increases. As the duty ratio of the drive signal S1 increases and the U-phase modulated wave Vu * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S1 decreases. That is, when the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW1 is repeatedly turned on and off at a duty ratio according to the output of the motor M. The carrier wave is a triangular wave, a sawtooth wave (sawtooth wave), a reverse sawtooth wave, or the like.

The switching element SW2 (second switching element) is turned on when the drive signal S2 is at a high level and is turned off when the drive signal S2 is at a low level. Specifically, when the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW2 sets the drive signal S2 having a duty ratio according to the U-phase modulated wave Vu *. When the U-phase modulated wave Vu * is the maximum value of the carrier wave, the duty ratio of the drive signal S2 becomes 0 [%], the duty ratio is always turned off, and the U-phase modulated wave Vu * is the carrier wave. When it is the minimum value, the duty ratio of the drive signal S2 becomes 100 [%] and is always on. When the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the U-phase modulated wave Vu * approaches the maximum value of the carrier wave as the output of the electric motor M increases. As the duty ratio of the drive signal S2 decreases and the U-phase modulated wave Vu * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S2 increases. That is, when the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW2 is repeatedly turned on and off at a duty ratio according to the output of the motor M.

The switching element SW3 (first switching element) is turned on when the drive signal S3 is at a high level and is turned off when the drive signal S3 is at a low level. Specifically, the switching element SW3 has a V-phase when the V-phase modulated wave Vv * (first modulated wave) corresponding to the output of the electric motor M is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave. It is repeatedly turned on and off based on the drive signal S3 having a duty ratio according to the modulated wave Vv *, and when the V-phase modulated wave Vv * is the maximum value of the carrier wave, the duty ratio of the drive signal S3 becomes 100 [%]. , Always on, and when the V-phase modulated wave Vv * is the minimum value of the carrier wave, the duty ratio of the drive signal S3 becomes 0 [%] and is always off. When the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, as the output of the electric motor M increases, the V-phase modulated wave Vv * approaches the maximum value of the carrier wave. As the duty ratio of the drive signal S3 increases and the V-phase modulated wave Vv * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S3 decreases. That is, when the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW3 is repeatedly turned on and off at a duty ratio according to the output of the motor M.

The switching element SW4 (first switching element) is turned on when the drive signal S4 is at a high level and is turned off when the drive signal S4 is at a low level. Specifically, when the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW4 sets the drive signal S4 having a duty ratio according to the V-phase modulated wave Vv *. When the V-phase modulated wave Vv * is the maximum value of the carrier wave, the duty ratio of the drive signal S4 becomes 0 [%], the duty ratio is always turned off, and the V-phase modulated wave Vv * is the carrier wave. When it is the minimum value, the duty ratio of the drive signal S4 becomes 100 [%] and is always on. When the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, as the output of the electric motor M increases, the V-phase modulated wave Vv * approaches the maximum value of the carrier wave. As the duty ratio of the drive signal S4 decreases and the V-phase modulated wave Vv * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S4 increases. That is, when the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW4 is repeatedly turned on and off at a duty ratio according to the output of the motor M.

The switching element SW5 (third switching element) is turned on when the drive signal S5 is at a high level and is turned off when the drive signal S5 is at a low level. Specifically, the switching element SW5 has a W phase when the W phase modulated wave Vw * (third modulated wave) corresponding to the output of the electric motor M is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave. It is repeatedly turned on and off based on the drive signal S5 having a duty ratio according to the modulated wave Vw *, and when the W-phase modulated wave Vw * is the maximum value of the carrier wave, the duty ratio of the drive signal S5 becomes 100 [%]. , Always on, and when the W-phase modulated wave Vw * is the minimum value of the carrier wave, the duty ratio of the drive signal S5 becomes 0 [%] and is always off. When the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, as the output of the electric motor M increases, the W-phase modulated wave Vw * approaches the maximum value of the carrier wave. As the duty ratio of the drive signal S5 increases and the W-phase modulated wave Vw * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S5 decreases. That is, when the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW5 is repeatedly turned on and off at a duty ratio according to the output of the motor M.

The switching element SW6 (third switching element) is turned on when the drive signal S6 is at a high level and is turned off when the drive signal S6 is at a low level. Specifically, when the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW6 sets the drive signal S6 having a duty ratio according to the W-phase modulated wave Vw *. When the W-phase modulated wave Vw * is the maximum value of the carrier wave, the duty ratio of the drive signal S6 becomes 0 [%], the duty ratio is always turned off, and the W-phase modulated wave Vw * is the carrier wave. When it is the minimum value, the duty ratio of the drive signal S6 becomes 100 [%] and is always on. When the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, as the output of the electric motor M increases, the W-phase modulated wave Vw * approaches the maximum value of the carrier wave. As the duty ratio of the drive signal S6 decreases and the W-phase modulated wave Vw * approaches the minimum value of the carrier wave, the duty ratio of the drive signal S6 increases. That is, when the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching element SW6 is repeatedly turned on and off at a duty ratio according to the output of the motor M. When the drive signals S1 to S6 are not particularly distinguished, they are simply referred to as drive signals S.

When the switching elements Sw1 to SW6 are turned on and off, the DC input voltage Vin output from the DC power supply P is different from each other by 120 degrees in phase from the first AC voltage Vv, the second AC voltage Vu, and It is converted to a third AC voltage Vw. Then, the first AC voltage Vv is applied to the V-phase input terminal of the motor M, the second AC voltage Vu is applied to the U-phase input terminal of the motor M, and the third AC voltage Vw is the motor M. When applied to the W-phase input terminal, the rotor of the motor M rotates.

The current sensor Si1 is composed of a Hall element, a shunt resistor, and the like, and detects the U-phase current Iu flowing in the U-phase of the motor M and outputs it to the control circuit 3. Further, the current sensor Si2 is composed of a Hall element, a shunt resistor, and the like, and detects the V-phase current Iv flowing in the V-phase of the electric motor M and outputs it to the control circuit 3.

The control circuit 3 includes a drive circuit 4, a calculation unit 5, and a storage unit 6. The storage unit 6 is composed of a RAM (Random Access Memory), a ROM (Read Only Memory), or the like, and will be described later with a section and a U-phase modulated wave Vu *, a V-phase modulated wave Vv *, and a W-phase modulated wave Vw. Information D1 indicating the correspondence with *, information D2 indicating the correspondence between the branching condition with the U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw *, etc. are stored. To do.

The drive circuit 4 is composed of an IC (Integrated Circuit) or the like, and compares the U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * output from the arithmetic unit 5 with the carrier wave. Drive signals S1 to S6 according to the comparison result are output to the respective gate terminals of the switching elements SW1 to SW6.

For example, in the drive circuit 4, when the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio increases as the U-phase modulated wave Vu * approaches the maximum value of the carrier wave. The drive signal S1 is output, and the duty ratio becomes smaller as the U-phase modulated wave Vu * approaches the minimum value of the carrier wave. Further, when the U-phase modulated wave Vu * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S1 having a duty ratio of 100 [%], and the U-phase modulated wave Vu * is the minimum value of the carrier wave. In this case, the drive signal S1 having a duty ratio of 0 [%] is output.

Further, in the drive circuit 4, when the U-phase modulated wave Vu * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio becomes smaller as the U-phase modulated wave Vu * approaches the maximum value of the carrier wave. The drive signal S2 is output, and the duty ratio increases as the U-phase modulated wave Vu * approaches the minimum value of the carrier wave. Further, when the U-phase modulated wave Vu * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S2 having a duty ratio of 0 [%], and the U-phase modulated wave Vu * is the minimum value of the carrier wave. In this case, the drive signal S2 having a duty ratio of 100 [%] is output.

Further, in the drive circuit 4, when the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio increases as the V-phase modulated wave Vv * approaches the maximum value of the carrier wave. The drive signal S3 is output, and the duty ratio becomes smaller as the V-phase modulated wave Vv * approaches the minimum value of the carrier wave. Further, when the V-phase modulated wave Vv * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S3 having a duty ratio of 100 [%], and the V-phase modulated wave Vv * is the minimum value of the carrier wave. In this case, the drive signal S3 having a duty ratio of 0 [%] is output.

Further, in the drive circuit 4, when the V-phase modulated wave Vv * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio becomes smaller as the V-phase modulated wave Vv * approaches the maximum value of the carrier wave. The drive signal S4 is output, and the duty ratio increases as the V-phase modulated wave Vv * approaches the minimum value of the carrier wave. Further, when the V-phase modulated wave Vv * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S4 having a duty ratio of 0 [%], and the V-phase modulated wave Vv * is the minimum value of the carrier wave. In this case, the drive signal S4 having a duty ratio of 100 [%] is output.

Further, in the drive circuit 4, when the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio increases as the W-phase modulated wave Vw * approaches the maximum value of the carrier wave. The drive signal S5 is output, and the duty ratio becomes smaller as the W-phase modulated wave Vw * approaches the minimum value of the carrier wave. Further, when the W-phase modulated wave Vw * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S5 having a duty ratio of 100 [%], and the W-phase modulated wave Vw * is the minimum value of the carrier wave. In this case, the drive signal S5 having a duty ratio of 0 [%] is output.

Further, in the drive circuit 4, when the W-phase modulated wave Vw * is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the duty ratio becomes smaller as the W-phase modulated wave Vw * approaches the maximum value of the carrier wave. The drive signal S6 is output, and the duty ratio increases as the W-phase modulated wave Vw * approaches the minimum value of the carrier wave. Further, when the W-phase modulated wave Vw * is the maximum value of the carrier wave, the drive circuit 4 outputs a drive signal S6 having a duty ratio of 0 [%], and the W-phase modulated wave Vw * is the minimum value of the carrier wave. In this case, the drive signal S6 having a duty ratio of 100 [%] is output.

The drive circuit 4 shall perform one-phase modulation control or square wave control in the control cycle (0 to 360 [deg]) of the electric motor M. The one-phase modulation control is a control in which the switching element of one of the three phases is repeatedly turned on and off, and the switching element of the remaining two phases is constantly turned on or off. Further, in the drive circuit 4, when performing one-phase modulation control, the phases in which the switching element SW is repeatedly turned on and off are in order (for example, V phase and U phase) at every 60 degrees of the control cycle of the motor M. , W phase). Further, the rectangular wave control is a control that constantly turns on or off each of the three-phase switching elements.

The calculation unit 5 is composed of a microcomputer or the like, and includes a speed calculation unit 7, a subtraction unit 8, a torque control unit 9, a torque / current command value conversion unit 10, a coordinate conversion unit 11, and a subtraction unit 12. It includes a subtraction unit 13, a current control unit 14, and a dq / uvw conversion unit 15. For example, when the microcomputer executes the program stored in the storage unit 6, the speed calculation unit 7, the subtraction unit 8, the torque control unit 9, the torque / current command value conversion unit 10, the coordinate conversion unit 11, and the subtraction unit 12, the subtraction unit 13, the current control unit 14, and the dq / uvw conversion unit 15 are realized.

