JP6742967B2 - Motor control device - Google Patents

Description

The present invention relates to a motor control device.

Conventionally, there has been a demand for a motor control device having improved responsiveness and followability. Patent Document 1 discloses PI calculation units 51a and 52a for calculating PI calculation values Vdo and Vqo, and a decoupling control amount calculation for calculating a decoupling control amount for decoupling control of a motor. Units 51b and 52b, addition units 51c and 52c that add the PI calculation values Vdo and Vqo and the decoupling control amount, and addition results of the addition units 51c and 52c are limited, and the limited values are used as the voltage command value Vd. Disclosed is a motor control device that includes limiters 51d and 52d that output * and Vq*, and subtraction units 51e and 52e that subtract decoupling control amounts from voltage command values Vd* and Vq*. In this motor control device, the PI calculation units 51a and 52a use the previous value of the subtraction result of the subtraction units 51e and 52e to calculate the PI calculation values Vdo and Vqo.

JP, 2009-81915, A

In the conventional technique described in Patent Document 1, it is difficult to maintain the torque accuracy within a desired range with respect to a rapid change in the torque command.

A motor control device according to the present invention controls the drive of an AC motor, and a current command value determination unit that determines a d-axis current command value and a q-axis current command value that determines the amount of current flowing in the AC motor, A d-axis current correction amount calculation unit for calculating a d-axis current correction amount for correcting the d-axis current command value, and a q-axis current for calculating a q-axis current correction amount for correcting the q-axis current command value. A correction amount calculation unit, a corrected d-axis current command value obtained by correcting the d-axis current command value by the d-axis current correction amount, and a corrected q after correcting the q-axis current command value by the q-axis current correction amount. A current control unit that calculates a voltage command value and a modulation rate for driving the AC motor based on a shaft current command value, and the q-axis current correction amount calculation unit is a PI using an integrator. A q-axis PI control unit that calculates the q-axis current correction amount by control, a limiter unit that limits the output from the integrator within a predetermined limit value, a rotor temperature of the AC motor, and the q-axis current command value. And a limit value changing unit that changes the limit value based on the above.

According to the present invention, the torque accuracy can be kept within a desired range with respect to a sudden change in the torque command.

The figure explaining the motor control system containing the motor control device which concerns on one Embodiment of this invention. The figure which shows the function structure of the d-axis current correction amount calculation part which concerns on one Embodiment of this invention. 3 is a flowchart illustrating a processing procedure of a d-axis current correction amount calculation unit according to an embodiment of the present invention. The figure which shows the function structure of the q-axis current correction amount calculation part which concerns on one Embodiment of this invention.

FIG. 1 is a diagram illustrating a motor control system including a motor control device according to an embodiment of the present invention. The motor control system shown in FIG. 1 includes a high-voltage power supply 1, a smoothing capacitor 2, an inverter 3, a motor 4 that is an AC motor, a rotation speed sensor 5, a phase current detector 6, and a motor control device 10. Have.

The motor control device 10 controls the drive of the motor 4 by controlling the inverter 3 connected to the motor 4, and includes a current command value determination unit 100, a d-axis current correction amount calculation unit 110, and a q-axis. It has a current correction amount calculation unit 120, a current control unit 130, a PWM circuit 140, a torque deviation calculation unit 150, and adders 160 and 170. The motor control device 10 can realize each of these functional blocks by executing a predetermined program in, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). Alternatively, each functional block may be realized by using hardware such as FPGA (Field-Programmable Gate Array).

In addition to the motor 4, the inverter 3 is connected to the high voltage power supply 1 and the smoothing capacitor 2. A rotation speed sensor 5 is installed in the motor 4, and a phase current detector 6 is installed between the inverter 3 and the motor 4.

The high-voltage power supply 1 is a power supply circuit for driving the system, and supplies DC power to the inverter 3. The smoothing capacitor 2 is connected between the high-voltage power supply 1 and the inverter 3, and reduces the voltage fluctuation of the DC power supplied from the high-voltage power supply 1 to the inverter 3. The inverter 3 has a plurality of switching elements, and the on/off state of each switching element is switched by the motor control device 10 to convert the DC power supplied from the high-voltage power supply 1 into a three-phase AC power to drive the motor. Output to 4. The DC side of the inverter 3 is connected to the high-voltage power supply 1 and the smoothing capacitor 2, and the three-phase AC side is connected to the motor 4.

