JP2010063221A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce torque ripples in a three-phase alternating-current motor and enhance the motor efficiency thereof. <P>SOLUTION: Fundamental voltage command values Vd*, Vq* corresponding to fundamental current command values Id*, Iq* are generated and harmonic voltage command values Vnd*, Vnq* corresponding to harmonic current command values Ind*, Inq* are generated. The harmonic voltage command values Vnd*, Vnq* are respectively added to the fundamental voltage command values Vd*, Vq* and motor current is generated according to the results of the additions. An amplitude/phase detection unit 45 detects the amplitude Indq and phase ϕ of the harmonic component of the motor current. When the phase ϕ deviates from a phase condition determined according to the amplitude Indq, an operation mode change unit 46 changes the operation mode so that harmonic voltage command values are not added to the fundamental voltage command values Vd*, Vq*. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device that controls a three-phase AC motor.

  Conventionally, three-phase AC motors have been widely used in various fields. For example, a large three-phase AC motor has been put into practical use as a traveling motor for an electric vehicle or a hybrid vehicle.

  However, a three-phase AC motor (particularly, a motor in which stator windings such as a concentrated winding IPM motor are wound in a concentrated manner) is distorted in magnetic flux distribution during rotor rotation due to structural factors. Torque ripple having a period of 6n times as large as that of the torque is generated. Torque ripple causes an increase in noise and vibration, or a decrease in efficiency due to current waveform distortion.

  As one technique for solving the above problem, there is known a method for controlling not only the fundamental wave current component of the motor current to be controlled by vector control but also the harmonic current component. That is, a technique for suppressing torque ripple by superimposing a 6n-order current in the dq coordinate system is known. Patent Document 1 describes a technique for reducing current distortion.

In the motor control device described in Patent Document 1, the fundamental wave current control means controls the fundamental wave component of the motor current in an orthogonal coordinate system that rotates in synchronization with the rotation of the three-phase AC motor. The harmonic current control means controls the harmonic component contained in the motor current in an orthogonal coordinate system that rotates at a frequency that is an integral multiple of the fundamental wave component of the motor current. The voltage command value generation means adds the output of the fundamental wave current control means and the output of the harmonic current control means to generate a three-phase AC voltage command value. The power conversion means converts the DC power supply voltage into a three-phase AC voltage corresponding to the three-phase AC voltage command value, and outputs it to the three-phase AC motor. The dead time compensation means corrects the three-phase AC voltage command value in order to compensate the output voltage due to the dead time of the power conversion means. The speed detection means detects the speed of the three-phase AC motor. When the rotational speed of the three-phase AC motor is equal to or lower than a predetermined threshold, the control selection means performs control by the harmonic current control means without performing correction by the dead time compensation means, and performs control of the three-phase AC motor. When the rotational speed is higher than the threshold value, the correction by the dead time compensation means is performed without the control by the harmonic current control means.
JP 2003-18900 A

  In the three-phase AC motor as described above, when the harmonic current is controlled, the characteristic may be deteriorated if the magnitude and / or phase of the harmonic current component is not properly controlled. For example, when the number of rotations of the motor becomes high, the current control followability is deteriorated, which may cause an increase in torque ripple or a decrease in efficiency.

  An object of the present invention is to prevent deterioration of system characteristics (increase in torque ripple, decrease in motor efficiency) according to operating conditions by appropriately controlling harmonic current in a three-phase AC motor.

  The motor control device of the present invention is a motor control device for controlling a three-phase AC motor, and includes a fundamental wave current control means for outputting a fundamental wave current command value of a motor current of the three-phase AC motor, and the fundamental wave current. A harmonic current control means for outputting a harmonic current command value having a frequency that is an integer multiple of the amplitude and smaller than the fundamental current, an output from the fundamental current control means, and an output from the harmonic current control means. A current control circuit for controlling the motor current of the three-phase AC motor, phase detection means for detecting the phase of the harmonic current, and the harmonic current when the phase of the harmonic current is out of the effective phase. Operation mode control means for reducing the amplitude of the wave current.

  The characteristics of the three-phase AC motor are improved by appropriately controlling the phase of the harmonic current. Therefore, when the phase of the harmonic current deviates from the effective phase, the amplitude of the harmonic current is decreased. Thereby, the deterioration of the characteristic by harmonic current control can be prevented.

  The operation mode control means may invalidate the output of the harmonic current control means when the phase of the harmonic current is out of the effective phase. By invalidating the output of the harmonic current control means when the phase of the harmonic current deviates from the effective phase, it is possible to reliably prevent deterioration of characteristics due to the harmonic current control.

