Fault detection method and system for permanent magnet synchronous motor

Abstract

The invention discloses a fault detection method and system for a permanent magnet synchronous motor, and relates to the technical field of permanent magnet synchronous motor fault detection.The method comprises the steps that stator three-phase current during operation of the permanent magnet synchronous motor is collected in real time, and zero-sequence current is calculated; carrying out multi-band frequency spectrum analysis based on the zero sequence current, respectively detecting a third harmonic amplitude and a sixth harmonic amplitude by adopting a parallel dual-channel FFT (Fast Fourier Transform) processor, and calculating a harmonic amplitude ratio; correcting the third harmonic amplitude and the sixth harmonic amplitude through a preset compensation coefficient matrix, and recalculating the corrected harmonic amplitude ratio; and performing fault classification on the corrected harmonic amplitude ratio based on a preset threshold value in combination with a time accumulation counter, and outputting a final fault code after continuous three times of consistent detection, thereby completing fault detection of the permanent magnet synchronous motor. The fault type can be rapidly positioned, the fault diagnosis precision is improved, it is ensured that an alarm is given after real faults are accumulated to the confirmable level, and the diagnosis reliability and stability are improved.

Description

Technical Field

[0001] This invention relates to the field of fault detection technology for permanent magnet synchronous motors, and in particular to a fault detection method and system for permanent magnet synchronous motors. Background Technology

[0002] In recent years, permanent magnet synchronous motors (PMSMs) have been widely used in new energy vehicles, industrial automation, and aerospace due to their advantages such as high power density, compact structure, and high efficiency. Online condition monitoring and fault diagnosis technologies for PMSMs have also developed rapidly. Early methods were mainly based on vibration signals and temperature monitoring, using accelerometers and thermocouples to obtain the motor's operating status. Subsequently, current signal analysis gradually became the mainstream research direction due to its ease of installation, low cost, and high sensitivity to faults. In particular, zero-sequence current detection technology can reveal inter-turn short circuits in the stator windings and rotor demagnetization faults through three-phase current imbalance components, while multi-band spectrum analysis can further separate the harmonic characteristics corresponding to different fault modes. In recent years, with the maturity of high-speed hardware platforms such as FPGAs and DSPs, parallel dual-channel FFT processors or narrowband DFT (such as the Goertzel algorithm) have been introduced into motor fault diagnosis, enabling real-time extraction of key harmonic components such as the third and sixth harmonics. Meanwhile, in order to overcome the influence of ambient temperature and mechanical load fluctuations on harmonic amplitude, researchers proposed a compensation strategy based on a temperature-load coupling model. The harmonic amplitude is dynamically corrected through a pre-calibrated coefficient matrix or an online adaptive algorithm, which improves the robustness and accuracy of diagnosis.

[0003] However, existing technologies still have several shortcomings. First, single threshold criteria are often too sensitive to transient disturbances and operating condition fluctuations, easily leading to false alarms or missed alarms in the early stages of a fault or during sudden load changes. Second, most studies on compensation for the effects of temperature or load rely solely on empirical formulas or simple linear corrections, failing to account for nonlinear coupling characteristics and resulting in limited compensation accuracy. Third, while spectrum analysis modules can extract multi-band harmonic amplitudes, the computational load of a complete FFT operation is too large under limited hardware resources; and narrowband algorithms often sacrifice resolution due to trade-offs between window length and real-time performance. Furthermore, many solutions lack a systematic fault confirmation mechanism, relying only on single or short-term window judgments and failing to utilize time-accumulated statistics, thus reducing the ability to detect progressively evolving faults. Summary of the Invention

[0004] In view of the problems existing in a fault detection method for permanent magnet synchronous motors, this invention is proposed. Therefore, the problem to be solved by this invention is to provide a fault detection method and system for permanent magnet synchronous motors.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a fault detection method for a permanent magnet synchronous motor, which includes real-time acquisition of the stator three-phase current during the operation of the permanent magnet synchronous motor and calculation of the zero-sequence current.