The motor 4 receives the three-phase AC power output from the inverter 3 and is driven to rotate. The motor 4 is connected between the AC side of the inverter 3 and the rotation speed sensor 5. The rotation speed sensor 5 is connected to the motor 4, acquires rotation speed and angle information of the motor 4, and outputs an electrical angular speed ωe according to the rotation speed of the motor 4. The phase current detector 6 detects the three-phase alternating current output from the inverter 3 to the motor 4, and outputs the current values iu, iv, iw of each phase.

The current command value determination unit 100 determines the d-axis current command value id* and the q-axis current command value iq* that determine the amount of current flowing through the motor 4. The current command value determination unit 100, based on the DC voltage command Vdc*, the torque command Trq*, and the motor rotation speed command ωr* input from an external controller (not shown), the d-axis current command value id* for these input values. And q-axis current command value iq* are determined. Specifically, the current command value determination unit 100 uses, for example, a d-axis current command value id as an output value corresponding to each input value from the external controller based on the relationship between the input value and the output value tabulated in advance. * And q-axis current command value iq* are determined. It should be noted that the d-axis current command value id* and the q-axis current command value iq* may be determined by a method other than this, for example, using a predetermined arithmetic expression. Further, one of the DC voltage command Vdc*, the torque command Trq*, and the motor rotation speed command ωr* may be replaced with another input value or may be omitted.

The d-axis current correction amount calculation unit 110 is connected between the current command value determination unit 100 and the current control unit 130, and corrects the d-axis current command value id* determined by the current command value determination unit 100. The d-axis current correction amount idcmp* of is calculated. Specifically, the d-axis current correction amount calculation unit 110 receives the d-axis current command value id* and the q-axis current command value iq* input from the current command value determination unit 100, and the rotation speed sensor 5. The d-axis current correction amount idcmp* is calculated based on the electrical angular velocity ωe and the modulation factor MF input from the current control unit 130. The details of the method of calculating the d-axis current correction amount idcmp* by the d-axis current correction amount calculation unit 110 will be described later with reference to FIG.

The q-axis current correction amount calculation unit 120 is connected between the current command value determination unit 100 and the current control unit 130, and corrects the q-axis current command value iq* determined by the current command value determination unit 100. The q-axis current correction amount iqcmp* of is calculated. Specifically, the q-axis current correction amount calculation unit 120 calculates the q-axis current command value iq* input from the current command value determination unit 100 and the d-axis current correction value input from the d-axis current correction amount calculation unit 110. Of the q-axis current correction amount iqcmp* based on the amount idcmp*, the amount of torque deviation ΔTrq input from the torque deviation calculation unit 150, and the rotor temperature Rtmp of the motor 4 and the rotor temperature reference value Rtmp_base input from the outside. Calculate. Note that a specific method of calculating the q-axis current correction amount iqcmp* by the q-axis current correction amount calculation unit 120 will be described later with reference to FIG.

The adder 160 corrects the d-axis current command value id* by adding the d-axis current correction amount idcmp* calculated by the d-axis current correction amount calculation unit 110 to the d-axis current command value id*. The corrected d-axis current command value idh* is calculated. The adder 170 corrects the q-axis current command value iq* by adding the q-axis current correction amount iqcmp* calculated by the q-axis current correction amount calculation unit 120 to the q-axis current command value iq*. Calculate the corrected q-axis current command value iqh*.

The current control unit 130 is connected between the adders 160 and 170 and the PWM circuit 140, and based on the corrected d-axis current command value idh* and the corrected q-axis current command value iqh*, the voltage of each phase. Command values Vu*, Vv*, Vw* are output. At this time, the current control unit 130 uses the current values iu, iv, iw of each phase input from the phase current detector 6 as feedback currents, and uses the voltage command values Vu*, Vv*, Vw according to the electrical angular velocity ωe. * Is calculated and output to the PWM circuit 140. Further, the current control unit 130 calculates the modulation factor MF from the calculation results of the voltage command values Vu*, Vv*, Vw* and outputs it to the d-axis current correction amount calculation unit 110.