  The motor control device of the present invention may include amplitude detection means for detecting the amplitude of the harmonic current. The effective phase changes according to the amplitude of the harmonic current. If this configuration is introduced, it can be more appropriately determined whether or not harmonic current control should be performed.

  The effective phase is, for example, a phase in which the torque ripple rate when the output of the harmonic current control unit is enabled is lower than the torque ripple rate when the output of the harmonic current control unit is disabled. If the effective phase is set in this way, a situation in which the torque ripple is increased due to the harmonic current control is avoided.

  Alternatively, the effective phase is, for example, a phase in which the torque ripple rate when the output of the harmonic current control means is enabled is lower than a predetermined torque ripple threshold value. Setting the effective phase in this way makes it easy to determine whether or not to perform harmonic current control.

Further, the effective phase may be determined based on the amplitude of the harmonic current command value. The effective phase may be a phase within a certain range from the phase of the harmonic current command value.
The motor control device according to the present invention includes a rotation speed detection unit that detects a rotation speed of the motor, a fundamental wave current detection unit that detects a current value of the fundamental wave current, and a phase of the harmonic current is out of an effective phase. Recording means for recording the rotational speed detected at the time and the current value of the fundamental wave current may be further provided. In this case, the operation mode control unit decreases the amplitude of the harmonic current in a predetermined operation region including the rotation speed and the current value of the fundamental wave current recorded in the recording unit. According to this configuration, it is possible to avoid in advance a situation in which the characteristics deteriorate due to the harmonic current control.

  In the motor control device of the present invention, the operation mode control means temporarily causes the harmonic current to flow by the harmonic current control means during a period in which the amplitude of the harmonic current is reduced. It is checked whether or not the phase of the current is an effective phase, and when it is an effective phase, the harmonic current control means may be normally controlled. According to this configuration, since it is possible to recognize at an early stage a situation in which it is more advantageous to perform harmonic current control than to perform harmonic current control, it is possible to appropriately suppress torque ripple.

  A motor control device according to another aspect of the present invention is a motor control device that controls a three-phase AC motor, and includes a fundamental wave current control unit that outputs a fundamental wave current command value of the motor current of the three-phase AC motor; Harmonic current control means for outputting a harmonic current command value having a frequency that is an integral multiple of the fundamental current, and output of the fundamental current control means and output of the harmonic current control means using the output of the harmonic current control means. A current control circuit for controlling a motor current of the phase AC motor, a calculation means for calculating a torque ripple rate of the three-phase AC motor, and an amplitude of the harmonic current when the calculated torque ripple rate is equal to or greater than a threshold value. Operating mode control means for controlling the current control circuit so as to reduce the current. According to this configuration, it is avoided that the torque ripple exceeds the threshold due to the harmonic current control.

  According to the present invention, it is possible to prevent deterioration of system characteristics (increase in torque ripple, decrease in motor efficiency) by appropriately controlling the harmonic current in accordance with the operation state in the three-phase AC motor.

  FIG. 1 is a diagram illustrating a configuration of a motor control device according to an embodiment of the present invention. The motor control device 1 according to the embodiment controls the motor 100 according to a torque instruction signal. The torque instruction signal is given by the user, for example. When the motor 100 is a traveling motor for an electric vehicle, the torque instruction signal is information indicating the depression angle of the accelerator. In this embodiment, the motor 100 is a three-phase AC motor. The motor 100 is, for example, an interior permanent magnet synchronous motor (IPMSM).

  The command value generation unit 11 generates a current command value according to the torque instruction signal. The current command value is represented by a d-axis component command value and a q-axis component command value in the dq coordinate system. The dq coordinate system is a coordinate system obtained by converting rotational coordinates synchronized with the rotation of the motor 100 from the UVW coordinate system. In this embodiment, a set of command values Id * and Iq * and a set of command values Ind * and Inq * are generated. Here, the command values Id * and Iq * are the target values of the d-axis component and the q-axis component of the fundamental wave current that are the fundamental wave components of the motor current, respectively. The command values Ind * and In1 * are target values for the d-axis component and the q-axis component of the harmonic current that are the harmonic components of the motor current, respectively.

  The error calculation unit 12 calculates a d-axis current error value representing an error between the fundamental wave current command value Id * and the d-axis current detection value Id. Similarly, the error calculator 13 generates a q-axis current error value that represents an error between the fundamental wave current command value Iq * and the q-axis current detection value Iq. The error calculators 12 and 13 are realized by a subtracter, for example.

