Method for Suppressing Harmonics of Motor Rotation Speed Based on Injection Voltage Harmonics and On-line Measurement

Abstract

The present invention relates to a method for suppressing motor speed harmonics based on injected voltage harmonics and on-line measurement, which comprises the following steps: First, measure the speed value of the motor, and extract the real part and the imaginary part of the speed harmonics through the angular domain single-point Fourier transform algorithm; Second, inject q-axis voltage harmonics into the system. The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command; Third, extract the real part and the imaginary part of the speed harmonics again, compare the changes in the speed harmonics before and after the injection of the voltage harmonics, and calculate the inverse matrix of the closed-loop transfer function matrix from the real part and the imaginary part of the q-axis injected voltage harmonics to the real part and the imaginary part of the speed harmonics; Fourth, design a speed harmonic controller according to the calculated closed-loop transfer function and the PI controller, and suppress the speed harmonics by injecting voltage harmonics. The present invention can avoid the problem of suppression failure when the relationship between the injected voltage harmonics and the speed harmonics changes.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly to a method for suppressing rotational speed harmonics based on injected voltage harmonics for permanent magnet synchronous motor control. Background Art

[0002] Permanent magnet synchronous motors (hereinafter referred to as PMSMs) have prominent advantages such as stable operation, high energy efficiency, diverse shapes, simple structures, and light weight. Currently, they have been widely used in daily life, modern industrial production, and national defense, such as in household appliances, automotive electronics, turntable systems, and aerospace systems. However, factors such as spatial harmonics of the magnetic field, time harmonics of the armature current, cogging torque, and phase imbalance cause obvious torque ripple in permanent magnet synchronous motors. To meet the requirements of these systems for servo accuracy and low-speed smoothness, low torque ripple has become an important design requirement for high-precision servo motors. Therefore, studying methods for suppressing torque ripple in permanent magnet synchronous motors has great practical significance.

[0003] Currently, the means for suppressing motor torque ripple are mainly divided into two types. One is to improve the mechanical design of the motor, and the other is to actively control the stator current using control algorithms. Technical literature (Wu Z, Yang Z, Ding K, et al. Order-Domain-Based harmonic injection method for multiple speed harmonics suppression of PMSM[J]. IEEE Transactions on Power Electronics, 2020, 36(4): 4478-4487.) (Feng G, Lai C, Tian J, et al. Multiple reference frame based torque ripple minimization for PMSM drive under both steady-state and transient conditions[J]. IEEE Transactions on Power Electronics, 2018, 34(7): 6685-6696.) designed harmonic injection algorithms to suppress torque ripple by suppressing rotational speed harmonics, but did not consider the influence of the change in the relationship between the injected voltage harmonics and the rotational speed harmonics. The relationship between the injected voltage harmonics and the rotational speed harmonics changes with different operating conditions, which brings difficulties to harmonic control. As a result, there is a problem of suppression failure when the relationship between the injected voltage harmonics and the rotational speed harmonics changes. Summary of the Invention

[0004] The object of the present invention is to provide a method for suppressing the speed harmonics of a motor based on injected voltage harmonics and on-line measurement, which can well solve the influence brought by the change of the relationship between the injected voltage harmonics and the speed harmonics, so that the injected voltage harmonics can more effectively regulate the speed harmonics.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for suppressing the speed harmonics of a motor based on injected voltage harmonics and on-line measurement, which comprises the following steps:

[0007] Step 1: Measure the speed value of the motor, and extract the real part and the imaginary part of the speed harmonics through the angular domain single-point Fourier transform algorithm;

[0008] Step 2: Inject q-axis voltage harmonics into the system. The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command; and then extract the real part and the imaginary part of the speed harmonics again through the angular domain single-point Fourier transform algorithm, compare the changes of the speed harmonics before and after the injection of the voltage harmonics, and calculate the inverse matrix H of the closed-loop transfer function matrix from the real part and the imaginary part of the q-axis injected voltage harmonics to the real part and the imaginary part of the speed harmonics;

[0009] Step 3: Design a speed harmonic controller according to the calculated inverse matrix and the PI controller. The input of the speed harmonic controller is the real part and the imaginary part of the speed harmonics fed back by the motor, and the output is the real part and the imaginary part of the q-axis injected voltage harmonics, and suppress the speed harmonics through the injected voltage harmonics.

