A method for diagnosing inter-turn short circuit fault of five-phase permanent magnet synchronous motor
By using signal analysis methods, including the symmetrical component method and Fourier transform, accurate diagnosis, location, and severity assessment of inter-turn short-circuit faults in five-phase permanent magnet synchronous motors were achieved. This solved the problem of high diagnostic difficulty in existing technologies, improved diagnostic reliability, and reduced hardware costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGNAN UNIV
- Filing Date
- 2025-01-22
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies are insufficient for effectively diagnosing inter-turn short-circuit faults in five-phase permanent magnet synchronous motors, especially in the early stages of faults, where accuracy and reliability are inadequate. Furthermore, diagnostic methods involve large computational loads or rely on a large amount of data, making them difficult to apply in practical engineering.
By employing signal analysis methods, the phase currents during the operation of a five-phase permanent magnet synchronous motor are collected. The current is transformed using the symmetrical component method and then subjected to Fourier transform. The amplitude and phase angle of the symmetrical current components are calculated to achieve the diagnosis, location, and severity assessment of inter-turn short-circuit faults.
It improves the reliability and accuracy of online diagnosis of inter-turn short circuit faults in five-phase permanent magnet synchronous motors, reduces hardware costs, and enables rapid fault location and severity assessment.
Smart Images
Figure CN119916198B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of multiphase permanent magnet synchronous motor technology, and in particular to a method for diagnosing inter-turn short circuit faults in a five-phase permanent magnet synchronous motor. Background Technology
[0002] Multiphase permanent magnet synchronous motors (PMSMs) have been widely used in many fields such as electric vehicles, wind power generation, and aerospace due to their advantages of low torque ripple, strong fault tolerance, and high power density. However, with the continuous development of motor control technology, the application scenarios of PMSMs are becoming increasingly complex, and the faults that may occur during long-term operation have gradually attracted the attention of researchers. Among them, inter-turn short circuit (ITSC) faults, as a common internal fault of PMSMs, have received much attention due to their strong concealment and serious hazards. If measures are not taken in time, the fault range may expand and even lead to serious consequences such as winding burnout or drive system shutdown.
[0003] Improving the accuracy and reliability of fault diagnosis in the early stages of faults and taking effective measures to control and eliminate them has become an important topic in ITSC fault research. Existing diagnostic methods for inter-turn short circuit faults mainly fall into three categories: artificial intelligence-based methods, model-based methods, and signal analysis-based methods. Artificial intelligence-based diagnostic methods typically require a large amount of data for training, making them 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 the fault, but the computational load is large and depends on accurate motor parameters. Signal analysis-based methods typically extract specific-order current harmonics from the motor's stator current to achieve fault diagnosis, requiring no large amount of data or accurate models, and have advantages such as good robustness and strong real-time performance. Furthermore, compared to traditional three-phase motors, the increased number of phases and the existence of harmonic subspace make inter-turn short circuit fault diagnosis in multi-phase motors more complex, further complicating the early diagnosis of inter-turn short circuit faults. Summary of the Invention
[0004] This application addresses the aforementioned problems and technical requirements by proposing a method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor. The technical solution of this application is as follows:
[0005] A method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor, comprising:
[0006] Phase currents during the operation of a five-phase permanent magnet synchronous motor are collected, and the phase currents are symmetrically transformed using the symmetrical component method to obtain four symmetrical current components. The four symmetrical current components include a first positive sequence component, a first negative sequence component, a second positive sequence component, and a second negative sequence component. The phase sequence corresponding to the first positive sequence component is phase A, phase B, phase C, phase D, and phase E; the phase sequence corresponding to the first negative sequence component is phase A, phase E, phase D, phase C, and phase B; the phase sequence corresponding to the second positive sequence component is phase A, phase C, phase E, phase B, and phase D; and the phase sequence corresponding to the second negative sequence component is phase A, phase D, phase B, phase E, and phase C.
[0007] The magnitude and phase angle of each current symmetric component are obtained by performing a Fourier transform on the four current symmetric components.
[0008] The inter-turn short-circuit fault diagnosis results for a five-phase permanent magnet synchronous motor are obtained based on the amplitude and phase angle of the four symmetrical current components.