  The dq current control unit 14 performs the PI calculation on the d-axis current error value and the q-axis current error value, thereby generating the fundamental voltage command values Vd * and Vq *. The adder 31 generates a d-axis voltage command value by adding a harmonic voltage command value Vnd (h) * described later to the fundamental voltage command value Vd * obtained by the dq current control unit 14. Similarly, the adder 32 generates a q-axis voltage command value by adding the harmonic voltage command value Vnq (h) * to the fundamental voltage command value Vq *. The two-phase / three-phase converter 15 converts the voltage command value in the dq coordinate system obtained by the adders 31 and 32 based on the phase θ of the motor 100 into the voltage command values Vu *, Vv *, Vw in the UVW coordinate system. Convert to *. The power conversion unit 16 is an inverter circuit including a semiconductor element such as an IGBT, for example, and applies voltages corresponding to the voltage command values Vu *, Vv *, and Vw * to the motor 100 by PWM control or the like.

  The phase calculation unit (rotational speed detection means) 17 detects the phase θ of the motor 100 and calculates the rotational speed ω of the motor 100 based on the detected phase θ. The detected phase θ is supplied to the 2-phase / 3-phase converter 15, the 3-phase / 2-phase converter 18, and the multiplier 24. Based on the phase θ of the motor 100, the three-phase / two-phase conversion unit (fundamental current detection means) 18 converts the motor currents Iu, Iv, Iw in the UVW coordinate system into the motor currents Id, Iq (d in the dq coordinate system). Converted into a shaft current detection value Id and a q-axis current detection value Iq). Here, the three-phase / two-phase converter 18 can obtain another one from any two (Iu, Iw in FIG. 1) of Iu, Iv, and Iw. Therefore, in the embodiment, a current sensor for detecting Iu and Iw is provided.

The error calculators 21 and 22 calculate errors between the harmonic current command values Ind * and Inq * and the detected harmonic currents Ind and Inq, respectively. The dq harmonic current control unit 23 generates harmonic voltage command values Vnd * and Vnq * corresponding to the error information obtained by the error calculation units 21 and 22. The multiplier 24 multiplies the phase θ of the motor 100 by “n”. Note that “n” is an integer, for example, “n = 6” when controlling the sixth harmonic. The harmonic coordinate inverse transform unit 25 uses the “nθ” obtained by the multiplier 24 to convert the harmonic voltage command values Vnd * and Vnq * on the harmonic coordinate system into the harmonic voltage command on the dq coordinate system. Converted to values Vnd (h) * and Vnq (h) *. This conversion corresponds to a reverse rotation calculation for canceling the phase rotation, and is expressed by the following equation.
Vnd (h) * = Vnd * ・ cos (nθ) −Vnq * ・ sin (nθ)
Vnq (h) * = Vnd * · sin (nθ) + Vnq * · cos (nθ)
The harmonic detection unit 26 is realized by, for example, a bandpass filter or a high pass filter, and detects the harmonic components Idh and Iqh from the motor currents Id and Iq obtained by the three-phase / two-phase conversion unit 18. The harmonic coordinate conversion unit 27 uses “nθ” to convert the harmonic components Idh and Iqh obtained by the harmonic detection unit 26 into the harmonic current values Ind and Inq on the harmonic coordinate system. The current values Ind and Inq obtained by the conversion are given to the error calculators 21 and 22. The conversion calculation by the harmonic coordinate conversion unit 27 is expressed by the following equation.
Ind = Idh · cos (nθ) + Iqh · sin (nθ)
Inq = -Idh · sin (nθ) + Iqh · cos (nθ)
In the motor control device 1 configured as described above, the error calculation units 12 and 13, the dq current control unit 14, the two-phase / three-phase conversion unit 15, the power conversion unit 16, and the three-phase / two-phase conversion unit 18 A feedback system for controlling wave components is configured. This feedback system minimizes the d-axis current error value and the q-axis current error value obtained by the error calculation units 12 and 13. By this feedback control, the fundamental component of the motor current is controlled to the current command values Id * and Iq *. That is, the motor 100 generates torque according to the torque instruction signal.

  Further, the error calculation units 21 and 22, the dq harmonic current control unit 23, the multiplier 24, the harmonic coordinate inverse conversion unit 25, the harmonic detection unit 26, and the harmonic coordinate conversion unit 27 convert the harmonic component of the motor current. Configure the feedback system to be controlled. This feedback system minimizes the harmonic current error value obtained by the error calculators 21 and 22. By this feedback control, the harmonic component of the motor current is controlled to the current command values Ind * and Inq *. That is, torque ripple of the motor 100 is suppressed.

