A three-phase motor harmonic current control method and system

Abstract

The present invention discloses a three-phase motor harmonic current control method and system, belonging to the field of motor servo and control technology. First, multiple three-phase virtual windings corresponding to the actual three-phase windings of the motor are established; then, the virtual winding current command value obtained by current command calculation replaces the feedback value of the virtual three-phase winding current, and is used together with the motor three-phase winding current sampling value to calculate the motor harmonic current feedback value; finally, the harmonic current is closed-loop controlled in the harmonic coordinate system, and the various harmonic currents (including zero-sequence current harmonics) of the motor are extracted without a filter or resonant controller, and closed-loop control is performed separately to achieve precise control of various harmonic currents of the three-phase motor. The method of the present invention improves the control accuracy and dynamic response speed of the harmonic current of the three-phase motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor servo and control, and more specifically, relates to a three-phase motor harmonic current control method and system. Background Art

[0002] In the common three-loop control system of position, speed, and current in motor control, the current loop is the inner loop and occupies the most central position. High-precision position and speed control are both based on high-precision current control. Motor current control often involves controlling harmonic currents. Factors such as the motor's no-load back EMF harmonics and inductance harmonics contribute to harmonic components in the motor current, necessitating controller design to suppress these harmonic currents. In some motor control applications, it is sometimes necessary to actively inject harmonics into the motor's three-phase windings. For example, negative-sequence current is actively injected in linear motor control to reduce thrust fluctuations. These situations require high-precision closed-loop control of harmonic currents within motor control.

[0003] PI controllers are widely used in traditional motor current control. PI controllers process the current tracking error through proportional and integral modules to adjust the voltage signal, achieving closed-loop control of the motor current. While traditional PI controllers have excellent tracking performance for DC signals, they have limited control bandwidth for harmonic currents. This results in poor dynamic performance and prevents high-precision tracking of harmonic currents.

[0004] Currently, the most widely used methods in the field of harmonic control are multi-synchronous rotating coordinate systems + filters to extract harmonics or resonant controllers. The multi-synchronous rotating coordinate system + filter method transforms the sampled three-phase current signal through multiple rotating coordinate systems, and introduces filters in each coordinate system to filter out the interference of other harmonics, retaining the harmonic components corresponding to the rotating coordinate system, thereby extracting different harmonic components in steady state. However, due to the introduction of multiple filters, the bandwidth of the filter needs to be reduced to ensure that the interference of other components is filtered out, resulting in its dynamic performance not being guaranteed. The resonant controller does not reduce its bandwidth due to the introduction of filters, but the design of the resonant part of the resonant controller involves the selection of multiple resonant parameters. The open-loop gain, phase margin, etc. need to be designed based on the Bode diagram of the open-loop transfer function of the control system composed of the resonant controller and the motor, which increases the difficulty of controller design. Summary of the Invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a three-phase motor harmonic current control method and system, aiming to solve the problems of low bandwidth of the multi-synchronous rotating coordinate system + filter method and large number of design parameters and increased difficulty in controller design, which lead to reduced control performance of the controller on the harmonic current of the three-phase motor.

[0006] To achieve the above objectives, the present invention provides a three-phase motor harmonic current control method that does not introduce multiple rotating coordinate systems, filters for extracting harmonic currents, or a resonant controller. To separate the harmonic currents of different frequencies in the motor's three-phase windings, multiple virtual three-phase windings corresponding to the motor's three-phase windings are introduced, and harmonic currents are passed through all windings. This allows the multi-phase current feedback values ​​to be processed using a coordinate transformation algorithm similar to a Fourier transform to extract the harmonic current amplitudes. To address the issue of how to sample the virtual multi-phase winding currents, the harmonic current command values ​​are directly calculated using the virtual winding multi-phase current command values, and these command values ​​are used as feedback values.