The speed calculation unit 7 calculates the rotation speed ω of the rotor of the electric motor M by using the electric angle θ detected by the electric angle detection unit Sp. For example, the speed calculation unit 6 obtains the rotation speed ω by dividing the electric angle θ by the operation clock of the calculation unit 5.

The subtraction unit 8 calculates the difference Δω between the rotation speed command value ω * input from the outside and the rotation speed ω output from the speed calculation unit 7.

The torque control unit 9 obtains the torque command value T * by using the difference Δω output from the subtraction unit 8. For example, the torque control unit 9 refers to the information stored in the storage unit 6 in which the rotation speed of the rotor of the electric motor M and the torque of the electric motor M are associated with each other, and the rotation corresponding to the difference Δω. The torque corresponding to the speed is obtained as the torque command value T *.

The torque / current command value conversion unit 10 converts the torque command value T * output from the torque control unit 9 into the d-axis current command value Id * and the q-axis current command value Iq *. For example, the torque / current command value conversion unit 10 stores information in the storage unit 6 in which the torque of the electric motor M and the d-axis current command value Id * and the q-axis current command value Iq * are associated with each other. The d-axis current command value Id * and the q-axis current command value Iq * corresponding to the torque corresponding to the torque command value T * are obtained with reference to.

The coordinate conversion unit 11 uses the U-phase current Iu detected by the current sensor Si1 and the V-phase current Iv detected by the current sensor Si2 to obtain the W-phase current Iw flowing in the W-phase of the motor M. Further, the coordinate conversion unit 11 uses the electric angle θ detected by the electric angle detecting unit Sp to generate the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw with the d-axis current Id (weakened field). (Current component for generating) and q-axis current Iq (current component for generating torque) are converted.

The current detected by the current sensors Si1 and Si2 is not limited to the combination of the U-phase current Iu and the V-phase current Iv, but is limited to the combination of the V-phase current Iv and the W-phase current Iw, or the U-phase current Iu and W. A combination of phase currents Iw may be used. When the V-phase current Iv and the W-phase current Iw are detected by the current sensors Si1 and Si2, the coordinate conversion unit 11 obtains the U-phase current Iu using the V-phase current Iv and the W-phase current Iw. When the U-phase current Iu and the W-phase current Iw are detected by the current sensors Si1 and Si2, the coordinate conversion unit 11 obtains the V-phase current Iv using the U-phase current Iu and the W-phase current Iw.

Further, when the inverter circuit 2 is further provided with a current sensor Si3 for detecting the current flowing in the W phase of the electric motor M in addition to the current sensors Si1 and Si2, the coordinate conversion unit 11 is detected by the electric angle detection unit Sp. Even if the electric angle θ is used to convert the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw detected by the current sensors Si1 to Si3 into the d-axis current Id and the q-axis current Iq. Good.

The subtraction unit 12 calculates the difference ΔId between the d-axis current command value Id * output from the torque / current command value conversion unit 10 and the d-axis current Id output from the coordinate conversion unit 11.

The subtraction unit 13 calculates the difference ΔIq between the q-axis current command value Iq * output from the torque / current command value conversion unit 10 and the q-axis current Iq output from the coordinate conversion unit 11.

The current control unit 14 controls the d-axis voltage command value Vd * and the q-axis voltage command value Vq by PI (Proportional Integral) control using the difference ΔId output from the subtraction unit 12 and the difference ΔIq output from the subtraction unit 13. * Calculate. For example, the current control unit 14 calculates the d-axis voltage command value Vd * using the following formula 1 and calculates the q-axis voltage command value Vq * using the following formula 2. Kp is a constant of the proportional term of PI control, Ki is a constant of the integral term of PI control, Lq is the q-axis inductance of the coil constituting the motor M, and Ld is the d-axis inductance of the coil constituting the motor M. Let ω be the rotational speed of the rotor of the motor M, and Ke be the induced voltage constant.

d-axis voltage command value Vd * = Kp × difference ΔId + ∫ (Ki × difference ΔId) −ωLqIq ・ ・ ・ Equation 1

q-axis voltage command value Vq * = Kp × difference ΔIq + ∫ (Ki × difference ΔIq) + ωLdId + ωKe ・ ・ ・ Equation 2

The dq / uvw conversion unit 15 uses the input voltage Vin detected by the voltage sensor Sv and the electric angle θ detected by the electric angle detection unit Sp to use the d-axis voltage command value Vd * and the q-axis voltage command value Vq *. Is converted into a U-phase modulated wave Vu *, a V-phase modulated wave Vv *, and a W-phase modulated wave Vw *. The results calculated by the calculation unit 5 (U-phase modulation wave Vu *, V-phase modulation wave Vv *, and W-phase modulation wave Vw *) are obtained by the inverter circuit 2 in the next calculation cycle T of the calculation unit 5. It shall be reflected in the operation.

Here, FIG. 2A shows the second AC voltage Vu applied to the U phase of the motor M, the first AC voltage Vv applied to the V phase of the motor M, and the W phase of the motor M. It is a figure which shows an example of the 3rd AC voltage Vw. Further, FIG. 2B is a diagram showing an example of a V-phase modulated wave Vv *. Further, FIG. 2C is a diagram showing an example of the U-phase modulated wave Vu *. Further, FIG. 2D is a diagram showing an example of a W-phase modulated wave Vw *. In the two-dimensional coordinates shown in FIGS. 2 (a) to 2 (d), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage. The solid line shown in FIG. 2A shows the AC voltage Vu, the broken line shown in FIG. 2A shows the AC voltage Vv, and the alternate long and short dash line shown in FIG. 2A shows the AC voltage Vw. The broken line shown in FIG. 2B indicates the V-phase modulated wave Vv *, the solid line shown in FIG. 2C indicates the U-phase modulated wave Vu *, and the alternate long and short dash line shown in FIG. 2D indicates the W-phase modulated wave Vw *. Suppose that is shown. The range of the target electric angle θv of 0 to 360 [deg] is defined as the control cycle of the motor M.

Further, FIG. 3A is a diagram showing an example of a comparison result between the V-phase modulated wave Vv * and the carrier wave. FIG. 3B is a diagram showing an example of the drive signal S3 obtained from the comparison result shown in FIG. 3A. FIG. 3C is a diagram showing an example of the drive signal S4 obtained from the comparison result shown in FIG. 3A. In the two-dimensional coordinates shown in FIGS. 3 (a) to 3 (c), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

Further, FIG. 4A is a diagram showing an example of a comparison result between the U-phase modulated wave Vu * and the carrier wave. FIG. 4B is a diagram showing an example of the drive signal S1 obtained from the comparison result shown in FIG. 4A. FIG. 4C is a diagram showing an example of the drive signal S2 obtained from the comparison result shown in FIG. 4A. In the two-dimensional coordinates shown in FIGS. 4A to 4C, the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

Further, FIG. 5A is a diagram showing an example of a comparison result between the W-phase modulated wave Vw * and the carrier wave. FIG. 5B is a diagram showing an example of the drive signal S5 obtained from the comparison result shown in FIG. 5A. FIG. 5C is a diagram showing an example of the drive signal S6 obtained from the comparison result shown in FIG. 5A. In the two-dimensional coordinates shown in FIGS. 5 (a) to 5 (c), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

The dq / uvw conversion unit 15 performs the dq / uvw conversion unit 15 in the first section (0 to 60 [deg]) of the control cycle of the electric motor M in which the peak on the positive side of the first AC voltage Vv shown in FIG. 2A exists. , As shown in FIG. 2B, the modulation factor Mref'(smaller than the maximum value (+1) of the carrier wave) according to the output of the motor M (rotation speed ω, d-axis current Id, q-axis current Iq) and A V-phase modulated wave Vv * having a modulation factor (Mref') larger than the minimum value (-1) of the carrier wave is generated. The modulation rate Mref'is assumed to be obtained for each calculation cycle T of the calculation unit 5, and -1 ≦ modulation rate Mref' ≦ + 1. Further, the control cycle of the electric motor M> the calculation cycle T of the calculation unit 5. Further, the dq / uvw conversion unit 15 generates a U-phase modulated wave Vu * in the first section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 2C. Further, the dq / uvw conversion unit 15 generates a W-phase modulated wave Vw * in the first section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 2D. Then, in the first section, the drive circuit 4 compares the V-phase modulated wave Vv *, which is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, with the carrier wave, as shown in FIG. 3A. As a result, as shown in FIG. 3 (b), the drive signal S3 in which the high level and the low level are repeated is output to the gate terminal of the switching element SW3, and as shown in FIG. 3 (c), the low level and the high level are output. The drive signal S4 whose level is repeated is output to the gate terminal of the switching element SW4. Further, in the first section, as shown in FIG. 4A, the drive circuit 4 compares the U-phase modulated wave Vu *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 4B, As shown, the low-level drive signal S1 is output to the gate terminal of the switching element SW1, and as shown in FIG. 4C, the high-level drive signal S2 is output to the gate terminal of the switching element SW2. Further, in the first section, as shown in FIG. 5A, the drive circuit 4 compares the W-phase modulated wave Vw *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 5B, As shown, the low-level drive signal S5 is output to the gate terminal of the switching element SW5, and as shown in FIG. 5C, the high-level drive signal SW6 is output to the gate terminal of the switching element S6. As a result, in the first section, the switching elements SW3 and SW4 are repeatedly turned on and off, the switching elements SW1 and SW5 are always turned off, and the switching elements SW2 and SW6 are always turned on. That is, in the first section, when the modulation factor Mref'is smaller than the maximum value of the carrier wave and larger than the minimum value, the electric motor M is driven by the one-phase modulation control.

Further, the dq / uvw conversion unit 15 has a second section (60 to 120 [deg]] of the control cycle of the electric motor M in which a peak on the negative side of the second AC voltage Vu shown in FIG. 2A exists. ), As shown in FIG. 2 (c), U-phase modulation having a modulation factor Mref'(a modulation factor Mref' that is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave) according to the output of the motor M. Generate wave Vu *. Further, the dq / uvw conversion unit 15 generates a V-phase modulated wave Vv * in the second section, which is the same value as the maximum value of the carrier wave, as shown in FIG. 2 (b). Further, the dq / uvw conversion unit 15 generates a W-phase modulated wave Vw * in the second section, which is the same value as the maximum value of the carrier wave, as shown in FIG. 2D. Then, in the second section, the drive circuit 4 compares the U-phase modulated wave Vu *, which is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, with the carrier wave, as shown in FIG. 4A. As a result, as shown in FIG. 4B, the drive signal S1 in which the high level and the low level are repeated is output to the gate terminal of the switching element SW1, and as shown in FIG. 4C, the low level and the high level are output. The drive signal S2 whose level is repeated is output to the gate terminal of the switching element SW2. Further, in the second section, as shown in FIG. 3A, the drive circuit 4 compares the V-phase modulated wave Vv *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 3B, As shown, the high-level drive signal S3 is output to the gate terminal of the switching element SW3, and as shown in FIG. 3C, the low-level drive signal S4 is output to the gate terminal of the switching element SW4. Further, in the second section, as shown in FIG. 5A, the drive circuit 4 compares the W-phase modulated wave Vw *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 5B, As shown, the high-level drive signal S5 is output to the gate terminal of the switching element SW5, and as shown in FIG. 5C, the low-level drive signal SW6 is output to the gate terminal of the switching element S6. As a result, in the second section, the switching elements SW1 and SW2 are repeatedly turned on and off, the switching elements SW3 and SW5 are constantly turned on, and the switching elements SW4 and SW6 are constantly turned off. That is, in the second section, when the modulation factor Mref'is smaller than the maximum value of the carrier wave and larger than the minimum value, the electric motor M is driven by the one-phase modulation control.