The current command values Id * and Iq * are generated by the command value control unit 11 according to the torque instruction signal. Further, the current command values Ind * and Inq * are generated in the command value generation unit 11 according to, for example, the following formula.
Ind * = Indq × cosφ
Inq * = Indq × sinφ
Indq = (Ind ² + Inq ² ) ^1/2
φ = tan ^-1 (Inq / Ind)
However, the current command values Ind * and Inq * for controlling the harmonic component of the motor current are generated according to different arithmetic expressions according to required characteristics (that is, reduction of torque ripple and improvement of efficiency). It may be.

  In the motor control device 1, the command value generation unit 11, the error calculation units 12 and 13, the dq current control unit 14, the 2 phase / 3 phase conversion unit 15, the phase calculation unit 17, the 3 phase / 2 phase conversion unit 18, the error calculation In this embodiment, the units 21 and 22, the dq harmonic current control unit 23, the multiplier 24, the harmonic coordinate inverse conversion unit 25, the harmonic detection unit 26, and the harmonic coordinate conversion unit 27 are software programs using a processor. It is realized by executing. The fundamental wave current control means according to the present invention corresponds to, for example, the error calculation units 12 and 13, the dq current control unit 14, and the 3 phase / 2 phase conversion unit 18. The harmonic current control means corresponds to, for example, the error calculation units 21 and 22, the dq harmonic current control unit 23, the multiplier 24, the harmonic coordinate inverse conversion unit 25, the harmonic detection unit 26, and the harmonic coordinate conversion unit 27. To do. The current control circuit corresponds to, for example, the adders 31 and 32, the two-phase / three-phase conversion unit 15, and the power conversion unit 16.

FIG. 2 is a diagram illustrating a change in the torque ripple rate with respect to the phase of the harmonic current. The characteristics shown in FIG. 2 are obtained when the harmonic current is controlled in order to reduce torque ripple. Here, the phase φ of the harmonic component of the motor current is calculated by the following equation.
φ = tan ^-1 (Inq / Ind)
Further, the torque ripple rate R is defined by the following equation. “T” represents the average torque of the motor 100, and “Tpp” represents the peak-to-peak torque of the motor 100.
R = 100 × {(Tpp) / 2} / T
A characteristic A indicates a torque ripple rate when the harmonic current control is not performed. Characteristics B to E show an example of a change in torque ripple rate when the amplitude of the harmonic current with respect to the fundamental current is increased in order.

  As shown in FIG. 2, when the motor 100 is driven by the motor control device 1 of the embodiment, the torque ripple rate is low when the phase φ of the harmonic component of the motor current is around 200 degrees. When the amplitude of the harmonic current is characteristic D and the phase φ is about 210 degrees, the torque ripple rate is minimum. In other words, if the amplitude of the harmonic current is controlled to the D characteristic and the phase φ is controlled to about 210 degrees, the torque ripple of the motor 100 is minimized.

  However, when the phase φ of the harmonic current is not properly controlled, the torque ripple rate becomes worse than when the harmonic current control is not performed. For example, when the phase φ is 0 to 140 degrees and 250 to 360 degrees in the characteristic D, the torque ripple becomes larger when the harmonic current control is performed than when the harmonic current control is not performed (A characteristic). . In other words, the harmonic current control is preferably executed only when the phase φ satisfies a predetermined phase condition (effective phase). In this case, the phase condition is, for example, a phase in which the torque ripple rate when performing harmonic current control is lower than the torque ripple rate when not performing harmonic current control. Alternatively, the phase condition is, for example, a phase at which a torque ripple rate when performing harmonic current control is lower than a predetermined torque ripple threshold (for example, the A characteristic is not necessarily limited to the A characteristic). is there.

  Therefore, the motor control device 1 according to the embodiment has a function of detecting the phase φ of the harmonic current and switching to an operation mode in which harmonic current control is not performed when the phase φ deviates from a predetermined phase condition. However, the phase condition for determining the operation mode switching changes depending on the amplitude of the harmonic current, as is apparent from FIG. Therefore, the motor control device 1 may detect the amplitude and phase φ of the harmonic component of the motor current and switch the operation mode when the phase φ deviates from the phase condition determined depending on the amplitude.

In order to provide the above-described operation mode switching function, the motor control device 1 includes switches 41 to 44, an amplitude / phase detection unit 45, and an operation mode switching unit 46 as shown in FIG.
Harmonic current command values Ind * and Inq * are given to the A terminals of the switches 41 and 42, respectively, and the detected harmonic currents Ind and Inq are given to the B terminals, respectively. Further, harmonic voltage command values Vnd * and Vnq * are given to the A terminals of the switches 43 and 44, respectively, and “zero” is given to the B terminals. Then, the switches 41 to 44 select data given to the A terminal or the B terminal in accordance with an instruction from the operation mode switching unit 46.

