JP2004180444A - Motor control arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably drive a motor as in rectangular wave control in a high speed and high torque region where sine wave PWM control is hard, without switching to a perfect rectangular wave control. <P>SOLUTION: A three-phase AC voltage command value is corrected to a three-phase AC voltage command value of intermediate wave in which a sine wave and a rectangular wave are synthesized when the time period, during which at least one of a d-axis voltage command value and a q-axis voltage command value exceeds a threshold, extends to a prescribed hour or longer. The three-phase AC voltage of the intermediate wave, where the sine wave and the rectangular wave is synthesized according to the three-phase AC voltage command value after correction, is applied to a motor. When the time period, during which at least one of the deviation between the d-axis current command value and the d-axis current and the deviation between the q-axis current command value and the q-axis current exceeds a threshold value, extends to a prescribed hour or longer, the three-phase AC voltage command value is corrected to the three-phase AC voltage command value of the intermediate wave where the sine wave is synthesized with the rectangular wave, and according to the corrected three-phase AC voltage command value, the three-phase AC voltage of the intermediate wave where the sine wave is synthesized with the rectangular wave is applied to a motor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor control device.
[0002]
[Prior art]
2. Description of the Related Art A motor control device that performs sine wave PWM (Pulse Width Modulation) control with high motor efficiency and performs square wave control in a high rotation and high torque region where sine wave PWM control is difficult is generally known ( For example, see Patent Document 1).
[0003]
Prior art documents related to the invention of this application include the following.
[Patent Document 1]
JP-A-11-285288
[Problems to be solved by the invention]
However, in the above-described conventional motor control device, switching from the sine wave PWM control to the rectangular wave control or from the rectangular wave control to the sine wave PWM control is not performed smoothly, and the rotational speed and torque of the motor fluctuate. There is.
[0005]
The present invention provides a motor control device that does not switch to complete rectangular wave control and that drives a motor stably in a high-speed, high-torque region where sine-wave PWM control is difficult, as in rectangular wave control. .
[0006]
[Means for Solving the Problems]
The present invention provides a three-phase AC voltage command value having a sine wave and a rectangular wave when a time during which at least one of the d-axis voltage command value and the q-axis voltage command value exceeds a threshold value is equal to or longer than a predetermined time. Are corrected to a combined three-phase AC voltage command value of the intermediate wave, and the three-phase AC voltage of the intermediate wave obtained by combining the sine wave and the rectangular wave is applied to the motor in accordance with the corrected three-phase AC voltage command value.
Further, according to the present invention, the time when at least one of the deviation between the d-axis current command value and the d-axis current and the deviation between the q-axis current command value and the q-axis current exceeds a threshold value is equal to or longer than a predetermined time. In this case, the three-phase AC voltage command value is corrected to an intermediate-wave three-phase AC voltage command value obtained by combining a sine wave and a square wave, and a sine wave and a square wave are synthesized according to the corrected three-phase AC voltage command value. The three-phase AC voltage of the intermediate wave is applied to the motor.
[0007]
【The invention's effect】
According to the present invention, a motor can be driven stably in a high-speed, high-torque region where sine-wave PWM control is difficult, without switching to complete rectangular-wave control, as in rectangular-wave control.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
In this embodiment, a motor is driven by a sine wave PWM voltage in a normal operation region, and an intermediate wave voltage between a sine wave PWM waveform and a rectangular wave is generated in a high speed and high torque region to drive the motor. First, a method of generating the intermediate wave voltage will be described.
[0009]
FIG. 2 shows a method of generating the U-V phase line voltage applied to the three-phase AC motor by the sine wave PWM control. As shown in FIG. 2A, the modulation triangular wave voltage and the sine wave control voltage of the inverter frequency are compared, and based on the magnitude relationship between the two, the inverter U-phase output terminal shown in FIG. , And a voltage Vv-0 between the inverter V-phase output terminal and the virtual middle point shown in FIG. 2C. Then, by calculating the difference between the U-phase midpoint voltage Vu-0 and the V-phase midpoint voltage Vv-0, the U-V phase line voltage Vu-v shown in FIG. 2D is generated. Note that a method of generating the three-phase line voltage Vu-v in the sine wave PWM control is known, and a detailed description thereof will be omitted. The same applies to the method of generating the VW phase line voltage Vv-w and the WU phase line voltage Vw-u, and their illustration and description are omitted.