[0010] Further, the above solution is that the speed harmonic controller is: after inputting the deviation between the actual value and the command value of the real part and the imaginary part of the speed harmonics extracted by measuring the motor into the PI controller, multiply it by the inverse matrix H, and output the real part and the imaginary part of the q-axis injected voltage harmonics.

[0011] Further, the above solution is that the formula of the angular domain single-point Fourier algorithm used is:

[0012]

[0013] N is the number of points of the speed signal participating in the Fourier transform algorithm, ω r ( θ i ) is the i-th sampling value of the speed signal, θ i is the i-th sampling value of the angle signal θ;

[0014] The motor is a permanent magnet synchronous motor. When the permanent magnet synchronous motor operates stably, according to the rotor rotation angle, the motor rotation angle θ and the speed are collected at equal angular intervals ω r, the real and imaginary parts of the k-th order rotational speed harmonic are extracted by the angular domain single-point Fourier transform algorithm, denoted as (ReΩr1, ImΩr1); k is the order of the rotational speed harmonic to be suppressed;

[0015] Step 2 includes:

[0016] 1). Inject a q-axis voltage harmonic into the system, whose real and imaginary parts are (a, 0) (V). The injected voltage harmonic is reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real and imaginary parts of the rotational speed harmonic after injecting the voltage harmonic, denoted as (ReΩr2, ImΩr2);

[0017] 2). Change the q-axis injected voltage harmonic so that its real and imaginary parts are (0, a) (V). The injected voltage harmonic is reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real and imaginary parts of the rotational speed harmonic after injecting the voltage harmonic, denoted as (ReΩr3, ImΩr3);

[0018] Thus, the calculation formula for the inverse matrix H of the closed-loop transfer function matrix from the real and imaginary parts of the q-axis injected voltage harmonic to the real and imaginary parts of the rotational speed harmonic is:

[0019] .

[0020] In the above solution, further, the q axis injected voltage harmonic U inq is reconstructed into an injected voltage signal in the angular domain u inq The formula is:

[0021] .

[0022] The present invention considers the change in the relationship between the injected voltage harmonic and the rotational speed harmonic, and measures the closed-loop transfer function from the injected voltage harmonic to the rotational speed harmonic in real time through on-line measurement, so as to obtain the relationship between the injected voltage harmonic and the rotational speed harmonic. The design of the rotational speed harmonic controller is guided by the closed-loop transfer function, so that the injected voltage harmonic can more effectively regulate the rotational speed harmonic; the problem of suppression failure can be avoided when the relationship between the injected voltage harmonic and the rotational speed harmonic changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the block schematic diagram of the present invention;

[0024] Figure 2 is the simulation model of the PMSM-VC drive system constructed in MATLAB Simulink software;

[0025] Figure 3 is the block diagram of the rotational speed harmonic controller;

[0026] Figure 4 is the real part of the 24th-order rotational speed harmonic;

[0027] Figure 5 is the imaginary part of the 24th-order rotational speed harmonic;

[0028] Figure 6 is the amplitude of the 24th-order rotational speed harmonic;

[0029] Figure 7 is the time-domain curve of the motor speed. Specific embodiments

[0030] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, features and effects of the present invention.

[0031] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0032] Refer to Figure 1 , 2 , as shown in Figure 3, the method for suppressing rotational speed harmonics of a motor based on injected voltage harmonics and on-line measurement provided by the present invention includes the following steps:

[0033] Step 1: Measure the rotational speed value of the motor, and extract the real part and the imaginary part of the rotational speed harmonics through the angular-domain single-point Fourier transform algorithm; the motor is a permanent magnet synchronous motor. When the permanent magnet synchronous motor is running stably, according to the rotor rotation angle, the motor rotation angle θ and rotational speed ω r are collected at equal angular intervals, and the real part and the imaginary part of the kth-order rotational speed harmonic are extracted through the angular-domain single-point Fourier transform algorithm, denoted as (ReΩr1, ImΩr1); k is the order of the rotational speed harmonic to be suppressed; the formula of the used angular-domain single-point Fourier algorithm is:

[0034]

[0035] N is the number of points of the rotational speed signal participating in the Fourier transform algorithm, ω r ( θ i ) is the ith sampling value of the rotational speed signal, θ i is the ith sampling value of the angle signal θ.