Further, the dq / uvw conversion unit 15 has a third section (120 to 180 [deg]) of the control cycle of the electric motor M in which a peak on the positive side of the third AC voltage Vw shown in FIG. 2A exists. ), As shown in FIG. 2D, W-phase modulation having a modulation factor Mref'(a modulation factor Mref' that is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave) according to the output of the motor M. Generate wave Vw *. Further, the dq / uvw conversion unit 15 generates a V-phase modulated wave Vv * in the third section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 2 (b). Further, the dq / uvw conversion unit 15 generates a U-phase modulated wave Vu * in the third section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 2C. Then, in the third section, the drive circuit 4 compares the W-phase modulated wave Vw *, which is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, with the carrier wave, as shown in FIG. 5A. As a result, as shown in FIG. 5B, the drive signal S5 in which the high level and the low level are repeated is output to the gate terminal of the switching element SW5, and as shown in FIG. 5C, the low level and the high level are output. The drive signal S6 whose level is repeated is output to the gate terminal of the switching element SW6. Further, in the third section, as shown in FIG. 3A, the drive circuit 4 compares the V-phase modulated wave Vv *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 3B, As shown, the low-level drive signal S3 is output to the gate terminal of the switching element SW3, and as shown in FIG. 3C, the high-level drive signal S4 is output to the gate terminal of the switching element SW4. Further, in the third section, as shown in FIG. 4A, the drive circuit 4 compares the U-phase modulated wave Vu *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 4B, As shown, the low-level drive signal S1 is output to the gate terminal of the switching element SW1, and as shown in FIG. 4C, the high-level drive signal S2 is output to the gate terminal of the switching element SW2. As a result, in the third section, the switching elements SW5 and SW6 are repeatedly turned on and off, the switching elements SW1 and SW3 are always turned off, and the switching elements SW2 and SW4 are always turned on. That is, in the third section, when the modulation factor Mref'is smaller than the maximum value of the carrier wave and larger than the minimum value, the electric motor M is driven by the one-phase modulation control.

As described above, when the modulation factor Mref'is smaller than the maximum value of the carrier wave and larger than the minimum value in the half cycle (0 to 180 [deg]) of the control cycle of the electric motor M, the dq / uvw conversion unit 15 is used. The electric motor M is driven by one-phase modulation control. The dq / uvw conversion unit 15 is used for the remaining half cycle of the control cycle of the motor M (first section (180 to 240 [deg]), second section (240 to 300 [deg]), and third. Even in the interval (300 to 360 [deg])), when the modulation factor Mref'is smaller than the maximum value of the carrier wave and larger than the minimum value, the electric motor M is driven by one-phase modulation control.

Further, FIG. 6A is a diagram showing an example of a second AC voltage Vu, a first AC voltage Vv, and a third AC voltage Vw. Further, FIG. 6B is a diagram showing an example of a V-phase modulated wave Vv *. Further, FIG. 6C is a diagram showing an example of the U-phase modulated wave Vu *. Further, FIG. 6D is a diagram showing an example of the W phase modulated wave Vw *. In the two-dimensional coordinates shown in FIGS. 6 (a) to 6 (d), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage. The solid line shown in FIG. 6A shows the AC voltage Vu, the broken line shown in FIG. 6A shows the AC voltage Vv, and the alternate long and short dash line shown in FIG. 6A shows the AC voltage Vw. The broken line shown in (b) indicates the V-phase modulated wave Vv *, the solid line shown in FIG. 6 (c) indicates the U-phase modulated wave Vu *, and the alternate long and short dash line shown in FIG. 6 (d) indicates the W-phase modulated wave Vw *. Suppose that is shown. The range of the target electric angle θv of 0 to 360 [deg] is defined as the control cycle of the motor M.

Further, FIG. 7A is a diagram showing an example of a comparison result between the V-phase modulated wave Vv * and the carrier wave. FIG. 7B is a diagram showing an example of the drive signal S3 obtained from the comparison result shown in FIG. 7A. FIG. 7C is a diagram showing an example of the drive signal S4 obtained from the comparison result shown in FIG. 7A. In the two-dimensional coordinates shown in FIGS. 7 (a) to 7 (c), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

Further, FIG. 8A is a diagram showing an example of a comparison result between the U-phase modulated wave Vu * and the carrier wave. FIG. 8B is a diagram showing an example of the drive signal S1 obtained from the comparison result shown in FIG. 8A. FIG. 8C is a diagram showing an example of the drive signal S2 obtained from the comparison result shown in FIG. 8A. In the two-dimensional coordinates shown in FIGS. 8 (a) to 8 (c), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

Further, FIG. 9A is a diagram showing an example of a comparison result between the W-phase modulated wave Vw * and the carrier wave. FIG. 9B is a diagram showing an example of the drive signal S5 obtained from the comparison result shown in FIG. 9A. FIG. 9C is a diagram showing an example of the drive signal S6 obtained from the comparison result shown in FIG. 9A. In the two-dimensional coordinates shown in FIGS. 9 (a) to 9 (c), the horizontal axis indicates the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. It is assumed that the target electric angle θv obtained by adding the phase angle δ corresponding to is indicated by, and the vertical axis indicates the voltage.

The dq / uvw conversion unit 15 performs the dq / uvw conversion unit 15 in the first section (0 to 60 [deg]) of the control cycle of the electric motor M in which the peak on the positive side of the first AC voltage Vv shown in FIG. 6A exists. , As shown in FIG. 6B, a V-phase modulated wave Vv * having a modulation factor Mref'(maximum value (+1) of the carrier wave) corresponding to the output of the electric motor M is generated. Further, the dq / uvw conversion unit 15 generates a U-phase modulated wave Vu * in the first section, which is the same value as the minimum value (-1) of the carrier wave, as shown in FIG. 6 (c). Further, the dq / uvw conversion unit 15 generates a W-phase modulated wave Vw * in the first section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 6D. Then, in the first section, as shown in FIG. 7A, the drive circuit 4 compares the V-phase modulated wave Vv *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 7B, As shown, the high-level drive signal S3 is output to the gate terminal of the switching element SW3, and as shown in FIG. 7C, the low-level drive signal S4 is output to the gate terminal of the switching element SW4. Further, in the first section, as shown in FIG. 8A, the drive circuit 4 compares the U-phase modulated wave Vu *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 8B, As shown, the low-level drive signal S1 is output to the gate terminal of the switching element SW1, and as shown in FIG. 8C, the high-level drive signal SW2 is output to the gate terminal of the switching element S2. Further, in the first section, as shown in FIG. 9A, the drive circuit 4 compares the W-phase modulated wave Vw *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 9B, As shown, the low-level drive signal S5 is output to the gate terminal of the switching element SW5, and as shown in FIG. 9C, the high-level drive signal SW6 is output to the gate terminal of the switching element S6. As a result, in the first section, the switching elements SW2, SW3, and SW6 are always on, and the switching elements SW1, SW4, and SW5 are always off. That is, in the first section, when the modulation factor Mref'is the maximum value of the carrier wave, the electric motor M is driven by the rectangular wave control.

Further, the dq / uvw conversion unit 15 has a second section (60 to 120 [deg]] of the control cycle of the electric motor M in which a peak on the negative side of the second AC voltage Vu shown in FIG. 6A exists. ), As shown in FIG. 6C, a U-phase modulated wave Vu * having a modulation factor Mref'(minimum value of the carrier wave) corresponding to the output of the electric motor M is generated. Further, the dq / uvw conversion unit 15 generates a V-phase modulated wave Vv * in the second section, which is the same value as the maximum value of the carrier wave, as shown in FIG. 6B. Further, the dq / uvw conversion unit 15 generates a W-phase modulated wave Vw * in the second section, which is the same value as the maximum value of the carrier wave, as shown in FIG. 6D. Then, in the second section, as shown in FIG. 8A, the drive circuit 4 compares the U-phase modulated wave Vu *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 8B, As shown, the low-level drive signal S1 is output to the gate terminal of the switching element SW1, and as shown in FIG. 8C, the high-level drive signal S2 is output to the gate terminal of the switching element SW2. Further, in the second section, as shown in FIG. 7A, the drive circuit 4 compares the V-phase modulated wave Vv *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 7B, As shown, the high-level drive signal S3 is output to the gate terminal of the switching element SW3, and as shown in FIG. 7C, the low-level drive signal SW4 is output to the gate terminal of the switching element S4. Further, in the second section, as shown in FIG. 9A, the drive circuit 4 compares the W-phase modulated wave Vw *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 9B, As shown, the high-level drive signal S5 is output to the gate terminal of the switching element SW5, and as shown in FIG. 9C, the low-level drive signal SW6 is output to the gate terminal of the switching element S6. As a result, in the second section, the switching elements SW2, SW3, and SW5 are always on, and the switching elements SW1, SW4, and SW6 are always off. That is, in the second section, when the modulation factor Mref'is the minimum value of the carrier wave, the electric motor M is driven by the rectangular wave control.

Further, the dq / uvw conversion unit 15 has a third section (120 to 180 [deg]) of the control cycle of the electric motor M in which a peak on the positive side of the third AC voltage Vw shown in FIG. 6A exists. ), As shown in FIG. 6D, a W-phase modulated wave Vw * having a modulation factor Mref'(maximum value of the carrier wave) corresponding to the output of the electric motor M is generated. Further, the dq / uvw conversion unit 15 generates a V-phase modulated wave Vv * in the third section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 6B. Further, the dq / uvw conversion unit 15 generates a U-phase modulated wave Vu * in the third section, which is the same value as the minimum value of the carrier wave, as shown in FIG. 6C. Then, in the third section, as shown in FIG. 9A, the drive circuit 4 compares the W-phase modulated wave Vw *, which is the maximum value of the carrier wave, with the carrier wave, and as shown in FIG. 9B, As shown, the high-level drive signal S5 is output to the gate terminal of the switching element SW5, and as shown in FIG. 9C, the low-level drive signal S6 is output to the gate terminal of the switching element SW6. Further, in the third section, as shown in FIG. 7 (a), the drive circuit 4 compares the V-phase modulated wave Vv *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 7 (b). As shown, the low-level drive signal S3 is output to the gate terminal of the switching element SW3, and as shown in FIG. 7C, the high-level drive signal SW4 is output to the gate terminal of the switching element S4. Further, in the third section, as shown in FIG. 8A, the drive circuit 4 compares the UW phase modulated wave Vu *, which is the minimum value of the carrier wave, with the carrier wave, and as shown in FIG. 8B, As shown, the low-level drive signal S1 is output to the gate terminal of the switching element SW1, and as shown in FIG. 8C, the high-level drive signal SW2 is output to the gate terminal of the switching element S2. As a result, in the third section, the switching elements SW2, SW4, and SW5 are always on, and the switching elements SW1, SW3, and SW6 are always off. That is, in the third section, when the modulation factor Mref'is the maximum value of the carrier wave, the electric motor M is driven by the rectangular wave control.