[0010]
The generation of the line voltages Vu-v, Vv-w, Vw-u in the sine wave PWM control shown in FIG. 2 is performed by digitizing the pattern of the modulation triangular wave voltage and the U, V, W phase sine wave control voltage into a memory. The two digitized data are compared with each other by a microcomputer, and duty command values of pulse-line-shaped line voltages Vu-v, Vv-w, and Vw-u are generated. The duty of the pulse-shaped line voltage waveform generated by the sine wave PWM control, that is, the ratio of the voltage output period to one cycle of the modulating triangular wave voltage (one cycle of the line voltage waveform) is determined by the change of the sine wave control voltage. Varies from 0 to 100% according to.
[0011]
Applying a pulse train line voltage waveform to the motor by the sine wave PWM control shown in FIG. 2D is equivalent to applying a sine wave voltage to the motor, and a sine wave AC current is applied to the motor. Flows.
[0012]
FIG. 3 shows a U-phase voltage Vu-o, a V-phase voltage Vv-o, and a W-phase voltage Vw-o applied to the three-phase AC motor in the rectangular wave control. In the rectangular wave control, positive and negative phase voltages are applied to the three-phase AC motor by an inverter every 180 degrees (electrical angle).
[0013]
In this embodiment, when the rotation speed ω of the motor is lower than the preset intermediate wave generation permission rotation speed ωo, the sine wave PWM control with high efficiency is selected. On the other hand, when the motor rotation speed ω is equal to or higher than the intermediate wave generation permission rotation speed ωo, the sine wave PWM control based on the dq axis voltage command values Vd ^* and Vq ^* , or the intermediate wave control between the sine wave PWM and the rectangular wave Select one of
[0014]
FIG. 4 shows a method for generating an intermediate wave between a sine wave and a rectangular wave. As described above, the line voltage applied to the motor is generated based on the magnitude relationship between the modulation triangular wave voltage and the sine wave control voltage, and as shown in FIG. That is, the ratio of the voltage output period to one cycle of the modulation triangular wave voltage (one cycle of the line voltage waveform) varies from 0 to 100%. Here, during a period in which the duty of the sine wave PWM control exceeds the positive threshold value THU and a period in which the duty is lower than the negative threshold value THL, the switching of the inverter is stopped to supply the power supply voltage to the motor. When the voltage is kept applied, a U-phase line voltage waveform as shown in FIG. 4B is obtained.
[0015]
In the example shown in FIG. 4, the inverter is not switched during the period t1 to t2 in which the duty exceeds the threshold value THU, and the power supply voltage + E / 2 (E is the power supply voltage) is kept output. Similarly, on the negative side, the inverter is not switched during the period from t3 to t4 when the duty is lower than the threshold value THL, and the power supply voltage -E / 2 is kept output.
[0016]
In the sine wave PWM control, the switching is stopped and the power supply voltage is kept output only during the period when the PWM duty exceeds the positive and negative threshold values THU and THL, thereby equivalently shown in FIG. Such a phase voltage is applied to the motor. In FIG. 5, while the PWM duty by the sine wave PWM control is equal to or less than the positive and negative threshold values THU and THL, an equivalent sine wave phase voltage Vu-o is applied to the motor. On the other hand, while the PWM duty exceeds the positive and negative threshold values THU and THL, the power supply voltage + E / 2 or -E / 2 remains output, and a rectangular wave phase voltage is applied to the motor. Although FIG. 5 shows only the equivalent phase voltage of the U phase, the same applies to the V phase and the W phase.
[0017]
That is, in this embodiment, a voltage of an intermediate wave between the sine wave and the rectangular wave obtained by converting an intermediate section of the sine wave voltage of the sine wave PWM control into a rectangular wave voltage is applied to the motor. Now, as shown in FIG. 5, based on the waveform peak value VP (broken line portion) of the equivalent phase voltage Vu-o and the equivalent phase voltage VTH when the PWM duty is the threshold value THU, the “rectangular wave conversion rate Is defined by the following equation. In FIG. 5, the waveform peak value Vp (broken line portion) of the equivalent phase voltage Vu-o by the sine wave PWM control is equal to the peak value + E / 2 by the square wave control. Since the peak value Vp of the phase voltage Vu-o changes according to the rotation speed and the torque of the motor, the two do not always match.
