Fault diagnosis method for double three-phase permanent magnet synchronous motor based on cross pole type detection coil

Abstract

The application provides a kind of double three-phase permanent magnet synchronous motor fault diagnosis method based on cross pole type detection coil, comprising the following steps: S1, detection coil is placed in the position close to slot of the stator tooth portion of double three-phase permanent magnet synchronous motor;S2, when motor is running, the port voltage of detection coil is collected and whether the motor is judged to occur fault according to the port voltage of detection coil;If port voltage is 0V, then motor is healthy;Otherwise, motor fails;S3, the frequency spectrum analysis of the port voltage of fault motor detection coil is carried out using fast fourier transform to obtain fault characteristic harmonic component, according to the amplitude variation of fault characteristic harmonic component, fault diagnosis and fault category are judged.The application can effectively realize the identification of double three-phase permanent magnet synchronous motor turn-to-turn short circuit fault, loss of excitation fault and eccentric fault diagnosis and identification, easy to realize, signal processing is simple, and the accuracy is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor fault diagnosis, and particularly relates to a double three-phase permanent magnet synchronous motor fault diagnosis method based on a cross-pole type detection coil. BACKGROUND

[0002] In recent years, with the development of industry, the reliability of equipment operation is increasingly important, and the operation reliability of the motor as a power system is also increasingly valued. Compared with the traditional three-phase permanent magnet synchronous motor, the multi-phase permanent magnet motor has the advantages of small torque ripple, strong fault tolerance, high reliability, and can realize low-voltage high-power, and is widely concerned in the fields of electric vehicles and wind power generation. Among them, the double three-phase permanent magnet synchronous motor has the advantages of multi-phase motor, and contains two sets of three-phase windings with a mutual difference of 30° electrical angle, can be powered by two independent three-phase inverters, and has good application prospect. During the operation of the permanent magnet synchronous motor, various different faults may occur. However, the current fault diagnosis method is difficult to realize the fault classification of the double three-phase permanent magnet synchronous motor. In order to improve the reliability of motor operation, motor fault diagnosis is an indispensable part. SUMMARY

[0003] Based on the technical problems in the background art, the present application provides a double three-phase permanent magnet synchronous motor fault diagnosis method based on a cross-pole type detection coil.

[0004] The double three-phase permanent magnet synchronous motor fault diagnosis method based on the cross-pole type detection coil provided by the present application comprises the following steps:

[0005] S1, placing the detection coil at the position close to the slot of the stator tooth of the double three-phase permanent magnet synchronous motor, and collecting the port voltage of the detection coil during the operation of the motor;

[0006] S2, judging whether the motor has a fault according to the port voltage of the detection coil; if the port voltage is 0V, the motor is healthy; otherwise, the motor has a fault;

[0007] S3, performing frequency spectrum analysis on the port voltage of the fault motor detection coil by using fast Fourier transform to obtain a fault characteristic harmonic component, and performing fault diagnosis and judging the fault category according to the amplitude change of the fault characteristic harmonic component.

[0008] Preferably, in step S1, the number of detection coils is two, and the span of the detection coils is one pole pitch.

[0009] Preferably, the specific steps of step S2 are as follows:

[0010] S21, when the motor is normally operated, the motor magnetic field is symmetrical, the air gap magnetic field of the motor is Fourier decomposed, and the magnetic field distribution of the motor air gap can be expressed as:

[0011]

[0012] wherein, α is the electrical angle, i is the harmonic number;

[0013] S22, when the motor is running, the magnetic flux of the detection coil wound on the tooth part changes with time as:

[0014]

[0015] wherein, l is the axial length of the detection coil, R is the axial distance of the detection coil, w is the electrical angular frequency, θ is the electrical angle spanned by the two elements of the detection coil, θ = π; r

[0016] S23, the port voltage u1 of the first detection coil is:

[0017]

[0018] the port voltage u2 of the second detection coil is:

[0019]

[0020] wherein, η is the electrical angle difference between the two detection coils, η = π;

[0021] The two detection coils are connected in series in phase, and the port voltages of the detection coils are added, and then the final port voltage u(t) of the detection coil is:

[0022]

[0023] S24, according to formula (5), when the motor is running normally, the air gap magnetic field of the motor is symmetrical, and the integer harmonic in the port voltage of the detection coil is cancelled, only the fractional harmonic magnetic field will affect the port voltage; The double three-phase permanent magnet synchronous motor with full-pitch winding does not contain fractional harmonic in the air gap magnetic field when running normally, and the port voltage output of the detection coil is 0V when the motor is running normally, at this time the motor is healthy; Otherwise, the motor is faulty.