As described above, in the dq / uvw conversion unit 15, the modulation factor Mref'is the maximum value of the carrier wave in the half cycle (0 to 180 [deg]) of the control cycle of the electric motor M, or the modulation factor Mref'is When it is the minimum value of the carrier wave, the electric motor M is driven by the rectangular wave control. The dq / uvw conversion unit 15 is used for the remaining half cycle of the control cycle of the motor M (first section (180 to 240 [deg]), second section (240 to 300 [deg]), and third. Even in the interval (300 to 360 [deg])), when the modulation factor Mref'is the maximum value of the carrier wave or when the modulation factor Mref'is the minimum value of the carrier wave, the electric motor M is driven by the square wave control. ..

As described above, the control device 1 of the electric motor M of the embodiment V-phase modulation according to the output of the electric motor M in the first section of the control cycle of the electric motor M in which the peak of the first AC voltage Vv exists. In the second section where the wave Vv * is output and the minimum or maximum value of the carrier is output as the U-phase modulated wave Vu * and the W-phase modulated wave Vw *, and the peak of the second AC voltage Vu * exists, The U-phase modulated wave Vu * corresponding to the output of the electric motor M is output, and the minimum or maximum value of the carrier is output as the V-phase modulated wave Vv * and the W-phase modulated wave Vw *, and the peak of the third AC voltage Vw. In the third section where is present, the W-phase modulated wave Vw * corresponding to the output of the electric motor M is output, and the minimum or maximum value of the carrier is output as the V-phase modulated wave Vv * and the U-phase modulated wave Vu *. ..

As a result, in the control cycle of the motor M (first to third sections), the V-phase modulated wave Vv *, the U-phase modulated wave Vu *, and the W-phase modulated wave Vw * corresponding to the output of the motor M become the carrier waves. When it is smaller than the maximum value and larger than the minimum value of the carrier wave, one-phase switching element of the three-phase switching elements can be repeatedly turned on and off, that is, one-phase modulation control can be performed. Further, in the control cycle of the motor M, when the V-phase modulated wave Vv *, the U-phase modulated wave Vu *, and the W-phase modulated wave Vw * corresponding to the output of the motor M are the minimum or maximum values of the carrier wave, 3 It is possible to always turn on or off each of the phase switching elements, that is, to perform square wave control. Further, in the control cycle of the motor M, the switching element can be turned on and off at a duty ratio corresponding to the V-phase modulated wave Vv *, the U-phase modulated wave Vu *, and the W-phase modulated wave Vw *. The on-time of the switching element can be gradually changed according to the output of. Therefore, even if the output of the motor M becomes high and the transition from the one-phase modulation control to the square wave control is performed, the on-time of the switching element can be seamlessly changed, so that the distortion of the current flowing through the motor M can be suppressed. , Torque fluctuation can be suppressed. Further, since it is only necessary to switch the phase for switching the switching element for each of the first to third sections and complicated calculation is not required, the calculation load of the control device 1 can be suppressed.

Further, according to the control device 1 of the electric motor M of the embodiment, the switching frequency of the switching elements SW1 to SW6 can be made higher than that of the control device of the electric motor that performs three-phase modulation control or two-phase modulation control. The switching frequency can be shifted outside the audible range, and noise can be reduced.

FIG. 10A is a diagram showing an example of the dq / uvw conversion unit 15.
The dq / uvw conversion unit 15 shown in FIG. 10A includes a phase angle calculation unit 151, an addition unit 152, a modulation rate calculation unit 153, a modulation rate expansion unit 154, and a modulation wave generation unit 155.

The phase angle calculation unit 151 calculates the phase angle δ corresponding to the d-axis voltage command value Vd * and the q-axis voltage command value Vq * output from the current control unit 14. For example, the phase angle calculation unit 151 sets the calculation result of the following equation 3 as the phase angle δ.

The addition unit 152 sets the addition result of the phase angle δ output from the phase angle calculation unit 151 and the electric angle θ output from the electric angle detection unit Sp as the target electric angle θv. It is assumed that the target electric angle calculation unit is composed of the phase angle calculation unit 151 and the addition unit 152.

The modulation factor calculation unit 153 uses the input voltage Vin detected by the voltage sensor Sv, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * output from the current control unit 14, and the modulation rate Muref. To calculate. For example, the modulation factor calculation unit 153 uses the calculation result of the following equation 4 as the modulation factor Mref. It should be noted that 0 <Mref <1.

The modulation rate expansion unit 154 obtains the modulation rate Mref'by expanding the modulation rate Mref output from the modulation rate calculation unit 153. For example, the modulation factor expansion unit 154 uses the calculation result of the following equation 5 as the modulation factor Mfer'. It should be noted that -1 <Mfer'<1.
Mr'= 2 × Mref-1 ・ ・ ・ Equation 5
The modulation wave generation unit 155 uses the target electric angle θv output from the addition unit 152 and the modulation rate Mrf'output from the modulation rate expansion unit 154 to use the U-phase modulation wave Vu * and the V-phase modulation wave Vv. * And W-phase modulated wave Vw * are generated. For example, the modulated wave generation unit 155 refers to the information D1 stored in the storage unit 6, and refers to the U-phase modulated wave Vu * and the V-phase modulated wave Vv corresponding to the target electric angle θv output from the adding unit 152. * And W-phase modulated wave Vw * are obtained.

FIG. 10B is a diagram showing an example of information D1.
In the information D1 shown in FIG. 10B, the first section "0 to 60 [deg]", the U-phase modulation wave Vu * "-1 (minimum value of the carrier wave)", and V-phase modulation The wave Vv * "Mref'" and the W-phase modulated wave Vw * "-1" are associated with each other. In addition, the second section "60 to 120 [deg]", the U-phase modulated wave Vu * "Mref'", and the V-phase modulated wave Vv * "+1 (maximum value of carrier wave)" , W-phase modulated wave Vw * "+1" is associated with each other. Further, the third section "120 to 180 [deg]", the U-phase modulated wave Vu * "-1", the V-phase modulated wave Vv * "-1", and the W-phase modulated wave "Mref'" which is Vw * is associated with each other. Further, the first section "180 to 240 [deg]", the U-phase modulated wave Vu * "+1", the V-phase modulated wave Vv * "Mref'", and the W-phase modulated wave Vw. "+1" which is * is associated with each other. Further, the second section "240 to 300 [deg]", the U-phase modulated wave Vu * "Mref'", the V-phase modulated wave Vv * "-1", and the W-phase modulated wave. "-1" which is Vw * is associated with each other. Further, the third section "300 to 360 [deg]", the U-phase modulated wave Vu * "+1", the V-phase modulated wave Vv * "+1", and the W-phase modulated wave Vw *. "Mref'" is associated with each other.

For example, when the target electric angle θv (54 [deg]) is in the first section (0 to 60 [deg]), the modulated wave generation unit 155 sets “-1” as the U-phase modulated wave Vu *. At the same time, "Mref'" is output as the V-phase modulated wave Vv *, and "-1" is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW3 and SW4 are repeatedly turned on and off in the first section, and the switching element SW1 is constantly turned off for switching. The element SW2 is always on, the switching element SW5 is always off, and the switching element SW6 is always on. When Mr. Ref'is the maximum value of the carrier wave, the switching element SW3 is always on, the switching element SW4 is always off, the switching element SW1 is always off, and the switching element SW2 is always on in the first section. , The switching element SW5 is always off, and the switching element SW6 is always on.

Further, when the target electric angle θv (108 [deg]) is in the second section (60 to 120 [deg]), the modulated wave generation unit 155 sets “Mref ′” as the U-phase modulated wave Vu *. At the same time, "+1" is output as the V-phase modulated wave Vv *, and "+1" is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW1 and SW2 are repeatedly turned on and off in the second section, and the switching element SW3 is always turned on for switching. The element SW4 is always off, the switching element SW5 is always on, and the switching element SW6 is always off. When Mr. Ref'is the minimum value of the carrier wave, the switching element SW1 is always turned off, the switching element SW2 is always turned on, the switching element SW3 is always turned on, and the switching element SW4 is always turned off in the second section. , The switching element SW5 is always on, and the switching element SW6 is always off.

Further, when the target electric angle θv (162 [deg]) is in the third section (120 to 180 [deg]), the modulated wave generation unit 155 sets “-1” as the U-phase modulated wave Vu *. At the same time, "-1" is output as the V-phase modulated wave Vv *, and "Mref'" is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW5 and SW6 are repeatedly turned on and off, and the switching element SW3 is constantly turned off for switching in the third section. The element SW4 is always on, the switching element SW1 is always off, and the switching element SW2 is always on. When Mr. Ref'is the maximum value of the carrier wave, the switching element SW5 is always on, the switching element SW6 is always off, the switching element SW3 is always off, and the switching element SW4 is always on in the third section. , The switching element SW1 is always off, and the switching element SW2 is always on.

That is, according to the dq / uvw conversion unit 15 shown in FIG. 10 (a), in the first section, the modulation factor Mref'corresponding to the output of the electric motor M is output as a V-phase modulation wave Vv * and the minimum of the carrier. The value or maximum value is output as U-phase modulated wave Vu * and W-phase modulated wave Vw *, and in the second section, the modulation factor Mrf'corresponding to the output of the electric motor M is output as U-phase modulated wave Vu *. The minimum or maximum value of the carrier is output as the V-phase modulation wave Vv * and the W-phase modulation wave Vw *, and in the third section, the modulation factor Mref'corresponding to the output of the electric motor M is the W-phase modulation wave Vw *. At the same time, the minimum value or the maximum value of the carrier can be output as V-phase modulated wave Vv * and U-phase modulated wave Vu *.

FIG. 11A is a diagram showing another example of the dq / uvw conversion unit 15.
The dq / uvw conversion unit 15 shown in FIG. 11A includes a two-phase three-phase conversion unit 156 and a modulated wave generation unit 157.

The two-phase three-phase conversion unit 156 uses the electric angle θ output from the electric angle detection unit Sp to obtain the d-axis voltage command value Vd * and the q-axis voltage command value Vq * output from the current control unit 14. U-phase voltage command value Vu ** (second voltage command value), V-phase voltage command value Vv ** (first voltage command value), and W-phase voltage command value Vw ** (third voltage command value) ). For example, the two-phase three-phase conversion unit 156 uses the conversion matrix C shown in the following equation 6 to convert the d-axis voltage command value Vd * and the q-axis voltage command value Vq * into the U-phase voltage command values Vu ** and V. It is converted to the phase voltage command value Vv ** and the W phase voltage command value Vw **.