[0036] Step 2: Inject q-axis voltage harmonics into the system. The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Then, the real and imaginary parts of the rotational speed harmonics are extracted again through the angular domain single-point Fourier transform algorithm, and the changes in the rotational speed harmonics before and after the injection of voltage harmonics are compared to calculate the inverse matrix H of the closed-loop transfer function matrix from the real and imaginary parts of the q-axis injected voltage harmonics to the real and imaginary parts of the rotational speed harmonics. Specifically, it includes:

[0037] 1) Inject a q-axis voltage harmonic into the system, whose real and imaginary parts are (a, 0) (V). The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real and imaginary parts of the rotational speed harmonics after injecting the voltage harmonics, denoted as (ReΩr2, ImΩr2);

[0038] 2) Change the q-axis injected voltage harmonic so that its real and imaginary parts are (0, a) (V). The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real and imaginary parts of the rotational speed harmonics after injecting the voltage harmonics, denoted as (ReΩr3, ImΩr3).

[0039] Thus, the calculation formula for the inverse matrix H of the closed-loop transfer function matrix from the real and imaginary parts of the q-axis injected voltage harmonics to the real and imaginary parts of the rotational speed harmonics is:

[0040] .

[0041] The q axis injected voltage harmonics U inq are reconstructed into an injected voltage signal in the angular domain u inq by the formula:

[0042] .

[0043] Step 3: Design a rotational speed harmonic controller according to the calculated inverse matrix and the PI controller. The input of this rotational speed harmonic controller is the real and imaginary parts of the rotational speed harmonics feedback from the motor, and the output is the real and imaginary parts of the q-axis injected voltage harmonics, and the rotational speed harmonics are suppressed by injecting voltage harmonics. The rotational speed harmonic controller is: After inputting the deviation between the actual values and the command values of the real and imaginary parts of the rotational speed harmonics extracted from the measured motor into the PI controller, multiply it by the inverse matrix H to output the real and imaginary parts of the q-axis injected voltage harmonics.

[0044] The present invention adopts an online measurement method to measure the relationship between the injected voltage harmonics and the rotational speed harmonics (i.e., the closed-loop function matrix) in real time, so as to design a rotational speed harmonic controller, which can more effectively suppress the rotational speed harmonics and avoid the problem of suppression failure when the relationship between the injected voltage harmonics and the rotational speed harmonics changes.

[0045] Embodiment:

[0046] The present invention is specifically applied to a permanent magnet synchronous motor control system based on a traditional vector control strategy to suppress the 24th-order speed harmonic. The simulation model is as Figure 2 shown. When operating under the conditions of a speed of 1500 rpm and a torque of 1.3 Nm, the proposed method is used to suppress the 24th-order speed harmonic. After the permanent magnet synchronous motor reaches the target speed and operates stably, the control algorithm of the present invention is started. The steps are as follows:

[0047] Step 1. When the permanent magnet synchronous motor is operating stably, according to the rotor rotation angle, the motor rotation angle θ , speed ω r are collected at equal angular intervals. The real part and the imaginary part of the 24th-order speed harmonic are extracted through the angular domain single-point Fourier transform algorithm (Re Ω r1 , Im Ω r1 ) are (1.38, 1.10) (m / s);

[0048] Step 2. Inject a q axis voltage harmonic into the system. Its real part and imaginary part are (0.2, 0) (V). The injected voltage harmonic is reconstructed into an injected voltage signal in the angular domain and added to the voltage command. The real part and the imaginary part of the speed harmonic after measuring the injected voltage harmonic (Re Ω r2 , Im Ω r2 ) are (1.17, 0.97) (m / s); change the q axis injected voltage harmonic so that its real part and imaginary part are (0, 0.2) (V). The injected voltage harmonic is reconstructed into an injected voltage signal in the angular domain and added to the voltage command. The real part and the imaginary part of the speed harmonic after measuring the injected voltage harmonic (Re Ω r3 , Im Ω r3 ) are (1.51, 0.89) (m / s);

[0049] Calculate the inverse matrix q of the closed-loop transfer function matrix from the real part and the imaginary part of the H axis injected voltage harmonic to the real part and the imaginary part of the speed harmonic:

[0050] ;

[0051] Step 3. Design a speed harmonic controller according to the calculated inverse matrix H and a PI controller. The input of the speed harmonic controller is the real part and the imaginary part of the feedback speed harmonic, and the output isq The real and imaginary parts of the shaft voltage harmonics are injected to suppress the speed harmonics. The controller block diagram is as follows: Figure 3 shown.

