Six-phase permanent magnet synchronous motor stator interphase short circuit fault detection method

Abstract

The invention discloses a six-phase permanent magnet synchronous motor stator phase-to-phase short circuit fault detection method, which comprises the following steps: taking a stator three-phase winding with a 120-degree difference as a set, dividing the six-phase permanent magnet synchronous motor winding into two sets, and collecting a line voltage of a six-phase inverter side and a motor stator phase current; extracting a total negative-sequence component of each three-phase current through a symmetric component method, eliminating a negative-sequence current component introduced by inherent asymmetry of a stator winding and interference of a nonlinear sensor and the like, and obtaining a negative-sequence current component generated by a stator fault; and judging whether the six-phase permanent magnet synchronous motor breaks down or not according to the negative sequence current component generated by the stator fault. According to the method, after the motor is judged to have the fault, the phase-to-phase short-circuit fault phase can be further determined through the line voltage, and a basis is provided for hazard assessment, detection and protection research of the phase-to-phase short-circuit fault of the six-phase permanent magnet synchronous motor. According to the method, only current and voltage signals are measured, the number of parameters needing to be measured is small, the sensor requirement is low, and state monitoring is easy to achieve.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-phase permanent magnet motor fault detection, and in particular to a method for detecting inter-phase short circuit faults of stators of six-phase permanent magnet synchronous motors. Background Art

[0002] The characteristics of multi-phase permanent magnet motors, such as high redundancy freedom, high power density, and high operating efficiency, make them widely used in electric vehicles, electric ship propulsion, aerospace, and other occasions that require high reliability and high power output. When a multi-phase permanent magnet motor has a phase-to-phase short circuit fault, the current flowing through the inverter switch tube rises sharply in a short time, which can easily burn the switch tube and damage the motor controller, posing a great safety hazard. When a phase-to-phase short circuit fault occurs, timely detection of the fault and positioning of the faulty phase are currently urgent problems to be solved. Summary of the invention

[0003] To this end, the present invention provides a method for detecting interphase short-circuit faults in a six-phase permanent magnet synchronous motor stator, which can accurately determine whether a motor fault occurs through negative sequence current, and further determine the interphase short-circuit fault phase through line voltage.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The present invention first provides a method for detecting a stator interphase short circuit fault of a six-phase permanent magnet synchronous motor, comprising the following steps:

[0006] 1) The three-phase stator windings with a mutual difference of 120° are used as one set, and the windings of the six-phase permanent magnet synchronous motor are divided into two sets; the motor stator phase current of the six-phase permanent magnet synchronous motor is collected;

[0007] 2) Calculate the total negative sequence component of each set of stator three-phase winding current by the symmetrical component method, wherein the total negative sequence component includes the negative sequence current generated by the inherent asymmetry of the stator winding, the negative sequence current generated by the nonlinear sensor and the negative sequence current generated by the stator fault;

[0008] 3) Eliminate the negative sequence current component introduced by the inherent asymmetry of the stator winding and the nonlinear sensor interference in the total negative sequence component, and obtain the negative sequence current component generated by the stator fault;

[0009] 4) Determine whether the six-phase permanent magnet synchronous motor has a fault based on the negative sequence current component generated by the stator fault.

[0010] As a preferred embodiment of the present invention, whether a six-phase permanent magnet synchronous motor has a fault is judged based on the negative sequence current component generated by the stator fault: if the system operates normally, the negative sequence current component generated by the stator fault is 0; if the negative sequence current component generated by the stator fault is not 0, then an interphase short circuit fault occurs in the six-phase permanent magnet synchronous motor.

[0011] As a preferred embodiment of the present invention, if a six-phase permanent magnet synchronous motor fails, the line voltage between each phase of the six-phase permanent magnet synchronous motor winding is collected to determine the faulty phase; the three-phase windings in the first set of windings are set to be phase A, phase B and phase C, and the three-phase windings in the second set of windings are set to be phase U, phase V and phase W, respectively. The line voltage between each phase of the six-phase permanent magnet synchronous motor winding includes the line voltage between phase A and phase B, the line voltage between phase B and phase C, the line voltage between phase C and phase A, the line voltage between phase U and phase V, the line voltage between phase V and phase W, and the line voltage between phase W and phase U.

[0012] Furthermore, if a fault occurs in the six-phase permanent magnet synchronous motor, the line voltage between each phase of the six-phase permanent magnet synchronous motor winding is collected to determine the fault phase. Specifically, when the motor is operating normally, the line voltage amplitude on the inverter side of the six-phase permanent magnet synchronous motor is the DC source voltage U dc When a six-phase permanent magnet synchronous motor fails, due to the appearance of interphase short-circuit resistance, the line voltage amplitude of the two faulty phases is smaller than the DC source voltage, and as the fault deepens, the line voltage amplitude of the two faulty phases decreases, and the line voltage amplitude of the remaining two phases remains unchanged at U dc , thereby determining the fault phase.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention discloses a method for detecting interphase short-circuit faults of stators of six-phase permanent magnet synchronous motors, which can accurately determine whether a motor fails through negative sequence current, and further determine the interphase short-circuit fault phase through line voltage. The detection method can diagnose the occurrence of faults and locate the fault phase in real time, and can also indicate the severity of the fault, thereby improving the fault tolerance of the motor, extending the service life of the motor, and improving the safety of the system, and providing a basis for the hazard assessment, detection and protection research of interphase short-circuit faults of six-phase permanent magnet synchronous motors. At the same time, the method only measures current and voltage signals, requires fewer parameters to be measured, has low sensor requirements, is easy to implement state monitoring, and has wide engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The figure is a flow chart of a method for detecting stator interphase short circuit faults of a six-phase permanent magnet synchronous motor.

[0016] Figure 2 This is the topology diagram of the drive circuit of the six-phase permanent magnet synchronous motor.

[0017] Figure 3 This is a diagram of the AB phase short circuit situation in a six-phase inverter according to a specific embodiment of the present invention.

[0018] Figure 4 This is a diagram of a BC phase short circuit in a six-phase inverter according to a specific embodiment of the present invention.

[0019] Figure 5 This is a diagram of a CA phase short circuit in a six-phase inverter according to a specific embodiment of the present invention.

[0020] Figure 6 This is a diagram of UV phase short circuit in a six-phase inverter according to a specific embodiment of the present invention.

[0021] Figure 7 This is a diagram of a VW phase short circuit in a six-phase inverter according to a specific embodiment of the present invention.

[0022] Figure 8 This is a diagram of a WU phase short circuit in a six-phase inverter according to a specific embodiment of the present invention.

[0023] Fig. 9 This is a simulation result diagram of the negative sequence current amplitude of the ABC three-phase winding of a six-phase permanent magnet synchronous motor according to a specific embodiment of the present invention.

[0024] Fig.10 This is a simulation result diagram of the negative sequence current amplitude of the UVW three-phase winding of a six-phase permanent magnet synchronous motor according to a specific embodiment of the present invention.

[0025] Fig.11 The figure is a simulation result of the line voltage between the three-phase windings ABC of a six-phase inverter according to a specific embodiment of the present invention.

[0026] Fig.12 The figure is a simulation result of the line voltage between the UVW three-phase windings of a six-phase inverter according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0028] like Figure 1 As shown, the method for detecting interphase short circuit fault of stator of six-phase permanent magnet synchronous motor of the present invention specifically comprises the following steps:

[0029] Step 101, taking the stator three-phase windings with a mutual difference of 120° as one set, dividing the six-phase permanent magnet synchronous motor windings into two sets, and collecting the line voltage and the motor stator phase current on the six-phase inverter side;

[0030] In a specific embodiment of the present invention, the six-phase permanent magnet synchronous motor winding adopts a double Y-shifted 30° six-phase permanent magnet synchronous motor winding, and the double Y-shifted 30° six-phase permanent magnet synchronous motor winding is divided into two sets of independent windings with a spatial electrical angle difference of 30°, with the stator three-phase windings of the double Y-shifted 30° windings being a set with a 120° difference. The three-phase windings of the first set of windings are defined as phase A, phase B, and phase C, and the second set of windings are defined as phase U, phase V, and phase W; a voltage sensor is used to collect line voltage, wherein the line voltage includes the line voltage between phase A and phase B, the line voltage between phase B and phase C, the line voltage between phase C and phase A, the line voltage between phase U and phase V, the line voltage between phase V and phase W, and the line voltage between phase W and phase U.

[0031] Step 102: Calculate the total negative sequence component of each set of stator three-phase winding current by a symmetrical component method, wherein the total negative sequence component includes the negative sequence current generated by the inherent asymmetry of the stator winding, the negative sequence current generated by the nonlinear sensor, and the negative sequence current generated by the stator fault;

[0032] In one embodiment of the present invention, taking the first set of windings including phase A, phase B and phase C in a six-phase permanent magnet synchronous motor as an example, the total negative sequence component of the three-phase winding current is calculated, specifically:

[0033] Get the positive, negative and zero sequence components of the current of the first set of stator windings of the motor

[0034]

[0035] in They are A, B, and C three-phase currents respectively;

[0036] Total negative sequence current Negative sequence currents due to inherent asymmetry in stator windings Negative sequence current generated by nonlinear sensors and negative sequence current generated by stator fault composition:

[0037]

[0038] The negative sequence current generated by the inherent asymmetry of the stator winding is:

[0039]

[0040] The A and B phase currents are collected by current sensors, and the C phase current can be expressed as:

[0041]

[0042] Therefore, the negative sequence current generated by the inherent asymmetry of the stator winding It is expressed as:

[0043]

[0044] Nonlinear sensors make the measured value the true value of the ke jp times, k is the amplitude change, and p is the phase change. Negative sequence current generated by nonlinear sensor It is expressed as:

[0045]

[0046] k a , k b 、p a 、p b are the nonlinear gain and phase angle of the current sensor for phase A and phase B respectively. Therefore, the negative sequence current generated by the nonlinear sensor can be transformed into:

[0047]

[0048] Similarly, the positive sequence current expression under nonlinear sensor can be derived:

[0049]

[0050] Combined with the above formula, the negative sequence current component generated by the nonlinear sensor can be separated from the positive sequence current

[0051]

[0052] Step 103, eliminating the negative sequence current component introduced by the inherent asymmetry of the stator winding and the nonlinear sensor interference in the total negative sequence component, and obtaining the negative sequence current component generated by the stator fault;

[0053] Since in practice k a , k b 、p a 、p b It is difficult to detect, so normally there is only negative sequence current generated by the nonlinear sensor in They are:

[0054]

[0055] The total negative sequence current generated by the nonlinear sensor is Half of the sum:

[0056]

[0057] The value of is approximately 1, so:

[0058]

[0059] In summary, the negative sequence current generated by stator fault alone is:

[0060]

[0061] Step 104: judging whether the six-phase permanent magnet synchronous motor has a fault according to the negative sequence current component generated by the stator fault; specifically:

[0062] If the system operates normally, only positive-sequence components exist in the motor stator current; if negative-sequence current components appear, a phase-to-phase short circuit fault may occur in the six-phase permanent magnet synchronous motor; in a specific embodiment of the present invention, the following situations are included: AB phase-to-phase short circuit, BC phase-to-phase short circuit, CA phase-to-phase short circuit, UV phase-to-phase short circuit, VW phase-to-phase short circuit, and WU phase-to-phase short circuit.

[0063] If the motor is not faulty, the system continues to operate normally; if the motor is faulty, the faulty phase is determined based on the line voltage;

[0064] In one embodiment of the present invention, when the motor is operating normally, the line voltage amplitude on the inverter side is set to be the DC source voltage U dc When the motor fails, due to the appearance of interphase short-circuit resistance, the line voltage amplitude of the faulty two phases is smaller than the DC source voltage U dc As the fault severity increases, the line voltage amplitude of the two faulty phases decreases, while the line voltage amplitude of the other two phases remains unchanged, still U dc Therefore, after determining that the motor has a fault, the faulty phase can be determined by detecting the line voltage.

[0065] Figure 2 The topology diagram of the driving circuit of the six-phase permanent magnet synchronous motor is shown in Figure 2. The motor adopts a double Y-shifted 30° six-phase permanent magnet synchronous motor. According to the six-phase structure of the motor, the inverter is composed of two three-phase bridge structures in parallel, and each three-phase bridge adopts a two-level topology. The inverter contains a total of six phases, and each phase bridge arm contains two IGBT or MOSFET switch tubes. Figure 3-8 FIG. 1 shows a short circuit between two phases in a six-phase inverter according to a specific embodiment of the present invention, wherein Figure 3 For the AB phase short circuit situation, Figure 4 In the case of BC phase short circuit, Figure 5 For the CA phase short circuit situation, Figure 6 UV phase short circuit situation, Figure 7 In the case of VW phase short circuit, Figure 8 It is the case of WU phase short circuit.

[0066] like Fig. 9 and Fig.10The figure shows the simulation result of the negative sequence current amplitude of each winding of a six-phase permanent magnet synchronous motor of a specific embodiment of the present invention. In the embodiment of the present invention, the short circuit fault time between the stator A phase winding and the B phase winding is set to 5s-5.5s, and the short circuit resistance is 0.0015Ω; the short circuit fault time between the stator A phase winding and the B phase winding is set to 6s-6.5s, and the short circuit resistance is 0.001Ω; the short circuit fault time between the stator A phase winding and the B phase winding is set to 7s-7.5s, and the short circuit resistance is 0.0005Ω; the short circuit fault time between the stator B phase winding and the C phase winding is set to 8s-8.5s, and the short circuit resistance is 0.0015Ω; when the short circuit fault occurs between the stator B phase winding and the C phase winding The time between the stator B-phase winding and the C-phase winding is 9s-9.5s, and the short-circuit resistance is 0.001Ω; the short-circuit fault time between the stator B-phase winding and the C-phase winding is 10s-10.5s, and the short-circuit resistance is 0.0005Ω; the short-circuit fault time between the stator C-phase winding and the A-phase winding is 11s-11.5s, and the short-circuit resistance is 0.0015Ω; the short-circuit fault time between the stator C-phase winding and the A-phase winding is 12s-12.5s, and the short-circuit resistance is 0.001Ω; the short-circuit fault time between the stator C-phase winding and the A-phase winding is 13s-13.5s, and the short-circuit resistance is 0.0005Ω. The motor mechanical angular velocity given value is 1885rad / s, and the motor load torque is 325N·m.

[0067] Depend on Fig. 9 and Fig.10 It can be seen that due to the phase-to-phase short circuit fault, negative sequence currents are generated in the three phases ABC and UVW. Since the short circuit fault occurs between the three phases ABC, the negative sequence current amplitude of the three phases ABC gradually increases with the deepening of the fault. In contrast, the negative sequence current amplitude of the three phases UVW is smaller than that of the three phases ABC. Therefore, it is possible to determine whether the motor has a phase-to-phase short circuit fault based on the negative sequence current amplitude, but it is impossible to locate the fault phase.

[0068] Fig.11 and Fig.12 The simulation results of the line voltage between the six-phase inverters are shown in Figure 2. Fig. 9 and Fig.10 The same simulation parameters are used. Fig.11 and Fig.12 From the line voltage waveforms between the six phases of the inverter output, it can be seen that the line voltage between the two phases with interphase short circuit fault will decrease, and as the fault severity deepens, the line voltage drop becomes more serious. The line voltage amplitude between the non-fault phases remains unchanged. Therefore, the location of the interphase short circuit fault and the severity of the fault can be determined based on the line voltage waveform.

[0069] In summary, the present solution can judge whether the motor fails and determine the phase of the interphase short circuit fault according to the change phenomenon of the negative sequence current and the line voltage by judging the negative sequence current and the line voltage, and the judgment process is accurate and rapid. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator, characterized in that: The following steps are involved: 1) The three-phase stator windings with a mutual difference of 120° are used as one set, and the windings of the six-phase permanent magnet synchronous motor are divided into two sets; the motor stator phase current of the six-phase permanent magnet synchronous motor is collected; 2) Calculate the total negative sequence component of each set of stator three-phase winding current by the symmetrical component method, wherein the total negative sequence component includes the negative sequence current generated by the inherent asymmetry of the stator winding, the negative sequence current generated by the nonlinear sensor and the negative sequence current generated by the stator fault; 3) Eliminate the negative sequence current component introduced by the inherent asymmetry of the stator winding and the nonlinear sensor interference in the total negative sequence component, and obtain the negative sequence current component generated by the stator fault; 4) Determine whether the six-phase permanent magnet synchronous motor has a fault based on the negative sequence current component generated by the stator fault.

2. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 1, characterized in that: The six-phase permanent magnet synchronous motor winding described in step 1) is a double Y-shifted 30° six-phase permanent magnet synchronous motor winding. The double Y-shifted 30° six-phase permanent magnet synchronous motor winding is divided into two sets of independent windings with a spatial electrical angle difference of 30°, with the stator three-phase windings with a mutual difference of 120° as a set.

3. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 1, characterized in that: The calculation formula for calculating the total negative sequence component of each set of stator three-phase winding current by the symmetrical component method in step 2) is: in, They are respectively the positive sequence component, negative sequence component and zero sequence component in the stator three-phase winding, j is the imaginary unit, They are the currents of the three phases in the three-phase winding of the stator.

4. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 1, characterized in that: The negative sequence current generated by the inherent asymmetry of the stator winding in step 2) is obtained by the following method: the three-phase windings in the stator three-phase winding are set to be phase A, phase B and phase C respectively; when the currents of phase A and phase B are known, the current of phase C is expressed as: Then, the negative sequence current generated by the inherent asymmetry of the stator winding is: in, It is the negative sequence current generated by the inherent asymmetry of the stator winding; They are the currents of the three phases in the three-phase winding of the stator.

5. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 4, characterized in that: The calculation formula of the negative sequence current generated by the nonlinear sensor in step 2) is: because The value of is approximately 1, so: in, is the negative sequence current generated by the nonlinear sensor, k a , k b 、p a 、p b are the nonlinear gain and phase angle of the A-phase and B-phase current sensors respectively.

6. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 5, characterized in that: The negative sequence current generated by the stator fault is the total negative sequence component minus the negative sequence current generated by the inherent asymmetry of the stator winding and the negative sequence current generated by the nonlinear sensor: in, is the negative sequence current generated by stator fault, is the total negative sequence component.

7. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 1, characterized in that: According to the negative sequence current component generated by the stator fault, it is judged whether the six-phase permanent magnet synchronous motor has a fault: if the system operates normally, the negative sequence current component generated by the stator fault is 0; if the negative sequence current component generated by the stator fault is not 0, then the six-phase permanent magnet synchronous motor has an interphase short circuit fault.

8. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 1, characterized in that: If a fault occurs in the six-phase permanent magnet synchronous motor, the line voltage between each phase of the six-phase permanent magnet synchronous motor winding is collected to determine the fault phase; the three-phase windings in the first set of windings are set to be phase A, phase B and phase C, and the three-phase windings in the second set of windings are set to be phase U, phase V and phase W. The line voltage between each phase of the six-phase permanent magnet synchronous motor winding includes the line voltage between phase A and phase B, the line voltage between phase B and phase C, the line voltage between phase C and phase A, the line voltage between phase U and phase V, the line voltage between phase V and phase W, and the line voltage between phase W and phase U.

9. The method for detecting interphase short circuit fault of a six-phase permanent magnet synchronous motor stator according to claim 8, characterized in that: If a six-phase permanent magnet synchronous motor fails, the line voltage between each phase of the six-phase permanent magnet synchronous motor winding is collected to determine the fault phase. Specifically, when the motor is operating normally, the line voltage amplitude on the inverter side of the six-phase permanent magnet synchronous motor is the DC source voltage U dc When a six-phase permanent magnet synchronous motor fails, due to the appearance of interphase short-circuit resistance, the line voltage amplitude of the two faulty phases is smaller than the DC source voltage, and as the fault deepens, the line voltage amplitude of the two faulty phases decreases, and the line voltage amplitude of the remaining two phases remains unchanged at U dc , thereby determining the fault phase.

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