The modulated wave generation unit 157 includes an input voltage Vin detected by the voltage sensor Sv, a d-axis voltage command value Vd * and a q-axis voltage command value Vq * output from the current control unit 14, and a two-phase three-phase conversion unit. Using the U-phase voltage command value Vu **, V-phase voltage command value Vv **, and W-phase voltage command value Vw ** output from 156, the U-phase voltage command value Vu * and V-phase voltage command value Vv * , And the W-phase modulated wave Vw * is calculated. For example, the modulated wave generation unit 157 obtains the phase angle δ by calculating the above equation 3, and sets the addition result of the phase angle δ and the electric angle θ output from the electric angle detection unit Sp as the target electric angle θv. , The modulation factor Mref is obtained by calculating the above equation 4, and the modulation factor Mfer'is obtained by calculating the above equation 5. Further, the modulated wave generation unit 157 refers to the information D2 stored in the storage unit 6, and the U-phase voltage command value Vu ** and the V-phase voltage command value Vv output from the two-phase three-phase conversion unit 156. The U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * corresponding to the branching conditions obtained by the ** and the W-phase voltage command value Vw ** are obtained.

FIG. 11B is a diagram showing an example of information D2.
In the information D2 shown in FIG. 11B, "when the absolute value of the V-phase voltage command value Vv ** is larger than the absolute value of the U-phase voltage command value Vu ** and the absolute value of the W-phase voltage command value Vw **. The branch condition is "when the V-phase voltage command value Vv ** is zero or more", the U-phase modulated wave Vu * is "-1 (minimum value of the carrier wave)", and the V-phase modulated wave Vv *. "Mref'" and "-1", which is a W-phase modulated wave Vw *, are associated with each other. Further, "when the absolute value of the U-phase voltage command value Vu ** is larger than the absolute value of the V-phase voltage command value Vv ** and the absolute value of the W-phase voltage command value Vw **, and the U-phase voltage command value The branching condition "when Vu ** is zero or more", "Mref'" which is a U-phase modulated wave Vu *, "+1 (maximum value of carrier)" which is a V-phase modulated wave Vv *, and W phase. The modulated wave Vw * "+1" is associated with each other. Further, "when the absolute value of the W-phase voltage command value Vw ** is larger than the absolute value of the V-phase voltage command value Vv ** and the absolute value of the U-phase voltage command value Vu **, and the W-phase voltage command value With the branching condition "when Vw ** is zero or more", the U-phase modulated wave Vu * "-1", the V-phase modulated wave Vv * "-1", and the W-phase modulated wave Vw * A certain "Mref'" is associated with each other. Further, "when the absolute value of the V-phase voltage command value Vv ** is larger than the absolute value of the U-phase voltage command value Vu ** and the absolute value of the W-phase voltage command value Vw **, and the V-phase voltage command value The branch condition that "Vv ** is smaller than zero", the U-phase modulated wave Vu * "+1", the V-phase modulated wave Vv * "Mref'", and the W-phase modulated wave Vw * " +1 ”is associated with each other. Further, "when the absolute value of the U-phase voltage command value Vu ** is larger than the absolute value of the V-phase voltage command value Vv ** and the absolute value of the W-phase voltage command value Vw **, and the U-phase voltage command value The branch condition is "when Vu ** is smaller than zero", "Mref'" which is a U-phase modulated wave Vu *, "-1" which is a V-phase modulated wave Vv *, and W-phase modulated wave Vw *. "-1" is associated with each other. Further, "when the absolute value of the W-phase voltage command value Vw ** is larger than the absolute value of the V-phase voltage command value Vv ** and the absolute value of the U-phase voltage command value Vu **, and the W-phase voltage command value The branch condition that "Vw ** is smaller than zero", the U-phase modulated wave Vu * "+1", the V-phase modulated wave Vv * "+1", and the W-phase modulated wave Vw * "Mref". ´ ”and are associated with each other.

For example, the modulated wave generation unit 157 is in the case where the absolute value of the V-phase voltage command value Vv ** is larger than the absolute value of the U-phase voltage command value Vu ** and the absolute value of the W-phase voltage command value Vw **. , When the V-phase voltage command value Vv ** is zero or more, that is, when the target electric angle θv is in the first section (0 to 60 [deg]), the U-phase modulated wave Vu * is set to "-". 1 ”is output,“ Muref ′ ”is output as the V-phase modulated wave Vv *, and“ -1 ”is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW3 and SW4 are repeatedly turned on and off in the first section, and the switching element SW1 is constantly turned off for switching. The element SW2 is always on, the switching element SW5 is always off, and the switching element SW6 is always on. When Mr. Ref'is the maximum value of the carrier wave, the switching element SW3 is always on, the switching element SW4 is always off, the switching element SW1 is always off, and the switching element SW2 is always on in the first section. , The switching element SW5 is always off, and the switching element SW6 is always on.

Further, the modulated wave generation unit 157 is in the case where the absolute value of the U-phase voltage command value Vu ** is larger than the absolute value of the V-phase voltage command value Vv ** and the absolute value of the W-phase voltage command value Vw **. , When the U-phase voltage command value Vu ** is zero or more, that is, when the target electric angle θv is in the second section (60 to 120 [deg]), “Mref” is set as the U-phase modulated wave Vu *. ’” Is output, “+1” is output as the V-phase modulated wave Vv *, and “+1” is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW1 and SW2 are repeatedly turned on and off in the second section, and the switching element SW3 is always turned on for switching. The element SW4 is always off, the switching element SW5 is always on, and the switching element SW6 is always off. When Mr. Ref'is the minimum value of the carrier wave, the switching element SW1 is always turned off, the switching element SW2 is always turned on, the switching element SW3 is always turned on, and the switching element SW4 is always turned off in the second section. , The switching element SW5 is always on, and the switching element SW6 is always off.

Further, the modulated wave generation unit 157 is in the case where the absolute value of the W-phase voltage command value Vw ** is larger than the absolute value of the V-phase voltage command value Vv ** and the U-phase voltage command value Vu **. , When the W-phase voltage command value Vw ** is zero or more, that is, when the target electric angle θv is in the third section (120 to 180 [deg]), the U-phase modulated wave Vu * is set to "-". "1" is output, "-1" is output as the V-phase modulated wave Vv *, and "Mref'" is output as the W-phase modulated wave Vw *. As a result, when Mr. Ref'is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the switching elements SW5 and SW6 are repeatedly turned on and off, and the switching element SW3 is constantly turned off for switching in the third section. The element SW4 is always on, the switching element SW1 is always off, and the switching element SW2 is always on. When Mr. Ref'is the maximum value of the carrier wave, the switching element SW5 is always on, the switching element SW6 is always off, the switching element SW3 is always off, and the switching element SW4 is always on in the third section. , The switching element SW1 is always off, and the switching element SW2 is always on.

That is, according to the dq / uvw conversion unit 15 shown in FIG. 11A, in the first section, the modulation factor Mref'corresponding to the output of the electric motor M is output as a V-phase modulation wave Vv * and the minimum of the carrier. The value or maximum value is output as U-phase modulated wave Vu * and W-phase modulated wave Vw *, and in the second section, the modulation factor Mrf'corresponding to the output of the electric motor M is output as U-phase modulated wave Vu *. The minimum or maximum value of the carrier is output as the V-phase modulation wave Vv * and the W-phase modulation wave Vw *, and in the third section, the modulation factor Mref'corresponding to the output of the electric motor M is the W-phase modulation wave Vw *. At the same time, the minimum value or the maximum value of the carrier can be output as V-phase modulated wave Vv * and U-phase modulated wave Vu *.

Further, the present invention is not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

<Modification example 1>
FIG. 12 is a flowchart showing an example of the operation of the dq / uvw conversion unit 15 in the modification 1.

First, the dq / uvw conversion unit 15 obtains the calculation cycle T of the calculation unit 5 (step S1). For example, the dq / uvw conversion unit 15 sets the difference between the electric angle θ acquired this time and the electric angle θ acquired last time as the calculation cycle T.

Next, the dq / uvw conversion unit 15 estimates the next calculation cycle T of the calculation unit 5 (step S2). For example, the dq / uvw conversion unit 15 sets the calculation timing after the calculation cycle T from the current calculation timing of the calculation unit 5 as the start timing of the next calculation cycle T of the calculation unit 5, and after the calculation cycle T from the start timing. The calculation timing of is defined as the end timing of the next calculation cycle T of the calculation unit 5, and the range from the start timing to the end timing is defined as the next calculation cycle T of the calculation unit 5. The U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * obtained at the current calculation timing are reflected in the operation of the inverter circuit 2 in the next calculation period T. And.

Next, in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15 switches the switching timings of the first to third sections (0 [deg], 60 [deg], 120 [deg], 180 [deg]. When (deg], 240 [deg], 300 [deg]) exists (step S3: Yes), the switching time ct is set (step S4). For example, the dq / uvw conversion unit 15 sets the difference between the switching timing of the first to third sections and the start timing of the next calculation cycle T as the switching time tk.

On the other hand, in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15 sets the switching time ct to be larger than the calculation cycle when the switching timing of the first to third sections does not exist (step S3: No). Set to a value (step S5).

Then, the dq / uvw conversion unit 15 uses the input voltage Vin and the electric angle θ to convert the d-axis voltage command value Vd * and the q-axis voltage command value Vq * into the U-phase modulation wave Vu * and the V-phase modulation wave Vv. * And W-phase modulated wave Vw * are converted, and when the start timing of the next calculation cycle T comes, U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw after the switching time tk elapses. Each value of * is switched (step S6).

FIG. 13 is a diagram for explaining the setting of the switching time tk. The horizontal axis of the two-dimensional coordinates shown in FIG. 13 is the target electricity obtained by adding the phase angle δ corresponding to the d-axis voltage command value Vd * and the q-axis voltage command value Vq * to the electric angle θ of the rotor of the motor M. The angle θv is shown, and the vertical axis shows the voltage. The solid line shown in FIG. 13 indicates the U-phase modulated wave Vu *, the broken line shown in FIG. 13 indicates the V-phase modulated wave Vv *, and the alternate long and short dash line shown in FIG. 13 indicates the W-phase modulated wave Vw *. Further, the calculation cycle T of the calculation unit 5 is set to 18 [deg].

For example, it is assumed that the target electric angle θv at the current calculation timing of the calculation unit 5 is 36 [deg]. Alternatively, when the absolute value of the V-phase voltage command value Vv ** is larger than the absolute value of the U-phase voltage command value Vu ** and the absolute value of the W-phase voltage command value Vw **, and the V-phase voltage command value Vv It is assumed that ** is zero or more.

The dq / uvw conversion unit 15 sets 36 [deg] +18 [deg] = 54 [deg] as the start timing of the next arithmetic cycle T of the arithmetic unit 5, and 54 [deg] +18 [deg] = 72 [deg]. Is the end timing of the next calculation cycle T of the calculation unit 5, and 54 [deg] to 72 [deg] is the next calculation cycle T of the calculation unit 5.