(Equation 1)
(Rectangular wave conversion rate) = (VP−VTH) / VP × 100%
As the rectangular wave conversion rate is lower, a phase voltage closer to a sine wave is applied to the motor, and as the square wave conversion rate is higher, a phase voltage closer to a rectangular wave is applied to the motor. The rectangular wave conversion rate may be defined by the ratio of the rectangular wave period T0 to the half cycle T of the equivalent phase voltage Vu-o (T0 / T × 100%).
[0018]
FIG. 6 shows a U-phase equivalent phase voltage waveform at a rectangular wave conversion rate of 15%, and FIG. 7 shows a U-phase equivalent phase voltage waveform at a rectangular wave conversion rate of 65%. The phase voltage waveforms of the V phase and the W phase are the same as the U phase waveform except that the phases are delayed by 120 degrees.
[0019]
FIG. 1 shows a configuration of an embodiment in which the present invention is applied to a motor control device of an electric vehicle. Note that the motor control device of the present invention is not limited to an electric vehicle, but can be applied to any industrial machine other than an automobile.
[0020]
An accelerator sensor 1 detects an accelerator pedal depression amount Acc, and a vehicle speed sensor 2 detects a traveling speed Vsp of the electric vehicle. The brake sensor 3 detects the amount Br of depression of the brake pedal. The torque command value generation circuit 4 stores a table of torque command values for a preset accelerator pedal depression amount, a brake pedal depression amount, and a traveling speed. From this table, the accelerator sensor 1, the vehicle speed sensor 2, and the brake sensor 3 are stored. , A torque command value Tr ^* corresponding to each of the detected values Acc, Vsp, Br is calculated.
[0021]
The current command value generation circuit 5 stores a table of dq-axis current command values for a preset torque command value, and a dq-axis current command value corresponding to the torque command value Tr ^* from the torque command value generation circuit 4. Id ^* and Iq ^* are subjected to a lookup operation. Here, the dq axis coordinate system is a coordinate system that rotates in synchronization with the motor M. The current control circuit 6 obtains a deviation between the dq-axis current command values Id ^* , Iq ^* from the current command value generation circuit 5 and the actual dq-axis currents Id, Iq flowing through the motor M, and PI control or PID Control is performed to calculate dq-axis voltage command values Vd ^* and Vq ^* for making the dq-axis currents Id and Iq coincide with the command values Id ^* and Iq ^* . The 2 / 3-phase conversion circuit 7 converts the dq-axis voltage command values Vd ^* and Vq ^* calculated by the current control circuit 6 into a three-phase AC voltage command based on the phase θ calculated by the speed phase calculation circuit 14 described later. The values are converted into values Vu ^* , Vv ^* , Vw ^* .
[0022]
The duty command value calculation circuit 8 converts the PWM duty command values Du ^* , Dv ^* , Dw ^* of each phase based on the three-phase AC voltage command values Vu ^* , Vv ^* , Vw ^* from the 2/3 phase conversion circuit 7. Calculate. That is, when the current of each corresponding phase is 0 [A], the duty is set to 50%, and the duty of each phase is increased from 50% in accordance with the amount by which the current of each phase increases from 0 [A]. The duty is decreased from 50% in accordance with the amount decreasing from 0 [A].
[0023]
When the sine wave PWM control is selected, the duty determination circuit 9 determines the PWM duty command values Du ^* , Dv ^* , and Dw ^* calculated by the duty command value calculation circuit 8 as the final PWM duty command values. I do. When the intermediate wave control is selected, the PWM duty command values Du ^* , Dv ^* , and Dw ^* calculated by the duty command value calculation circuit 8 are converted into a PWM set by a threshold setting circuit 15 described later. When the duty of the PWM duty command values Du ^* , Dv ^* , Dw ^* is larger than the positive threshold value THU, the duty is set to 100% in comparison with the positive and negative threshold values THU, THL, and the command values Du ^* , Dv ^When the duty of ^* , Dw ^* is smaller than the negative threshold THL, the duty is set to 0%, and the duty of the command values Du ^* , Dv ^* , Dw ^* is less than the positive threshold THU and the negative threshold. If the value is equal to or greater than the value THL, the duty is set to the duty of the command values Du ^* , Dv ^* , and Dw ^* , so that the PWM signal of the intermediate wave is used. The duty command values Du ', Dv', Dw 'are determined.