[0007] Multi-band spectrum analysis based on zero-sequence current is performed. A parallel dual-channel FFT processor is used to detect the amplitude of the third harmonic and the sixth harmonic respectively, and the harmonic amplitude ratio is calculated.

[0008] The amplitudes of the third and sixth harmonics are corrected using a predetermined compensation coefficient matrix, and the ratio of the corrected harmonic amplitudes is recalculated.

[0009] Based on a predetermined threshold and a time-accumulating counter, the corrected harmonic amplitude ratio is classified into faults, and the final fault code is output after three consecutive consistent checks, thus completing the fault detection of the permanent magnet synchronous motor.

[0010] In a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the calculation of the zero-sequence current includes:

[0011] The stator three-phase current is obtained at each sampling time, and the zero-sequence current is calculated in real time and expressed as:

[0012]

[0013] In the formula: i0[n] is the zero-sequence current at the nth sampling point, i a [n]、i b [n] and i c [n] represents the stator three-phase current at the nth sampling point.

[0014] As a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the multi-band spectrum analysis based on zero-sequence current includes:

[0015] Based on the obtained zero-sequence current, the fundamental frequency is calibrated, the motor mechanical speed is obtained, and the fundamental electrical frequency of the motor stator is calculated, expressed as:

[0016]

[0017] In the formula: p is the number of pole pairs of the motor, n r f1 is the mechanical speed of the motor, and f1 is the fundamental electrical frequency of the motor stator.

[0018] Parallel dual-channel FFT processing is performed to detect the amplitudes of the third and sixth harmonics, respectively. The target frequency components are calculated using the Goertzel algorithm for both channels, as follows:

[0019]

[0020] In the formula: X k Let f be the spectral value of channel k, N be the sliding window length, i0[nm] be the zero-sequence current of the nm-th sampling point, m be the index number, j be the imaginary unit, and f be the frequency. hk For the target harmonic frequency, f s Let w(m) be the sampling frequency, and w(m) be the window function coefficients.

[0021] The harmonic amplitude is obtained and expressed as:

[0022] I h3 =|X ch1 |,I h6 =|X ch2 |

[0023] In the formula: I h3 I is the amplitude of the third harmonic. h6 X is the amplitude of the sixth harmonic. ch1 X is the spectral value of the third harmonic. ch2 This is the spectral value of the sixth harmonic.

[0024] In a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the expression for the harmonic amplitude ratio is:

[0025]

[0026] In the formula: K fau This represents the harmonic amplitude ratio.

[0027] In a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the step of correcting the amplitudes of the third and sixth harmonics using a predetermined compensation coefficient matrix includes:

[0028] The fundamental electrical frequency component of the motor stator is extracted synchronously by performing Goertzel operation on the zero-sequence current, and is expressed as:

[0029]

[0030] In the formula: X represents the load current amplitude of the motor under current operating conditions. base This represents the spectral value of the fundamental electrical frequency of the motor stator;

[0031] In the laboratory, calibration was performed under different temperatures and load conditions to obtain a set of two-dimensional coefficient matrices, i.e., the predetermined compensation coefficient matrix. A correspondence table between the load current amplitude and the predetermined compensation coefficient matrix was constructed. Based on the real-time measured load current amplitude, the compensation coefficients used to correct the third and sixth harmonic amplitudes were obtained. The original third and sixth harmonic amplitudes were then corrected to obtain the corrected harmonic amplitudes, expressed as follows:

[0032] I h3 ′=I h3 ×φ h3

[0033] I h6 ′=I h6 ×φ h6

[0034] In the formula: I h3 ′ represents the corrected third harmonic amplitude, I h6 ′ represents the corrected sixth harmonic amplitude, φ h3 φ is the compensation coefficient for the third harmonic amplitude. h6 The compensation coefficient for the sixth harmonic amplitude;

[0035] The new harmonic amplitude ratio is calculated using the corrected harmonic amplitude values, which is the corrected harmonic amplitude ratio.