The amplitude / phase detection unit (phase detection unit and amplitude detection unit) 45 calculates the amplitude Indq and the phase φ of the harmonic current using the detected harmonic currents Ind and Inq. The amplitude Indq and the phase φ of the harmonic current are calculated by the following equations.
Indq = (Ind ² + Inq ² ) ^1/2
φ = tan ^-1 (Inq / Ind)
The operation mode switching unit 46 switches the operation mode of the motor control device 1 based on the amplitude Indq and the phase φ of the harmonic current. The operation mode switching unit 46 can also use the rotational speed ω of the motor 100 and the motor currents Id and Iq as parameters for switching the operation mode.

  The operation mode of the motor control device 1 is basically controlled as follows. That is, when the phase φ of the harmonic current satisfies a predetermined phase condition, the operation mode switching unit 46 gives an instruction to select data of the A terminal to each of the switches 41 to 44. Thereby, the feedback system for controlling the harmonic current operates. In this case, the harmonic coordinate inverse transform unit 25 converts the harmonic voltage command values Vnd * and Vnq * obtained by the dq harmonic current control unit 23 into the harmonic voltage command values Vnd (h) *, dq coordinate system, Convert to Vnq (h) * and output. Then, the motor current to which the harmonic current is added is given to the motor 100. That is, when the phase φ of the harmonic current satisfies a predetermined phase condition, normal harmonic current control is performed. The predetermined phase condition is, for example, as described with reference to FIG.

  On the other hand, when the phase φ of the harmonic current deviates from the predetermined phase condition, the operation mode switching unit 46 gives an instruction to select the data of the B terminal to each of the switches 41 to 44. In this case, the harmonic coordinate inverse conversion unit 25 outputs “zero” as the harmonic voltage command values Vnd (h) * and Vnq (h) *. That is, the output of the harmonic control system is invalidated. Then, the motor 100 is supplied with motor currents corresponding to the fundamental wave voltage command values Vd * and Vq *. That is, the harmonic current control is not performed when the phase φ of the harmonic current deviates from a predetermined phase condition.

  When the harmonic current phase φ deviates from a predetermined phase condition, the switches 41 and 42 select the harmonic current detection values Ind and Inq instead of the harmonic current command values Ind * and Inq *. . Then, “zero” is input to the dq harmonic current control unit 23. Therefore, even when the motor control device 1 restarts the harmonic current, the operation of the dq harmonic current control unit 23 is stabilized.

  3 and 4A are flowcharts showing the operation of the motor control device 1 of the embodiment. Here, the sixth harmonic current is controlled. In addition, the harmonic current command values I6d * and I6q *, which are target values of the sixth harmonic current, are generated by the command value generation unit 11 using a predetermined algorithm.

In step S1, the rotational speed ω of the motor 100, the amplitude Idq of the fundamental wave current, and the phase φdq of the fundamental wave current are calculated. The amplitude Idq of the fundamental wave current and the phase φdq of the fundamental wave current are calculated by the following equations.
Idq = (Id ² + Iq ² ) ^1/2
φdq = tan ^-1 (Iq / Id)
In step S2, it is checked whether or not the state in which harmonic current control should be started has been reached. Specifically, it is checked whether the rotational speed ω of the motor 100 and the amplitude Idq of the fundamental wave current satisfy the following conditions. “Ωstart” and “Idqstart” may be zero.
ωstart <ω
Idqstart <Idq
If the above condition is not satisfied, the harmonic current control is invalidated in step S3. That is, an instruction for selecting data of the B terminal is given to the switches 41 to 44. On the other hand, if the above condition is satisfied, in step S4, the rotational speed ω of the motor 100 and the state of the fundamental wave current are referred to, and the motor control device 1 enters the harmonic stop region where the harmonic current control should be stopped. Check if it is in. In this embodiment, the check is performed according to the following formula.
ωs−Δωs ≦ ω ≦ ωs + Δωs
Idqs−ΔIdqs ≦ Idq ≦ Idqs + ΔIdqs
φdqs−Δφdqs ≦ φdq ≦ φdqs + Δφdqs
Here, “ωs”, “Idqs”, and “φdqs” are described in detail later, but the rotational speed of the motor 100 detected when it is determined that the harmonic current control should be stopped in the past operation, The amplitude of the fundamental wave current and the phase of the fundamental wave current are stored in a memory (recording means) accessible by the operation mode switching unit 46. “Δωs”, “ΔIdqs”, and “Δφdqs” are values that determine the size of the harmonic stop region, and can be appropriately determined in consideration of a control error or the like. That is, in step S4, it is detected that the harmonic current control has approached the same state as that determined in the past that the harmonic current control should be stopped.