Next, the dq / uvw conversion unit 15 determines that the target electric angle θv falls within the first section (0 to 60 [deg]), or the absolute value of the V-phase voltage command value Vv ** is the U-phase. When it is larger than the absolute value of the voltage command value Vu ** and the absolute value of the W phase voltage command value Vw **, and the V phase voltage command value Vv ** is determined to be zero or more, the next calculation cycle T In (54 [deg] to 72 [deg]), if it is determined that 60 [deg] exists as the switching timing from the first section to the second section, 60 [deg] -54 [deg] = 6 [deg]. The time corresponding to is defined as the switching time tk.

Then, the dq / uvw conversion unit 15 reaches the start timing (54 [deg]) of the next calculation cycle T, and after the switching time ct (time corresponding to 6 [deg]) elapses, the U-phase modulated wave Vu *, The values of the V-phase modulated wave Vv * and the W-phase modulated wave Vw * are switched. That is, when the dq / uvw conversion unit 15 reaches 60 [deg], the value of the V-phase modulated wave Vv * is switched from the modulation factor Mref'to the maximum value of the carrier wave, and the value of the W-phase modulated wave Vw * is changed to the value of the carrier wave. While switching from the minimum value to the maximum value, the value of the U-phase modulated wave Vu * is switched from the minimum value of the carrier wave to the modulation factor Mref'. If there is no switching timing between the first section and the second section in the next calculation cycle T of the calculation unit 5, the modulated wave in the middle of the calculation cycle is not changed until the next calculation cycle is reached. Continuously output.

As described above, in the next calculation cycle T, the dq / uvw conversion unit 15 in the modification 1 has the switching timing from the first section to the second section and the switching timing from the second section to the third section. Or, if there is a switching timing from the third section to the first section, the start timing of the next calculation cycle T is adjusted to the switching timing. In other words, the dq / uvw conversion unit 15 in the first modification has the switching timing from the first section to the second section, the switching timing from the second section to the third section, in the next calculation cycle T. Alternatively, when there is a switching timing from the third section to the first section, the switching timing is shifted from the start timing of the calculation cycle of the calculation unit 5 after the switching time tk has elapsed.

As a result, U-phase modulation is performed at the switching timing from the first section to the second section, the switching timing from the second section to the third section, or the switching timing from the third section to the first section. Since the values of wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * can be switched, the switching element can be turned on or the switching element can be turned on when it is not necessary to turn on the switching element. It is possible to prevent the switching element from being turned off when it is necessary to make the motor M, further suppress the distortion generated in the current flowing through the electric motor M, and further suppress the fluctuation of the torque.

<Modification 2>
FIG. 14 is a flowchart showing an example of the operation of the dq / uvw conversion unit 15 in the modification 2. Note that steps S1, S2, S3, and S5 shown in FIG. 14 are the same as steps S1, S2, S3, and S5 shown in FIG. 12, and the description thereof will be omitted.

The flowchart shown in FIG. 14 differs from the flowchart shown in FIG. 12 in the case where the switching timing of the first to third sections exists in the next calculation cycle T of the calculation unit 5 (step S3: Yes). The switching times ct1 to ct3 are set based on the modulated waves corresponding to the first to third priorities (step S4'), and when the start timing of the next calculation cycle T comes, U after the switching times ct1 to tk3 elapse. This is a point at which the values of the phase-modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * are switched (step S6'). The modulated wave corresponding to the first priority is a modulated wave that switches from the modulation factor Mref'to the minimum value or the maximum value of the carrier wave at the switching timing of the first to third sections. Further, the modulated wave corresponding to the second priority is a modulated wave that switches from the minimum value of the carrier wave to the maximum value or a modulated wave that switches from the maximum value of the carrier wave to the minimum value at the switching timing of the first to third sections. To do. Further, the modulated wave corresponding to the third priority is a modulated wave that switches from the minimum value or the maximum value of the carrier wave to the modulation factor Mref'at the switching timing of the first to third sections.

In the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15 has a modulated wave corresponding to the first priority in the switching timing when the switching timings of the first to third sections exist. The values of the U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * are set in the order of the modulated wave corresponding to the second priority and the modulated wave corresponding to the third priority. Switch.

That is, when the switching timing from the first section to the second section exists in the next calculation cycle T, the dq / uvw conversion unit 15 modulates the value of the V-phase modulated wave Vv * at the switching timing. After switching from the rate Mref'to the minimum or maximum value of the carrier wave, the value of the W-phase modulated wave Vw * is switched from the minimum value to the maximum value of the carrier wave or from the maximum value of the carrier wave to the minimum value, and then the U-phase modulated wave. The value of Vu * is switched from the minimum value or the maximum value of the carrier wave to the modulation factor Mref'.

Further, the dq / uvw conversion unit 15 modulates the value of the U-phase modulated wave Vu * at the switching timing when there is a switching timing from the second section to the third section in the next calculation cycle T. After switching from the rate Mrf'to the minimum or maximum value of the carrier wave, the value of the V-phase modulated wave Vv * is switched from the minimum value to the maximum value of the carrier wave or from the maximum value of the carrier wave to the minimum value, and then the W-phase modulated wave. The value of Vw * is switched from the minimum or maximum value of the carrier wave to the modulation factor.

Further, the dq / uvw conversion unit 15 modulates the value of the W-phase modulated wave Vw * at the switching timing when there is a switching timing from the third section to the first section in the next calculation cycle T. After switching from the rate Mrf'to the minimum or maximum value of the carrier wave, the value of the U-phase modulated wave Vu * is switched from the minimum value of the carrier wave to the maximum value or the maximum value of the carrier wave to the minimum value, and then the V-phase modulated wave Vv. The value of * is switched from the minimum or maximum value of the carrier wave to the modulation factor.

15 (a) to 15 (c) are diagrams for explaining the setting of the switching times tc1 to tk3. The horizontal axes of the two-dimensional coordinates shown in FIGS. 15 (a) to 15 (c) correspond to the d-axis voltage command value Vd * and the q-axis voltage command value Vq * with respect to the electric angle θ of the rotor of the electric motor M. The target electric angle θv obtained by adding the phase angle δ is shown, and the vertical axis shows the voltage. The solid line shown in FIGS. 15 (a) to 15 (c) indicates the U-phase modulated wave Vu *, and the broken line shown in FIGS. 15 (a) to 15 (c) indicates the V-phase modulated wave Vv *. The alternate long and short dash line shown in FIGS. 15 (a) to 15 (c) indicates the W-phase modulated wave Vw *. Further, the calculation cycle T of the calculation unit 5 is set to 18 [deg].

For example, it is assumed that the target electric angle θv at the current calculation timing of the calculation unit 5 is 36 [deg]. Alternatively, when the absolute value of the V-phase voltage command value Vv ** is larger than the absolute value of the U-phase voltage command value Vu ** and the absolute value of the W-phase voltage command value Vw **, and the V-phase voltage command value Vv It is assumed that ** is zero or more.

The dq / uvw conversion unit 15 sets 36 [deg] +18 [deg] = 54 [deg] as the start timing of the next arithmetic cycle T of the arithmetic unit 5, and 54 [deg] +18 [deg] = 72 [deg]. Is the end timing of the next calculation cycle T of the calculation unit 5, and 54 [deg] to 72 [deg] is the next calculation cycle T of the calculation unit 5.

Next, the dq / uvw conversion unit 15 determines that the target electric angle θv falls within the first section (0 to 60 [deg]), or the absolute value of the V-phase voltage command value Vv ** is the U-phase. When it is larger than the absolute value of the voltage command value Vu ** and the absolute value of the W phase voltage command value Vw **, and the V phase voltage command value Vv ** is determined to be zero or more, the next calculation cycle T In (54 [deg] to 72 [deg]), if it is determined that 60 [deg] exists as the switching timing from the first section to the second section, the switching times ct1 to tk3 are set.

For example, as shown in FIG. 15A, the dq / uvw conversion unit 15 sets the time corresponding to 60 [deg] -54 [deg] = 6 [deg] as the switching time ct2, and Δt from the switching time tk2. The short time is defined as the switching time ct1, and the time Δt longer than the switching time ct2 is defined as the switching time ct3. Note that Δt is U-phase modulated wave Vu *, V-phase modulated so that the timing of switching the values of the U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * does not match each other. It is a time (electrical angle) for shifting the timing of switching the respective values of the wave Vv * and the W-phase modulated wave Vw *, and the switching element repeats twice the time of Δt at twice the time of Δt. The minimum time that can tolerate the distortion of the current flowing through the electric motor M is set even if it is not turned on or off.

Alternatively, as shown in FIG. 15B, the dq / uvw conversion unit 15 sets the time corresponding to 60 [deg] -54 [deg] = 6 [deg] as the switching time ct1 and Δt from the switching time ct1. A long time may be set as the switching time ct2, and a time Δt longer than the switching time ct2 may be set as the switching time ct3.

Alternatively, as shown in FIG. 15C, the dq / uvw conversion unit 15 sets the time corresponding to 60 [deg] -54 [deg] = 6 [deg] as the switching time ct3, and Δt from the switching time tk3. The short time may be set as the switching time ct2, and the time Δt shorter than the switching time ct2 may be set as the switching time ct1.

Then, when the start timing (54 [deg]) of the next calculation cycle T is reached, the dq / uvw conversion unit 15 changes the value of the V-phase modulation wave Vv * from the modulation factor Mref'to the maximum of the carrier wave after the switching time ct1 elapses. Switch to a value, switch the value of the W-phase modulated wave Vw * from the minimum value of the carrier wave to the maximum value after the switching time ct2 elapses, and modulate the value of the U-phase modulated wave Vu * from the minimum value of the carrier wave after the switching time ct3 elapses. Switch to rate Mref'.

As described above, the dq / uvw conversion unit 15 in the second modification is the switching timing from the first section to the second section, the switching timing from the second section to the third section, or from the third section. U-phase modulated wave Vu so that the switching timings of the U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * do not overlap each other at the switching timing to the first section. The switching timings of the values of *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * are shifted.

As a result, switching different from each other at the switching timing from the first section to the second section, the switching timing from the second section to the third section, or the switching timing from the third section to the first section. Since it is possible to prevent the elements from being turned on at the same time, it is possible to suppress the generation of reverse polarity pulses and suppress electromagnetic noise. Therefore, the distortion generated in the current flowing through the electric motor can be further suppressed, and the fluctuation of the torque can be further suppressed.

<Modification example 3>
By the way, as in the modification 1 and the modification 2, in the next calculation cycle T of the calculation unit 5, there is a switching timing of the first to third sections, and the switching timing is set to the calculation cycle of the calculation unit 5. When shifting from the start timing after the switching time ct or the switching time ct1 has elapsed, the error between the duty ratio of the drive signal S and the desired duty ratio may become relatively large.

FIG. 16 is a diagram showing an example of the V-phase modulated wave Vv *, the carrier wave, and the drive signal S3 in the modified example 1 or the modified example 2. It should be noted that one cycle of the carrier wave is 9 [deg].

In FIG. 16, when the start timing (54 [deg]) of the next calculation cycle T is reached, the dq / uvw conversion unit 15 V is after the switching time ct or the switching time ct1 (time corresponding to 6 [deg]) elapses. The value of the phase modulation wave Vv * is switched from the modulation factor Mref'to the maximum value of the carrier wave.

