Five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method

Abstract

The invention discloses a five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method, and relates to the technical field of multi-phase permanent magnet synchronous motors. Performing symmetric transformation on the phase current according to a symmetric component method to obtain a first positive-sequence component, a first negative-sequence component, a second positive-sequence component and a second negative-sequence component of the current, and performing Fourier transformation on the four current symmetric components to obtain an amplitude and a phase angle of each current symmetric component; and a turn-to-turn short circuit fault diagnosis result of the five-phase permanent magnet synchronous motor can be obtained according to the amplitudes and phase angles of the four current symmetrical components. According to the method, early turn-to-turn short circuit fault diagnosis can be realized by using current symmetric components by adopting a signal analysis method, and the reliability and the accuracy of online diagnosis are improved.

Description

Technical Field

[0001] The present application relates to the technical field of multi-phase permanent magnet synchronous motors, and in particular to a method for diagnosing turn-to-turn short-circuit faults of five-phase permanent magnet synchronous motors. Background Art

[0002] Multiphase permanent magnet synchronous motor (PMSM) has been widely used in many fields such as electric vehicles, wind power generation, and aerospace due to its advantages such as small torque ripple, strong fault tolerance, and high power density. However, with the continuous development of motor control technology, the application scenarios of PMSM are becoming increasingly complex, and the faults that may occur during long-term operation have gradually attracted the attention of researchers. Among them, the inter-turn short circuit (ITSC) fault, as a common internal fault of PMSM, has attracted much attention due to its strong concealment and serious harm. If timely measures are not taken, the expansion of the fault scope may even cause serious consequences such as burning of the winding or shutdown of the drive system.

[0003] Improving the accuracy and reliability of fault diagnosis in the early stage of faults and taking effective measures to control and eliminate them have become an important topic in ITSC fault research. There are three main diagnostic methods for turn-to-turn short-circuit faults: artificial intelligence-based methods, model-based methods, and signal analysis-based methods. Artificial intelligence-based diagnostic methods usually require a large amount of data for training, so they are generally difficult to apply directly in engineering practice; diagnostic methods based on motor mathematical models can accurately describe the changes in electromagnetic parameters caused by faults, but the calculation is large and depends on accurate motor parameters; signal analysis-based methods usually extract specific order current harmonics from the stator current of the motor to realize fault diagnosis, without the need for a large amount of data and accurate models, and have the advantages of good robustness and strong real-time performance. In addition, compared with traditional three-phase motors, due to the increase in the number of phases and the existence of harmonic subspaces, the turn-to-turn short-circuit fault diagnosis of multi-phase motors is more complicated, which makes the early fault diagnosis of turn-to-turn short circuits more difficult. Summary of the invention

[0004] In view of the above problems and technical requirements, this application proposes a method for diagnosing inter-turn short-circuit faults of a five-phase permanent magnet synchronous motor. The technical solution of this application is as follows:

[0005] A five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method, the five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method comprising:

[0006] The phase current of the five-phase permanent magnet synchronous motor is collected during operation, and the phase current is symmetrically transformed according to the symmetrical component method to obtain four current symmetrical components, and the four current symmetrical components include a first positive sequence component, a first negative sequence component, a second positive sequence component, and a second negative sequence component; wherein, the phase sequence corresponding to the first positive sequence component is A phase, B phase, C phase, D phase, and E phase, the phase sequence corresponding to the first negative sequence component is A phase, E phase, D phase, C phase, and B phase, the phase sequence corresponding to the second positive sequence component is A phase, C phase, E phase, B phase, and D phase, and the phase sequence corresponding to the second negative sequence component is A phase, D phase, B phase, E phase, and C phase;

[0007] Performing Fourier transform on the four current symmetrical components to obtain the amplitude and phase angle of each current symmetrical component;

[0008] The turn-to-turn short-circuit fault diagnosis result of the five-phase permanent magnet synchronous motor is obtained according to the amplitude and phase angle of the four symmetrical current components.