[0007] The present invention provides a three-phase motor harmonic current control method. First, based on the number of motor harmonic currents that need to be controlled, multiple three-phase virtual windings are introduced on the basis of the motor's three-phase windings to jointly form a multi-phase system, and the phase difference between each phase is the same. The sampled multi-phase current is subjected to coordinate transformation, and different harmonic currents are transformed to different harmonic planes to achieve separation of different harmonic currents. Different harmonic currents are subjected to PARK transformation to obtain harmonic d-axis and q-axis components under different harmonic planes. The harmonic d-axis and q-axis current components under different harmonic planes are respectively controlled by current PI controllers for closed-loop control, and the harmonic d-axis and q-axis voltages under different harmonic planes are output. The harmonic d-axis and q-axis voltages under different harmonic planes are subjected to inverse PARK coordinate transformation and a new coordinate transformation to obtain a multi-phase voltage command. The three-phase voltage command value corresponding to the three-phase motor in the multi-phase voltage command is extracted, and the switching logic signal of the inverter is calculated through SVPWM modulation. The permanent magnet synchronous linear motor is controlled by the inverter. The present invention improves the control accuracy of the three-phase motor current controller for harmonic current.

[0008] By adding multiple three-phase virtual windings to the actual three-phase windings of the motor to form a multiphase system, a novel coordinate transformation is applied to the multiphase system parameters to obtain the amplitudes corresponding to different harmonics in the new coordinate system. In other words, by introducing a multiphase system and a multiphase coordinate system, the motor parameters, which were originally mixed with multiple frequencies, are decoupled and transformed into independent harmonic planes. This allows independent closed-loop control of variable harmonics of a specific frequency in different harmonic planes without affecting the variable harmonic control of other harmonic planes. On different harmonic planes, the harmonic currents of different frequencies are decoupled from each other, and the different harmonic planes do not interfere with each other.

[0009] The present invention also provides a drive system for a three-phase motor, wherein the three-phase actual windings of the three-phase motor correspond to multiple three-phase virtual windings, and the system includes an inverter, a DC power supply and a control circuit; the DC power supply supplies power to the DC input side of the inverter, the inverter receives the drive signal of the control circuit, drives the three-phase motor to operate, and transmits the current signal of the three-phase motor to the control circuit through a sensor for calculation of the drive signal; the control circuit includes a current detection unit, a drive unit and a main control unit, and the main control unit controls the operation of the three-phase motor; the current detection unit includes a current sensor and a current sampling circuit, the signal output by the current detection unit is output to the main control unit, and the main control unit outputs the drive signal for driving the three-phase motor after calculation and processing based on the received current signal and harmonic current instruction, and the drive signal is output to the inverter through the drive unit to control the switching device in the inverter and drive the three-phase motor to operate;

[0010] The main control unit includes a virtual current calculation module, a control voltage calculation module, and an SVPWM module. The virtual current calculation module is used to obtain a virtual multi-phase winding current command value, and the control voltage calculation module is used to obtain a multi-phase voltage command value, and extract the motor three-phase voltage command value corresponding to the three-phase motor from the multi-phase voltage command value; the motor three-phase voltage command value is calculated by the SVPWM module to obtain the drive signal of the six switching tubes of the inverter, and the inverter is powered by a DC power supply to drive the three-phase motor rotor to operate.

[0011] Furthermore, the virtual current calculation module includes a current instruction PARK inverse transformation unit and a current instruction Fourier coordinate inverse transformation. The harmonic current d-axis and q-axis instruction values ​​on different harmonic planes are calculated by the current instruction PARK inverse transformation unit to obtain the harmonic current α-axis and β-axis instruction values ​​on different harmonic planes. The harmonic current α-axis and β-axis instruction values ​​on different harmonic planes are calculated by the current instruction Fourier coordinate inverse transformation to obtain multi-phase current instruction values, wherein the multi-phase current instruction values ​​include virtual multi-phase winding current instruction values.

[0012] Furthermore, the control voltage calculation module includes a current sampling Fourier coordinate forward transformation, a current sampling PARK forward transformation unit, a voltage instruction PARK inverse transformation unit, a voltage instruction Fourier coordinate inverse transformation, and a current PI controller;