As described above, in the next calculation cycle T, when the switching timing of the first to third sections exists and the switching time ct or the switching time ct1 is shorter than one cycle of the carrier wave, the next calculation is performed. Since the V-phase modulated wave Vv * switches from the modulated wave Mref'to the maximum value of the carrier wave in the middle of the period from the start timing of the period T to the elapse of one cycle of the carrier wave, the duty ratio of the drive signal S3 becomes the modulated wave Mref'. It will not match the corresponding duty ratio. That is, in the next calculation cycle T, when the switching timing of the first to third sections exists, the error between the duty ratio of the drive signal S and the desired duty ratio may become relatively large. If the error between the duty ratio of the drive signal S and the desired duty ratio becomes relatively large, low-order harmonics (beats) may be added to the current flowing through the electric motor M, and torque ripple and noise vibration may increase.

Therefore, in the control device 1 of the electric motor M in the modification 3, if the switching timing of the first to third sections exists in the next calculation cycle T, the switching time ct elapses from the start timing of the next calculation cycle T. The frequency f of the carrier wave is switched to a predetermined frequency so that the error between the duty ratio of the drive signal S and the desired duty ratio becomes relatively small in the period until the above.

FIG. 17 is a diagram showing an example of the control device 1 of the electric motor M in the modified example 3. The same components as those shown in FIG. 1 are designated by the same reference numerals.

The control device 1 of the electric motor M shown in FIG. 17 differs from the control device 1 of the electric motor M shown in FIG. 1 in that instead of the dq / uvw conversion unit 15 and the drive circuit 4, the dq / uvw conversion unit 15'and the drive The point is that the circuit 4'is provided.

The dq / uvw conversion unit 15'uses the input voltage Vin detected by the voltage sensor Sv and the electric angle θ detected by the electric angle detection unit Sp, and uses the d-axis voltage command value Vd * and the q-axis voltage command value Vq. * Is converted into a U-phase modulated wave Vu *, a V-phase modulated wave Vv *, and a W-phase modulated wave Vw *, and the frequency f of the carrier wave is set to a predetermined frequency. The results calculated by the calculation unit 5 (U-phase modulation wave Vu *, V-phase modulation wave Vv *, W-phase modulation wave Vw *, and frequency f) are obtained by the inverter in the next calculation cycle T of the calculation unit 5. It shall be reflected in the operation of the circuit 2.

The drive circuit 4'is composed of an IC or the like, and is converted into dq / uvw with U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * output from the dq / uvw conversion unit 15'. The carrier wave of the frequency f output from the unit 15'is compared, and the drive signals S1 to S6 corresponding to the comparison result are output to the respective gate terminals of the switching elements SW1 to SW6.

FIG. 18A is a diagram showing an example of the dq / uvw conversion unit 15'. The same components as those shown in FIG. 10A are designated by the same reference numerals.

The dq / uvw conversion unit 15'shown in FIG. 18A includes a phase angle calculation unit 151, an addition unit 152, a modulation rate calculation unit 153, a modulation rate expansion unit 154, and a modulation wave generation unit 155'. It includes a speed calculation unit 158.

The speed calculation unit 158 calculates the rotation speed ω of the rotor of the electric motor M by using the electric angle θ detected by the electric angle detection unit Sp. For example, the speed calculation unit 158 obtains the rotation speed ω by differentiating the electric angle θ with respect to time.

The modulation wave generation unit 155'uses a target electric angle θv output from the addition unit 152, a modulation rate Muref' output from the modulation rate expansion unit 154, and a rotation speed ω calculated by the speed calculation unit 158. Therefore, the U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * are generated, and the frequency f of the carrier wave is set to a predetermined frequency. For example, the modulated wave generation unit 155'refers to the information D1 stored in the storage unit 6, and refers to the U-phase modulated wave Vu * and the V-phase modulated wave corresponding to the target electric angle θv output from the adding unit 152. Vv * and W-phase modulated wave Vw * are obtained. Further, the modulated wave generation unit 155'sets the frequency f of the carrier wave to the default frequency fd, the frequency fc which is the reciprocal of the switching time ct, or the frequency fc1 which is the reciprocal of the switching time tk1. The default frequency fd is, for example, a frequency corresponding to the calculation cycle and the rotation speed ω of the calculation unit 5.

FIG. 18B is a diagram showing another example of the dq / uvw conversion unit 15'. The same reference numerals are given to the configurations shown in FIG. 11A and the same configurations as those shown in FIG. 18A.

The dq / uvw conversion unit 15'shown in FIG. 18B includes a two-phase three-phase conversion unit 156, a modulated wave generation unit 157', and a speed calculation unit 158.

The modulated wave generation unit 157'has two-phase and three-phase conversion with the input voltage Vin detected by the voltage sensor Sv, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * output from the current control unit 14. Using the U-phase voltage command value Vu **, V-phase voltage command value Vv **, and W-phase voltage command value Vw ** output from unit 156, the U-phase voltage command value Vu * and V-phase voltage command value Vv * And W-phase modulated wave Vw * are generated, and the frequency f of the carrier is set to a predetermined frequency. For example, the modulated wave generation unit 157'obtains the phase angle δ by calculating the above equation 3, and adds the phase angle δ and the electric angle θ output from the electric angle detection unit Sp to the target electric angle θv. Then, the modulation factor Mref is obtained by calculating the above equation 4, and the modulation factor Mfer'is obtained by calculating the above equation 5. Further, the modulated wave generation unit 157'refers to the information D2 stored in the storage unit 6, and the U-phase voltage command value Vu ** and the V-phase voltage command value output from the two-phase three-phase conversion unit 156. The U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * corresponding to the branching conditions obtained by the Vv ** and the W-phase voltage command value Vw ** are obtained. Further, the modulated wave generation unit 157'sets the frequency f of the carrier wave to the frequency fd, the frequency fc, or the frequency fc1.

FIG. 19 is a flowchart showing an example of the operation of the dq / uvw conversion unit 15'. Note that steps S1 to S5 shown in FIG. 19 are the same as steps S1 to S5 shown in FIG.

First, the dq / uvw conversion unit 15'obtains the calculation cycle T of the calculation unit 5 (step S1), estimates the next calculation cycle T of the calculation unit 5 (step S2), and then the next calculation cycle of the calculation unit 5. In T, it is determined whether or not there is a switching timing of the first to third sections (step S3).

Next, when the switching timing of the first to third sections exists in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15'is based on the switching timing (step S3: Yes). When the switching time ct is set (step S4) and the switching time ct is the minimum time t_min or more (step S7: Yes), the frequency f of the carrier wave is set to the frequency fc (step S8), and the process proceeds to step 10. The minimum time t_min is the minimum value of one cycle of the carrier wave when the switching elements SW1 to SW6 can be switched from off to on or from on to off.

On the other hand, in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15'sets the switching time ct to the next calculation when the switching timing of the first to third sections does not exist (step S3: No). A value larger than the period T is set (step S5), the frequency f of the carrier wave is set to the frequency fd (step S9), and the process proceeds to step S10.

Further, when the switching time tc is shorter than the minimum time t_min (step S7: No), the dq / uvw conversion unit 15'sets the frequency f of the carrier wave to the frequency fd (step S9), and proceeds to step S10.

Next, in step S10, the dq / uvw conversion unit 15'sets the d-axis voltage command value Vd * and the q-axis voltage command value Vq * using the input voltage Vin and the electric angle θ, and sets the U-phase modulated wave Vu *. , V-phase modulated wave Vv *, and W-phase modulated wave Vw *, and when the start timing of the next calculation cycle T comes, U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * Is output to the drive circuit 4'and the frequency f is output to the drive circuit 4'.

Further, in step S10, when the switching time tk elapses from the start timing of the next calculation cycle T, the dq / uvw conversion unit 15'is a U-phase modulated wave Vu *, a V-phase modulated wave Vv *, and a W-phase modulated wave. Vw * is calculated from the modulation factor Mref'to the maximum value of the carrier wave, from the minimum value of the carrier wave to the modulation factor Mref', from the minimum value of the carrier wave to the maximum value of the carrier wave, from the maximum value of the carrier wave to the minimum value of the carrier wave, and from the modulation factor Mref'to the carrier wave. The minimum value of the carrier wave or the maximum value of the carrier wave is switched to the modulation factor Mref', and the frequency f is switched to the frequency fd.

FIG. 20 is a flowchart showing another example of the operation of the dq / uvw conversion unit 15'. Note that steps S1 to S4'and step S5 shown in FIG. 20 are the same as steps S1 to S4'and step S5 shown in FIG. Further, steps S9 and S10 shown in FIG. 20 are the same as steps S9 and S10 shown in FIG.

First, the dq / uvw conversion unit 15'obtains the calculation cycle T of the calculation unit 5 (step S1), estimates the next calculation cycle T of the calculation unit 5 (step S2), and then the next calculation cycle of the calculation unit 5. In T, it is determined whether or not there is a switching timing of the first to third sections (step S3).

Next, when the switching timing of the first to third sections exists in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15'is based on the switching timing (step S3: Yes). When the switching time ct1 to tk3 is set (step S4') and the switching time ct1 is equal to or longer than the minimum time t_min (step S11: Yes), the frequency f is set to the frequency fc1 (step S12), and the process proceeds to step S10. ..

On the other hand, in the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15'sets the switching time ct to the next calculation when the switching timing of the first to third sections does not exist (step S3: No). A value larger than the period T is set (step S5), the frequency f is set to the frequency fd (step S9), and the process proceeds to step S10.

Further, when the switching time tc1 is shorter than the minimum time t_min (step S11: No), the dq / uvw conversion unit 15'sets the frequency f to the frequency fd (step S9) and proceeds to step S10.

Next, in step S10, the dq / uvw conversion unit 15'sets the d-axis voltage command value Vd * and the q-axis voltage command value Vq * using the input voltage Vin and the electric angle θ, and sets the U-phase modulated wave Vu *. , V-phase modulated wave Vv *, and W-phase modulated wave Vw *, and when the start timing of the next calculation cycle T comes, U-phase modulated wave Vu *, V-phase modulated wave Vv *, and W-phase modulated wave Vw * Is output to the drive circuit 4'and the frequency f is output to the drive circuit 4'.

Further, in step S10, when the switching time tk elapses from the start timing of the next calculation cycle T, the dq / uvw conversion unit 15'is a U-phase modulated wave Vu *, a V-phase modulated wave Vv *, and a W-phase modulated wave. Vw * is defined as the maximum value of the carrier wave from the modulation rate Mref', the minimum value of the carrier wave to the modulation rate Mref', the minimum value of the carrier wave to the maximum value of the carrier wave, the maximum value of the carrier wave to the minimum value of the carrier wave, and the modulation factor Mref'to the carrier wave. The minimum value of the carrier wave or the maximum value of the carrier wave is switched to the modulation factor Mref', and the frequency f is switched to the frequency fd.

As a result, in the next calculation cycle T of the calculation unit 5, if the switching timing of the first to third sections does not exist, in the next calculation cycle T, the U-phase modulation wave Vu *, the V-phase modulation wave Vv *, And the W phase modulated wave Vw * does not switch with the same value.