[0009] The beneficial technical effects of this application are:
[0010] This application discloses a method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor. This method employs signal analysis, acquiring the phase currents during the motor's operation, analyzing the phase currents using the symmetrical component method, calculating their symmetrical components, and performing Fourier transforms. The amplitude ratio and phase difference of the symmetrical current components are then used to diagnose early inter-turn short-circuit faults, improving the reliability and accuracy of online diagnosis. Furthermore, this method eliminates the need for auxiliary circuitry, reducing the hardware cost of online diagnosis. This method can not only diagnose inter-turn short-circuit faults but also locate the fault and assess its severity, demonstrating high theoretical innovation and practical application value. Attached Figure Description
[0011] Figure 1 This is the equivalent circuit diagram of a five-phase permanent magnet synchronous motor during normal operation and when an inter-turn short circuit occurs in phase A.
[0012] Figure 2 This is a schematic diagram of the decomposition of the symmetrical components of the five-phase current in one embodiment of this application.
[0013] Figure 3 This is a flowchart illustrating a method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor according to one embodiment of this application.
[0014] Figure 4 This is a simulation waveform diagram of a five-phase permanent magnet synchronous motor under normal operation and inter-turn short circuit fault in a simulation example of this application.
[0015] Figure 5This is a simulation waveform diagram of a five-phase permanent magnet synchronous motor under normal operation and inter-turn short circuit fault in another simulation example of this application. Detailed Implementation
[0016] The specific embodiments of this application will be further described below with reference to the accompanying drawings.
[0017] This application discloses a method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor. The five-phase permanent magnet synchronous motor includes five stator windings, denoted as phase A, phase B, phase C, phase D, and phase E. The equivalent circuit of the five-phase permanent magnet synchronous motor during normal operation is as follows: Figure 1 As shown in (a) of the diagram. Where, L s R represents the inductance of the stator winding. s e represents the resistance of the stator winding. p i represents the back electromotive force of each phase stator winding. p The phase currents of each phase stator winding are represented by p = a, b, c, d, and e, which represent phases A, B, C, D, and E of the five-phase permanent magnet synchronous motor, respectively.
[0018] When an inter-turn short circuit fault exists, taking an inter-turn short circuit in phase A as an example, the equivalent circuit model is as follows: Figure 1 As shown in (b) above, the A-phase stator winding is divided into a healthy section and a short-circuited section. R ah L ah e ah The resistance, inductance, and back electromotive force of the healthy portion (not short-circuited) of phase A stator winding, R af L af and e af R represents the resistance, inductance, and back electromotive force of the short-circuited portion of the A-phase stator winding. f For short-circuit resistance, i f M is the short-circuit current flowing through the branch with the short-circuit resistor. ahaf For the healthy part of phase A winding L ah With fault section L af The mutual inductance between phases is considered, neglecting the influence of the mutual inductance between phase A and the non-faulty phases. Furthermore, we have:
[0019]
[0020] Wherein, 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 phase rotation, four new phase sequences can be identified in a five-phase system, and these four phase sequences constitute the four current symmetrical components of the five-phase system, namely:
[0022] (1) First positive sequence: Phase A, Phase B, Phase C, Phase D, Phase E. The first positive sequence component corresponding to this phase sequence includes I.a1 I b1 I c1 I d1 I e1 ,like Figure 2 As shown in (a) in the figure.
[0023] (2) First negative phase sequence: phase A, phase E, phase D, phase C and phase B. The first negative sequence component corresponding to this phase sequence includes I. a2 I e2 I d2 I c2 I b2 ,like Figure 2 As shown in (b) of the diagram.
[0024] (3) Second positive sequence: Phase A, Phase C, Phase E, Phase B, Phase D. This 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 the figure.
[0025] (4) Second negative phase sequence: phase A, phase D, phase B, phase E, and phase C. This phase sequence corresponds to the second negative sequence component, including I. a4 I d4 I b4 I e4 I c4 ,like Figure 2 As shown in (d) in the figure.
[0026] Of the four symmetrical current components mentioned above, I p1 I represents the first positive sequence component of each phase stator winding. p2 I represents the first negative sequence component of each phase stator winding. p3 I represents the second positive sequence component of each phase stator winding. p4 The second negative sequence component of each phase stator winding is represented by p = a, b, c, d, e, which represent phases A, B, C, D, and E of the five-phase permanent magnet synchronous motor, respectively.
[0027] Based on the above four phase sequences and the symmetrical current components they form, the phase currents of the five-phase stator windings can be decomposed into the following based on the symmetrical current components:
[0028]
[0029] Where α=e j72° , j represents the imaginary unit.
[0030] Using the transformation matrix, the four symmetrical current components of phase A can be obtained as follows:
[0031]
[0032] In a healthy state, only the first positive-order component is non-zero, while all other components are zero.