[0009] The beneficial technical effects of this application are:

[0010] The present application discloses a method for diagnosing a turn-to-turn short-circuit fault of a five-phase permanent magnet synchronous motor. The method adopts a signal analysis method, collects the phase current during the operation of the five-phase permanent magnet synchronous motor, analyzes the motor phase current using the symmetrical component method, calculates its symmetrical component and performs Fourier transform, and then uses the amplitude ratio and phase difference of the current symmetrical component to realize early turn-to-turn short-circuit fault diagnosis, thereby improving the reliability and accuracy of online diagnosis. In addition, the method does not need to add auxiliary circuits, thereby reducing the hardware cost of online diagnosis. The method can not only diagnose the existence of turn-to-turn short-circuit faults, but also realize fault location and severity assessment, and has high theoretical innovation and practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is the equivalent circuit diagram of the five-phase permanent magnet synchronous motor when it is working normally and when a turn-to-turn short circuit occurs in phase A.

[0012] Figure 2 It is a schematic diagram of the decomposition of the symmetrical components of the five-phase current in one embodiment of the present application.

[0013] Figure 3 It is a flow chart of a method for diagnosing a turn-to-turn short-circuit fault of a five-phase permanent magnet synchronous motor in one embodiment of the present application.

[0014] Figure 4 It is a simulation waveform diagram of a five-phase permanent magnet synchronous motor in a simulation example of the present application under normal operation and turn-to-turn short circuit fault.

[0015] Figure 5This is a simulation waveform diagram of a five-phase permanent magnet synchronous motor in another simulation example of the present application under normal operation and turn-to-turn short circuit fault. DETAILED DESCRIPTION

[0016] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0017] The present application discloses a method for diagnosing a short-circuit fault between turns of a five-phase permanent magnet synchronous motor. The five-phase permanent magnet synchronous motor includes five-phase stator windings, which are respectively recorded as phase A, phase B, phase C, phase D, and phase E. The equivalent circuit of the five-phase permanent magnet synchronous motor when it is working normally is as follows: Figure 1 As shown in (a) in the figure. Among them, L s Represents the inductance of the stator winding, R s represents the resistance of the stator winding, e p represents the back electromotive force of each phase stator winding, i p represents the phase current of each phase stator winding, and p=a, b, c, d, e represent the A phase, B phase, C phase, D phase, and E phase of the five-phase permanent magnet synchronous motor respectively.

[0018] When there is a turn-to-turn short circuit fault, take the turn-to-turn short circuit of phase A as an example. At this time, the equivalent circuit model is as follows: Figure 1 As shown in (b) in the figure, the A-phase stator winding is divided into a healthy part and a short-circuited part. ah , L ah 、e ah is the resistance, inductance and back electromotive force of the healthy part (not short-circuited) of the A-phase stator winding, R af , L af and e af is the resistance, inductance and back electromotive force of the short-circuited part of the A-phase stator winding. f is the short-circuit resistance, i f M is the short-circuit current flowing through the short-circuit resistance branch. ahaf The healthy part L of phase A winding ah With fault part L af The mutual inductance between phase A and the non-fault phase is ignored. And:

[0019]

[0020] Among them, the short-circuit turns ratio 0<μ≤1 is the ratio of the number of short-circuited turns to the total number of turns.

[0021] Based on the phase rotation, four new phase sequences can be identified in the five-phase system, and these four phase sequences constitute the four current symmetric components of the five-phase system, which are:

[0022] (1) The first positive phase sequence: phase A, phase B, phase C, phase D, phase E. The first positive sequence component of this phase sequence includes Ia1 ,I b1 ,I c1 ,I d1 ,I e1 ,like Figure 2 As shown in (a) in .

[0023] (2) The first negative phase sequence: phase A, phase E, phase D, phase C and phase B. The first negative sequence component of this phase sequence includes I a2 ,I e2 ,I d2 ,I c2 ,I b2 ,like Figure 2 As shown in (b) in .

[0024] (3) The second positive phase sequence: phase A, phase C, phase E, phase B, phase D. The phase sequence corresponds to the second positive sequence component including I a3 ,I c3 ,I e3 ,I b3 ,I d3 ,like Figure 2 As shown in (c) in .

[0025] (4) The second negative phase sequence: phase A, phase D, phase B, phase E and phase C. The second negative sequence component of this phase sequence includes I a4 ,I d4 ,I b4 ,I e4 ,I c4 ,like Figure 2 As shown in (d) in .

[0026] Among the above four current symmetrical components, I p1 Represents the first positive sequence component of each phase stator winding, I p2 Represents the first negative sequence component of each phase stator winding, I p3 Represents the second positive sequence component of each phase stator winding, I p4 It represents the second negative sequence component of the stator winding of each phase, and p=a, b, c, d, e respectively represent the A phase, B phase, C phase, D phase, and E phase of the five-phase permanent magnet synchronous motor.

[0027] According to the above four phase sequences and the current symmetrical components, the phase current of the five-phase stator winding can be decomposed based on the current symmetrical components into:

[0028]

[0029] Where α = e j72° , j represents the imaginary unit.

[0030] Using the transformation matrix, we can get the four symmetrical current components of phase A as follows:

[0031]

[0032] In a healthy state, only the first positive sequence component is non-zero, and the other components are all zero.

[0033] Assume that the phase current of the five-phase stator winding of the five-phase permanent magnet synchronous motor is expressed as follows in the natural coordinate system when it is operating normally:

[0034]

[0035] in, is the initial phase angle, I m is the amplitude of the phase current, ω represents the angular frequency, and t represents the time.

[0036] When a five-phase permanent magnet synchronous motor has a turn-to-turn short circuit fault, an unbalance factor is generated, and the phase currents of the five-phase stator windings are no longer symmetrical, thus generating the first negative sequence component, the second positive sequence component, and the second negative sequence component:

[0037]

[0038] Where I1 is the amplitude of the first positive sequence component, is the phase angle of the first positive sequence component. I2 is the amplitude of the second positive sequence component, is the phase angle of the second positive sequence component. I3 is the amplitude of the third positive sequence component, is the phase angle of the third positive sequence component. I4 is the amplitude of the fourth positive sequence component, is the phase angle of the fourth positive sequence component.

[0039] Based on the above, after collecting the phase current during the operation of the five-phase permanent magnet synchronous motor and performing symmetrical transformation on the phase current according to the symmetrical component method to obtain four current symmetrical components, the four current symmetrical components of the phase current are Fourier transformed to obtain the amplitude and phase angle of each current symmetrical component. The turn-to-turn short-circuit fault diagnosis result of the five-phase permanent magnet synchronous motor can be obtained according to the amplitude and phase angle of the four current symmetrical components. Figure 3 Flowchart:

[0040] The obtained turn-to-turn short-circuit fault diagnosis result includes an indication of whether a turn-to-turn short-circuit fault occurs in the five-phase permanent magnet synchronous motor, including:

[0041] Calculate the amplitude ratio of the first positive sequence component amplitude I1 to the first negative sequence component amplitude I2 As a turn-to-turn short-circuit fault diagnosis indicator, when an abnormal fluctuation of the amplitude ratio k is detected during the stable operation of the five-phase permanent magnet synchronous motor, it is determined that the five-phase permanent magnet synchronous motor has a turn-to-turn short-circuit fault; otherwise, it is determined that the five-phase permanent magnet synchronous motor does not have a turn-to-turn short-circuit fault.

[0042] On this basis, in order to eliminate the influence of the load, the change of the amplitude ratio k is not directly evaluated, but the amplitude ratio k and the phase current effective value I are calculated. rms The signal ratio is Then evaluate the signal ratio k f The fluctuation of the amplitude ratio k is determined by the change of the value of f When the decrease amplitude of reaches the predetermined amplitude threshold, it is determined that the fluctuation of the amplitude ratio k is abnormal, otherwise it is determined that the fluctuation of the amplitude ratio k is normal. The predetermined amplitude threshold can be customized, for example, when the signal ratio k at a certain moment is f When the signal ratio decreases by 50% or more compared to the previous moment, the signal ratio k is determined. f The decrease amplitude reaches the predetermined amplitude threshold, and then it is determined that the fluctuation of the amplitude ratio k is abnormal, and it is determined that there is an inter-turn short-circuit fault in the five-phase permanent magnet synchronous motor.

[0043] Furthermore, in another embodiment, fault location can be achieved according to the phase angles of the four symmetrical current components, that is, the obtained turn-to-turn short-circuit fault diagnosis result also indicates the faulty phase winding, and the faulty phase winding is the stator winding in which the turn-to-turn short-circuit fault occurs in the five-phase permanent magnet synchronous motor, including:

[0044] When determining that a five-phase permanent magnet synchronous motor has a turn-to-turn short-circuit fault, calculate the phase angle of the second positive sequence component Phase angle with the first negative sequence component Phase difference And according to the phase difference Locate the faulty phase winding. In one embodiment, according to the phase difference Locating the faulty phase winding includes: calculating the phase difference The phase angle of the phase current of any phase winding p after a turn-to-turn short circuit fault occurs in a five-phase permanent magnet synchronous motor Phase difference When the phase difference When the average value of is within the error range, the phase winding p is determined to be the faulty phase winding. The error range can be customized, for example, to ±25°.

[0045] Furthermore, after the fault location is realized, in another embodiment, the fault severity evaluation can be realized according to the amplitude and phase angle of the four symmetrical current components, so that the obtained turn-to-turn short circuit fault diagnosis result also includes a severity evaluation result, and the severity evaluation result indicates the severity of the turn-to-turn short circuit fault occurring in the faulty phase winding, including:

[0046] The severity assessment result of the inter-turn short-circuit fault of the faulty phase winding is obtained according to the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component. As described above, the severity of the inter-turn short-circuit fault of the faulty phase winding can be quantified by the short-circuit turn ratio μ. The short-circuit turn ratio 0<μ≤1 is the ratio of the number of short-circuited turns to the total number of turns in the faulty phase winding. The larger the short-circuit turn ratio μ of the faulty phase winding, the higher the severity of the inter-turn short-circuit fault of the faulty phase winding. Therefore, the short-circuit turn ratio μ of the faulty phase winding is calculated according to the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component as the severity assessment result, including:

[0047] The average values ​​of the amplitude I3 of the second positive sequence component and the amplitude I4 of the second negative sequence component in K current fundamental wave cycles are calculated as the short-circuit turns ratio of the fault phase winding, and the integer parameter K ≥ 2. The parameter K here can be set by user, for example, set to 5.

[0048] In a simulation example, the speed setting is set to 500rpm and the load setting is set to 10Nm. The phase current of the five-phase permanent magnet synchronous motor during normal operation is as follows: Figure 4 As shown in (a) of Figure 4 It can be seen from (a) that when there is no inter-turn short-circuit fault, the phase current waveform of the five-phase stator winding is balanced and sinusoidal.

[0049] At t = 0.020s, a turn-to-turn short-circuit fault is injected into the A-phase stator winding, and the short-circuit turn ratio μ = 0.1, the short-circuit resistance R f =0.08Ω, resulting in the destruction of the balance and symmetry of the phase current.

[0050] The signal ratio k calculated by the fault diagnosis method of the present application is f The curve is as Figure 4 As shown in (b) of Figure 4 As can be seen from (b) in Figure 1, before the turn-to-turn short-circuit fault is injected into the A-phase stator winding, the signal ratio k f Basically stable, at t = 0.028s, the signal ratio k f It dropped from 33.49 to 8.33, which was more than 75% lower than the original value. The fault diagnosis indicator K c Changes from 0 to 1. At this time, the fault diagnosis method of the present application can be used to diagnose that a short circuit fault occurs in the five-phase permanent magnet synchronous motor.

[0051] The phase difference calculated by the fault diagnosis method of the present application The curve is as Figure 4 As shown in (c) in Figure 4 As can be seen from (c) in the figure, the phase difference is detected at t = 0.023s. The temperature rises from -300° to around 120°, and The closest to The average value is within the error range, thus determining that the A-phase stator winding has a turn-to-turn fault and is the faulty phase winding.

[0052] The sum of the amplitude I3 of the second positive sequence component and the amplitude I4 of the second negative sequence component calculated by the fault diagnosis method of the present application gradually rises and fluctuates around 0.1. The curve of the sum of the amplitude I3 and the amplitude I4 is as follows: Figure 4 As shown in (d) in FIG. 1 , the average value of the sum of the amplitude I3 and the amplitude I4 in the first five current fundamental cycles is calculated at t = 0.035s as the estimated value of the short-circuit turns ratio μ = 0.098, which is basically consistent with the actual value of 0.1, and the estimated result is in line with expectations.

[0053] In another simulation example, the speed setting is also set to 500rpm and the load setting is set to 10Nm. The phase current of the five-phase stator winding of the five-phase permanent magnet synchronous motor when it is working normally is as follows: Figure 5 As shown in (a) in Figure 5 As shown in (a) in FIG. 1 , when no turn-to-turn short-circuit fault occurs, the phase current waveforms of the five-phase stator windings are balanced and sinusoidal.

[0054] At t = 0.020s, a turn-to-turn short-circuit fault is injected into the E-phase stator winding, and the short-circuit turn ratio μ = 0.12, the short-circuit resistance R f =0.05Ω, resulting in the destruction of the balance and symmetry of the phase current. Figure 4 A simulation example is shown in which the current distortion caused by the turn-to-turn short circuit is more serious.

[0055] The signal ratio k calculated by the fault diagnosis method of the present application is f The curve is as Figure 5 As shown in (b) of Figure 5 As can be seen from (b) in Figure 1, before the turn-to-turn short-circuit fault is injected into the E-phase stator winding, the signal ratio k f Basically stable, at t = 0.028s, the signal ratio k f The value of K dropped from 33.65 to 4.21, which was more than 87% lower than the original value. c Changes from 0 to 1. At this time, the fault diagnosis method of the present application can be used to diagnose that a short circuit fault occurs in the five-phase permanent magnet synchronous motor.

[0056] The phase difference calculated by the fault diagnosis method of the present application The curve is as Figure 5 As shown in (c) in Figure 5 As can be seen from (c) in the figure, the phase difference is detected at t = 0.023s. The temperature rises from -300° to -180°, which is similar to The closest to The average value of is within the error range, thus determining that the E-phase stator winding has a turn-to-turn fault and is the faulty phase winding.

[0057] The sum of the amplitude I3 of the second positive sequence component and the amplitude I4 of the second negative sequence component calculated by the fault diagnosis method of the present application gradually rises and fluctuates between 0.1 and 0.2. The curve of the sum of the amplitude I3 and the amplitude I4 is as follows: Figure 5 As shown in (d) in FIG. 1 , the average value of the sum of the amplitude I3 and the amplitude I4 in the first five current fundamental cycles is calculated at t = 0.035s as the estimated value of the short-circuit turns ratio μ = 0.120, which is basically consistent with the actual value of 0.12, and the estimated result is in line with expectations.

[0058] pass Figure 4 and Figure 5 It can be seen from the simulation results of the simulation example that the fault diagnosis method of the present application can quickly and accurately realize fault diagnosis and fault location, and estimate the short-circuit turns ratio, thereby realizing the evaluation of the severity of the fault, and has good dynamic response capability.

[0059] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method, characterized in that: The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method comprises: The phase current of the five-phase permanent magnet synchronous motor is collected during operation, and the phase current is symmetrically transformed according to the symmetrical component method to obtain four current symmetrical components, and the four current symmetrical components include a first positive sequence component, a first negative sequence component, a second positive sequence component, and a second negative sequence component; wherein, the phase sequence corresponding to the first positive sequence component is A phase, B phase, C phase, D phase, and E phase, the phase sequence corresponding to the first negative sequence component is A phase, E phase, D phase, C phase, and B phase, the phase sequence corresponding to the second positive sequence component is A phase, C phase, E phase, B phase, and D phase, and the phase sequence corresponding to the second negative sequence component is A phase, D phase, B phase, E phase, and C phase; Performing Fourier transform on the four current symmetrical components to obtain the amplitude and phase angle of each current symmetrical component; The turn-to-turn short-circuit fault diagnosis result of the five-phase permanent magnet synchronous motor is obtained according to the amplitude and phase angle of the four symmetrical current components.

2. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 1 is characterized in that: The turn-to-turn short-circuit fault diagnosis results of the five-phase permanent magnet synchronous motor include: Calculate the amplitude ratio of the first positive sequence component amplitude I1 to the first negative sequence component amplitude I2 When an abnormal fluctuation of the amplitude ratio k is detected during the stable operation of the five-phase permanent magnet synchronous motor, it is determined that the five-phase permanent magnet synchronous motor has an inter-turn short circuit fault, otherwise it is determined that the five-phase permanent magnet synchronous motor does not have an inter-turn short circuit fault.

3. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 2 is characterized in that: The turn-to-turn short-circuit fault diagnosis results of the five-phase permanent magnet synchronous motor also include: When determining that a five-phase permanent magnet synchronous motor has a turn-to-turn short-circuit fault, calculate the phase angle of the second positive sequence component Phase angle with the first negative sequence component Phase difference And according to the phase difference Locate the faulty phase winding, which is the stator winding with a turn-to-turn short-circuit fault.

4. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 3 is characterized in that: The turn-to-turn short-circuit fault diagnosis results of the five-phase permanent magnet synchronous motor also include: The severity assessment result of the turn-to-turn short-circuit fault occurring in the faulty phase winding is obtained according to the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component.

5. The five-phase permanent magnet synchronous motor turn-to-turn short-circuit fault diagnosis method according to claim 4 is characterized in that: The severity assessment results of the turn-to-turn short-circuit fault occurring in the faulty phase winding include: The short-circuit turns ratio μ of the faulty phase winding is calculated according to the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component as the severity assessment result. The short-circuit turns ratio 0<μ≤1 is the ratio of the number of short-circuited turns to the total number of turns in the faulty phase winding. The larger the short-circuit turns ratio μ of the faulty phase winding, the higher the severity of the inter-turn short-circuit fault of the faulty phase winding.

6. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 2 is characterized in that: Checking whether the fluctuation of the amplitude ratio k is abnormal includes: Calculate the amplitude ratio k and the effective value of the phase current I rms The signal ratio is When the decrease amplitude of the signal ratio reaches a predetermined amplitude threshold, it is determined that the fluctuation of the amplitude ratio k is abnormal; otherwise, it is determined that the fluctuation of the amplitude ratio k is normal.

7. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 3 is characterized in that: According to the phase difference Locating faulty phase windings includes: Calculate the phase difference The phase angle of the phase current of any phase winding p after a turn-to-turn short circuit fault occurs in a five-phase permanent magnet synchronous motor Phase difference When the phase difference When the average value of is within a certain error range, the phase winding p is determined to be the faulty phase winding; Among them, p=a, b, c, d, e respectively represent the A phase, B phase, C phase, D phase, and E phase of the five-phase permanent magnet synchronous motor.

8. The five-phase permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method according to claim 5 is characterized in that: Determining the short-circuit turns ratio of the faulty phase winding in the five-phase permanent magnet synchronous motor according to the amplitude I3 of the second positive sequence component and the amplitude I4 of the second negative sequence component includes: The average values ​​of the amplitude I3 of the second positive sequence component and the amplitude I4 of the second negative sequence component in K current fundamental wave cycles are calculated as the short-circuit turns ratio of the faulty phase winding, and the integer parameter K≥2.

Images