Further, in the next calculation cycle T of the calculation unit 5, if the switching timing of the first to third sections does not exist, the frequency f of the carrier wave is not switched in the next calculation cycle T while being set to the frequency fd.

On the other hand, in the next calculation cycle T of the calculation unit 5, when the switching timing of the first to third sections exists, the switching time ct or the switching time ct1 has elapsed from the start timing of the next calculation cycle T. The U-phase modulated wave Vu *, the V-phase modulated wave Vv *, and the W-phase modulated wave Vw * are from the modulation factor Mref'to the maximum value of the carrier wave, from the minimum value of the carrier wave to the modulation factor Mref', and from the minimum value of the carrier wave to the carrier wave. The maximum value, the maximum value of the carrier wave to the minimum value of the carrier wave, the modulation factor Mref'to the minimum value of the carrier wave, or the maximum value of the carrier wave to the modulation factor Mref'.

Further, in the next calculation cycle T of the calculation unit 5, when the switching timing of the first to third sections exists, the period from the start timing of the next calculation cycle T until the switching time ct or the switching time ct1 elapses. In, the frequency f of the carrier wave is set to the frequency fc or the frequency fc1, and the frequency f of the carrier wave becomes the frequency fd in the period from the timing at which the switching timing time ct or the switching time ct1 has elapsed to the end timing of the next calculation cycle T. Set.

FIG. 21 is a diagram showing an example of the V-phase modulated wave Vv *, the carrier wave, and the drive signal S3 in the modified example 3. Each calculation cycle of the calculation unit 5 is set to 18 [deg], and one cycle of the carrier wave when the frequency f is set to the frequency fd is set to 9 [deg].

First, the dq / uvw conversion unit 15'sets 36 [deg] + 18 [deg] = 54 [deg] as the start timing of the next calculation cycle T of the calculation unit 5, and 54 [deg] +18 [deg] = 72. Let [deg] be the end timing of the next calculation cycle T of the calculation unit 5, and let 54 to 72 [deg] be the next calculation cycle T of the calculation unit 5.

Next, the dq / uvw conversion unit 15'determines that the target electric angle θv falls within the first section (0 to 60 [deg]), or the absolute value of the V-phase voltage command value Vv ** is U. When it is larger than the absolute value of the phase voltage command value Vu ** and the absolute value of the W phase voltage command value Vw **, and the V phase voltage command value Vv ** is determined to be zero or more, the calculation unit 5 determines. In the next calculation cycle T (54 [deg] to 72 [deg]), if it is determined that 60 [deg] exists as the switching timing from the first section to the second section, 60 [deg] -54 [deg] The time corresponding to = 6 [deg] is defined as the switching time ct or the switching time ct1.

Next, the dq / uvw conversion unit 15'sets the frequency f of the carrier wave to the frequency fc or the frequency fc1 when it determines that the switching time ct or the switching time ct1 is equal to or longer than the minimum time t_min.

Next, when the dq / uvw conversion unit 15' arrives at the start timing (54 [deg]) of the next calculation cycle T of the calculation unit 5, the dq / uvw conversion unit 15'sets the modulation factor Murf' as the V-phase modulation wave Vv * to the drive circuit 4'. At the same time, the frequency fc or the frequency fc1 is output to the drive circuit 4'as the frequency f.

Next, when the switching time tc elapses (60 [deg]), the dq / uvw conversion unit 15'sets the V-phase modulation wave Vv * output to the drive circuit 4'from the modulation factor Mref'to the maximum value of the carrier wave. At the same time, the frequency f output to the drive circuit 4'is switched from the frequency fc or the frequency fc1 to the frequency fd.

Then, the dq / uvw conversion unit 15'sets the maximum value of the carrier wave to the drive circuit 4'as a V-phase modulated wave Vv * until the end timing (72 [deg]) of the next calculation cycle T of the calculation unit 5 is reached. At the same time, the frequency fd is output to the drive circuit 4'as the frequency f.

That is, when the dq / uvw conversion unit 15'exists in the switching timing of the first to third sections in the next calculation cycle T of the calculation unit 5, the switching time tk or the switching time tk from the start timing of the next calculation cycle T or The frequency f of the carrier wave in the period until the switching time ct1 elapses is switched from the default frequency fd to the frequency fc which is the reciprocal of the switching time ct or the frequency fc1 which is the reciprocal of the switching time tk1.

As a result, in the period from the start timing of the next calculation cycle T to the elapse of the switching time ct or the switching time ct1, one cycle of the carrier wave can be matched with the switching time tk or the switching time ct1. Alternatively, it is possible to prevent the V-phase modulation wave Vv * from switching from the modulation factor Mref'to the maximum value of the carrier wave in the middle of the switching time tc1. Therefore, the duty ratio of the drive signal S3 can be made to match the duty ratio according to the modulation rate Mref'in the period from the start timing of the next calculation cycle T until the switching time ct or the switching time ct1 elapses.

As described above, in the control device 1 of the electric motor M in the modification 3, when the switching timing of the first to third sections exists in the next calculation cycle T of the calculation unit 5, the frequency f of the carrier wave is switched and the switching time tk. By setting the frequency fc, which is the inverse of the frequency fc, or the frequency fc1, which is the inverse of the switching time ct1, the error between the duty ratio of the drive signal S and the desired duty ratio can be reduced, so that the current flowing through the electric motor M can be changed. It is possible to suppress the riding of low-order harmonics, and it is possible to suppress the increase in torque ripple and noise vibration.

1 Control device 2 Inverter circuit 3 Control circuit 4 Drive circuit 4'Drive circuit 5 Calculation unit 6 Storage unit 7 Speed calculation unit 8 Subtraction unit 9 Torque control unit 10 Torque / current command value conversion unit 11 Coordinate conversion unit 12 Subtraction unit 13 Subtraction Unit 14 Current control unit 15 dq / uvw conversion unit 15'dq / uvw conversion unit 151 Phase angle calculation unit 152 Addition unit 153 Modulation rate calculation unit 154 Extended modulation rate calculation unit 155 Modulation wave generation unit 155'Modulation wave generation unit 156 2 Phase 3-phase conversion unit 157 Modulation wave generation unit 157'Modulation wave generation unit 158 Speed calculation unit

Claims (6)

When the first modulated wave is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, the first modulated wave is repeatedly turned on and off at a duty ratio corresponding to the first modulated wave, and the first modulated wave is said. When the minimum or maximum value of the carrier wave is the minimum value or the maximum value of the carrier wave, the first switching element which is always on or off and the second modulated wave are smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave. A second switching element that repeatedly turns on and off at a duty ratio corresponding to the second modulated wave, and always turns on or off when the second modulated wave is the minimum or maximum value of the carrier wave, and a second When the modulated wave of 3 is smaller than the maximum value of the carrier wave and larger than the minimum value of the carrier wave, it is repeatedly turned on and off at a duty ratio corresponding to the third modulated wave, and the third modulated wave is said. When it is the minimum value or the maximum value of the carrier wave, it is provided with a third switching element that is always on or off, and when the first to third switching elements are turned on and off, the three phases of the electric machine are in phase with each other. An inverter circuit that drives the electric motor by applying different first to third AC voltages, and
Among the control cycles of the electric motor including the first to third sections, the first modulated wave corresponding to the output of the electric motor is output in the first section where the peak of the first AC voltage exists. At the same time, the minimum value or the maximum value of the carrier wave is output as the second and third modulated waves, and in the second section where the peak of the second AC voltage exists, the second section corresponding to the output of the electric motor. In the third section where the second modulated wave is output and the minimum or maximum value of the carrier wave is output as the first and third modulated waves and the peak of the third AC voltage exists, the electric motor A control circuit that outputs the third modulated wave according to the output and outputs the minimum or maximum value of the carrier wave as the first and second modulated waves.
A control device for an electric motor. The electric motor control device according to claim 1.
It is provided with an electric angle detection unit that detects the electric angle of the rotor of the electric motor.
The control circuit
A target electric angle calculation unit that calculates a target electric angle based on a voltage command value corresponding to the output of the electric motor and an electric angle detected by the electric angle detection unit.
When the target electric angle is within the first section, the modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value is set as the first modulation wave and the minimum value of the carrier. Alternatively, the maximum value is the second and third modulated waves, and when the target electric angle is within the second section, the modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value. Is the second modulated wave, and the minimum or maximum value of the carrier is the first and third modulated waves, and when the target electric angle is within the third section, the inverter circuit A modulation wave generator that uses the modulation factor obtained by using the input voltage and the voltage command value as the third modulation wave and the minimum or maximum value of the carrier as the first and second modulation waves. ,
A control device for an electric motor. The electric motor control device according to claim 1.
It is provided with an electric angle detection unit that detects the electric angle of the rotor of the electric motor.
The control circuit
The voltage command value corresponding to the output of the electric motor and the electric angle detected by the electric angle detection unit correspond to the first voltage command value corresponding to the first AC voltage and the second AC voltage. A voltage command value calculation unit that calculates a second voltage command value and a third voltage command value corresponding to the third AC voltage, and
When the absolute value of the first voltage command value is larger than the absolute value of the second and third voltage command values, the input voltage of the inverter circuit and the voltage command value corresponding to the output of the electric motor are used. The modulation factor obtained is the first modulation wave, the minimum or maximum value of the carrier is the second and third modulation waves, and the absolute value of the second voltage command value is the first and third. When it is larger than the absolute value of the third voltage command value, the modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value corresponding to the output of the electric motor is set as the second modulation wave. When the minimum value or the maximum value of the carrier is the first and third modulated waves and the absolute value of the third voltage command value is larger than the absolute value of the first and second voltage command values, The modulation factor obtained by using the input voltage of the inverter circuit and the voltage command value corresponding to the output of the electric motor is set as the third modulation wave, and the minimum or maximum value of the carrier is set as the first and second. A control device for an electric motor, which comprises a modulated wave generator as a modulated wave of the above. The control device for an electric motor according to any one of claims 1 to 3.
In the next calculation cycle, the control circuit starts from the switching timing from the first section to the second section, the switching timing from the second section to the third section, or from the third section. A control device for an electric motor, characterized in that, when a switching timing to the first section exists, the start timing of the next calculation cycle is matched with the switching timing. The control device for an electric motor according to claim 4.
The control circuit may switch from the first section to the second section, from the second section to the third section, or from the third section to the first section. The feature is that the switching timings of the respective values of the first to third modulated waves are shifted so that the switching timings of the respective values of the first to third modulated waves do not overlap each other. Control device for electric motors. The control device for an electric motor according to claim 4 or 5.
In the next calculation cycle, the control circuit starts from the switching timing from the first section to the second section, the switching timing from the second section to the third section, or from the third section. When the switching timing to the first section exists, the switching time from the start timing of the next calculation cycle to the switching timing is obtained, and the frequency which is the reciprocal of the switching time is set to the start timing of the next calculation cycle. A control device for an electric motor, characterized in that the frequency of the carrier wave is set in the period from the time when the switching time elapses.

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