[0024]
The inverter 10 controls each of the PWM duty command values Du ^* , Dv ^* , Dw ^{* of} the sine wave PWM control determined by the duty determination circuit 9 or the PWM duty command values Du ′, Dv ′, Dw ′ of the intermediate wave control. A switching operation is performed by the phase switching elements, and the DC power of the battery 11 is converted into AC power to generate three-phase AC voltages Vu, Vv, and Vw, which are applied to the motor M. The current sensor 12 detects three-phase alternating currents Iu, Iv, Iw flowing through the motor M. The rotation sensor 13 outputs a pulse signal for each predetermined rotation angle of the motor M. The speed phase calculation circuit 14 calculates the rotation speed ω and the phase θ of the motor M based on the cycle of the pulse signal from the rotation sensor 13 and the number of pulses per unit time.
[0025]
The threshold value setting circuit 15 stores a preset intermediate wave generation permission rotation speed ωo, and stores the q-axis voltage command value Vq when the motor rotation speed ω is equal to or higher than the intermediate wave generation permission rotation speed ωo. ^{when *} is is equal to or higher than the threshold Vqo a preset state continues for more than to hours, or, when the d-axis voltage command value Vd ^* is the state of the above threshold Vdo continued above to hours, sinusoidal PWM waveform Output the threshold values THU and THL for generating an intermediate wave. In this embodiment, the threshold values THU and THL are set to fixed values set in advance, and are set to values at which the above-described rectangular wave conversion rate becomes 15%. Note that the rectangular wave conversion rate for providing the threshold values THU and THL is not limited to 15%. When the motor rotation speed ω is lower than the intermediate wave generation permission rotation speed ωo, no intermediate wave is generated, the voltage waveform of the sine wave PWM is applied to the motor, and the threshold values THU and THL are not output.
[0026]
The 3/2 phase conversion circuit 16 converts the motor currents Iu, Iv, Iw detected by the current sensor 12 into dq axis currents Iq, Id based on the motor phase θ calculated by the speed phase calculation circuit 14.
[0027]
The torque command value generation circuit 4, current command value generation circuit 5, current control circuit 6, 2/3 phase conversion circuit 7, duty command value calculation circuit 8, duty determination circuit 9, The speed phase operation circuit 14, the threshold value setting circuit 15 and the 3/2 phase conversion circuit 16 are realized by one or more microcomputers in the form of software.
[0028]
FIG. 10 is a flowchart showing a motor control program according to one embodiment. The operation of the embodiment will be described with reference to this flowchart. This motor control program is repeatedly executed while the main switch (not shown) of the electric vehicle is turned on.
[0029]
In step 1, the accelerator pedal depression amount Acc, the vehicle speed Vsp, and the brake pedal depression amount Br are detected by the accelerator sensor 1, the vehicle speed sensor 2, and the brake sensor 3, and the dq-axis current is detected by the current sensor 12 and the 3/2 phase conversion circuit 16. Id and Iq are detected, and the motor rotation speed ω and the rotation phase θ are detected by the rotation sensor 13 and the speed phase calculation circuit 14. In step 2, the torque command value generation circuit 4 refers to the table to look up a torque command value Tr ^* corresponding to the accelerator pedal depression amount Acc, the vehicle speed Vsp, and the brake pedal depression amount Br, and further generates a current command value generation circuit. 5, the dq-axis current command values Id ^* and Iq ^* are generated from the torque command value Tr ^* by referring to the table.
[0030]
Dq-axis current command value ^Id * in step 3 in the current control circuit 6, Iq ^* and the dq-axis current Id, deviation between ^{Iq (Id * -Id, Iq *} -Iq) the determined, by performing PI control on the deviation The dq-axis voltage command values Vd ^* and Vq ^* are calculated. In the following step 4, the 2 / 3-phase converter 7 converts the dq-axis voltage command values Vd ^* , Vq ^* into three-phase voltage command values Vu ^* , Vv ^* , Vw ^* . In step 5, the duty command value calculation circuit 8 calculates the PWM duty command values Du ^* , Dv ^* , Dw ^* of each phase based on the three-phase voltage command values Vu ^* , Vv ^* , Vw ^* . That is, when the current of each corresponding phase is 0 [A], the duty is set to 50%, and the duty of each phase is increased from 50% in accordance with the amount by which the current of each phase increases from 0 [A]. The duty is decreased from 50% in accordance with the amount decreasing from 0 [A].