[0024] Preferably, the step of judging the fault category in step S3 is as follows:

[0025] S31, if there is an obvious odd harmonic in the port voltage of the detection coil, the fault of the motor is static eccentricity fault or turn-to-turn short circuit fault;

[0026] S32, if there is an obvious fractional harmonic in the port voltage of the detection coil and no odd harmonic, the fault of the motor is permanent magnet fault or dynamic eccentricity fault.

[0027] ​Preferably, the step S31 further comprises the following steps:

[0028] S311, the 3rd and 15th harmonics in the port voltage are analyzed, if the 3rd harmonic amplitude in the port voltage is much larger than the 15th harmonic amplitude, the motor occurs turn-to-turn short circuit fault, otherwise static eccentricity fault.

[0029] Preferably, the step S32 further comprises the following steps:

[0030] S321, the 1 / 2 and 3 / 2 harmonics in the port voltage are analyzed, when the 1 / 2 harmonic amplitude of the port voltage is less than the 3 / 2 harmonic amplitude, the motor occurs dynamic eccentricity fault, otherwise permanent magnet fault; when the 5 / 2 harmonic appears in the port voltage, the motor occurs permanent magnet damage fault, otherwise permanent magnet demagnetization fault.

[0031] The double three-phase permanent magnet synchronous motor fault diagnosis method based on the cross pole type detection coil provided by the application uses the detection coil as an invasive detection method, the method is easy to implement, the detection signal is easy to process, and the detection precision is high; according to the port voltage signal of the detection coil, the double three-phase permanent magnet synchronous motor fault detection and identification can be effectively realized, the turn-to-turn short circuit fault, the demagnetization fault and the eccentricity fault of the double three-phase permanent magnet synchronous motor can be effectively identified, the method is easy to implement, the signal processing is simple, and the accuracy is high. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The double three-phase permanent magnet synchronous motor fault diagnosis method based on the cross pole type detection coil provided by the application is a block diagram;

[0033] Figure 2 The specific placement position structure diagram of the detection coil in the 24-slot 4-pole double three-phase permanent magnet synchronous motor in the application is shown in the figure;

[0034] Figure 3 The placement method diagram of the cross pole type detection coil in the application is shown in the figure. DETAILED DESCRIPTION

[0035] REFERENCE Figure 1 The application provides a double three-phase permanent magnet synchronous motor fault diagnosis method based on a cross pole type detection coil, which comprises the following steps:

[0036] S1, two detection coils are placed at the tooth part of the double three-phase permanent magnet synchronous motor close to the slot opening, the detection coil placement method is shown in the figures of Figure 2 、 Figure 3 The span of the detection coil is one pole pitch. When the motor is running, the port voltage of the detection coil is collected.

[0037] S2, judging whether the motor is in failure according to the port voltage of the detection coil; if the port voltage is 0V, the motor is healthy; otherwise, the motor is in failure. The specific steps are as follows:

[0038] S21, when the motor is in normal operation, the motor magnetic field is symmetrical, the air gap magnetic field of the motor is Fourier decomposed, and the magnetic field distribution of the motor air gap can be expressed as:

[0039]

[0040] In the formula, α is an electric angle, and i is a harmonic number;

[0041] S22, when the motor is in operation, the magnetic flux of the detection coil wound on the tooth part changes with time as:

[0042]

[0043] In the formula, l is the axial length of the detection coil, R is the axial distance of the detection coil, w r is the electric angle frequency, and θ is the electric angle spanned by the two elements of the detection coil, θ=π;

[0044] S23, the port voltage u1 of the first detection coil is:

[0045]

[0046] The port voltage u2 of the second detection coil is:

[0047]

[0048] In the formula, η is the electric angle difference between the two detection coils, η=π;

[0049] The two detection coils are connected in series in phase, the detection coil port voltages are added, and then the final port voltage u(t) of the detection coil is:

[0050]

[0051] S24, according to formula (5), when the motor is in normal operation, the motor air gap magnetic field is symmetrical, the integer harmonic in the detection coil port voltage is offset, and only the fractional harmonic magnetic field can affect the port voltage; the fractional harmonic is not included in the air gap magnetic field of the full-pitch winding double three-phase permanent magnet synchronous motor in normal operation, so when the motor is in normal operation, the detection coil port voltage output is 0V, and the motor is healthy; otherwise, the motor is in failure, and the waveforms of the detection coil port voltage are different under different failure conditions.

[0052] S3, frequency spectrum analysis is performed on the fault motor detection coil port voltage by using fast Fourier transform to obtain a fault characteristic harmonic component, and according to the amplitude variation of the fault characteristic harmonic component, fault diagnosis is performed and the fault category is judged. The steps of judging the fault category are as follows:

[0053] S31, if an obvious odd harmonic appears in the detection coil port voltage, the motor fault is a static eccentric fault or a turn-to-turn short circuit fault.