[0036] In a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the fault classification of the corrected harmonic amplitude ratio includes:

[0037] The inter-turn short circuit threshold and demagnetization fault threshold are predetermined, and the number of sampling points corresponding to one electrical cycle is obtained based on the current fundamental electrical frequency of the motor stator.

[0038] The corrected harmonic amplitude ratio is calculated once for each sampling point. When the corrected harmonic amplitude ratio is less than the inter-turn short circuit threshold, the short circuit counter is incremented by one. If the value is always true within the number of sampling points in 5 consecutive electrical cycles, the inter-turn short circuit is considered to be initially triggered. If the value is not met at any sampling point, the short circuit counter is cleared and the accumulation starts again.

[0039] When the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold, the demagnetization fault is considered to be initially triggered, and the sixth harmonic amplitude differential rate is calculated simultaneously.

[0040] If the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold and the sixth harmonic amplitude differential rate is less than the predetermined rate, then increment the demagnetization counter by one; otherwise, clear it to zero and start accumulating again.

[0041] When any counter reaches three consecutive initial triggers, the fault is considered confirmed and a fault code is output: if the short circuit counter reaches three triggers first, an inter-turn short circuit fault code is output; if the demagnetizing counter reaches three triggers first, a demagnetizing fault code is output. After the fault code is output, both the short circuit counter and the demagnetizing counter are reset, and the next round of online monitoring begins.

[0042] In a preferred embodiment of the fault detection method for permanent magnet synchronous motors described in this invention, the expression for the sixth harmonic amplitude differential rate is:

[0043]

[0044] In the formula: R h6 I is the amplitude difference rate of the sixth harmonic. h6 ′(t) is the corrected sixth harmonic amplitude at time t, I h6 ′(t-Δt) is the corrected sixth harmonic amplitude at time t-Δt, and Δt is the predetermined detection time.

[0045] Secondly, the present invention provides a fault detection system for a permanent magnet synchronous motor, comprising:

[0046] The acquisition module is used to collect the stator three-phase current in real time during the operation of the permanent magnet synchronous motor and calculate the zero-sequence current.

[0047] The analysis module is used for multi-band spectrum analysis based on zero-sequence current. It uses a parallel dual-channel FFT processor to detect the amplitude of the third harmonic and the sixth harmonic respectively, and calculates the harmonic amplitude ratio.

[0048] The correction module is used to correct the amplitudes of the third and sixth harmonics using a predetermined compensation coefficient matrix, and to recalculate the corrected harmonic amplitude ratio.

[0049] The detection module is used to classify the faults based on the corrected harmonic amplitude ratio according to a predetermined threshold and a time cumulative counter, and outputs the final fault code after three consecutive consistent tests, thus completing the fault detection of the permanent magnet synchronous motor.

[0050] Thirdly, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of a fault detection method for a permanent magnet synchronous motor.

[0051] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements the steps of a fault detection method for a permanent magnet synchronous motor.

[0052] The beneficial effects of this invention are as follows: This method can improve the early response of fault detection, realize the real-time separation of multi-mode fault features; distinguish the different spectral characteristics of inter-turn short circuits and demagnetization faults, quickly locate the fault type, improve the accuracy of fault diagnosis, realize the coupling compensation for the influence of ambient temperature fluctuations and load changes, ensure the stability and consistency of extracted features, enhance the robustness of fault indicators and reduce false alarms caused by operating condition interference. It achieves multi-level confirmation of fault status, which can suppress misjudgments of transient interference and short-term fluctuations, while ensuring that the actual fault accumulates to a confirmable level before alarm, thus improving the reliability and stability of diagnosis. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a flowchart of a fault detection method for permanent magnet synchronous motors. Detailed Implementation

[0055] To make the above-mentioned objects, features, and advantages of the present invention more readily understood, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0056] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0057] Secondly, the term "one embodiment" or "example" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. An embodiment appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment that selectively excludes other embodiments.