The PWM circuit 140 is connected between the current control unit 130 and the inverter 3, and uses the voltage command values Vu*, Vv*, and Vw* of each phase acquired from the current control unit 130 to switch each of the inverters 3. A PWM signal for the element is generated and output to the inverter 3. By switching-driving each switching element of the inverter 3 according to the PWM signal, AC power is supplied from the inverter 3 to the motor 4, and the motor 4 is rotationally driven.

The torque deviation calculation unit 150 is connected between the current command value determination unit 100 and the q-axis current correction amount calculation unit 120. The torque deviation calculation unit 150 receives the d-axis current command value id* and the q-axis current command value iq* input from the current command value determination unit 100, and the corrected d-axis current command value idh obtained by correcting them. * Based on the corrected q-axis current command value iqh* and the rotor temperature Rtmp of the motor 4, calculate the torque deviation ΔTrq corresponding to the difference between the torque command Trq* and the torque actually output by the motor 4. Then, it is output to the q-axis current correction amount calculation unit 120. The torque deviation ΔTrq may be calculated by measuring the output torque of the motor 4 and obtaining the difference between the value and the torque command Trq*.

FIG. 2 is a diagram showing a functional configuration of the d-axis current correction amount calculation unit 110 according to the embodiment of the present invention. The d-axis current correction amount calculator 110 includes a field weakening current calculator 200, a d-axis PI controller 210, a d-axis current correction output first determiner 220, and a d-axis current correction output second determiner 230. Have.

The field weakening current calculation unit 200 has respective arithmetic elements of a subtractor 201, a limiter 202, a divider 203, a multiplier 204, a d-axis inductance table 205, and a divider 206. The subtractor 201 calculates the difference between the maximum modulation rate MFmax and the modulation rate MF input to the d-axis current correction amount calculation section 110. The limiter 202 limits the difference between the maximum modulation rate MFmax calculated by the subtractor 201 and the modulation rate MF within a predetermined range. The divider 203 divides the difference between the maximum modulation rate MFmax and the modulation rate MF limited by the limiter 202 by the electrical angular velocity ωe input to the d-axis current correction amount calculation unit 110. The multiplier 204 multiplies the division result of the divider 203 by a predetermined control angular frequency ωCLK. The d-axis inductance table 205 is based on the d-axis current command value id* and the q-axis current command value iq* input to the d-axis current correction amount calculation unit 110, and the d-axis inductance Ld corresponding to these input values. Is output. The divider 206 divides the multiplication result of the multiplier 204 by the d-axis inductance Ld obtained by the d-axis inductance table 205, and outputs the calculation result as a field weakening current idw*.

The field-weakening current calculation unit 200 performs the above-described calculation in each calculation element to obtain the d-axis current command value id* and the q-axis current command value iq* input to the d-axis current correction amount calculation unit 110. And the field-weakening current idw* for the motor 4 can be calculated based on the rotation speed of the motor 4.

The d-axis PI control unit 210 has arithmetic elements of a multiplier 211, an adder 212, a multiplier 213, an adder 214, and an integrator 215. The multiplier 211 calculates the proportional component idp* of the d-axis current correction amount by multiplying the field weakening current idw* by a predetermined proportional gain Kdp. The multiplier 213 multiplies the field weakening current idw* by a predetermined integral gain Kdi. The adder 212 calculates the integral component idi* of the d-axis current correction amount by adding the output from the integrator 215 to the multiplication result of the multiplier 213. The adder 214 calculates the d-axis current correction amount idcmp* by summing the proportional component idp* of the d-axis current correction amount and the integral component idi*. The integrator 215 integrates the output from the d-axis current correction output second determiner 230 and outputs the integrated output to the adder 212.

The d-axis PI control unit 210 performs the above-described calculation in each calculation element to perform the PI control based on the field-weakening current idw* calculated by the field-weakening current calculation unit 200, thereby performing the d-axis current correction amount. You can calculate idcmp*.