[0054] Further analysis is performed on the 3rd and 15th harmonics in the port voltage, if the amplitude of the 3rd harmonic in the port voltage is much larger than the amplitude of the 15th harmonic, the motor is in a turn-to-turn short circuit fault, otherwise it is in a static eccentric fault.

[0055] S32, if an obvious fractional harmonic appears in the detection coil port voltage and does not contain an odd harmonic, the motor fault is a permanent magnet fault or a dynamic eccentric fault.

[0056] At this time, the 1 / 2 and 3 / 2 harmonics in the port voltage are analyzed: when the amplitude of the 1 / 2 harmonic in the port voltage is less than the amplitude of the 3 / 2 harmonic, the motor is in a dynamic eccentric fault, otherwise it is in a permanent magnet fault. At the same time, the type of the permanent magnet fault can be further judged according to the content of the 5 / 2 harmonic, when the 5 / 2 harmonic appears in the port voltage, the motor is in a permanent magnet damage fault, otherwise it is in a permanent magnet demagnetization fault.

[0057] By using the method of the application, turn-to-turn short circuit fault, demagnetization fault and eccentric fault of a double three-phase permanent magnet synchronous motor can be effectively identified, the method is easy to implement, signal processing is simple, and the accuracy is high.

[0058] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the application within the technical range disclosed by the application, which should be covered in the protection scope of the application.

Claims

1. A fault diagnosis method for a dual three-phase permanent magnet synchronous motor based on a cross pole type search coil, characterized by, Includes the following steps: S1. Place the detection coil near the slot opening on the stator teeth of the dual three-phase permanent magnet synchronous motor, and collect the port voltage of the detection coil while the motor is running. S2. Determine if the motor is faulty based on the port voltage of the detection coil; if the port voltage is 0V, the motor is healthy; otherwise, the motor is faulty. S3. Use Fast Fourier Transform to perform spectrum analysis on the voltage at the port of the fault motor detection coil to obtain the fault characteristic harmonic components. Based on the amplitude variation of the fault characteristic harmonic components, perform fault diagnosis and determine the fault type. In step S1, the number of detection coils is two, and the span of the detection coils is one pole pitch; The steps for determining the fault category in step S3 are as follows: S31. If obvious odd-order harmonics appear in the voltage at the probe coil port, the fault in the motor is a static eccentricity fault or an inter-turn short circuit fault. S32. If obvious fractional harmonics appear in the voltage of the detection coil port but do not contain odd harmonics, the fault of the motor is a permanent magnet fault or a dynamic eccentricity fault. Step S31 also includes the following steps: S311. Analyze the 3rd and 15th harmonics in the port voltage. If the amplitude of the 3rd harmonic in the port voltage is much greater than that of the 15th harmonic, then the motor is experiencing an inter-turn short circuit fault; otherwise, it is experiencing a static eccentricity fault. Step S32 also includes the following steps: S321. Analyze the 1 / 2 and 3 / 2 harmonics in the port voltage; when the amplitude of the 1 / 2 harmonic of the port voltage is less than the amplitude of the 3 / 2 harmonic, the motor is experiencing a dynamic eccentricity fault, otherwise it is a permanent magnet fault; when the 5 / 2 harmonic appears in the port voltage, the motor is experiencing a permanent magnet damage fault, otherwise it is a permanent magnet demagnetization fault.

2. The fault diagnosis method for a dual three-phase permanent magnet synchronous motor based on a transpole detection coil according to claim 1, characterized in that, The specific steps for the judgment in step S2 are as follows: S21. When the motor is running normally, the motor's magnetic field is symmetrical. Fourier decomposition of the motor's air gap magnetic field yields the following expression: In the formula, α is the electrical angle and i is the harmonic order; S22. When the motor is running, the magnetic flux through the detection coil wound around the teeth changes with time as follows: where l is the axial length of the search coil, R is the axial distance of the search coil, w r is the electrical angular frequency, and θ is the electrical angle spanned by the two elements of the search coil, θ = π. S23, the port voltage u1 of the first detection coil is: The port voltage u2 of the second detection coil is: In the formula, η is the electrical angle difference between the two detection coils, η=π; When the two detection coils are connected in series in phase, and the voltages at the ports of the detection coils are added together, the final port voltage u(t) of the detection coils is: S24. As can be seen from equation (5), when the motor is running normally, the air gap magnetic field of the motor is symmetrical, and the integer harmonics in the voltage of the probe coil port are all canceled out. Only the fractional harmonic magnetic field will affect the port voltage. When the double three-phase permanent magnet synchronous motor with full pitch winding is running normally, the air gap magnetic field will not contain fractional harmonics. When the motor is running normally, the voltage output of the probe coil port is 0V, and the motor is healthy. Otherwise, the motor will malfunction.

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