[0013] The measured three-phase current feedback values ​​of the three-phase motor and the virtual multi-phase winding current command values ​​are calculated through the current sampling Fourier coordinate forward transformation to obtain the harmonic current α-axis and β-axis feedback values ​​on different harmonic planes. The harmonic current α-axis and β-axis feedback values ​​on different harmonic planes are calculated through the current sampling PARK forward transformation unit to obtain the harmonic current d-axis and q-axis feedback values ​​on different harmonic planes. The harmonic current d-axis and q-axis feedback values ​​on different harmonic planes and the harmonic current d-axis and q-axis command values ​​on different harmonic planes are calculated through the current PI controller to obtain the harmonic d-axis and q-axis voltage command values ​​on different harmonic planes. The harmonic d-axis and q-axis voltage command values ​​on different harmonic planes are calculated through the voltage command PARK inverse transformation unit to obtain the harmonic α-axis and β-axis voltage command values ​​on different harmonic planes. The harmonic α-axis and β-axis voltage command values ​​on different harmonic planes are calculated through the voltage command Fourier coordinate inverse transformation to obtain the multi-phase voltage command value.

[0014] Compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0015] The present invention first establishes multiple three-phase virtual windings corresponding to the actual three-phase windings of the motor. Then, the virtual winding current command value obtained by current command calculation replaces the feedback value of the virtual three-phase winding current. Together with the motor three-phase winding current sampling value, it is used to calculate the motor harmonic current feedback value. Finally, the harmonic current is closed-loop controlled in different harmonic planes, and each harmonic current (including zero-sequence current harmonics) of the motor is extracted without a filter or resonant controller. The closed-loop control is then performed separately to achieve precise control of the various harmonic currents of the three-phase motor. The method of the present invention improves the control accuracy and dynamic response speed of the harmonic current of the three-phase motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural block diagram of a three-phase motor drive according to an embodiment of the present invention;

[0017] Figure 2 This is a structural block diagram of a control system for a motor according to an embodiment of the present invention;

[0018] Figure 3 This is a structural block diagram of the virtual current calculation module of the present invention;

[0019] Figure 4 This is a structural block diagram of the control voltage calculation module of the present invention;

[0020] Figure 5 A schematic diagram of a nine-phase system according to an embodiment of the present invention;

[0021] Figure 6 Schematic diagram of the harmonic plane mapping relationship of the nine-phase system according to an embodiment of the present invention;

[0022] Reference numerals:

[0023] 1-three-phase motor, 2-inverter, 3-DC power supply, 4-control circuit, 5-current detection unit, 6-drive unit, 7-main control unit, 8-current command PARK inverse transformation unit, 9-current command Fourier coordinate inverse transformation, 10-current sampling Fourier coordinate forward transformation, 11-current sampling PARK forward transformation unit, 12-voltage command PARK inverse transformation unit, 13-voltage command Fourier coordinate inverse transformation, 14-current PI controller, 15-virtual current calculation module, 16-control voltage calculation module, 17-SVPWM module. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The drawings are provided for reference and illustration only and are not intended to limit the present invention. The dimensions shown in the drawings are only for the convenience of clear description and do not limit the proportional relationship.

[0026] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] Please refer to Figure 1 , Figure 1The structural block diagram of the three-phase motor 1 drive system provided by an embodiment of the present invention is shown. The drive system of the three-phase motor 1 mainly includes an inverter 2, a DC power supply 3, a control circuit 4 and a three-phase motor 1. Among them, the control circuit 4 includes a current detection unit 5, a drive unit 6 and a main control unit 7, and the main control unit 7 controls the operation of the three-phase motor 1. The current detection unit 5 includes a current sensor and a current sampling circuit. The signal output by the current detection unit 5 is output to the main control unit 7. The main control unit 7 outputs a drive signal for driving the three-phase motor 1 after calculation and processing based on the received current signal and harmonic current instruction. The drive signal is output to the inverter 2 through the drive unit 6 to control the switching device in the inverter 2 and drive the three-phase motor 1 to operate. The design process of each controller is described in detail below.

[0028] Please refer to Figure 2 , Figure 2 This is a block diagram of the control system of the motor of the present invention. The motor control system includes a virtual current calculation module 15, a control voltage calculation module 16, and an SVPWM module 17. For the internal structure of the virtual current calculation module 15, please refer to Figure 3 , including the current command PARK inverse transformation unit 8 and the current command Fourier coordinate inverse transformation unit 9. Please refer to the internal structure of the control voltage calculation module 16 Figure 4 , including a current sampling Fourier coordinate forward transformation 10, a current sampling PARK forward transformation unit 11, a voltage instruction PARK inverse transformation unit 12, a voltage instruction Fourier coordinate inverse transformation 13, and a current PI controller 14.