The modulation factor MF and the d-axis current correction amount idcmp* calculated by the d-axis PI control unit 210 are input to the d-axis current correction output first determiner 220. The first d-axis current correction output determiner 220 compares the modulation factor MF with a predetermined threshold value, and when the modulation factor MF is less than or equal to the threshold value, the d-axis current correction amount calculation unit 110 calculates the d-axis current correction amount idcmp*. The result is output as 0. On the other hand, when the modulation factor MF exceeds the threshold value, the d-axis current correction amount idcmp* calculated by the d-axis PI control unit 210 is directly used as the calculation result of the d-axis current correction amount idcmp* by the d-axis current correction amount calculation unit 110. Output as.

The modulation factor MF and the integral component idi* of the d-axis current correction amount calculated by the d-axis PI control unit 210 are input to the d-axis current correction output second determiner 230. The second d-axis current correction output determiner 230 compares the modulation factor MF with a predetermined threshold value, and when the modulation factor MF is less than or equal to the threshold value, 0, and when it exceeds the threshold value, the integral component idi* of the d-axis current correction amount. , To the integrator 215 of the d-axis PI controller 210. The threshold value compared with the modulation factor MF in the d-axis current correction output second determiner 230 may be the same as or different from the d-axis current correction output first determiner 220.

Below, the calculation contents in the d-axis current correction amount calculation unit 110 will be further explained. As described above, the d-axis current correction amount calculation unit 110 calculates the d-axis current command value id* and the q-axis current command value iq* determined by the current command value determination unit 100 and the current control unit 130. The field weakening current calculator 200 calculates the field weakening current idw* based on the modulation factor MF and the maximum modulation factor MF. By performing PI control on the field weakening current idw* by the d-axis PI control unit 210, the d-axis current correction amount idcmp* is calculated. Accordingly, the d-axis current correction amount calculation unit 110 corrects and controls the d-axis current command value id* so that the applied voltage does not exceed the specified voltage in the speed region of the motor 4 in which the applied voltage of the motor 4 exceeds the limit value. To do. That is, the motor 4 configured by using a PMSM (Permanent Magnet Synchronous Motor) that obtains a magnetic field flux by a permanent magnet cannot directly control the magnetic field flux, but a reduction caused by passing a negative d-axis current to the motor 4. Due to the magnetic effect, the magnetic flux in the d-axis direction can be reduced. The d-axis current correction amount calculation unit 110 utilizes this to control the d-axis current amount and suppress the induced voltage of the motor 4 to a predetermined value or less, thereby suppressing the line voltage of the motor 4 to be within the specified voltage. I have to.

If the maximum value of the flux linkage in the motor 4 is φmax, the voltage limit value is Vlim, the electrical angular velocity is ωe, the d-axis inductance is Ld, the q-axis inductance is Lq, and the q-axis current is Iq, the d-axis current in weakening flux control Id is represented by the following formula (1).

Further, when the control angular frequency is ωCLK, the field weakening gain Kfw is expressed by the following equation (2).

When the modulation rate is MF and the maximum modulation rate is MFmax, the field weakening current idw* is represented by the following equation (3) from the above equations (1) and (2).

The configuration of the field weakening current calculation unit 200 shown in FIG. 2 corresponds to the calculation of the above equation (3). The d-axis PI control unit 210 calculates the d-axis current correction amount idcmp* by PI-controlling the field weakening current idw* calculated by the equation (3). The current control unit 130 uses the corrected d-axis current command value idh* obtained by adding the d-axis current correction amount idcmp* thus calculated to the d-axis current command value id*, and the current control unit 130 determines the voltage command value Vu*. , Vv*, Vw* are calculated. As a result, the induced voltage of the motor 4 can be suppressed and the line voltage can be suppressed within the specified voltage. As a result, stable current control of the motor 4 can be realized while maintaining the maximum torque output even in the high rotation range.

FIG. 3 is a flowchart illustrating a processing procedure of the d-axis current correction amount calculation unit 110 according to the embodiment of the present invention.