[0058] Reference Figure 1 This is the first embodiment of the present invention, which provides a fault detection method for a permanent magnet synchronous motor, including:

[0059] S1: Real-time acquisition of the stator three-phase current during operation of the permanent magnet synchronous motor, and calculation of the zero-sequence current;

[0060] Specifically, each of the three phases is equipped with a Hall effect or resistive shunt current sensor to measure the instantaneous current of the stator winding. A low-pass filter is added to each current signal, with a cutoff frequency approximately half the sampling frequency, to prevent aliasing.

[0061] The stator three-phase current is obtained at each sampling moment, and the zero-sequence current is calculated in real time within the previous cycle of the FPGA or DSP, and expressed as:

[0062]

[0063] In the formula: i0[n] is the zero-sequence current at the nth sampling point, i a [n]、i b [n] and i c [n] represents the stator three-phase current at the nth sampling point.

[0064] S2: Multi-band spectrum analysis based on zero-sequence current is performed. A parallel dual-channel FFT processor is used to detect the amplitude of the third harmonic and the sixth harmonic respectively, and the harmonic amplitude ratio is calculated.

[0065] Specifically, the zero-sequence current obtained from the input is used for fundamental frequency calibration. The motor's mechanical speed is acquired in real time via a rotary encoder or tachogenerator, and the fundamental electrical frequency of the motor stator is calculated, expressed as:

[0066]

[0067] In the formula: p is the number of pole pairs of the motor, n r f1 is the mechanical speed of the motor and f2 is the fundamental electrical frequency of the motor stator.

[0068] Parallel dual-channel FFT processing is performed, with two parallel processing channels, one for the third harmonic and the other for the sixth harmonic: Channel 1: Target frequency f h3 =3f1; Channel 2: Target frequency f h6 =6f1.

[0069] The target frequency components are directly calculated using the Goertzel algorithm for both channels, as follows:

[0070]

[0071] In the formula: X k Let f be the spectral value of channel k, N be the sliding window length, i0[nm] be the zero-sequence current of the nm-th sampling point, m be the index number, j be the imaginary unit, and f be the frequency. hk For the target harmonic frequency, f sLet w(m) be the sampling frequency, and w(m) be the window function coefficients.

[0072] The amplitude of the calculated result is the harmonic component, expressed as:

[0073] I h3 =|X ch1 |,I h6 =|X ch2 |

[0074] In the formula: I h3 I is the amplitude of the third harmonic. h6 X is the amplitude of the sixth harmonic. ch1 X is the spectral value of the third harmonic. ch2 This is the spectral value of the sixth harmonic.

[0075] The harmonic amplitude ratio is calculated and expressed as:

[0076]

[0077] In the formula: K fau This represents the harmonic amplitude ratio.

[0078] Each time a channel completes a calculation, the harmonic amplitude and harmonic amplitude ratio can be updated once.

[0079] S3: Correct the amplitudes of the third and sixth harmonics using a predetermined compensation coefficient matrix, and recalculate the corrected harmonic amplitude ratio.

[0080] Specifically, the fundamental electrical frequency component of the motor stator is extracted synchronously by performing Goertzel operation on the zero-sequence current signal, and its amplitude is denoted as:

[0081]

[0082] In the formula: X represents the load current amplitude of the motor under current operating conditions. base This represents the spectral value of the fundamental electrical frequency of the motor stator.