[0031]
In step 6, it is confirmed whether or not the motor rotation speed ω is equal to or higher than the intermediate wave generation permission rotation speed ωo. If ω ≧ ωo, the process proceeds to step 7, and if ω <ωo, the process proceeds to step 11. If the motor rotation speed ω is lower than the intermediate wave generation permission rotation speed ωo, the timer for measuring the excess time T is reset to 0 in step 11. This timer is a software timer for measuring a time T when the dq-axis voltage command values Vq ^* and Vd ^* exceed predetermined threshold values Vqo and Vdo. In the following step 12, sine wave PWM control for applying a sine wave PWM voltage to the motor is selected.
[0032]
If the motor rotation speed ω is equal to or higher than the intermediate wave generation permission rotation speed ωo, in step 7, the q-axis voltage command value Vq ^* output from the current control circuit 6 is equal to or higher than a predetermined threshold value Vqo, or the d-axis. It is checked whether voltage command value Vd ^* is equal to or greater than a preset threshold value Vdo. When Vq ^* ≧ Vqo or Vd ^* ≧ Vdo, the process proceeds to step 8, and when Vq ^* <Vqo and Vd ^* <Vdo, the process proceeds to step 11. When the dq-axis voltage command values Vq ^* and Vd ^* are both smaller than the threshold values Vqo and Vdo, the excess time T of the timer is reset to 0 as described above in steps 11 to 12, and the sine wave PWM control is performed. select.
[0033]
On the other hand, when the q-axis voltage command value Vq ^* is equal to or greater than the threshold value Vqo, or when the d-axis voltage command value Vd ^* is equal to or greater than the threshold value Vdo, the process proceeds to step 8, where Vq ^* ≧ Vqo or Vd ^* ≧ A timer for counting the duration (excess time) T of the state of Vdo is counted up. In the following step 9, it is confirmed whether or not the excess time T has become equal to or greater than a preset threshold value To. When T ≧ To, the process proceeds to step 10, and when T <To, the process returns to step 1.
[0034]
When the motor rotation speed ω is equal to or higher than the intermediate wave generation permission rotation speed ωo and at least one of the dq axis voltage command values Vq ^* and Vd ^* is equal to or higher than the threshold value (Vqo, Vdo) for more than To time. Determines that the back electromotive voltage of the motor is high and there is no margin for the output voltage, the control margin in current control and torque control and sufficient responsiveness cannot be ensured, and the sine wave PWM waveform and the rectangular wave And selects intermediate wave control for generating an intermediate wave voltage obtained by combining the above and applying the voltage to the motor. Then, it outputs to the duty determination circuit 9 the PWM duty threshold values THU and THL for switching from the preset sine wave PWM control to rectangular wave control.
[0035]
In step 13, if the duty of the PWM duty command values Du ^* , Dv ^* , Dw ^* is larger than the positive threshold value THU, the duty is set to 100% by the duty determination circuit 9, and the command values Du ^* , Dv ^* , Dw ^{* are set.} Is smaller than the negative threshold THL, the duty is set to 0%, and the duty of the command values Du ^* , Dv ^* , Dw ^* is equal to or less than the positive threshold THU and equal to or greater than the negative threshold THL. Generates the PWM duty command values Du ′, Dv ′, Dw ′ of the intermediate wave by setting the duty to the duty of the command values Du ^* , Dv ^* , Dw ^* .
[0036]
In step 14, when sine wave PWM control is selected by the inverter 10, DC power is converted into three-phase AC power according to the sine wave PWM duty command values Du ^* , Dv ^* , Dw ^* , while the intermediate wave control is performed. When selected, DC power is converted into three-phase AC power according to the intermediate-wave PWM duty command values Du ′, Dv ′, Dw ′, and three-phase AC voltages Vu, Vv, Vw are generated. Then, in step 15, the three-phase AC voltages Vu, Vv, Vw are applied to the motor M for driving. Thereafter, the process returns to step 1 and repeats the above-described processing.
