A fast and accurate permanent magnet synchronous motor current harmonic extraction system and method

Abstract

The application provides a fast and accurate permanent magnet synchronous motor current harmonic system and method, relates to the permanent magnet synchronous motor current harmonic detection technical field, solves the technical problem that the current harmonic detection method in the prior art cannot guarantee high-level current reconstruction accuracy and improves the dynamic response characteristics of harmonic detection without needing to open up an array space for storing a large amount of data; and a technical scheme is as follows: the extraction system is a d-axis harmonic current extraction module and a q-axis harmonic current extraction module; the extraction method is that a current transient judgment unit and a gain matrix automatic updating mechanism are used; the application guarantees high-level current reconstruction accuracy and improves the dynamic response characteristics of harmonic detection; in addition, it does not need to open up an array space for storing a large amount of data, and therefore has low requirements on storage resources.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor current harmonic detection technology, specifically to a fast and accurate permanent magnet synchronous motor current harmonic extraction system and method. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) possess advantages such as high efficiency, high power density, and high dynamic response, leading to their widespread application in high-end fields such as aerospace, industrial automation, and new energy vehicles. However, due to various disturbances such as inverter nonlinearity, sampling errors, cogging torque, and load fluctuations, PMSM systems typically contain a significant amount of current harmonics, resulting in problems such as torque ripple, motor overheating, and noise pollution. Therefore, reducing the current harmonics of PMSMs is a crucial measure to improve the control performance of drive systems. Real-time extraction of current harmonics is a key step in achieving harmonic suppression, and its performance directly affects the steady-state accuracy and dynamic response of harmonic suppression.

[0003] Currently, methods for extracting current harmonics are mainly divided into frequency domain methods and time domain methods. Time domain methods include second-order generalized integrators (SOGI), adaptive notch filters (ANF), synchronous harmonic coordinate rotation transformations (MRF), etc. Frequency domain methods are based on Fourier transform extraction methods, which can be further divided into discrete Fourier transform (DFT), fast Fourier transform (FFT), iterative Fourier transform (RDFT), etc.

[0004] Regarding methods for extracting current harmonics, scholars both domestically and internationally have conducted research from different perspectives. Among them, the literature "Liu Bing, Zhou Bo, Ni Tianheng. Nonlinear compensation strategy for SPMSM sensorless control inverter based on generalized second-order integrator [J]. Proceedings of the CSEE, 2018, 38(11): 3365-3374" designed a second-order generalized integrator (SOGI) method to extract harmonics in the q-axis current, aiming to reduce the impact of inverter nonlinearity on the accuracy of position estimation; however, the selection of SOGI parameters requires a trade-off between filtering effect and response speed, and it is sensitive to current changes during transient processes.

[0005] The literature “Feng Guodong, Lai Chunyan, Tian Jiangbo, et al. Multiple Reference Frame Based Torque Ripple Minimization for PMSM Drive Under Both Steady-State and Transient Conditions[J].IEEE Trans. Power Electron., 2019, 34(07), 6685-6696” proposes to use a low-pass filter to separate the DC and harmonic components in the current in the synchronous harmonic coordinate system (MRF), thereby achieving high-precision control of different components. It is worth noting that the introduction of a low-pass filter will produce a hysteresis effect on the dynamic rate of harmonic separation, and in severe cases, it may even reduce the stability of the control loop.

[0006] The literature “Wang Shuo, Kang Jinsong, et al. A method for current harmonic extraction and suppression of permanent magnet synchronous motor based on adaptive linear neural network algorithm [J]. Journal of Electrical Engineering, 2019, 34(4): 654-663” proposes to use the adaptive linear neural network algorithm (ADALINE) to decompose the 6th and 12th current harmonics of the dq axis and obtains high current control accuracy. However, in the above scheme, the authors did not optimize the dynamic performance of harmonic extraction, resulting in a slow adjustment rate of current harmonics when the load changes abruptly. The literature “Wu Zhaoqian, Yang Zhiqian, Ding Kang, et al. Order-Domain-Based HarmonicInjection Method for Multiple Speed ​​Harmonics Suppression of PMSM [J]. IEEE Trans. Power Electron., 2021, 36(4), 4478-4487” proposes a real-time angular domain Fourier transform (AFT) method to extract harmonic components. However, this method requires multiple arrays to store the sampled data points, which places high demands on the chip's storage resources. Summary of the Invention

[0007] The purpose of this invention is to provide a fast and accurate permanent magnet synchronous motor current harmonic extraction system and method. This invention solves the problem that existing current harmonic detection methods cannot guarantee high-level current reconstruction accuracy and improve the dynamic response characteristics of harmonic detection, while eliminating the need to allocate array space for storing large amounts of data. This invention improves the dynamic response characteristics of harmonic detection while ensuring high-level current reconstruction accuracy; in addition, it does not require the allocation of array space for storing large amounts of data, thus reducing storage resource requirements.

[0008] This invention is achieved through the following measures: This invention provides a fast and accurate permanent magnet synchronous motor current harmonic extraction system, comprising:

[0009] d-axis harmonic current extraction module and q-axis harmonic current extraction module;

[0010] The d-axis harmonic current extraction module includes a d-axis current reconstruction error unit, a d-axis current DC component calculation unit, a d-axis current transient judgment unit, a d-axis current harmonic coefficient calculation unit, and a d-axis current reconstruction signal calculation unit.

[0011] The q-axis harmonic current extraction module includes a q-axis current reconstruction error unit, a q-axis current DC component calculation unit, a q-axis current transient judgment unit, a q-axis current harmonic coefficient calculation unit, and a q-axis current reconstruction signal calculation unit.

[0012] The input terminal of the d-axis current reconstruction error unit is connected to the output terminal of the d-axis current sampling value id and the d-axis current reconstruction signal unit. The input terminal of the d-axis current DC component calculation unit is connected to the output terminal of the d-axis current reconstruction error unit. The input terminal of the d-axis current transient judgment unit is connected to the output terminal of the d-axis current reconstruction error unit. The input terminal of the d-axis current harmonic coefficient calculation unit is connected to the output terminals of the d-axis current reconstruction error unit and the d-axis current transient judgment unit. The input terminal of the d-axis current reconstruction signal calculation unit is connected to the output terminals of the d-axis current DC component calculation unit and the d-axis current harmonic coefficient calculation unit.

[0013] The input terminal of the q-axis current reconstruction error unit is connected to the output terminal of the q-axis current sampling value id and the q-axis current reconstruction signal unit. The input terminal of the q-axis current DC component calculation unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current transient judgment unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current harmonic coefficient calculation unit is connected to the output terminals of the q-axis current reconstruction error unit and the q-axis current transient judgment unit. The input terminal of the q-axis current reconstruction signal calculation unit is connected to the output terminals of the q-axis current DC component calculation unit and the q-axis current harmonic coefficient calculation unit.

[0014] Preferably, the d-axis and q-axis current transient judgment unit will determine the current estimation error ε based on the current estimation error ε. d ε q Determine whether the current harmonic component calculation unit is enabled in the current cycle, when the current estimation error meets the following condition:

[0015] |ε d |<ε d_lim ,|ε q |<ε q_lim (1)

[0016] The current detection module will execute the current harmonic component calculation unit; otherwise, it will skip the harmonic extraction step. Wherein, ε d_lim ε q_lim These are the threshold values ​​for judging transient currents on the d and q axes.

[0017] Preferably, the threshold values ​​for judging transient currents along the d and q axes are set as follows:

[0018] ε d_lim =0.01*I dN , ε q_lim =0.01*I qN (2)

[0019] Among them, I dN I qN These are the rated values ​​of the d-axis and q-axis currents.

[0020] This invention also provides a fast and accurate method for extracting harmonics from the current of a permanent magnet synchronous motor. Based on the aforementioned fast and accurate permanent magnet synchronous motor current harmonic extraction system, the d-axis and q-axis current reconstruction error unit is based on the current d-axis and q-axis current signals i d i q The current estimation error ε is obtained by reconstructing the current signal along the d and q axes. d ε q The implementation method includes the following steps:

[0021] S1: Collect the current mechanical position θ of the motor m Determine the main harmonic frequencies in the current signal, and calculate the transformation factor required to reconstruct the current. The expression for the transformation factor is:

[0022] Θ=[cos(0) sin(0) cos(0.2p n θ m sin(0.2p) n θ m cos(6p) n θ m sin(6p) n θ m cos(12p) n θ m sin(12p) n θ m (3)

[0023] Where, p n It is the number of pole pairs of the motor. The main harmonic frequencies of the current signal of the motor under test include the 0.2 harmonic caused by rotor eccentricity and the 6th and 12th harmonics caused by inverter nonlinearity.

[0024] S2: Calculate the d-axis and q-axis currents based on the d-axis and q-axis reconstructed current coefficients obtained from the previous control cycle and the transformation factor obtained in step S1. The expression for the current reconstruction coefficient is:

[0025]

[0026] Among them, I d_cos0 I d_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the d-axis current, I d_cos0p2 I d_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the d-axis current. d_cos6 I d_sin6 I is the sine and cosine reconstruction coefficient of the 6th harmonic component of the d-axis current. d_cos12 I d_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the d-axis current; I q_cos0 I q_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the q-axis current, I q_cos0p2 I q_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the q-axis current. q_cos6 I q_sin6 These are the sine and cosine reconstruction coefficients of the 6th harmonic component of the q-axis current, I q_cos12 I q_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the q-axis current;

[0027] S3: Calculate the reconfiguration current using the following formula:

[0028]

[0029] S4: Calculate the current estimation errors εd and εq, using the following expressions:

[0030]

[0031] Preferably, the d-axis and q-axis current DC component calculation unit calculates the current estimation error ε. d ε q The sine and cosine coefficients of the DC component are obtained iteratively, and the method includes the following steps:

[0032] S1: Update the sine and cosine coefficients of the DC component in the current cycle based on the sine and cosine coefficients of the DC component in the previous cycle.

[0033]

[0034]

[0035] Among them, I d_cos0(k), I d_sin0 (k) represents the sine and cosine reconstruction coefficients of the DC component of the current d-axis current in the current period, I d_cos0 (k-1), I d_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the d-axis current in the previous cycle, M d_cos0 (k-1), M d_sin0 (k-1) is the iteration factor for the DC component of the d-axis current; I q_cos0 (k), I q_sin0 (k) are the sine and cosine reconstruction coefficients of the DC component of the current q-axis current in the current period, I q_cos0 (k-1), I q_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the q-axis current in the previous cycle.

[0036] M q_cos0 (k-1), M q_sin0 (k-1) is the iteration factor for the DC component of the q-axis current;

[0037] S2: Calculate the iteration factor for the DC component of the d-axis and q-axis currents in the current period.

[0038]

[0039] Where λ is the forgetting factor, with a value between 0.95 and 1; σ0(k) is the gain of the current period change.

[0040] Preferably, the value of the updated gain σ0(k) is as follows:

[0041]

[0042] Preferably, the d-axis and q-axis current harmonic coefficient calculation unit will calculate the harmonic coefficients based on the current estimation error ε. d ε q The sine and cosine coefficients of the harmonic components are obtained iteratively, and the method includes the following steps:

[0043] S1: The sine and cosine coefficients of the harmonic components in the current period are updated using the sine and cosine coefficients of each harmonic component in the previous period. The calculation formula is as follows:

[0044]

[0045]

[0046] Among them, I d_cosn (k), I d_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's d-axis current harmonic components, I d_cosn (k-1), I d_sinn (k-1) are the sine and cosine reconstruction coefficients of the d-axis current harmonic components in the previous cycle, Md_cosn (k-1), M d_sinn (k-1) is the iteration factor for the d-axis current harmonic components; I q_cosn (k), I q_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's q-axis current harmonic components, I q_cosn (k-1), I q_sinn (k-1) are the sine and cosine reconstruction coefficients of the q-axis current harmonic components in the previous cycle, M q_cosn (k-1), M q_sinn (k-1) is the iteration factor for the q-axis current harmonic components;

[0047] S2: Calculate the iteration factor for the harmonic components of the d-axis and q-axis currents in the current period:

[0048]

[0049] Wherein, P(k-1) is a matrix containing the change gain.

[0050] Preferably, the gain matrix is ​​updated:

[0051]

[0052] Preferably, the initial value of the gain matrix P(k) is set to P(0) = σ0(0)I.

[0053] The present invention has the following advantages over the prior art:

[0054] 1. The present invention provides a fast and accurate method for extracting harmonics from the current of a permanent magnet synchronous motor. The harmonic extraction accuracy is high. The present invention ensures that a high harmonic extraction accuracy is achieved without affecting the convergence rate of the reconstructed signal, and avoids the problem of difficulty in coordinating dynamic response and steady-state accuracy caused by unreasonable setting of key parameters in traditional schemes.

[0055] 2. The present invention provides a fast and accurate method for extracting harmonic currents of permanent magnet synchronous motors, which improves dynamic response. The present invention includes a current transient judgment unit and an automatic gain matrix update mechanism. The former effectively weakens the impact of current transient changes on the harmonic coefficient iteration process, while the latter accelerates the convergence rate of the harmonic reconstruction signal. Combining the advantages of both will help improve the dynamic response of current harmonic extraction.

[0056] 3. The fast and accurate method for extracting harmonic current of permanent magnet synchronous motor provided by the present invention is convenient for parameter adjustment. The harmonic coefficients used in the current reconstruction process of the present invention have automatic adaptive adjustment capabilities. The algorithm iteration only requires setting the initial values ​​of the forgetting factor λ and the gain matrix P(k).

[0057] 4. The fast and accurate permanent magnet synchronous motor current harmonic extraction method provided by the present invention has low requirements for chip storage resources. The present invention does not require a large-capacity array to store sampling data for several cycles. The harmonic coefficients of the reconstructed signal are all single-valued variables, so the requirements for chip storage resources are low. Attached Figure Description

[0058] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used to explain the invention but do not constitute a limitation thereof.

[0059] Figure 1 This is a control block diagram of a permanent magnet synchronous motor drive system including a current harmonic detection module, according to the present invention.

[0060] Figure 2 This is a flowchart illustrating the implementation of the current harmonic detection module provided by the present invention.

[0061] Figure 3 This is a graph showing the harmonic coefficients of the current reconstruction signal using ADALINE in this invention.

[0062] Figure 4 This is a current reconstruction signal curve using ADALINE in this invention.

[0063] Figure 5 This is a graph showing the harmonic coefficients of the current reconstructed signal using the proposed scheme in this invention.

[0064] Figure 6 This is a current reconstruction signal curve using the proposed scheme in this invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. The technical solutions of this invention will be further described in detail below with reference to the accompanying drawings:

[0066] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0067] Example 1:

[0068] Figure 1 This is a control block diagram of a permanent magnet synchronous motor system that includes current harmonic extraction functionality. It comprises several parts, including a speed regulator, a d-axis current regulator, a q-axis current regulator, a speed filter, a mathematical model of the controlled object (torque model, motion model), and a current harmonic detection module. It is a speed reference command. It is a current reference command, Te It is the electromagnetic torque of the motor, T L It is the load torque, ω m That's the actual speed. It is an estimate of speed, i d i q It is the dq-axis current. This is the reconstructed current obtained through the current harmonic detection module. The current harmonic detection module plays an important role in extracting harmonic content in stages, monitoring current fluctuation levels, and suppressing current harmonics.

[0069] Traditional current harmonic extraction schemes are mainly divided into frequency domain methods and time domain methods. Frequency domain methods are signal extraction methods based on Fourier transform. These methods have high accuracy in harmonic signal detection, but require a large amount of storage space to store the sampled data and have poor real-time performance. Time domain methods include generalized second-order integrators, adaptive filters, synchronous harmonic coordinate rotation transformations, etc. These schemes have better real-time performance, but it is difficult to guarantee a smooth and fast response in harmonic extraction under instantaneous current changes. To address this, this invention discloses an improved current harmonic extraction scheme. Compared with traditional schemes, this scheme improves the dynamic rate of signal extraction while maintaining harmonic detection accuracy.

[0070] This invention mainly includes a d-axis harmonic current extraction module and a q-axis harmonic current extraction module. The d-axis harmonic current extraction module includes a d-axis current reconstruction error unit, a d-axis current DC component calculation unit, a d-axis current transient judgment unit, a d-axis current harmonic coefficient calculation unit, and a d-axis current reconstruction signal calculation unit. The q-axis harmonic current extraction module includes a q-axis current reconstruction error unit, a q-axis current DC component calculation unit, a q-axis current transient judgment unit, a q-axis current harmonic coefficient calculation unit, and a q-axis current reconstruction signal calculation unit.

[0071] Specifically, the input terminal of the d-axis current reconstruction error unit is connected to the output terminal of the d-axis current sampling value id and the d-axis current reconstruction signal unit; the input terminal of the d-axis current DC component calculation unit is connected to the output terminal of the d-axis current reconstruction error unit; the input terminal of the d-axis current transient judgment unit is connected to the output terminal of the d-axis current reconstruction error unit; the input terminal of the d-axis current harmonic coefficient calculation unit is connected to the output terminals of the d-axis current reconstruction error unit and the d-axis current transient judgment unit; and the input terminal of the d-axis current reconstruction signal calculation unit is connected to the output terminals of the d-axis current DC component calculation unit and the d-axis current harmonic coefficient calculation unit.

[0072] The input terminal of the q-axis current reconstruction error unit is connected to the output terminal of the q-axis current sampling value id and the q-axis current reconstruction signal unit. The input terminal of the q-axis current DC component calculation unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current transient judgment unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current harmonic coefficient calculation unit is connected to the output terminals of the q-axis current reconstruction error unit and the q-axis current transient judgment unit. The input terminal of the q-axis current reconstruction signal calculation unit is connected to the output terminals of the q-axis current DC component calculation unit and the q-axis current harmonic coefficient calculation unit.

[0073] The d-axis and q-axis current transient judgment unit will determine the current estimation error ε based on the current estimation error ε. d ε q Determine whether the current harmonic component calculation unit is enabled in the current cycle, when the current estimation error meets the following condition:

[0074] |ε d |<ε d_lim ,|ε q |<ε q_lim (1)

[0075] The current detection module will execute the current harmonic component calculation unit; otherwise, it will skip the harmonic extraction step. Wherein, ε d_lim ε q_lim These are the threshold values ​​for transient current judgment on the d and q axes. A harmonic detection system incorporating a transient current judgment unit will effectively reduce the impact of variable speed or loading conditions on the reconstructed transient current characteristics, thus improving the dynamic response of harmonic extraction.

[0076] The threshold values ​​for judging transient current on the d and q axes are set as follows:

[0077] ε d_lim =0.01*I dN , ε q_lim =0.01*I qN (2)

[0078] Among them, I dN I qN These are the rated values ​​of the d-axis and q-axis currents.

[0079] Example 2:

[0080] This embodiment provides a fast and accurate method for extracting current harmonics in a permanent magnet synchronous motor. Based on the fast and accurate permanent magnet synchronous motor current harmonic extraction system described in claim 1, the d-axis and q-axis current reconstruction error unit is based on the current d-axis and q-axis current signals i d i q The current estimation error ε is obtained by reconstructing the current signal along the d and q axes. d εq The implementation method includes the following steps:

[0081] S1: Collect the current mechanical position θ of the motor m Determine the main harmonic frequencies in the current signal, and calculate the transformation factor required to reconstruct the current. The expression for the transformation factor is:

[0082] Θ=[cos(0) sin(0) cos(0.2p n θ m sin(0.2p) n θ m cos(6p) n θ m sin(6p) n θ m cos(12p) n θ m sin(12p) n θ m (3)

[0083] Where, p n It is the number of pole pairs of the motor. The main harmonic frequencies of the current signal of the motor under test include the 0.2 harmonic caused by rotor eccentricity and the 6th and 12th harmonics caused by inverter nonlinearity.

[0084] S2: Calculate the d-axis and q-axis currents based on the d-axis and q-axis reconstructed current coefficients obtained from the previous control cycle and the transformation factor obtained in step S1. The expression for the current reconstruction coefficient is:

[0085]

[0086] Among them, I d_cos0 I d_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the d-axis current, I d_cos0p2 I d_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the d-axis current. d_cos6 I d_sin6 I is the sine and cosine reconstruction coefficient of the 6th harmonic component of the d-axis current. d_cos12 I d_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the d-axis current; I q_cos0 I q_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the q-axis current, I q_cos0p2 I q_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the q-axis current. q_cos6 I q_sin6 These are the sine and cosine reconstruction coefficients of the 6th harmonic component of the q-axis current, Iq_cos12 I q_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the q-axis current;

[0087] S3: Calculate the reconfiguration current using the following formula:

[0088]

[0089] S4: Calculate the current estimation errors εd and εq, using the following expressions:

[0090]

[0091] In this embodiment, the d-axis and q-axis current DC component calculation unit calculates the current estimation error ε. d ε q The sine and cosine coefficients of the DC component are obtained iteratively, and the method includes the following steps:

[0092] S1: Update the sine and cosine coefficients of the DC component in the current cycle based on the sine and cosine coefficients of the DC component in the previous cycle.

[0093]

[0094]

[0095] Among them, I d_cos0 (k), I d_sin0 (k) represents the sine and cosine reconstruction coefficients of the DC component of the current d-axis current in the current period, I d_cos0 (k-1), I d_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the d-axis current in the previous cycle, M d_cos0 (k-1), M d_sin0 (k-1) is the iteration factor for the DC component of the d-axis current; I q_cos0 (k), I q_sin0 (k) are the sine and cosine reconstruction coefficients of the DC component of the current q-axis current in the current period, I q_cos0 (k-1), I q_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the q-axis current in the previous cycle, M q_cos0 (k-1), M q_sin0 (k-1) is the iteration factor for the DC component of the q-axis current;

[0096] S2: Calculate the iteration factor for the DC component of the d-axis and q-axis currents in the current period.

[0097]

[0098] Where λ is the forgetting factor, with a value between 0.95 and 1; σ0(k) is the gain of the current period change.

[0099] The updated value of the change gain σ0(k) is as follows:

[0100]

[0101] In this embodiment, the d-axis and q-axis current harmonic coefficient calculation unit will calculate the harmonic coefficients based on the current estimation error ε. d ε q The sine and cosine coefficients of the harmonic components are obtained iteratively, and the method includes the following steps:

[0102] S1: The sine and cosine coefficients of the harmonic components in the current period are updated using the sine and cosine coefficients of each harmonic component in the previous period. The calculation formula is as follows:

[0103]

[0104]

[0105] Among them, I d_cosn (k), I d_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's d-axis current harmonic components, I d_cosn (k-1), I d_sinn (k-1) are the sine and cosine reconstruction coefficients of the d-axis current harmonic components in the previous cycle, M d_cosn (k-1), M d_sinn (k-1) is the iteration factor for the d-axis current harmonic components; I q_cosn (k), I q_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's q-axis current harmonic components, I q_cosn (k-1), I q_sinn (k-1) are the sine and cosine reconstruction coefficients of the q-axis current harmonic components in the previous cycle, M q_cosn (k-1), M q_sinn (k-1) is the iteration factor for the q-axis current harmonic components;

[0106] S2: Calculate the iteration factor for the harmonic components of the d-axis and q-axis currents in the current period:

[0107]

[0108] Wherein, P(k-1) is a matrix containing the change gain.

[0109] S3: Update the gain matrix:

[0110]

[0111] The initial value of the gain matrix P(k) is set as P(0) = σ0(0)I.

[0112] Figures 3 to 6 Comparison results of the current harmonic extraction scheme based on ADALINE and the proposed current harmonic extraction scheme under the same conditions are presented. The static and dynamic characteristics of the measured current signal (original signal) are consistent under both schemes. As can be seen from the figure, because ADALINE cannot well coordinate dynamic characteristics and steady-state accuracy, the dynamic changes of the current reconstruction coefficient and the overall signal waveform are large during the speed change and loading stages, and the process of recovering to steady state is long. In contrast, the proposed scheme significantly reduces the sensitivity of signal reconstruction to instantaneous state changes, and the current transient judgment unit and gain matrix update mechanism effectively improve the response rate of current harmonic extraction.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fast and accurate permanent magnet synchronous motor current harmonic extraction system, characterized in that, include: d-axis harmonic current extraction module and q-axis harmonic current extraction module; The d-axis harmonic current extraction module includes a d-axis current reconstruction error unit, a d-axis current DC component calculation unit, a d-axis current transient judgment unit, a d-axis current harmonic coefficient calculation unit, and a d-axis current reconstruction signal calculation unit. The q-axis harmonic current extraction module includes a q-axis current reconstruction error unit, a q-axis current DC component calculation unit, a q-axis current transient judgment unit, a q-axis current harmonic coefficient calculation unit, and a q-axis current reconstruction signal calculation unit. The input terminal of the d-axis current reconstruction error unit is connected to the output terminal of the d-axis current sampling value id and the d-axis current reconstruction signal unit. The input terminal of the d-axis current DC component calculation unit is connected to the output terminal of the d-axis current reconstruction error unit. The input terminal of the d-axis current transient judgment unit is connected to the output terminal of the d-axis current reconstruction error unit. The input terminal of the d-axis current harmonic coefficient calculation unit is connected to the output terminals of the d-axis current reconstruction error unit and the d-axis current transient judgment unit. The input terminal of the d-axis current reconstruction signal calculation unit is connected to the output terminals of the d-axis current DC component calculation unit and the d-axis current harmonic coefficient calculation unit. The input terminal of the q-axis current reconstruction error unit is connected to the output terminal of the q-axis current sampling value id and the q-axis current reconstruction signal unit. The input terminal of the q-axis current DC component calculation unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current transient judgment unit is connected to the output terminal of the q-axis current reconstruction error unit. The input terminal of the q-axis current harmonic coefficient calculation unit is connected to the output terminals of the q-axis current reconstruction error unit and the q-axis current transient judgment unit. The input terminal of the q-axis current reconstruction signal calculation unit is connected to the output terminals of the q-axis current DC component calculation unit and the q-axis current harmonic coefficient calculation unit.

2. The rapid and accurate permanent magnet synchronous motor current harmonic extraction system according to claim 1, characterized in that, The d-axis and q-axis current transient judgment unit will determine the current estimation error ε based on the current estimation error ε. d ε q Determine whether the current harmonic component calculation unit is enabled in the current cycle, when the current estimation error meets the following condition: |e d |<e d_lim ,|e q |<e q_lim (1) The current detection module will execute the current harmonic component calculation unit; otherwise, it will skip the harmonic extraction step. Wherein, ε d_lim ε q_lim These are the threshold values ​​for judging transient currents on the d and q axes.

3. The rapid and accurate permanent magnet synchronous motor current harmonic extraction system according to claim 1, characterized in that, The threshold values ​​for judging transient current on the d and q axes are set as follows: e d_lim =0.01*I dN ,he q_lim =0.01*I qN (2) Among them, I dN I qN These are the rated values ​​of the d-axis and q-axis currents.

4. A fast and accurate method for extracting harmonics from the current of a permanent magnet synchronous motor, characterized in that, The extraction method is based on the fast and accurate permanent magnet synchronous motor current harmonic extraction system according to any one of claims 1-3, wherein the d-axis and q-axis current reconstruction error units are based on the current d-axis and q-axis current signals i d i q The current estimation error ε is obtained by reconstructing the current signal along the d and q axes. d ε q The implementation method includes the following steps: S1: Collect the current mechanical position θ of the motor m Determine the main harmonic frequencies in the current signal, and calculate the transformation factor required to reconstruct the current. The expression for the transformation factor is: Θ=[cos(0) sin(0) cos(0.2p n i m ) sin(0.2p n i m ) cos(6p n i m ) sin(6p n i m ) cos(12p n i m ) sin(12p n i m )] (3) Where, p n It is the number of pole pairs of the motor. The main harmonic frequencies of the current signal of the motor under test include the 0.2 harmonic caused by rotor eccentricity and the 6th and 12th harmonics caused by inverter nonlinearity. S2: Calculate the d-axis and q-axis currents based on the d-axis and q-axis reconstructed current coefficients obtained from the previous control cycle and the transformation factor obtained in step S1. The expression for the current reconstruction coefficient is: Among them, I d_cos0 I d_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the d-axis current, I d_cos0p2 I d_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the d-axis current. d_cos6 I d_sin6 I is the sine and cosine reconstruction coefficient of the 6th harmonic component of the d-axis current. d_cos12 I d_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the d-axis current; I q_cos0 I q_sin0 These are the sine and cosine reconstruction coefficients of the DC component of the q-axis current, I q_cos0p2 I q_sin0p2 I is the sine and cosine reconstruction coefficient of the 0.2nd harmonic component of the q-axis current. q_cos6 I q_sin6 These are the sine and cosine reconstruction coefficients of the 6th harmonic component of the q-axis current, I q_cos12 I q_sin12 These are the sine and cosine reconstruction coefficients of the 12th harmonic component of the q-axis current; S3: Calculate the reconfiguration current using the following formula: S4: Calculate the current estimation errors εd and εq, using the following expressions:

5. The method for rapid and accurate extraction of current harmonics in a permanent magnet synchronous motor according to claim 4, characterized in that, The d-axis and q-axis current DC component calculation unit is based on the current estimation error ε d ε q The sine and cosine coefficients of the DC component are obtained iteratively, and the method includes the following steps: S1: Update the sine and cosine coefficients of the DC component in the current cycle based on the sine and cosine coefficients of the DC component in the previous cycle. Among them, I d_cos0 (k), I d_sin0 (k) are the sine and cosine reconstruction coefficients of the DC component of the d-axis current in the current period, I d_cos0 (k-1), I d_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the d-axis current in the previous cycle, M d_cos0 (k-1), M d_sin0 (k-1) is the iteration factor for the DC component of the d-axis current; I q_cos0 (k), I q_sin0 (k) are the sine and cosine reconstruction coefficients of the DC component of the current q-axis current in the current period, I q_cos0 (k-1), I q_sin0 (k-1) are the sine and cosine reconstruction coefficients of the DC component of the q-axis current in the previous cycle, M q_cos0 (k-1), M q_sin0 (k-1) is the iteration factor for the DC component of the q-axis current; S2: Calculate the iteration factor for the DC component of the d-axis and q-axis currents in the current period. Where λ is the forgetting factor, with a value between 0.95 and 1; σ0(k) is the current periodic change gain.

6. The method for rapid and accurate extraction of current harmonics in a permanent magnet synchronous motor according to claim 4, characterized in that, The updated value of the change gain σ0(k) is as follows:

7. The method for rapid and accurate extraction of current harmonics in a permanent magnet synchronous motor according to claim 5, characterized in that, The d-axis and q-axis current harmonic coefficient calculation unit will calculate based on the current estimation error ε. d ε q The sine and cosine coefficients of the harmonic components are obtained iteratively, and the method includes the following steps: S1: The sine and cosine coefficients of the harmonic components in the current period are updated using the sine and cosine coefficients of each harmonic component in the previous period. The calculation formula is as follows: Among them, I d_cosn (k), I d_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's d-axis current harmonic components, I d_cosn (k-1), I d_sinn (k-1) are the sine and cosine reconstruction coefficients of the d-axis current harmonic components in the previous cycle, M d_cosn (k-1), M d_sinn (k-1) is the iteration factor for the d-axis current harmonic components; I q_cosn (k), I q_sinn (k) represents the sine and cosine reconstruction coefficients of the current period's q-axis current harmonic components, I q_cosn (k-1), I q_sinn (k-1) are the sine and cosine reconstruction coefficients of the q-axis current harmonic components in the previous cycle, M q_cosn (k-1), M q_sinn (k-1) is the iteration factor for the q-axis current harmonic components; S2: Calculate the iteration factor for the harmonic components of the d-axis and q-axis currents in the current period: Wherein, P(k-1) is a matrix containing the change gain.

8. The method for rapid and accurate extraction of current harmonics in a permanent magnet synchronous motor according to claim 7, characterized in that, Update the gain matrix:

9. The method for rapid and accurate extraction of current harmonics in a permanent magnet synchronous motor according to claim 8, characterized in that, The initial value of the gain matrix P(k) can be set as P(0) = σ0(0)I.

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