[0083] In the laboratory, calibration was performed under different temperatures and load conditions to obtain a set of two-dimensional coefficient matrices, i.e., the predetermined compensation coefficient matrix. A table corresponding to the load current amplitude and the predetermined compensation coefficient matrix was constructed. The real-time measured load current amplitude was input into the table for lookup to obtain dimensionless compensation coefficients used to correct the amplitudes of the third and sixth harmonics, respectively. The original harmonic amplitudes were corrected using the compensation coefficient matrix to obtain the corrected characteristic harmonic amplitudes, expressed as:

[0084] I h3 ′=I h3 ×φ h3

[0085] I h6 ′=I h6 ×φ h6

[0086] In the formula: I h3 ′ represents the corrected third harmonic amplitude, I h6 ′ represents the corrected sixth harmonic amplitude, φ h3 φ is the compensation coefficient for the third harmonic amplitude. h6 The compensation coefficient for the sixth harmonic amplitude;

[0087] The new harmonic amplitude ratio is calculated using the corrected harmonic amplitude values, which is the corrected harmonic amplitude ratio.

[0088] S4: Based on a predetermined threshold and a time-accumulating counter, the corrected harmonic amplitude ratio is classified into faults, and the final fault code is output after three consecutive consistent checks, thus completing the fault detection of the permanent magnet synchronous motor.

[0089] Specifically, predetermined inter-turn short circuit thresholds and demagnetization fault thresholds are defined. When the corrected harmonic amplitude ratio drops below the inter-turn short circuit threshold, the motor is considered to have an inter-turn short circuit tendency; when the corrected harmonic amplitude ratio rises above the demagnetization fault threshold, the motor is considered to have a demagnetization fault tendency.

[0090] Calculate the number of sampling points N corresponding to one electrical cycle based on the current fundamental electrical frequency of the motor stator. cycle , represented as:

[0091]

[0092] The corrected harmonic amplitude ratio is calculated once for each sampling point. When the corrected harmonic amplitude ratio is less than the inter-turn short circuit threshold, the short circuit counter is incremented by one. If this condition is always met within the number of sampling points for 5 consecutive electrical cycles, the inter-turn short circuit is considered to be initially triggered. If the condition is not met at any sampling point within the time window, the short circuit counter is cleared and the accumulation starts again.

[0093] When the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold, the demagnetization fault is considered to have been initially triggered. Simultaneously, the sixth harmonic amplitude differential rate is calculated, expressed as:

[0094]

[0095] In the formula: R h6 I is the amplitude difference rate of the sixth harmonic. h6 ′(t) is the corrected sixth harmonic amplitude at time t, I h6 ′(t-Δt) is the corrected sixth harmonic amplitude at time t-Δt, and Δt is the predetermined detection time;

[0096] If the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold and the sixth harmonic amplitude differential rate is less than the predetermined rate, then increment the demagnetization counter by one; otherwise, clear it to zero and start accumulating again.

[0097] The fault confirmation timer is activated when any fault counter (short circuit or demagnetization) reaches three consecutive initial triggers, indicating a fault has been confirmed and a fault code is output. If the short circuit counter reaches three triggers first, an inter-turn short circuit fault code is output; if the demagnetization counter reaches three triggers first, a demagnetization fault code is output. After the fault code is output, both the short circuit counter and the demagnetization counter are reset, and the next round of online monitoring begins.

[0098] Furthermore, this embodiment also provides a fault detection system for a permanent magnet synchronous motor, including:

[0099] The acquisition module is used to collect the stator three-phase current in real time during the operation of the permanent magnet synchronous motor and calculate the zero-sequence current.

[0100] The analysis module is used for multi-band spectrum analysis based on zero-sequence current. It uses a parallel dual-channel FFT processor to detect the amplitude of the third harmonic and the sixth harmonic respectively, and calculates the harmonic amplitude ratio.

[0101] The correction module is used to correct the amplitudes of the third and sixth harmonics using a predetermined compensation coefficient matrix, and to recalculate the corrected harmonic amplitude ratio.

[0102] The detection module is used to classify the faults based on the corrected harmonic amplitude ratio according to a predetermined threshold and a time cumulative counter, and outputs the final fault code after three consecutive consistent tests, thus completing the fault detection of the permanent magnet synchronous motor.

[0103] This embodiment also provides a computer device applicable to a fault detection method for a permanent magnet synchronous motor, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement all or part of the steps of the method described in the above embodiments of the present invention.

[0104] This embodiment also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, it performs the method in any optional implementation of the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0105] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0106] In summary, this method improves early response to fault detection, achieves real-time separation of multi-mode fault features, distinguishes between the different spectral characteristics of inter-turn short circuits and demagnetization faults, rapidly locates fault types, improves fault diagnosis accuracy, and achieves coupled compensation for the effects of ambient temperature fluctuations and load abrupt changes, ensuring the stability and consistency of extracted features, enhancing the robustness of fault indicators, and reducing false alarms caused by operating condition interference. It enables multi-level confirmation of fault states, suppressing misjudgments due to transient interference and short-term fluctuations, while ensuring that alarms are only triggered after the actual fault has accumulated to a confirmable level, thus improving diagnostic reliability and stability.

[0107] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fault detection method for permanent magnet synchronous motors, characterized in that: include, Real-time acquisition of the stator three-phase current during operation of the permanent magnet synchronous motor, and calculation of the zero-sequence current; Multi-band spectrum analysis based on zero-sequence current is performed. A parallel dual-channel FFT processor is used to detect the amplitude of the third harmonic and the sixth harmonic respectively, and the harmonic amplitude ratio is calculated. The amplitudes of the third and sixth harmonics are corrected using a predetermined compensation coefficient matrix, and the ratio of the corrected harmonic amplitudes is recalculated. Based on a predetermined threshold and a time-accumulating counter, the corrected harmonic amplitude ratio is classified into faults, and the final fault code is output after three consecutive consistent checks, thus completing the fault detection of the permanent magnet synchronous motor.

2. The fault detection method for a permanent magnet synchronous motor as described in claim 1, characterized in that: The calculation of the zero-sequence current includes: obtaining the stator three-phase current at each sampling time, calculating the zero-sequence current in real time, and expressing it as: In the formula: i0[n] is the zero-sequence current at the m-th sampling point, i a [n]、i b [n] and i c [n] represents the stator three-phase current at the nth sampling point.

3. The fault detection method for a permanent magnet synchronous motor as described in claim 2, characterized in that: The multi-band spectrum analysis based on zero-sequence current includes: Based on the obtained zero-sequence current, the fundamental frequency is calibrated, the motor mechanical speed is obtained, and the fundamental electrical frequency of the motor stator is calculated, expressed as: In the formula: p is the number of pole pairs of the motor, n r f1 is the mechanical speed of the motor, and f1 is the fundamental electrical frequency of the motor stator. Parallel dual-channel FFT processing is performed to detect the amplitudes of the third and sixth harmonics, respectively. The target frequency components are calculated using the Goertzel algorithm for both channels, as follows: In the formula: X k Let f be the spectral value of channel k, N be the sliding window length, i0[nm] be the zero-sequence current of the nm-th sampling point, m be the index number, j be the imaginary unit, and f be the frequency. hk For the target harmonic frequency, f s Let w(m) be the sampling frequency, and w(m) be the window function coefficients. The harmonic amplitude is obtained and expressed as: I h3 =|X ch1 |,I h6 =|X ch2 | In the formula: I h3 I is the amplitude of the third harmonic. h6 X is the amplitude of the sixth harmonic. ch1 X is the spectral value of the third harmonic. ch2 This is the spectral value of the sixth harmonic.

4. The fault detection method for a permanent magnet synchronous motor as described in claim 3, characterized in that: The expression for the harmonic amplitude ratio is: Where: K fau This represents the harmonic amplitude ratio.