In step S10, the d-axis current correction amount calculation unit 110 acquires the control parameters of the maximum modulation rate MFmax, the modulation rate MF, the electrical angular velocity ωe, the d-axis current command value id*, and the q-axis current command value iq*.

In step S20, the d-axis current correction amount calculation unit 110 uses the limiter 202 of the field weakening current calculation unit 200 to determine the magnitude of the maximum modulation rate MFmax and the modulation rate MF acquired in step S10. As a result, when the modulation rate MF is larger than the maximum modulation rate MFmax, that is, when the inequality of MFmax-MF<0 is satisfied, the process proceeds to step S30. On the other hand, when the modulation rate MF is less than or equal to the maximum modulation rate MFmax, that is, when the inequality is not satisfied, the process proceeds to step S40.

In step S30, the d-axis current correction amount calculation unit 110 causes the field weakening current calculation unit 200 to calculate the field weakening current idw* from each control parameter acquired in step S10. Then, the process proceeds to step S50.

In step S40, the d-axis current correction amount calculation unit 110 sets the output from the limiter 202 of the field weakening current calculation unit 0 to 0, and thus sets the calculation result of the field weakening current idw* to 0. As a result, the field weakening current idw* flowing through the motor 4 is controlled to approach zero. Then, the process proceeds to step S50.

In step S50, the d-axis current correction amount calculation unit 110 uses the d-axis current correction output first determiner 220 to determine the magnitude of the modulation factor MF acquired in step S10 and the predetermined modulation factor threshold. As a result, if the modulation factor MF is greater than the threshold value, the process proceeds to step S60, and if it is less than or equal to the threshold value, the process proceeds to step S70.

In step S60, the d-axis current correction amount calculation unit 110 calculates the d-axis current correction amount idcmp* from the field weakening current idw* calculated in step S30 by the d-axis PI control unit 210. Then, the process proceeds to step S80.

In step S70, the d-axis current correction amount calculation unit 110 sets the output from the d-axis current correction output first determiner 220 to 0, thereby setting the calculation result of the d-axis current correction amount idcmp* to 0. As a result, the d-axis current command value id* is prevented from being corrected by the weakening magnetic flux control. Then, the process proceeds to step S80.

In step S80, the d-axis current correction amount calculation unit 110 outputs the calculation result of step S60 or step S70 executed according to the determination result of step S50 as the d-axis current correction amount idcmp*.

FIG. 4 is a diagram showing a functional configuration of the q-axis current correction amount calculation unit 120 according to the embodiment of the present invention. The q-axis current correction amount calculation unit 120 includes a q-axis PI control unit 400, a limit value changing unit 410, and a q-axis current correction amount integral term limiter 420.

The q-axis PI control unit 400 has arithmetic elements of a multiplier 401, an adder 402, a multiplier 403, an adder 404, and an integrator 405. The multiplier 401 calculates the proportional component iqp* of the q-axis current correction amount by multiplying the torque deviation ΔTrq input from the torque deviation calculation unit 150 to the q-axis current correction amount calculation unit 120 by a predetermined proportional gain Kqp. To do. The multiplier 403 multiplies the torque deviation ΔTrq by a predetermined integral gain Kqi. The adder 402 calculates the integral component iqi* of the q-axis current correction amount by adding the output from the integrator 405 to the multiplication result of the multiplier 403. The adder 404 calculates the q-axis current correction amount iqcmp* by summing the proportional component iqp* and the integral component iqi* of the q-axis current correction amount. The integrator 405 integrates the output from the q-axis current correction amount integral term limiter 420 and outputs it to the adder 402.

The q-axis PI control unit 400 can calculate the q-axis current correction amount iqcmp* by PI control using the integrator 405 by performing the above-described calculation in each calculation element.

The q-axis current correction amount integral term limiter 420 performs limit processing for limiting the integral component iqi* of the q-axis current correction amount output from the q-axis PI control unit 400 within a predetermined limit value. That is, the q-axis current correction amount integral term limiter 420 limits the integral component iqi* of the q-axis current correction amount, which is the output from the integrator 405 of the q-axis PI control unit 400, within a predetermined limit value. The limit value in the q-axis current correction amount integral term limiter 420 is changed according to the output from the limit value changing unit 410 as described later.