  When the rotational speed of the motor 100 and the fundamental current enter the harmonic stop region, the harmonic current control is invalidated in step S5. That is, an instruction for selecting data of the B terminal is given to the switches 41 to 44. On the other hand, if the rotation speed of the motor 100 and the fundamental wave current are not in the harmonic stop region, the harmonic current control is validated in step S6. That is, an instruction for selecting data of the A terminal is given to the switches 41 to 44. In step S7, the process waits for the passage of time necessary for the harmonic current control operation to stabilize.

In step S11, the amplitude I6dq and the phase φ6dq of the harmonic current are calculated according to the following equation.
I6dq = (I6d ² + I6q ² ) ^1/2
φ6dq = tan ^-1 (I6q / I6d)
In step S12, it is checked whether the harmonic current is controlled according to the command value according to the following equation.
I6dq * −ΔI6dq ≦ I6dq ≦ I6dq * + ΔI6dq
φ6dq * −Δφ6dq ≦ φ6dq ≦ φ6dq * + Δφ6dq
Here, “I6dq *” is a command value of the amplitude of the sixth-order harmonic current, and “φ6dq *” is a command value of the phase of the sixth-order harmonic current.

  The above formula is a formula for determining whether the values of I6dq and φ6dq are within the error range. The error between I6dq and φ6dq is due to the error between Ind and Inq. The error between Ind and Inq depends on the detection error of output current detection Iu, Iw and motor magnetic pole position detection θ and the calculation error in the CPU. Determined.

  If the harmonic current is not controlled according to the command value, the harmonic current control is invalidated in step S13. That is, an instruction for selecting data of the B terminal is given to the switches 41 to 44. Subsequently, in step S14, the rotational speed of the motor 100, the amplitude of the fundamental wave current, and the phase of the fundamental wave current at the time when it is determined that “the harmonic current is not controlled according to the command value” are detected. ωs ”,“ Idqs ”, and“ φdqs ”are recorded in the memory. These values are used in step S4 described above in subsequent operations of the motor control device 1. Note that a plurality of sets of “ωs”, “Idqs”, and “φdqs” can be stored in the memory.

  If the harmonic current is controlled according to the command value, the harmonic current control is validated in step S15. That is, an instruction for selecting data of the A terminal is given to the switches 41 to 44.

Instead of the procedure shown in FIG. 4A, the procedure shown in FIG. 4B may be executed. That is, in the procedure shown in FIG. 4B, step S16 is executed instead of step S12. In step S16, it is checked whether the phase φ6dq of the harmonic current satisfies a predetermined phase condition. The predetermined phase condition is, for example, a phase in which the torque ripple rate when performing harmonic current control is lower than the torque ripple rate when not performing harmonic current control. That is, the determination is performed using the following equation.
φmin ≤ φ6dqn ≤ φmax
Here, “φmax” and “φmin” are, for example, the upper limit value and the lower limit value of the phase range in which the torque ripple rate when performing harmonic current control is lower than the torque ripple rate when not performing harmonic current control. “Φmax” and “φmin” may be changed according to the amplitude of the harmonic current, or may be a fixed value.

  If the phase of the harmonic current does not satisfy the phase condition, steps S13 to S14 are executed. That is, the harmonic current control is invalidated by giving an instruction for selecting data of the B terminal to the switches 41 to 44, and “ωs”, “Idqs”, and “φdqs” are recorded in the memory. On the other hand, if the phase of the harmonic current satisfies the phase condition, the harmonic current control is validated in step S17. That is, an instruction for selecting data of the A terminal is given to the switches 41 to 44.

  As described above, in the motor control device 1 of the embodiment, the harmonic current control is performed during the period in which the phase φ of the harmonic current satisfies the predetermined phase condition, and the period in which the phase φ does not satisfy the phase condition. Since harmonic current control is stopped, it is possible to prevent deterioration of torque ripple characteristics. Also, the rotational speed of the motor 100 and the fundamental wave current conditions that deviate from the harmonic current target value during the harmonic current control period are recorded, and when such a state is likely to occur, the harmonic current control is performed. I am trying not to. Therefore, deterioration of characteristics can be prevented also by this function.