5. The fault detection method for a permanent magnet synchronous motor as described in claim 4, characterized in that: The correction of the third and sixth harmonic amplitudes using a predetermined compensation coefficient matrix includes: The fundamental electrical frequency component of the motor stator is extracted synchronously by performing Goertzel operation on the zero-sequence current, and is expressed as: In the formula: X represents the load current amplitude of the motor under current operating conditions. base This represents the spectral value of the fundamental electrical frequency of the motor stator; In the laboratory, calibration was performed under different temperatures and load conditions to obtain a set of two-dimensional coefficient matrices, i.e., the predetermined compensation coefficient matrix. A correspondence table between the load current amplitude and the predetermined compensation coefficient matrix was constructed. Based on the real-time measured load current amplitude, the compensation coefficients used to correct the third and sixth harmonic amplitudes were obtained. The original third and sixth harmonic amplitudes were then corrected to obtain the corrected harmonic amplitudes, expressed as follows: I h3 ′=I h3 ×φ h3 I h6 ′=I h6 ×φ h6 In the formula: I h3 ′ represents the corrected third harmonic amplitude, I h6 ′ represents the corrected sixth harmonic amplitude, φ h3 φ is the compensation coefficient for the third harmonic amplitude. h6 The compensation coefficient for the sixth harmonic amplitude; The new harmonic amplitude ratio is calculated using the corrected harmonic amplitude values, which is the corrected harmonic amplitude ratio.

6. The fault detection method for a permanent magnet synchronous motor as described in claim 5, characterized in that: The fault classification of the corrected harmonic amplitude ratio includes: The inter-turn short circuit threshold and demagnetization fault threshold are predetermined, and the number of sampling points corresponding to one electrical cycle is obtained based on the current fundamental electrical frequency of the motor stator. The corrected harmonic amplitude ratio is calculated once for each sampling point. When the corrected harmonic amplitude ratio is less than the inter-turn short circuit threshold, the short circuit counter is incremented by one. If the value is always true within the number of sampling points in 5 consecutive electrical cycles, the inter-turn short circuit is considered to be initially triggered. If the value is not met at any sampling point, the short circuit counter is cleared and the accumulation starts again. When the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold, the demagnetization fault is considered to be initially triggered, and the sixth harmonic amplitude differential rate is calculated simultaneously. If the corrected harmonic amplitude ratio is greater than the demagnetization fault threshold and the sixth harmonic amplitude differential rate is less than the predetermined rate, the demagnetization counter is incremented by one; otherwise, it is reset to zero and the accumulation starts again. When any counter reaches three consecutive initial triggers, the fault is considered confirmed and a fault code is output: if the short circuit counter reaches three triggers first, an inter-turn short circuit fault code is output; if the demagnetizing counter reaches three triggers first, a demagnetizing fault code is output. After the fault code is output, both the short circuit counter and the demagnetizing counter are reset, and the next round of online monitoring begins.

7. A fault detection method for a permanent magnet synchronous motor as described in claim 6, characterized in that: The expression for the sixth harmonic amplitude difference rate is: In the formula: R h6 I is the amplitude difference rate of the sixth harmonic. h6 ′(t) is the corrected sixth harmonic amplitude at time t, I h6 ′(t-Δt) is the corrected sixth harmonic amplitude at time t-Δt, and Δt is the predetermined detection time.

8. A fault detection system for a permanent magnet synchronous motor, based on the fault detection method for a permanent magnet synchronous motor according to any one of claims 1 to 7, characterized in that: include, The acquisition module is used to collect the stator three-phase current in real time during the operation of the permanent magnet synchronous motor and calculate the zero-sequence current. The analysis module is used for multi-band spectrum analysis based on zero-sequence current. It uses a parallel dual-channel FFT processor to detect the amplitude of the third harmonic and the sixth harmonic respectively, and calculates the harmonic amplitude ratio. The correction module is used to correct the amplitudes of the third and sixth harmonics using a predetermined compensation coefficient matrix, and to recalculate the corrected harmonic amplitude ratio. The detection module is used to classify the faults based on the corrected harmonic amplitude ratio according to a predetermined threshold and a time cumulative counter, and outputs the final fault code after three consecutive consistent tests, thus completing the fault detection of the permanent magnet synchronous motor.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the fault detection method for a permanent magnet synchronous motor as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the fault detection method for a permanent magnet synchronous motor as described in any one of claims 1 to 7.

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