The limit value changing unit 410 has respective calculation elements of a subtractor 411, multipliers 412 to 414, and an adder 415. The subtractor 411 calculates the difference between the rotor temperature Rtmp and the rotor temperature reference value Rtmp_base, which are input to the q-axis current correction amount calculation unit 120. The multiplier 412 multiplies the difference between the rotor temperature Rtmp calculated by the subtractor 411 and the rotor temperature reference value Rtmp_base by a predetermined proportional gain Kiq. The multiplier 413 multiplies the calculation result of the multiplier 412 by the q-axis current command value iq* input to the q-axis current correction amount calculation unit 120. The multiplier 414 multiplies the d-axis current correction amount idcmp* input from the d-axis current correction amount calculation unit 110 to the q-axis current correction amount calculation unit 120 by a predetermined proportional gain Kid. The adder 415 sums the calculation result of the multiplier 413 and the calculation result of the multiplier 414, and outputs the calculation result as the limit value Iqi_lmt of the q-axis current correction amount integral term limiter 420.

The q-axis current correction amount integral term limiter 420 uses the limit value Iqi_lmt output from the limit value changing unit 410 to perform the above limit processing. As a result, the integral component iqi* of the q-axis current correction amount output from the integrator 405 of the q-axis PI control unit 400 is limited within the range corresponding to the limit value Iqi_lmt. That is, the limit value changing unit 410 performs q on the basis of the rotor temperature Rtmp of the motor 4, the q-axis current command value iq*, and the d-axis current correction amount idcmp* by performing the above-described calculation on each calculation element. The limit value Iqi_lmt for the integral component iqi* of the axis current correction amount can be changed.

Below, the calculation contents in the q-axis current correction amount calculation unit 120 will be further explained. As described above, the q-axis current correction amount calculation unit 120 calculates the q-axis current correction amount iqcmp* by performing the PI control by the q-axis PI control unit 400 using the torque deviation ΔTrq with respect to the torque command Trq*. To do. The integral component iqi* of the q-axis current correction amount used in this PI control is limited within the range of the limit value Iqi_lmt by the limit processing performed by the q-axis current correction amount integral term limiter 420. At this time, the limit value changing unit 410 uses the rotor temperature Rtmp of the motor 4 and the rotor temperature reference value Rtmp_base, the q-axis current command value iq*, and the d-axis current correction amount idcmp* to determine the limit value Iqi_lmt in the limit process. Is calculated. Thereby, the q-axis current correction amount calculation unit 120 corrects and controls the q-axis current command value iq* according to the rotor temperature of the motor 4.

If the deviation of the actual torque from the torque command of the motor 4 is ΔTrq, the rotor temperature of the motor 4 is Rtmp, the rotor temperature reference value is Rtmp_base, the q-axis current command value is Iq*, and the d-axis current correction amount is Idcmp*, the integral term The limit value Iqi_lmt of is expressed by the following equation (4).

In the above equation (4), both the d-axis current gain Kid and the q-axis current gain Kiq are constants. These constants are predetermined based on, for example, the rotor temperature within the mounting range of the motor 4, the reference temperature, the d-axis current command value, and the q-axis current command value.

The integral component Iqi* of the q-axis current correction amount is limited by the following equation (5) by the limit value Iqi_lmt of the integral term derived by the above equation (4).

The configurations of the limit value changing unit 410 and the q-axis current correction amount integral term limiter 420 shown in FIG. 4 correspond to the calculations of the above expressions (4) and (5), respectively. That is, the q-axis current correction amount integral term limiter 420 uses the positive value of the limit value Iqi_lmt as the upper limit value and the negative value of the limit value Iqi_lmt as the lower limit value, and the integrator of the q-axis PI control unit 400 according to the equation (5). The output from 405 is limited to a value that is greater than or equal to the lower limit and less than or equal to the upper limit. Further, the limit value changing unit 410 changes the limit value for the integrator 405 by increasing/decreasing the difference between the lower limit value and the upper limit value represented by Expression (5) according to Expression (4).