Note that, for example, the following conditions 1 to 3 may be adopted as conditions to be recorded in the memory in step S14.
Condition 1:
(Id−Idnow) ² + (Iq−Iqnow) ² ≦ α and ωnow −β ≦ ω ≦ ωnow + β
Condition 2:
Idnow −α ≦ Id d ≦ Idnow + α and Iqnow −α ≦ Iq ≦ Iqnow + α and ωnow −β ≦ ω ≦ ωnow + β
Condition 3:
The Id increase period is “Idnow ≦ Id ≦ Idnow + α”, the Id decrease period is “Idnow−α ≦ Id ≦ Idnow”, the Iq increase period is “Iqnow ≦ Iq ≦ Iqnow + α”, and the Iq decrease period is “Iqnow−α ≦ Iq”. ≦ Iqnow ”and ω increase period is“ ωnow ≦ ω ≦ ωnow + β ”, and ω decrease period is“ ωnow −β ≦ ω ≦ ωnow ”.
It is assumed that appropriate values for the constants α and β are selected through experiments and simulations.
Here, “Idnow”, “Iqnow”, and “ωnow” in the conditions 1 to 3 indicate “Id”, “Iq”, and “ω” when “NO” is determined in Step S16.

<Other embodiments>
FIG. 5 is a flowchart showing the operation of another embodiment. It is assumed that the process of this flowchart is repeatedly executed at predetermined time intervals, for example.

In step S21, the d-axis component and the q-axis component (Id, Iq) of the fundamental current are detected. In step S22, the rotational speed ω of the motor 100 is detected. In step S23, it is checked whether the following condition is satisfied. However, “Id0”, “Iq0”, and “ω0” are predetermined initial values, and each may be “zero”. As an example, Id0, Iq0, and ω0 are positive.
Id> Id0 and Iq> Iq0 and ω> ω0
Note that the processing of steps S21 to S23 corresponds to steps S1 to S2 shown in FIG.

  In step S24, the current operation mode of the motor control device 1 is checked. If harmonic current control is being executed, the amplitude of the harmonic current is detected in step S25, and the phase of the harmonic current is detected in step S26. In step S27 (calculation means), the torque ripple rate is calculated by referring to the map using the amplitude and phase of the harmonic current detected in steps S25 to S26 as keys. In the map referred to here, for example, the characteristics shown in FIG. 2 are stored as data.

  In step S28, the calculated torque ripple rate is compared with a threshold value. The threshold value may be a fixed value or a value that changes according to the amplitude of the harmonic current. If the calculated torque ripple rate is lower than the threshold value, harmonic current control is validated in step S29. On the other hand, if the calculated torque ripple rate is greater than or equal to the threshold value, harmonic current control is disabled in step S30.

  If the motor control device 1 is not performing harmonic current control (step S24: No), harmonic current control is temporarily executed in step S31. That is, an instruction to select data of the A terminal is given to the switches 41 to 44 for a predetermined time. Here, the predetermined time corresponds to, for example, the time required until the feedback system for controlling the harmonic current is stabilized. Thereafter, the processing after step S25 is executed.

  As described above, in the procedure shown in FIG. 5, it is checked whether the harmonic current control may be resumed by temporarily executing the harmonic current control during the period when the harmonic current control is not performed. And if it is the environment where harmonic current control may be performed, harmonic current control is continued as it is. Therefore, if this procedure is introduced, harmonic current control is performed as much as possible in an environment where it is advantageous to perform harmonic current control. As a result, torque ripple can be improved.

<Still another embodiment>
When the operation mode of the motor control device 1 is switched from the harmonic current control invalid state to the harmonic current control valid state, the following procedure may be introduced. That is, in the harmonic current control invalid state, the harmonic command values Ind * and Inq * are reset with the harmonic current detection values Ind and Inq. Then, the harmonic command values Ind * and Inq * are gradually changed to the actual target values from the time of switching to the harmonic current control enabled state. As a result, it is possible to suppress the current oscillation in which the valid state / invalid state is switched alternately.

The phase condition for determining whether or not to execute the harmonic current control may be determined without depending on the amplitude of the harmonic current.
The phase condition does not need to hold characteristic data as shown in FIG. 2 in the map, and may simply store a phase threshold value for each amplitude of the harmonic current.

  The phase condition does not need to be set based on the torque ripple rate when the harmonic current control is not performed (A characteristic in the example shown in FIG. 2), and a torque ripple rate lower than that or a torque ripple rate higher than that is set. You may make it set as a reference | standard.

  When the current phase is such that the torque ripple rate can be reduced more than the torque ripple rate when no harmonics are controlled, the harmonic current control is invalidated (for example, steps S16 and S13 in FIG. 4B). By performing the control to reduce, the range of the invalid phase of the harmonic current control may be expanded. Further, the harmonic current control may be invalidated after the control for reducing the amplitude of the harmonic current.

  In the above-described embodiment, a period (for example, steps S2 to S3 shown in FIG. 3) in which the harmonic current control is not performed when the motor control device 1 is started is provided, but this period may be omitted.

  In the above-described embodiment, the configuration for controlling the sixth-order harmonic current is shown. However, two or more harmonic currents (for example, sixth-order and twelfth-order) may be controlled. In this case, a plurality of harmonic current control systems are provided in parallel.