[0033] Suppose the phase currents of the five-phase stator windings in the natural coordinate system during normal operation of a five-phase permanent magnet synchronous motor are expressed as follows:
[0034]
[0035] in, Let I be the initial phase angle. m Let ω represent the amplitude of the phase current, ω represent the angular frequency, and t represent time.
[0036] When a five-phase permanent magnet synchronous motor experiences an inter-turn short-circuit fault, an imbalance factor is generated, and the phase currents of the five-phase stator windings are no longer symmetrical, thus generating a first negative sequence component, a second positive sequence component, and a second negative sequence component:
[0037]
[0038] Where I1 is the amplitude of the first positive sequence component. I0 is the phase angle of the first positive-sequence component. I2 is the amplitude of the second positive-sequence component. I is the phase angle of the second positive sequence component. I3 is the amplitude of the third positive sequence component. I is the phase angle of the third positive sequence component. I4 is the amplitude of the fourth positive sequence component. It is the phase angle of the fourth positive sequence component.
[0039] Based on the preceding text, after collecting the phase currents during the operation of the five-phase permanent magnet synchronous motor and performing a symmetrical transformation on the phase currents using the symmetrical component method to obtain four symmetrical current components, a Fourier transform is performed on these four symmetrical current components to obtain the amplitude and phase angle of each component. Therefore, the inter-turn short-circuit fault diagnosis result of the five-phase permanent magnet synchronous motor can be obtained based on the amplitude and phase angle of the four symmetrical current components. Please refer to... Figure 3 Flowchart:
[0040] The obtained inter-turn short-circuit fault diagnosis results include indicators of whether an inter-turn short-circuit fault has occurred in the five-phase permanent magnet synchronous motor, including:
[0041] Calculate the amplitude ratio of the first positive-sequence component I1 to the amplitude of the first negative-sequence component I2. As a diagnostic indicator for inter-turn short circuit faults, when an abnormal fluctuation in the amplitude ratio k is detected during the stable operation of a 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.
[0042] Based on this, in order to eliminate the influence of load, the change in the amplitude ratio k is not directly evaluated. Instead, the amplitude ratio k and the effective value of the phase current I are calculated. rms The ratio of the signal to the value of the signal Then evaluate the signal ratio k. f The fluctuation of the amplitude ratio k is determined by the change in the value of k. When the signal ratio k f When the decrease in amplitude reaches a predetermined threshold, the fluctuation of the amplitude ratio k is determined to be abnormal; otherwise, the fluctuation of the amplitude ratio k is determined to be normal. This predetermined threshold can be customized; for example, when the signal strength at a certain moment is greater than k... f When the signal ratio decreases by 50% or more compared to the previous time step, determine the signal ratio k. f The decrease in amplitude reached the predetermined amplitude threshold, which determined that the fluctuation of amplitude ratio k was abnormal and that the five-phase permanent magnet synchronous motor had an inter-turn short circuit fault.
[0043] Furthermore, in another embodiment, fault location can also be achieved based on the phase angles of the four symmetrical current components. That is, the obtained inter-turn short-circuit fault diagnosis result also indicates the faulty phase winding. The faulty phase winding is the stator winding in the five-phase permanent magnet synchronous motor that experiences an inter-turn short-circuit fault, including:
[0044] When determining that a five-phase permanent magnet synchronous motor has an inter-turn short-circuit fault, the phase angle of the second positive sequence component is calculated. Phase angle with the first negative sequence component phase difference And based on the phase difference Locate the faulty phase winding. In one embodiment, based on the phase difference... Locating the faulty phase winding includes: calculating the phase difference. Phase angle of the phase current of any phase winding p after an inter-turn short circuit fault occurs in a five-phase permanent magnet synchronous motor phase difference When phase difference When the average value is within the error range, phase winding p is determined to be the faulty phase winding. This error range can be customized, for example, set to ±25°.
[0045] Furthermore, after fault location is achieved, in another embodiment, the severity of the fault can be assessed based on the amplitude and phase angle of the four symmetrical current components. Therefore, the obtained inter-turn short-circuit fault diagnosis result also includes a severity assessment result, which indicates the severity of the inter-turn short-circuit fault occurring in the faulty phase winding, including:
[0046] The severity assessment result of the inter-turn short-circuit fault in the faulty phase winding is obtained based on the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component. As mentioned above, the severity of the inter-turn short-circuit fault in the faulty phase winding can be quantified using the short-circuit turns ratio μ. 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 in the faulty phase winding. Therefore, the short-circuit turns ratio μ of the faulty phase winding is calculated as the severity assessment result based on the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component, including:
[0047] The average value of the amplitude I3 of the second positive-sequence component and the amplitude I4 of the second negative-sequence component over K fundamental current cycles is used as the short-circuit turns ratio of the faulty phase winding, with the integer parameter K ≥ 2. The parameter K can be set custom-defined, for example, to 5.
[0048] In a simulation example, the speed setpoint is set to 500 rpm and the load setpoint is set to 10 Nm. The phase current of the five-phase permanent magnet synchronous motor during normal operation is as follows: Figure 4 As shown in (a) above, by means of Figure 4 As can be seen from (a) in the figure, when no inter-turn short circuit fault occurs, the phase current waveform of the five-phase stator winding is balanced and sinusoidal.
[0049] At t = 0.020s, an inter-turn short-circuit fault is injected into the stator winding of phase A, with a short-circuit turns ratio μ = 0.1 and a short-circuit resistance R. f =0.08Ω, which disrupts the balance and symmetry of the phase current.
[0050] The signal ratio k calculated using the fault diagnosis method of this application f The curve is as follows Figure 4 As shown in (b) above, by Figure 4 As can be seen from (b), before an inter-turn short-circuit fault is injected into the A-phase stator winding, the signal strength is higher than that of k. f The signal is basically stable, and at t=0.028s, the signal ratio k f The value plummeted from 33.49 to 8.33, a decrease of over 75% of the original value, indicating a fault diagnosis. c When the value changes from 0 to 1, the fault diagnosis method of this application can be used to diagnose a short circuit fault in the five-phase permanent magnet synchronous motor.
[0051] The phase difference calculated using the fault diagnosis method of this application The curve is as follows Figure 4 As shown in (c) in the figure, by Figure 4 As can be seen from (c), a phase difference was detected at t = 0.023s. The temperature rises from a given -300° to around 120°, compared to... The closest to make The average value is within the error range, thus determining that the A-phase stator winding has an inter-turn fault and is the faulty phase winding.
[0052] The sum of the amplitudes I3 of the second positive-sequence component and I4 of the second negative-sequence component, calculated using the fault diagnosis method of this application, gradually increases and fluctuates around 0.1. The curve of the sum of amplitudes I3 and I4 is shown below. Figure 4 As shown in (d) in the figure. The average value of the sum of amplitudes I3 and I4 calculated at t = 0.035s over the first 5 fundamental current cycles was used as the short-circuit turns ratio estimate μ = 0.098, which is basically consistent with the actual value of 0.1. The estimation result meets expectations.
[0053] In another simulation example, the speed setpoint was also set to 500 rpm, and the load setpoint was set to 10 Nm. The phase currents of the five-phase stator windings of the five-phase permanent magnet synchronous motor during normal operation are as follows: Figure 5 As shown in (a) above, similarly, by Figure 5 As shown in (a), when no inter-turn short-circuit fault occurs, the phase current waveform of the five-phase stator winding is balanced and sinusoidal.
[0054] At t = 0.020s, an inter-turn short-circuit fault is injected into the E-phase stator winding, with a short-circuit turns ratio μ = 0.12 and a short-circuit resistance R. f =0.05Ω, which disrupts the balance and symmetry of the phase current, compared to Figure 4 The simulation example shows that the current distortion caused by the short circuit between the incoming turns is very serious.
[0055] The signal ratio k calculated using the fault diagnosis method of this application f The curve is as follows Figure 5 As shown in (b) above, by Figure 5 As can be seen from (b), before an inter-turn short-circuit fault is injected into the E-phase stator winding, the signal strength is higher than that of k. f The signal is basically stable, and at t=0.028s, the signal ratio k f The value plummeted from 33.65 to 4.21, a decrease of over 87% of the original value, indicating a fault diagnosis. c When the value changes from 0 to 1, the fault diagnosis method of this application can be used to diagnose a short circuit fault in the five-phase permanent magnet synchronous motor.
[0056] The phase difference calculated using the fault diagnosis method of this application The curve is as follows Figure 5 As shown in (c) in the figure, by Figure 5 As can be seen from (c), a phase difference was detected at t = 0.023s. The temperature rises from a given -300° to around -180°, compared to... The closest to make The average value is within the error range, thus determining that the E-phase stator winding has an inter-turn fault and is the faulty phase winding.