The q-axis PI control unit 400 of the q-axis current correction amount calculation unit 120 performs PI control using the integral component iqi* of the q-axis current correction amount subjected to the upper and lower limit processing as described above. As a result, the q-axis current correction amount iqcmp* corresponding to the rotor temperature Rtmp of the motor 4 can be calculated, so that it is possible to cope with a sharp change in the q-axis current command value iq*. As a result, it is possible to maintain the torque accuracy in a desired range even with a sudden change in the torque command, such as during rapid acceleration/deceleration in an environment where the rotor temperature changes drastically. That is, when the torque command changes abruptly, the q-axis current command value iq* is unnecessarily corrected by the conventional control method, which may cause a torque shock. On the other hand, in the present embodiment, in the q-axis current correction amount calculation unit 120, the q-axis current correction limit process according to the rotor temperature Rtmp of the motor 4 and the q-axis current command value iq* is performed by the above-described process. This is performed for the integrator 405 provided in the PI control unit 400. As a result, overcorrection of the q-axis current command value iq* can be prevented, and abrupt changes in the torque command can be handled. Therefore, when the motor 4 is mounted on a vehicle such as an automobile, it is possible to prevent abnormal noise of the motor 4 due to torque shock, vibration of the vehicle, and the like, and avoid the possibility of impairing the ride comfort and running performance of the driver.

According to the embodiment of the present invention described above, the following operational effects are obtained.

(1) The motor control device 10 that controls the drive of the motor 4 that is an AC motor determines the current command value that determines the d-axis current command value id* and the q-axis current command value iq* that determine the amount of current that flows in the motor 4. Unit 100, d-axis current correction amount calculation unit 110 for calculating d-axis current correction amount idcmp* for correcting d-axis current command value id*, and q-axis for correcting q-axis current command value iq* The q-axis current correction amount calculation unit 120 that calculates the current correction amount iqcmp*, the corrected d-axis current command value idh* obtained by correcting the d-axis current command value id* with the d-axis current correction amount idcmp*, and the q-axis current Voltage command values Vu*, Vv*, Vw* and modulation rate for driving the motor 4 based on the corrected q-axis current command value iqh* obtained by correcting the q-axis current command value iq* with the correction amount iqcmp* And a current control unit 130 that calculates MF. The q-axis current correction amount calculation unit 120 calculates the q-axis current correction amount iqcmp* by PI control using the integrator 405, and the q-axis current correction amount output from the integrator 405. Limiter unit that limits the integral component iqi* of the motor to a predetermined limit value Iqi_lmt, that is, the q-axis current correction amount integral term limiter 420, the rotor temperature Rtmp of the motor 4, and the q-axis current command value iq*. A limit value changing unit 410 that changes Iqi_lmt. Since this is done, the motor control device 10 can cope with a sharp change in the q-axis current command value iq*, and as a result, the torque accuracy can be maintained within a desired range with respect to a sudden change in the torque command. ..

(2) In the motor control device 10, the limit value changing unit 410 further changes the limit value Iqi_lmt based on the d-axis current correction amount idcmp*. Since it did in this way, it can be set as the optimal limit value Iqi_lmt so that the induced voltage of the motor 4 may be suppressed below a predetermined value.

(3) The limit value Iqi_lmt has a lower limit value and an upper limit value, and the q-axis current correction amount integral term limiter 420 sets the output from the integrator 405 to a value equal to or higher than the lower limit value and equal to or lower than the upper limit value of the limit value Iqi_lmt. Restrict. The limit value changing unit 410 changes the limit value Iqi_lmt by increasing or decreasing the difference between the lower limit value and the upper limit value. Since it did in this way, the integral component iqi* of the q-axis current correction amount output from the integrator 405 can be appropriately limited.

(4) The d-axis current correction amount calculation unit 110 sets the calculation result of the d-axis current correction amount idcmp* to 0 when the modulation factor MF is less than or equal to a predetermined threshold value (FIG. 3, step S50: NO) (step S60). .. Since it did in this way, according to the magnitude of the modulation factor MF, when weakening magnetic flux control is unnecessary, it can be stopped.