[0037]
As described above, in the above-described embodiment, the time T in which at least one of the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* exceeds the threshold values Vdo, Vqo exceeds the predetermined time To. In the case where the three-phase AC voltage command value is corrected, the three-phase AC voltage command value is corrected to an intermediate wave three-phase AC voltage command value obtained by combining a sine wave and a square wave, and the sine wave and the square wave are corrected according to the corrected three-phase AC voltage command value. The three-phase AC voltage of the intermediate wave obtained by combining the above is applied to the motor without switching to the complete rectangular wave control, and the motor is equivalent to the rectangular wave control in a high-speed, high-torque region where sine-wave PWM control is difficult. Can be driven stably.
[0038]
When the motor is driven by the voltage of the intermediate wave that combines the sine wave and the rectangular wave, the voltage utilization can be improved compared to the case of driving the motor with the sine wave voltage. A larger current can flow than in the case of voltage driving. In the intermediate wave drive, a larger current flows in the rectangular wave portion than in the sine wave drive. As a result, the voltage command value decreases due to the current feedback control, and the rectangular wave portion in the intermediate wave decreases. In other words, the rectangular wave portion in the intermediate wave increases or decreases by an amount necessary to flow a large current. Therefore, when the motor is driven at high speed and high torque, the back electromotive force rises, so even if a large current cannot be supplied to the motor by sine wave control, a large current can be supplied by the intermediate voltage drive, Rotation speed control and torque control in the high-speed, high-torque region of the motor become possible.
[0039]
In addition, since the power supply voltage is always applied to the motor in a complete rectangular wave, the rectangular wave voltage drive cannot be performed in an operation region where the rotation speed is low and an operation region where the motor current is small. In the embodiment, since the sine wave and the rectangular wave are driven by the voltage of the intermediate wave that is synthesized, the intermediate voltage that retains the advantage of the rectangular wave voltage driving even in the low-speed, small-current operation region that cannot be controlled by the complete rectangular wave voltage driving. With this, the motor can be driven stably.
[0040]
In the above-described embodiment, when the time during which at least one of the d-axis voltage command value and the q-axis voltage command value exceeds the threshold value becomes equal to or longer than a predetermined time, the three-phase AC voltage command value Is corrected to a three-phase AC voltage command value of an intermediate wave obtained by combining a sine wave and a square wave, and a three-phase AC voltage of an intermediate wave obtained by combining a sine wave and a square wave is corrected according to the corrected three-phase AC voltage command value. An example in which the voltage is applied to the motor has been described. However, when the time during which at least one of the deviation between the d-axis current command value and the d-axis current and the deviation between the q-axis current command value and the q-axis current exceeds the threshold value is equal to or longer than a predetermined time, 3 The phase AC voltage command value is corrected to an intermediate wave three-phase AC voltage command value obtained by combining a sine wave and a rectangular wave, and the sine wave and the rectangular wave are synthesized according to the corrected three-phase AC voltage command value. Even if a three-phase AC voltage is applied to the motor, the above-described effects can be obtained.
[0041]
Further, according to one embodiment, when the rotation speed of the motor is lower than a preset threshold value, the three-phase AC voltage command value is not corrected to the intermediate wave voltage command value. The intermediate-wave voltage drive can obtain the same effect as the rectangular-wave voltage drive when the motor is in a high-speed, high-torque state. Also has high motor efficiency. Therefore, set a threshold value for determining whether the motor rotation speed is low or high. If the motor rotation speed is lower than the threshold value, select sine wave voltage drive, and set the motor rotation speed to the threshold value. In the above case, by selecting the intermediate-wave voltage drive, the motor efficiency can be improved at low speeds, and the control margin and responsiveness of speed control and torque control can be secured at high speeds.
[0042]
The correspondence between the components of the claims and the components of the embodiment is as follows. That is, the current sensor 12 is a current detecting means, the 3/2 phase conversion circuit 16 is a current converting means, the current command value generating circuit 5 is a current command value generating means, the current control circuit 6 is a current controlling means, and The three-phase conversion circuit 7 constitutes voltage command value conversion means, the duty command value calculation circuit 8, the duty determination circuit 9 and the inverter 10 constitute power conversion means, and the threshold value setting circuit 15 constitutes voltage command value correction means. Note that each component is not limited to the above configuration as long as the characteristic functions of the present invention are not impaired.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment.