[0057] The sum of the amplitudes I3 of the second positive-sequence component and I4 of the second negative-sequence component, calculated using the fault diagnosis method of this application, gradually increases and fluctuates between 0.1 and 0.2. The curve of the sum of amplitudes I3 and I4 is shown below. Figure 5 As shown in (d) in the figure. The average value of the sum of amplitudes I3 and I4 calculated at t = 0.035s over the first 5 fundamental current cycles was used as the short-circuit turns ratio estimate μ = 0.120, which is basically consistent with the actual value of 0.12. The estimation result meets expectations.
[0058] pass Figure 4 and Figure 5 The simulation results of the simulation examples show that the fault diagnosis method of this application can quickly and accurately realize fault diagnosis and fault location, and estimate the short-circuit turns ratio, thereby realizing the assessment of the fault severity and having good dynamic response capability.
[0059] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.
Claims
1. A method for diagnosing a turn-to-turn short circuit fault of a five-phase permanent magnet synchronous motor, characterized by, The method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor includes: Phase currents during the operation of a five-phase permanent magnet synchronous motor are collected, and the phase currents are symmetrically transformed using the symmetrical component method to obtain four symmetrical current components. The four symmetrical current components include a first positive sequence component, a first negative sequence component, a second positive sequence component, and a second negative sequence component. The phase sequence corresponding to the first positive sequence component is phase A, phase B, phase C, phase D, and phase E; the phase sequence corresponding to the first negative sequence component is phase A, phase E, phase D, phase C, and phase B; the phase sequence corresponding to the second positive sequence component is phase A, phase C, phase E, phase B, and phase D; and the phase sequence corresponding to the second negative sequence component is phase A, phase D, phase B, phase E, and phase C. The magnitude and phase angle of each current symmetric component are obtained by performing a Fourier transform on the four current symmetric components. The inter-turn short-circuit fault diagnosis results for a five-phase permanent magnet synchronous motor are obtained based on the amplitudes and phase angles of the four symmetrical current components, including the calculation of the amplitude of the first positive sequence component. I 1 and the amplitude of the first negative sequence component I 2 amplitude ratio When an amplitude ratio is detected during the stable operation of a five-phase permanent magnet synchronous motor When the fluctuation is abnormal, 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. When an inter-turn short circuit fault is determined to exist in the five-phase permanent magnet synchronous motor, the phase angle of the second positive sequence component is calculated. Phase angle between 3 and the first negative sequence component Phase difference of 2 f = 3 - 2+90°, and based on the phase difference f Locate the faulty phase winding, which is the stator winding that has experienced an inter-turn short circuit fault.
2. The method for diagnosing inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor according to claim 1, characterized in that, The diagnostic results for inter-turn short-circuit faults in a five-phase permanent magnet synchronous motor also include: Based on the amplitude of the second positive sequence component I 3. Amplitude of the second negative sequence component I 4. Obtain the severity assessment results of the inter-turn short-circuit fault occurring in the faulty phase winding.
3. The method of claim 2, wherein, The severity assessment results of the inter-turn short-circuit fault occurring in the faulty phase winding include: Based on the amplitude of the second positive sequence component I 3. Amplitude of the second negative sequence component I 4. Calculate the short-circuit turns ratio of the faulty phase winding. μ As a result of the severity assessment, the short-circuit turns ratio is 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 short-circuit turns ratio of the faulty phase winding. μ The larger the value, the more severe the inter-turn short-circuit fault in the faulty phase winding.
4. The method of claim 1, wherein, Detection amplitude ratio Whether the fluctuations are abnormal includes: Calculate the amplitude ratio With the effective value of phase current I rms The ratio of the signal to the value of the signal When the decrease in signal ratio reaches a predetermined amplitude threshold, the amplitude ratio is determined. The fluctuation is abnormal; otherwise, determine the amplitude ratio. The fluctuations are normal.
5. The method of claim 1, wherein, According to the phase difference f Positioning the faulty phase winding comprises: Calculate phase difference f After an inter-turn short circuit fault occurs in any phase winding of a five-phase permanent magnet synchronous motor p Phase angle of phase current p phase difference p = f - p When the phase difference p When the average value is within a certain error range, the phase winding is determined. p The faulty phase winding; in, p =a,b,c,d,e represent phases A, B, C, D, and E of a five-phase permanent magnet synchronous motor, respectively.
6. The method of claim 3, wherein, determining a shorted turn ratio of a fault phase winding in a five-phase permanent magnet synchronous motor based on a magnitude of a second positive sequence component I 3 and a magnitude of a second negative sequence component I 4 the magnitude of the second positive sequence component I 3 and the magnitude of the second negative sequence component I 4 the average value over K current fundamental periods as the short circuit turn ratio of the faulted phase winding, the integer parameter K ≥ 2.