[0029] The harmonic current d-axis and q-axis command values ​​on different harmonic planes are calculated by the current command PARK inverse transformation unit 8 to obtain the harmonic current α-axis and β-axis command values ​​on different harmonic planes. The harmonic current α-axis and β-axis command values ​​on different harmonic planes are calculated by the current command Fourier coordinate inverse transformation 9 to obtain the multiphase current command value. The measured three-phase current feedback values ​​of the three-phase motor and the virtual multiphase winding current command value are calculated by the current sampling Fourier coordinate forward transformation 10 to obtain the harmonic current α-axis and β-axis feedback values ​​on different harmonic planes. The harmonic current α-axis and β-axis feedback values ​​on different harmonic planes are calculated by the current sampling PARK forward transformation unit 11 to obtain the harmonic current d-axis and q-axis feedback values ​​on different harmonic planes. The harmonic current d-axis and q-axis feedback values ​​on different harmonic planes and the harmonic current d-axis and q-axis command values ​​on different harmonic planes are calculated by the current PI controller 14 to obtain the harmonic d-axis and q-axis voltage command values ​​on different harmonic planes. The harmonic d-axis and q-axis voltage command values ​​on different harmonic planes are calculated by the voltage command PARK inverse transformation unit 12 to obtain the harmonic α-axis and β-axis voltage command values ​​on different harmonic planes. The harmonic α-axis and β-axis voltage command values ​​on different harmonic planes are calculated by the voltage command Fourier coordinate inverse transformation 13 to obtain the multi-phase voltage command values. The three-phase voltage corresponding to the three-phase motor in the multi-phase voltage command values ​​is extracted to obtain the three-phase voltage command values ​​of the three-phase motor. The three-phase voltage command values ​​of the motor are calculated by the SVPWM module 17 to obtain the drive signals for the six switching tubes of the inverter 2. The inverter 2 is powered by the DC power supply 3 to drive the rotor of the three-phase motor 1.

[0030] Those skilled in the art can understand that the current command PARK inverse transformation unit 8, the current command Fourier coordinate inverse transformation 9, the current sampling Fourier coordinate forward transformation 10, the current sampling PARK forward transformation unit 11, the voltage command PARK inverse transformation unit 12, the voltage command Fourier coordinate inverse transformation 13, the current PI controller 14, the virtual current calculation module 15, the control voltage calculation module 16, and the SVPWM module 17 can be a series of computer program segments that can be executed by the main control unit 7 and can complete fixed functions.

[0031] Taking the construction of an N-phase system as an example, the phase differences between the N phases are equal, and the mathematical model of the current sampling Fourier coordinate forward transform 10 is:

[0032]

[0033] in

[0034] Multi-phase virtual winding parameters are obtained through T αβ After transformation, we get the components in the new coordinate system. αβThe parameters obtained after the transformation in the first and second rows correspond to the first-order plane, the parameters obtained after the transformation in the third and fourth rows correspond to the third-order plane, and so on. The harmonics in the multiphase virtual winding are assigned to different harmonic planes, such as the first-order plane and the third-order plane. The planes do not affect each other, achieving decoupling of harmonics of different frequencies.

[0035] The mathematical models of the current command Fourier coordinate inverse transform 9 and the voltage command Fourier coordinate inverse transform 13 are:

[0036]

[0037] The mathematical model of the current sampling PARK positive conversion unit 11 is:

[0038]

[0039] The mathematical model of the voltage command PARK inverse conversion unit 12 is:

[0040]

[0041] Taking the nine-phase motor as an example, on the basis of the three-phase motor winding, six phases are added to form a nine-phase system, such as Figure 5 As shown in the figure. The blue part shows the winding position relationship of the three-phase motor, and the black part is the 6 phases added later. The phases between the 9 phases are equal. The mathematical model of the current sampling Fourier coordinate forward transform 10 is:

[0042]

[0043] in

[0044] The mathematical models of the current command Fourier coordinate inverse transform 9 and the voltage command Fourier coordinate inverse transform 13 are:

[0045]

[0046] Taking the fifth-order frequency current controlled in the 5th plane and the seventh-order frequency current controlled in the 7th plane as an example, let

[0047]

[0048] The mathematical model of the current sampling PARK positive conversion unit 11 is:

[0049]

[0050] The mathematical model of the voltage command PARK inverse conversion unit 12 is:

[0051]

[0052] It should be noted that the so-called 5th plane and 7th plane are just a naming method, and have nothing to do with the specific frequency harmonics controlled on this plane. That is, harmonics such as 3rd frequency and negative sequence 1st frequency can be controlled on the 5th plane.

[0053] The harmonic plane mapping relationship of the 9-phase system is as follows Figure 6 As shown. Take X(4) as an example to represent the 4th plane. For a three-phase motor with three-phase Y connection, the 3rd plane corresponds to the zero sequence and can be ignored. The remaining 1st plane and 8th plane are mapped to each other, the 2nd plane and 7th plane are mapped to each other, and the 4th plane and 5th plane are mapped to each other. When allocating harmonic currents to each harmonic plane, it should be noted that the two mutually mapped planes cannot simultaneously allocate the harmonic currents that need to be controlled. Therefore, for a 9-phase system, there are three frequencies of current that can be allocated, which can be placed in the 1st plane (or 8th plane), the 2nd plane (or 7th plane), and the 4th plane (or 5th plane) for closed-loop control. For a three-phase open-winding motor, since there is a zero-sequence loop, the 3rd plane also has meaning at this time, and the harmonic current on the zero-sequence loop can be controlled in the 3rd plane.

[0054] The virtual multi-phase winding current command value calculated based on the harmonic current command value is used as the virtual three-phase winding current feedback value to prove the convergence of this controller. Taking the 1st plane to control the fundamental current, the 5th plane to control the 5th current, and the 7th plane to control the 7th current as an example, the PI controller transfer function used is

[0055]

[0056] Select k p =L s w c and k i =R s w c , where L s Indicates the motor inductance parameter, R s Indicates the motor resistance parameter, w c represents the bandwidth parameter of the controller, and the closed-loop control transfer function of each harmonic current is expressed as:

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] The transfer function from each harmonic current command to its actual current is expressed as a low-pass filter, which effectively restores the low-frequency portion of the command and suppresses high-frequency interference. The transfer function from each harmonic current command to the actual current of other harmonic planes is expressed as a high-pass filter, which effectively suppresses coupling interference from other harmonic planes.

[0067] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-phase motor harmonic current control method, characterized in that: Establishing multiple three-phase virtual windings corresponding to the three-phase actual windings of the motor includes the following steps: The multi-phase voltage command value is calculated by using the virtual multi-phase winding current command value. The three-phase voltage corresponding to the three-phase motor is extracted from the multi-phase voltage command value to obtain the three-phase voltage command value of the three-phase motor. The harmonic current is distributed to different harmonic planes and closed-loop control is performed separately. The drive signal of the inverter switch tube is calculated to drive the rotor of the three-phase motor to operate; The virtual multi-phase winding current command value is obtained by the following steps: The harmonic current d-axis and q-axis command values ​​on different harmonic planes are obtained by PARK inverse transformation to obtain the harmonic current α-axis and β-axis command values ​​on different harmonic planes, and the harmonic current α-axis and β-axis command values ​​on different harmonic planes are obtained by Fourier coordinate inverse transformation to obtain multi-phase current command values, wherein the multi-phase current command values ​​include virtual multi-phase winding current command values; The multi-phase voltage command value is obtained by the following steps: The measured three-phase current feedback values ​​of the three-phase motor and the virtual multi-phase winding current command values ​​are transformed into the harmonic current α-axis and β-axis feedback values ​​on different harmonic planes through Fourier coordinate forward transformation, the harmonic current α-axis and β-axis feedback values ​​on different harmonic planes are transformed into the harmonic current d-axis and q-axis feedback values ​​on different harmonic planes through PARK forward transformation, the harmonic current d-axis and q-axis feedback values ​​on different harmonic planes and the harmonic current d-axis and q-axis command values ​​on different harmonic planes are controlled through current PI control to obtain the harmonic d-axis and q-axis voltage command values ​​on different harmonic planes, the harmonic d-axis and q-axis voltage command values ​​on different harmonic planes are transformed into the harmonic α-axis and β-axis voltage command values ​​on different harmonic planes through PARK inverse transformation, and the harmonic α-axis and β-axis voltage command values ​​on different harmonic planes are calculated through Fourier coordinate inverse transformation to obtain the multi-phase voltage command values.