(5) The d-axis current correction amount calculation unit 110 calculates the field weakening current idw* based on the d-axis current command value id* and the q-axis current command value iq* and the rotation speed of the motor 4. A field current calculation unit 200 and a d-axis PI control unit 210 that calculates a d-axis current correction amount idcmp* by PI control based on the field-weakening current idw* calculated by the field-weakening current calculation unit 200. .. The field weakening current calculation unit 200 sets the calculation result of the field weakening current idw* to 0 (step S30) when the modulation factor MF is equal to or lower than the predetermined maximum modulation factor MFmax (FIG. 3, step S20: YES). Since this is done, it is possible to control the field weakening current idw* to approach 0 according to the magnitude of the modulation factor MF.

In the above-described embodiment, the limit value changing unit 410 of the q-axis current correction amount calculation unit 120 uses the d-axis current correction amount idcmp* when determining the limit value Iqi_lmt. The limit value Iqi_lmt may be obtained without using the correction amount idcmp*. By doing so, it is possible to cope with sharp changes in the q-axis current command value iq* to some extent while reducing the calculation load of the limit value changing unit 410. Therefore, the torque accuracy can be maintained within a desired range with respect to a rapid change in the torque command.

The embodiments and various modifications described above are merely examples, and the present invention is not limited to these contents unless the characteristics of the invention are impaired. Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other modes that are conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

1: High-voltage power supply 2: Smoothing capacitor 3: Inverter 4: Motor 5: Rotation speed sensor 6: Phase current detector 10: Motor control device 100: Current command value determination unit 110: d-axis current correction amount calculation unit 120: q-axis Current correction amount calculation unit 130: current control unit 140: PWM circuit 150: torque deviation calculation unit 160: adder 170: adder 200: field weakening current calculation unit 210: d-axis PI control unit 220: d-axis current correction output First determiner 230: d-axis current correction output second determiner 400: q-axis PI control unit 410: limit value changing unit 420: q-axis current correction amount integral term limiter

Claims (5)

A motor control device for controlling the drive of an AC motor,
A current command value determining unit that determines a d-axis current command value and a q-axis current command value that determine the amount of current flowing through the AC motor;
A d-axis current correction amount calculation unit that calculates a d-axis current correction amount for correcting the d-axis current command value;
A q-axis current correction amount calculation unit that calculates a q-axis current correction amount for correcting the q-axis current command value,
A corrected d-axis current command value obtained by correcting the d-axis current command value by the d-axis current correction amount and a corrected q-axis current command value obtained by correcting the q-axis current command value by the q-axis current correction amount. Based on, a current control unit that calculates a voltage command value and a modulation factor for driving the AC motor,
The q-axis current correction amount calculation unit
A q-axis PI control unit that calculates the q-axis current correction amount by PI control using an integrator,
A limiter unit for limiting the output from the integrator within a predetermined limit value,
And a limit value changing unit that changes the limit value based on the rotor temperature of the AC motor and the q-axis current command value. The motor control device according to claim 1, wherein
The limit value changing unit further changes the limit value based on the d-axis current correction amount. The motor control device according to claim 1 or 2, wherein
The limit value has a lower limit value and an upper limit value,
The limiter unit limits the output from the integrator to a value of the lower limit value or more and the upper limit value or less,
The limit value changing unit changes the limit value by increasing or decreasing a difference between the lower limit value and the upper limit value. The motor control device according to claim 1 or 2, wherein
The motor control device in which the d-axis current correction amount calculation unit sets the calculation result of the d-axis current correction amount to 0 when the modulation rate is equal to or less than a predetermined threshold value. The motor control device according to claim 1 or 2, wherein
The d-axis current correction amount calculation unit
A field-weakening current calculator that calculates a field-weakening current based on the d-axis current command value, the q-axis current command value, and the rotation speed of the AC motor;
A d-axis PI controller that calculates the d-axis current correction amount by PI control based on the field-weakening current calculated by the field-weakening current calculator.
The motor control device, wherein the field weakening current calculation unit sets the calculation result of the field weakening current to 0 when the modulation factor is equal to or lower than a predetermined maximum modulation factor.

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