[0052] The results of speed harmonic suppression using the present invention in this embodiment are as follows: Figures 4 - 7 As shown; when the motor speed is stable, the inverse matrix of the closed-loop transfer function matrix is ​​performed at 0.5~0.53 seconds H After the matrix parameters are obtained, the speed harmonic controller parameters are set. The speed harmonic suppression is performed at 0.53 seconds. After suppression, the amplitude of the 24th-order speed harmonic is reduced from 1.75m / s to 0.005m / s, and the speed harmonic amplitude is reduced by 99.7%. At the same time, the speed fluctuation range is reduced from 3.6rpm to 0.3rpm, a reduction of 91.7%.

[0053] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by others to the technical solution of the present invention should all fall within the protection scope of the present invention.

Claims

1. Motor speed harmonic suppression method based on injected voltage harmonics and on-line measurement, characterized in that, it includes the following steps: Step 1: Measure the speed value of the motor, and extract the real part and imaginary part of the speed harmonics through the angular domain single-point Fourier transform algorithm; Step 2: Inject q-axis voltage harmonics into the system. The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command; And again extract the real part and imaginary part of the speed harmonics through the angular domain single-point Fourier transform algorithm, compare the changes in the speed harmonics before and after the injection of the voltage harmonics, and calculate the inverse matrix H of the closed-loop transfer function matrix from the real part and imaginary part of the q-axis injected voltage harmonics to the real part and imaginary part of the speed harmonics; Step 3: Design a speed harmonic controller according to the calculated inverse matrix and the PI controller. The input of the speed harmonic controller is the real part and imaginary part of the speed harmonics fed back by the motor, and the output is the real part and imaginary part of the q-axis injected voltage harmonics. Suppress speed harmonics by injecting voltage harmonics; The speed harmonic controller is: After inputting the deviation between the actual value and the command value of the real part and imaginary part of the speed harmonics extracted from the measured motor into the PI controller, multiply it by the inverse matrix H to output the real part and imaginary part of the q-axis injected voltage harmonics; The formula of the used angular domain single-point Fourier algorithm is: ； N is the number of points for the rotational speed signal to participate in the Fourier transform algorithm, ω r ( θ i ) is the i-th sampled value of the rotational speed signal, θ i is the i-th sampled value of the angle signal θ; The motor is a permanent magnet synchronous motor. When the permanent magnet synchronous motor operates stably, according to the rotor rotation angle, the motor rotation angle θ and speed are collected at equal angular intervals. ω r , and the real part and imaginary part of the k-th order speed harmonic are extracted through the angular domain single-point Fourier transform algorithm, denoted as (ReΩr1, ImΩr1); k is the order of the speed harmonic to be suppressed. Step 2 includes: 1). Inject a q-axis voltage harmonic into the system, whose real part and imaginary part are (a, 0) (V). The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real part and imaginary part of the speed harmonics after injecting the voltage harmonics, denoted as (ReΩr2, ImΩr2); 2). Change the q-axis injected voltage harmonic so that its real part and imaginary part are (0, a) (V). The injected voltage harmonics are reconstructed into an injected voltage signal in the angular domain and added to the voltage command. Measure the real part and imaginary part of the speed harmonics after injecting the voltage harmonics, denoted as (ReΩr3, ImΩr3); Thus, the calculation formula for the inverse matrix H of the closed-loop transfer function matrix from the real part and imaginary part of the q-axis injected voltage harmonics to the real part and imaginary part of the speed harmonics is: ； The q axis injection voltage harmonics U inq are reconstructed into an injection voltage signal in the angular domain u inq The formula is as follows: 。

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