2. A three-phase motor drive system, wherein the three-phase actual windings of the three-phase motor (1) correspond to a plurality of three-phase virtual windings, characterized in that: The invention comprises an inverter (2), a DC power supply (3) and a control circuit (4); the DC power supply (3) supplies power to the DC input side of the inverter (2); the inverter (2) receives a drive signal from the control circuit (4) and drives the three-phase motor (1) to operate, and transmits the current signal of the three-phase motor (1) to the control circuit (4) through a sensor for calculation of the drive signal; the control circuit (4) comprises a current detection unit (5), a drive unit (6) and a main control unit (7); the main control unit (7) controls the operation of the three-phase motor (1); the current detection unit (5) comprises a current sensor and a current sampling circuit; the signal output by the current detection unit (5) is output to the main control unit (7); the main control unit (7) outputs a drive signal for driving the three-phase motor (1) after calculation and processing based on the received current signal and harmonic current instruction; the drive signal is output to the inverter (2) through the drive unit (6) to control the switching device in the inverter (2) and drive the three-phase motor (1) to operate; The main control unit (7) includes a virtual current calculation module (15), a control voltage calculation module (16), and an SVPWM module (17). The virtual current calculation module (15) is used to obtain a virtual multi-phase winding current command value, and the control voltage calculation module (16) is used to obtain a multi-phase voltage command value, and extract the motor three-phase voltage command value corresponding to the three-phase motor from the multi-phase voltage command value; the motor three-phase voltage command value is calculated by the SVPWM module (17) to obtain the driving signals of the six switching tubes of the inverter (2); the inverter (2) is powered by a DC power supply (3) to drive the three-phase motor (1) to operate; The virtual current calculation module (15) includes a current instruction PARK inverse transformation unit (8) and a current instruction Fourier coordinate inverse transformation unit (9). Harmonic current d-axis and q-axis instruction values ​​on different harmonic planes are calculated by the current instruction PARK inverse transformation unit (8) to obtain harmonic current α-axis and β-axis instruction values ​​on different harmonic planes. The harmonic current α-axis and β-axis instruction values ​​on different harmonic planes are calculated by the current instruction Fourier coordinate inverse transformation unit (9) to obtain multi-phase current instruction values, wherein the multi-phase current instruction values ​​include virtual multi-phase winding current instruction values. The control voltage calculation module (16) includes a current sampling Fourier coordinate forward transformation (10), a current sampling PARK forward transformation unit (11), a voltage instruction PARK inverse transformation unit (12), a voltage instruction Fourier coordinate inverse transformation (13), and a current PI controller (14); The measured three-phase current feedback values ​​of the three-phase motor and the virtual multi-phase winding current command values ​​are calculated by current sampling Fourier coordinate forward transformation (10) to obtain harmonic current α-axis and β-axis feedback values ​​on different harmonic planes. The harmonic current α-axis and β-axis feedback values ​​on different harmonic planes are calculated by current sampling PARK forward transformation unit (11) to obtain harmonic current d-axis and q-axis feedback values ​​on different harmonic planes. The harmonic current d-axis and q-axis feedback values ​​on different harmonic planes and the harmonic current d-axis and q-axis command values ​​on different harmonic planes are calculated by current PI controller (14) to obtain harmonic d-axis and q-axis voltage command values ​​on different harmonic planes. The harmonic d-axis and q-axis voltage command values ​​on different harmonic planes are calculated by voltage command PARK inverse transformation unit (12) to obtain harmonic α-axis and β-axis voltage command values ​​on different harmonic planes. The harmonic α-axis and β-axis voltage command values ​​on different harmonic planes are calculated by voltage command Fourier coordinate inverse transformation (13) to obtain multi-phase voltage command values.

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