FIG. 2 is a diagram illustrating a method of generating a U-V phase line voltage applied to a three-phase AC motor in sine wave PWM control.
FIG. 3 is a diagram showing a U-V phase line voltage applied to a three-phase AC motor in rectangular wave control.
FIG. 4 is a diagram illustrating a method of generating an intermediate wave between a sine wave PWM and a rectangular wave.
FIG. 5 is a diagram showing an intermediate wave between a sine wave PWM and a rectangular wave.
FIG. 6 is a diagram showing a U-phase equivalent phase voltage waveform at a rectangular wave conversion rate of 15%.
FIG. 7 is a diagram showing a U-phase equivalent phase voltage waveform at a rectangular wave conversion rate of 65%.
FIG. 8 is a flowchart showing a motor control program according to one embodiment.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 accelerator sensor 2 vehicle speed sensor 3 brake sensor 4 torque command value generation circuit 5 current command value generation circuit 6 current control circuit 7 2/3 phase conversion circuit 8 duty command value calculation circuit 9 duty determination circuit 10 inverter 11 battery 12 current sensor 13 Rotation sensor 14 Speed phase calculation circuit 15 Threshold setting circuit 16 3 / 2-phase conversion circuit M 3-phase AC motor

Claims (3)

Current detection means for detecting a three-phase alternating current flowing through the three-phase AC motor;
Current converting means for converting a three-phase alternating current flowing through the motor into a dq-axis current in a dq-axis coordinate system rotating in synchronization with the motor, and a current generating a dq-axis current command value according to a torque command value of the motor Command value generation means,
Current control means for calculating a dq-axis voltage command value for causing the dq-axis current to match the dq-axis current command value;
Voltage command value conversion means for converting the dq axis voltage command value into a three-phase AC voltage command value;
A motor control device comprising: DC power converted to AC power according to the three-phase AC voltage command value, and power conversion means for applying the power to the motor,
Voltage command value correction means for correcting the three-phase AC voltage command value to a voltage command value of an intermediate wave obtained by combining a sine wave and a rectangular wave,
When the time during which at least one of the dq-axis voltage command values exceeds a threshold value is equal to or longer than a predetermined time, the voltage command value correction unit converts the three-phase AC voltage command value into a sine wave and a rectangular wave. The power conversion unit corrects the voltage command value of the synthesized intermediate wave, and the power conversion unit outputs the three-phase AC of the intermediate wave obtained by combining the sine wave and the rectangular wave according to the three-phase AC voltage command value corrected by the voltage command value correction unit. A motor control device for applying a voltage to the motor. Current detection means for detecting a three-phase alternating current flowing through the three-phase AC motor;
Current converting means for converting a three-phase alternating current flowing through the motor into a dq-axis current in a dq-axis coordinate system rotating in synchronization with the motor, and a current generating a dq-axis current command value according to a torque command value of the motor Command value generation means,
Current control means for calculating a dq-axis voltage command value for causing the dq-axis current to match the dq-axis current command value;
Voltage command value conversion means for converting the dq axis voltage command value into a three-phase AC voltage command value;
A motor control device comprising: DC power converted to AC power according to the three-phase AC voltage command value, and power conversion means for applying the power to the motor,
Voltage command value correction means for correcting the three-phase AC voltage command value to a voltage command value of an intermediate wave obtained by combining a sine wave and a rectangular wave,
When the time during which at least one of the deviation between the dq-axis current command value and the deviation between the dq-axis currents exceeds a threshold value is equal to or longer than a predetermined time, the voltage command value correction means changes the three-phase AC voltage command value. The power conversion means corrects the voltage command value of the intermediate wave obtained by combining the sine wave and the square wave, and combines the sine wave and the square wave according to the three-phase AC voltage command value corrected by the voltage command value correction means. A three-phase AC voltage of the intermediate wave applied to the motor. The motor control device according to claim 1 or 2,
Speed detecting means for detecting the rotation speed of the motor,
When the rotation speed of the motor is lower than a predetermined threshold value, the voltage command value correction means does not correct the three-phase AC voltage command value to the voltage command value of the intermediate wave. apparatus.

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