  The motor 100 is, for example, an IPM, but is not limited to this, and may be, for example, a surface permanent magnet synchronous motor (SPMSM).

  In the above-described embodiment, the control system for controlling the fundamental current and the control system for controlling the harmonic current are separated from each other. However, these control systems may be integrated. In this case, the command value generation unit 11 generates a motor current command value obtained by adding the harmonic current command value to the fundamental current command value. When stopping the harmonic current control, the command value generation unit 11 controls the harmonic current command value to zero, and the fundamental current command value is output as the motor current command value.

It is a figure which shows the structure of the motor control apparatus of embodiment of this invention. It is a figure which shows the change of the torque ripple rate with respect to the phase of a harmonic current. It is a flowchart (the 1) which shows operation | movement of a motor control apparatus. It is a flowchart (the 2) which shows operation | movement of a motor control apparatus. It is a modification of the flowchart which shows operation | movement of a motor control apparatus. It is a flowchart which shows operation | movement of other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 11 Command value generation part 12, 13 Error calculation part 14 dq current control part 15 2 phase / 3 phase conversion part 16 Power conversion part 17 Phase calculation part 18 3 phase / 2 phase conversion part 21, 22 Error calculation part 23 dq harmonic current control unit 24 multiplier 25 harmonic coordinate inverse conversion unit 26 harmonic detection unit 27 harmonic coordinate conversion units 31 and 32 adders 41 to 44 switch 45 amplitude / phase detection unit 46 operation mode switching unit 100 motor

Claims (10)

A motor control device for controlling a three-phase AC motor,
Fundamental wave current control means for outputting a fundamental wave current command value of the motor current of the three-phase AC motor;
Harmonic current control means having a frequency that is an integral multiple of the fundamental current, and outputting a harmonic current command value having an amplitude smaller than the fundamental current;
A current control circuit for controlling the motor current of the three-phase AC motor using the output of the fundamental current control means and the output of the harmonic current control means;
Phase detection means for detecting the phase of the harmonic current;
An operation mode control means for reducing the amplitude of the harmonic current when the phase of the harmonic current is out of the effective phase;
A motor control device comprising: The motor control device according to claim 1,
The motor control device, wherein the operation mode control means invalidates the output of the harmonic current control means when the phase of the harmonic current deviates from an effective phase. The motor control device according to claim 1,
Further comprising amplitude detection means for detecting the amplitude of the harmonic current;
The effective phase changes according to the amplitude of the harmonic current. The motor control device according to any one of claims 1 to 3,
The effective phase is a phase in which the torque ripple rate when the output of the harmonic current control unit is enabled is lower than the torque ripple rate when the output of the harmonic current control unit is disabled. Motor control device. The motor control device according to any one of claims 1 to 3,
The motor control device, wherein the effective phase is a phase at which a torque ripple rate when the output of the harmonic current control means is enabled is lower than a predetermined torque ripple threshold value. The motor control device according to claim 4 or 5,
The motor control device, wherein the effective phase is determined based on an amplitude of the harmonic current command value. The motor control device according to any one of claims 1 to 3,
The motor control device, wherein the effective phase is a phase within a certain range from the phase of the harmonic current command value. The motor control device according to claim 1,
Rotation speed detection means for detecting the rotation speed of the motor;
Fundamental wave current detecting means for detecting a current value of the fundamental wave current;
Recording means for recording the rotational speed detected when the phase of the harmonic current deviates from the effective phase and the current value of the fundamental wave current;
The operation mode control means controls the current control circuit so as to reduce the amplitude of the harmonic current in a predetermined operation region including the rotation speed and the current value of the fundamental wave current recorded in the recording means. The motor control apparatus characterized by the above-mentioned. The motor control device according to claim 1,
The operation mode control means causes the harmonic current to flow temporarily by the harmonic current control means during a period in which the amplitude of the harmonic current is reduced, so that the phase of the harmonic current is an effective phase. The harmonic current control means is normally controlled when it is in an effective phase. A motor control device for controlling a three-phase AC motor,
Fundamental wave current control means for outputting a fundamental wave current command value of the motor current of the three-phase AC motor;
Harmonic current control means for outputting a harmonic current command value having a frequency that is an integral multiple of the fundamental current;
A current control circuit for controlling the motor current of the three-phase AC motor using the output of the fundamental current control means and the output of the harmonic current control means;
Calculating means for calculating a torque ripple rate of the three-phase AC motor;
An operation mode control means for controlling the current control circuit to reduce the amplitude of the harmonic current when the calculated torque ripple rate is equal to or greater than a threshold;
A motor control device comprising: