A high-frequency pulse injection-based permanent magnet synchronous motor demagnetization fault diagnosis method

Abstract

The application discloses a kind of permanent magnet synchronous motor demagnetization fault diagnosis methods based on high-frequency pulse injection, it is related to the field of permanent magnet synchronous motor fault diagnosis, comprising: superimposing high-frequency pulse voltage signal to d-axis voltage instruction;Three-phase stator current is collected, d-axis current and q-axis current are obtained by coordinate transformation;Filtering fundamental frequency component, extract q-axis high-frequency current response signal;Band-pass filtering and synchronous demodulation are carried out, and in-phase component and quadrature component are obtained;Envelope detection is carried out, and the time-domain sequence of high-frequency response amplitude is obtained, and time-domain sequence is resampled spatial amplitude sequence;Frequency spectrum analysis is carried out, and the amplitude of its two times electric frequency harmonic component is extracted;Calculate demagnetization diagnostic index, judge whether demagnetization fault occurs, and estimate demagnetization position and demagnetization degree.The method realizes permanent magnet synchronous motor demagnetization fault non-invasive, high sensitivity online diagnosis and accurate positioning quantitative evaluation by high-frequency injection and space signal processing.

Description

Technical Field

[0001] This invention relates to the field of fault diagnosis of permanent magnet synchronous motors, and more specifically to a method for diagnosing demagnetization faults of permanent magnet synchronous motors based on high-frequency pulse injection. Background Technology

[0002] Permanent magnet synchronous motors are widely used in high-performance fields such as electric vehicle drive, industrial servo control and wind power generation due to their high efficiency and power density. However, demagnetization failure of permanent magnets under complex working conditions can lead to a decrease in torque output, reduced efficiency and potential overheating risks.

[0003] In existing technologies, one type of method relies on shutdown detection or offline signal analysis. For example, the back EMF method requires the motor to be running under no-load and cannot achieve online monitoring. Although the current harmonic analysis method can be performed online, it is not sensitive to early slight demagnetization, and the diagnostic signal is easily affected by load fluctuations. The characteristic frequency components may also be confused with faults such as rotor eccentricity, leading to misjudgment.

[0004] Another type of method attempts to achieve online diagnosis by adding hardware or complex algorithms, but it also has obvious limitations. The flux density measurement method requires the installation of Hall sensors in the air gap, which is an invasive modification, costly and reduces system reliability. The model reference adaptive method relies heavily on accurate motor parameters, and the time-varying parameters in actual operation will affect its robustness, and the computational burden is heavy. Although the rotating high-frequency injection method can extract salient pole information, its process involves complex transformations, is sensitive to non-ideal factors such as inverter nonlinearity, and is difficult to effectively distinguish between local demagnetization and uniform demagnetization.

[0005] In addition, existing diagnostic methods have common shortcomings in modeling and feature utilization. Most methods do not fully consider the dynamic changes of inductance parameters with magnetic saturation state, and often simply assume that they are constant, which affects the accuracy of the model under real working conditions. At the same time, they fail to make full use of the modulation characteristics of faults in the spatial dimension, making it difficult to simultaneously and accurately decouple the fault location and degree information from a single response signal.

[0006] Therefore, how to design a method for diagnosing demagnetization faults of permanent magnet synchronous motors based on high-frequency pulse injection, and achieve high sensitivity, accurate location and quantitative assessment of demagnetization faults of permanent magnet synchronous motors, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a method for diagnosing demagnetization faults of permanent magnet synchronous motors based on high-frequency pulse injection. Without adding hardware or affecting the operation of the motor, it can achieve online, early and accurate diagnosis of demagnetization faults of permanent magnet synchronous motors, thereby overcoming the shortcomings of existing methods in terms of detection sensitivity, fault location capability, anti-interference ability and online implementation feasibility, and thus improving the reliability and maintainability of the motor system.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for diagnosing demagnetization faults in permanent magnet synchronous motors based on high-frequency pulse injection includes the following steps: S1. Superimpose a high-frequency pulsed voltage signal onto the d-axis voltage command of the motor control system to generate a d-axis voltage command containing high-frequency excitation. S2. Collect the three-phase stator current of the permanent magnet synchronous motor and perform coordinate transformation to obtain the d-axis current and q-axis current; S3. The fundamental frequency component is filtered out from the q-axis current using a notch filter to extract the q-axis high-frequency current response signal. S4. Perform bandpass filtering and synchronous demodulation on the q-axis high-frequency current response signal to obtain in-phase and quadrature components. S5. Perform envelope detection on the in-phase component and the quadrature component to obtain a time-domain sequence of the high-frequency response amplitude, and resample the time-domain sequence into a uniformly distributed spatial amplitude sequence. S6. Perform spectral analysis on the spatial amplitude sequence to extract the amplitude of its second harmonic component. S7. Based on the amplitude of the second harmonic component of the electrical frequency, calculate the demagnetization diagnostic index, determine whether a demagnetization fault has occurred, and estimate the location and degree of demagnetization.

[0010] Preferably, step S1 includes a d-axis voltage command with high-frequency excitation. Represented as:

[0011]

[0012] in, This is the d-axis voltage command of the original control system. The amplitude of the injected high-frequency voltage, The angular frequency of the injected high-frequency voltage.

[0013] Preferably, in step S2, the coordinate transformation includes: The three-phase current is converted using the Clark transformation. , , Current transformed to a two-phase stationary coordinate system , ; Combining rotor electrical angle The Park transformation is used to convert the current in the two-phase stationary coordinate system. , Current transformed to synchronous rotating coordinate system , .

[0014] Preferably, in step S3, the transfer function of the notch filter... Represented as:

[0015] Where s is the Laplace operator, The fundamental angular frequency that needs to be filtered out. The damping ratio is denoted as .

[0016] Preferably, S4 includes: Using the center angular frequency as The bandpass filter's response signal to the q-axis high-frequency current signal Filtering is performed to obtain the signal. ; Generate orthogonal carrier signals with the same frequency as the injected high-frequency voltage, including in-phase carriers. and orthogonal carriers ; Multiply the filtered signal by the quadrature carrier signal respectively: , ; The multiplied signal and The demodulated in-phase components are obtained by passing each component through a low-pass filter. and orthogonal components .

[0017] Preferably, the transfer function of the bandpass filter Represented as:

[0018] Where s is the Laplace operator and K is the filter gain. ω is the center angular frequency of the bandpass filter, and Q is the quality factor.

[0019] Preferably, the transfer function of the low-pass filter for:

[0020] Where s is the Laplace operator, This is the cutoff angular frequency of the low-pass filter.

[0021] Preferably, S5 includes: For in-phase components and orthogonal components Envelope calculation is performed to obtain the time-domain sequence of the high-frequency response amplitude. ; Based on rotor electrical angle The time-domain sequence The sequence was resampled into a uniform spatial angle sequence using Lagrange interpolation. .

[0022] Preferably, S6 includes: For spatial amplitude sequences Perform a discrete Fourier transform and calculate the complex coefficients of its second harmonic component. :

[0023] Where N is the number of spatially uniform sampling points, The rotor electrical angle corresponding to the kth spatial sampling point. The imaginary unit; Based on the complex coefficients To obtain the amplitude of the harmonic component at twice the electrical frequency. .

[0024] Preferably, S7 includes: Calculate the normalized diagnostic index DI. If DI < demagnetization amplitude threshold γ, then a demagnetization fault is determined to have occurred. Calculate the symmetry index. ,like If the symmetry threshold δ is exceeded, it is determined to be local demagnetization; According to the formula Estimate the demagnetization location. For operations involving complex arguments; and for calculating the degree of demagnetization based on the demagnetization estimation model. .

[0025] As can be seen from the above technical solution, compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. This method injects a specific high-frequency signal into the d-axis of the motor and extracts the twice-frequency component related to the spatial position in the q-axis current response, thus simultaneously completing the detection of demagnetization faults, precise location positioning, and quantitative assessment of the degree of demagnetization, overcoming the limitation of difficulty in simultaneously considering both positioning and quantitative analysis.

[0026] 2. It employs multi-level signal processing, including notch filtering, synchronous demodulation, and spatial domain spectrum analysis, which can effectively separate and extract weak modulation signals reflecting demagnetization characteristics from strong background noise and fundamental components. This enhances the ability to identify slight demagnetization and localized non-uniform demagnetization, and improves the anti-interference capability of the diagnostic process against external load disturbances and other interference factors.

[0027] 3. Based on the existing electronic control system and current sensor signals of the motor, without the need to install additional dedicated hardware sensors or change the motor body structure, signal injection and feature analysis are realized, enabling the method to be implemented seamlessly in the normal operation or static state of the motor, and to complete online status monitoring and early fault warning of permanent magnet synchronous motor. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 The flowchart illustrates a method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection, as provided in an embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, this embodiment provides a method for diagnosing demagnetization faults in permanent magnet synchronous motors based on high-frequency pulse injection, including the following steps: S1. Superimpose a high-frequency pulsed voltage signal onto the d-axis voltage command of the motor control system to generate a d-axis voltage command containing high-frequency excitation. S2. Collect the three-phase stator current of the permanent magnet synchronous motor and perform coordinate transformation to obtain the d-axis current and q-axis current; S3. The fundamental frequency component is filtered out from the q-axis current using a notch filter to extract the q-axis high-frequency current response signal. S4. Perform bandpass filtering and synchronous demodulation on the q-axis high-frequency current response signal to obtain in-phase and quadrature components. S5. Perform envelope detection on the in-phase component and the quadrature component to obtain a time-domain sequence of the high-frequency response amplitude, and resample the time-domain sequence into a uniformly distributed spatial amplitude sequence. S6. Perform spectral analysis on the spatial amplitude sequence to extract the amplitude of its second harmonic component. S7. Based on the amplitude of the second harmonic component of the electrical frequency, calculate the demagnetization diagnostic index, determine whether a demagnetization fault has occurred, and estimate the location and degree of demagnetization.

[0032] This method is performed when the motor is stationary or running at low speed, and the angular frequency of the injected high-frequency voltage is... Choose a frequency higher than the control system current loop bandwidth and avoid the inverter switching frequency and its multipliers; By injecting a high-frequency signal into the d-axis of the motor and extracting the spatial second harmonic modulation component from the q-axis current response, it achieves integrated diagnosis of demagnetization fault detection, location, and severity assessment. The multi-level signal processing method it employs enhances the detection capability and anti-interference ability for early and local demagnetization. This method is based on the existing electronic control system, requires no external sensors, and supports non-invasive online monitoring.

[0033] The following provides a further detailed explanation of each step and related feature in the above method: In this embodiment, S1, a high-frequency pulse voltage signal is superimposed on the d-axis voltage command of the motor control system to generate a d-axis voltage command containing high-frequency excitation. This includes d-axis voltage commands with high-frequency excitation. Represented as:

[0034]

[0035] in, This is the d-axis voltage command of the original control system. The amplitude of the injected high-frequency voltage, The angular frequency of the injected high-frequency voltage.

[0036] In practical implementation, the selection of high-frequency voltage signal parameters is crucial. In an embodiment for a motor with a rated speed of 1000 rpm and a pole pair count of p=2, the injected high-frequency voltage angular frequency... 800Hz can be selected, amplitude The frequency should be 5V, and it needs to be significantly higher than the fundamental frequency of the motor and the bandwidth of the current loop of the control system to ensure that the excitation signal is not affected by the basic control loop and can effectively excite the cross-coupling effect between the d and q axes. At the same time, this frequency should be carefully avoided to avoid the switching frequency of the inverter and its main harmonics, so as to minimize the pollution of the high-frequency response signal by power switching noise. It uses the pulsating high-frequency voltage injected into the d-axis as a non-invasive probe, avoiding the additional torque pulsation that may be caused by injecting signals into the q-axis, ensuring minimal interference to the normal operation of the motor during the diagnostic process. The injected signal generates a specific high-frequency response containing fault characteristic information in the q-axis current, laying the signal foundation for subsequent feature extraction.

[0037] In this embodiment, S2, the three-phase stator current of the permanent magnet synchronous motor is collected, and coordinate transformation is performed to obtain the d-axis current and q-axis current; wherein, the coordinate transformation includes: The three-phase current is converted using the Clark transformation. , , Current transformed to a two-phase stationary coordinate system , ; Combining rotor electrical angle The Park transformation is used to convert the current in the two-phase stationary coordinate system. , Current transformed to synchronous rotating coordinate system , ;in, , ; By transforming coordinates, the three-phase time-varying current signal is converted into a dq-axis DC signal oriented by the rotor magnetic field, which simplifies the complexity of subsequent signal processing and separates the fault characteristics caused by demagnetization and modulated in spatial angle from the strong fundamental background in the time domain to the specific frequency band of the q-axis current.

[0038] In this embodiment, S3, the fundamental frequency component is filtered out from the q-axis current using a notch filter to extract the q-axis high-frequency current response signal; wherein, the transfer function of the notch filter is... Represented as:

[0039] Where s is the Laplace operator, The fundamental angular frequency that needs to be filtered out. The damping ratio is denoted as .

[0040] In practical implementation, for a motor with a fundamental frequency of 50Hz, the damping ratio of the notch filter is... A value of around 0.7 is typically chosen to strike a balance between filter depth and bandwidth. After processing by this filter, the output signal... The main components retained are the response current generated by the injected high-frequency voltage excitation and its sideband components modulated by the demagnetization fault; When the motor is running normally, the amplitude of the fundamental component in the q-axis current is much larger than that of the high-frequency response component. The notch filter effectively removes this strongest source of interference, preventing it from causing saturation or nonlinear distortion in subsequent amplification and demodulation stages, thus ensuring that the weak high-frequency signal containing fault characteristics is completely preserved.

[0041] In embodiment S4, the q-axis high-frequency current response signal is bandpass filtered and synchronously demodulated to obtain in-phase and quadrature components; including: Using the center angular frequency as The bandpass filter's response signal to the q-axis high-frequency current signal Filtering is performed to obtain the signal. ; Generate orthogonal carrier signals with the same frequency as the injected high-frequency voltage, including in-phase carriers. and orthogonal carriers ; Multiply the filtered signal by the quadrature carrier signal respectively: , ; The multiplied signal and The demodulated in-phase components are obtained by passing each component through a low-pass filter. and orthogonal components .

[0042] Furthermore, the transfer function of the bandpass filter Represented as:

[0043] Where s is the Laplace operator and K is the filter gain. ω is the center angular frequency of the bandpass filter, and Q is the quality factor.

[0044] Furthermore, the transfer function of the low-pass filter for:

[0045] Where s is the Laplace operator, This is the cutoff angular frequency of the low-pass filter.

[0046] In this step, the center angular frequency of the bandpass filter The injection frequency must be strictly aligned. The quality factor Q can be set to 40 to obtain a sufficiently narrow bandwidth. During synchronous demodulation, orthogonal carriers that are strictly in phase and frequency with the injected signal need to be generated. and The signal needs to pass through a cutoff frequency much lower than The low-pass filter removes harmonics of second harmonic frequency and higher, ultimately yielding a low-frequency in-phase component containing fault modulation information. and orthogonal components ; The demagnetization fault modulates the inductor parameters, causing the amplitude and phase of the q-axis high-frequency current response to change with the rotor position. The synchronous demodulation process demodulates this modulated signal, decoupling the amplitude and phase information hidden in the single high-frequency signal into in-phase components. and orthogonal components This allows for the extraction of fault features from the frequency domain to the more easily processed amplitude-phase domain, providing a reliable data foundation for subsequent envelope analysis and spatial positioning.

[0047] In embodiment S5, envelope detection is performed on the in-phase and quadrature components to obtain a time-domain sequence of high-frequency response amplitudes, and the time-domain sequence is resampled into a uniformly distributed spatial amplitude sequence; including: For in-phase components and orthogonal components Envelope calculation is performed to obtain the time-domain sequence of the high-frequency response amplitude. ; Based on rotor electrical angle The time-domain sequence The sequence was resampled into a uniform spatial angle sequence using Lagrange interpolation. ; Specifically, the k-th Lagrange interpolation basis function is expressed as:

[0048] in, , The rotor electrical angles corresponding to the j-th and k-th original sampling points; In this step, the envelope is calculated. Next, it needs to be converted from a time series to a spatial series. Since the motor speed may fluctuate, the rotor electrical angle at the sampling time will vary. It is non-uniform; during implementation, N uniform grid points need to be defined within the target spatial angle range. Using Lagrange interpolation, based on non-uniform original data points ( , Calculate each uniform grid point amplitude on ; The essence of motor demagnetization fault is abnormal magnetic properties in spatial position. The key to its diagnosis lies in obtaining the distribution of fault characteristics with mechanical angle. This step transforms the basis of signal analysis from time to space by resampling with rotor angle as the link, eliminating the influence of speed fluctuation on the analysis results. This ensures that the subsequent spectrum analysis is directly aimed at the spatial angular frequency, so that the extracted double electrical frequency component can uniquely and directly correspond to the physical spatial period of the fault.

[0049] In this embodiment, S6, spectral analysis is performed on the spatial amplitude sequence to extract the amplitude of its second harmonic component; including: For spatial amplitude sequences Perform a discrete Fourier transform and calculate the complex coefficients of its second harmonic component. :

[0050] Where N is the number of spatially uniform sampling points, The rotor electrical angle corresponding to the kth spatial sampling point. The imaginary unit; Based on the complex coefficients To obtain the amplitude of the harmonic component at twice the electrical frequency. .

[0051] Specifically, for spatially uniform sequences When performing a discrete Fourier transform, the number of sampling points N should be sufficiently large to improve frequency resolution, and the complex coefficients should be calculated. The formula directly addresses the harmonic with a spatial angular frequency of 2, corresponding to two periodic changes in fault characteristics per revolution of the motor, which corresponds to the second harmonic of the electrical angular frequency. The amplitude of this harmonic is calculated. A key scalar index characterizing the overall intensity of demagnetization faults was obtained.

[0052] After complex signal processing, the spatial distribution information of demagnetization faults is highly condensed into the harmonic amplitude of a specific order (n=2) in the DFT spectrum. On the one hand, this suppresses other irrelevant harmonic noise in the spatial spectrum; on the other hand, since the focus is on a fixed spatial order, it is not sensitive to the absolute value of the motor speed and only depends on the periodicity of the spatial distribution. It serves as a stable and reliable macroscopic fault diagnosis indicator, suitable for assessing demagnetization status under different operating conditions.

[0053] In this embodiment, S7, based on the amplitude of the second harmonic component, demagnetization diagnostic indicators are calculated to determine whether a demagnetization fault has occurred, and the location and degree of demagnetization are estimated; including: Calculate the normalized diagnostic index DI. If DI < demagnetization amplitude threshold γ, then a demagnetization fault is determined to have occurred. Calculate the symmetry index. ,like If the symmetry threshold δ is exceeded, it is determined to be local demagnetization; According to the formula Estimate the demagnetization location. For operations involving complex arguments; and for calculating the degree of demagnetization based on the demagnetization estimation model. .

[0054] At that place, , The second harmonic amplitude value is used as a reference when the motor is in a healthy state.

[0055] Where N is the number of spatial sampling points, The twice response amplitude at the point is calculated by comparing the amplitude difference between two points 180° electrical degrees apart in space to determine the overall degree of asymmetry. If the magnetic properties of the motor are symmetrically distributed, the amplitudes at the corresponding points should be similar, and the difference should be close to zero. Alternatively, you can use:

[0056] in, The complex coefficients representing the first harmonic frequency component, under uniform demagnetization, show that the spatial response mainly exhibits a second harmonic periodic variation, while the first harmonic component is very weak. Approaching zero; during local demagnetization, a significant first-harmonic modulation component appears in the spatial response. The value will increase significantly; therefore, if If the value is greater than the threshold δ, it is determined to be local demagnetization. This indicator is directly based on the results of spectrum analysis and is not affected by the spatial location of the fault. It can reliably distinguish the type of demagnetization.

[0057] When performing a diagnostic test, it is necessary to obtain a reference amplitude of the motor's health condition in advance through experiments or simulations. The normalized index (DI) directly reflects the deviation of the current state from the healthy state, while the symmetry index... The calculation can be performed using the formula. When its value is greater than the threshold δ, it indicates that the fault is spatially asymmetrical, and is judged as local demagnetization; the demagnetization location is determined by... The estimated angle directly corresponds to the center electrical angle of the faulty magnetic pole, while the degree of demagnetization is determined by the calibration model. Estimate the coefficients. It needs to be obtained by fitting experimental data of different demagnetization degrees; This step ultimately completes the decision-making and evaluation process from characteristic signals to fault conclusions, constructing a multi-level, multi-dimensional diagnostic system: DI is used to detect the presence or absence of faults. Used to distinguish fault types Provides spatial positioning, This enables quantitative assessment; the comprehensive criteria here overcome the risk of misjudgment that may exist with a single indicator. For example, load changes may cause slight fluctuations in DI, but usually will not lead to... Significantly increased or A stable peak value is observed; therefore, this scheme not only achieves fault detection, but also enables a refined description of the fault's nature, location, and severity.

[0058] The online diagnosis method for demagnetization faults of permanent magnet synchronous motors based on high-frequency pulse injection in this embodiment is described in this embodiment. Through systematic signal injection, transformation, extraction and analysis steps, fault characteristics are effectively separated from complex motor operation signals and transformed into quantifiable diagnostic indicators. It makes full use of the existing hardware and software resources of the electric control system, and provides a practical implementation path for the detection, location and severity assessment of demagnetization faults in permanent magnet synchronous motors without changing the motor structure or adding additional sensors, thereby improving the condition monitoring capability and operation and maintenance efficiency of the motor system.

[0059] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0060] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for diagnosing demagnetization faults in permanent magnet synchronous motors based on high-frequency pulse injection, characterized in that, Includes the following steps: S1. Superimpose a high-frequency pulsed voltage signal onto the d-axis voltage command of the motor control system to generate a d-axis voltage command containing high-frequency excitation. S2. Collect the three-phase stator current of the permanent magnet synchronous motor and perform coordinate transformation to obtain the d-axis current and q-axis current; S3. The fundamental frequency component is filtered out from the q-axis current using a notch filter to extract the q-axis high-frequency current response signal. S4. Perform bandpass filtering and synchronous demodulation on the q-axis high-frequency current response signal to obtain in-phase and quadrature components. S5. Perform envelope detection on the in-phase component and the quadrature component to obtain a time-domain sequence of the high-frequency response amplitude, and resample the time-domain sequence into a uniformly distributed spatial amplitude sequence. S6. Perform spectral analysis on the spatial amplitude sequence to extract the amplitude of its second harmonic component. S7. Based on the amplitude of the second harmonic component of the electrical frequency, calculate the demagnetization diagnostic index, determine whether a demagnetization fault has occurred, and estimate the location and degree of demagnetization.

2. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection as described in claim 1, characterized in that, S1 includes a d-axis voltage command with high-frequency excitation. Represented as: in, This is the d-axis voltage command of the original control system. The amplitude of the injected high-frequency voltage, The angular frequency of the injected high-frequency voltage.

3. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection as described in claim 1, characterized in that, In S2, the coordinate transformation includes: The three-phase current is converted using the Clark transformation. , , Current transformed to a two-phase stationary coordinate system , ; Combining rotor electrical angle The Park transformation is used to convert the current in the two-phase stationary coordinate system. , Current transformed to synchronous rotating coordinate system , .

4. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection as described in claim 1, characterized in that, In S3, the transfer function of the notch filter Represented as: Where s is the Laplace operator, The fundamental angular frequency that needs to be filtered out. is the damping ratio.

5. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection as described in claim 1, characterized in that, S4 includes: Using the center angular frequency as The bandpass filter's response signal to the q-axis high-frequency current signal Filtering is performed to obtain the signal. ; Generate orthogonal carrier signals with the same frequency as the injected high-frequency voltage, including in-phase carriers. and orthogonal carriers ; Multiply the filtered signal by the quadrature carrier signal respectively: , ; The multiplied signal and The demodulated in-phase components are obtained by passing each component through a low-pass filter. and orthogonal components .

6. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection according to claim 5, characterized in that, The transfer function of the bandpass filter Represented as: Where s is the Laplace operator and K is the filter gain. ω is the center angular frequency of the bandpass filter, and Q is the quality factor.

7. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection according to claim 5, characterized in that, The transfer function of the low-pass filter for: Where s is the Laplace operator, This is the cutoff angular frequency of the low-pass filter.

8. The method for diagnosing demagnetization faults of a permanent magnet synchronous motor based on high-frequency pulse injection according to claim 1, characterized in that, S5 includes: For in-phase components and orthogonal components Envelope calculation is performed to obtain the time-domain sequence of the high-frequency response amplitude. ; Based on rotor electrical angle The time-domain sequence The sequence was resampled into a uniform spatial angle sequence using Lagrange interpolation. .

9. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection according to claim 1, characterized in that, S6 includes: For spatial amplitude sequences Perform a discrete Fourier transform and calculate the complex coefficients of its second harmonic component. : Where N is the number of spatially uniform sampling points, The rotor electrical angle corresponding to the kth spatial sampling point. The imaginary unit; Based on the complex coefficients To obtain the amplitude of the harmonic component at twice the electrical frequency. .

10. The method for diagnosing demagnetization faults in a permanent magnet synchronous motor based on high-frequency pulse injection according to claim 1, characterized in that, S7 includes: Calculate the normalized diagnostic index DI. If DI < demagnetization amplitude threshold γ, then a demagnetization fault is determined to have occurred. Calculate the symmetry index. ,like If the symmetry threshold δ is exceeded, it is determined to be local demagnetization; According to the formula Estimate the demagnetization location. For operations involving complex arguments; and for calculating the degree of demagnetization based on the demagnetization estimation model. .

Images