A five-phase permanent magnet motor driving system open-phase fault diagnosis method

Abstract

The application discloses a kind of five-phase permanent magnet motor drive system open-phase fault diagnosis method, it is related to the technical field of fault diagnosis, it solves the technical problem that existing technology is easily influenced by motor load in the process of five-phase permanent magnet motor drive system open-phase fault diagnosis, poor reliability and robustness;The five-phase stator current of five-phase permanent magnet motor is clark converted to obtain fault detection variable, whether five-phase permanent magnet motor is normally operated according to fault detection variable;When five-phase permanent magnet motor is abnormal, two space current vectors are obtained by spatial vector decomposition transformation to five-phase stator current, and then fault diagnosis variable is constructed, to realize fault phase positioning;The application can effectively realize five-phase permanent magnet motor single-phase and two-phase open-phase fault detection and positioning, and has the advantages of simple, high reliability, strong robustness, low cost, easy to realize.

Description

Technical Field

[0001] This invention belongs to the field of fault diagnosis and relates to a phase loss fault diagnosis technology for a five-phase permanent magnet motor drive system, specifically a phase loss fault diagnosis method for a five-phase permanent magnet motor drive system. Background Technology

[0002] Compared to three-phase motors, five-phase permanent magnet motors have lower torque ripple, higher power density, and stronger fault tolerance, making them widely used in many industries. However, during long-term operation, there is an urgent need to improve the reliability and safety of these motors, especially in demanding operating conditions. Failures can lead to secondary failures in other components, and even cause significant economic losses and safety accidents.

[0003] Existing methods for diagnosing phase loss faults in permanent magnet motor drive systems can be categorized from a signal perspective into voltage-based and current-based methods. Current-based methods utilize fault characteristic quantities extracted from the stator current to diagnose phase loss faults. Compared to voltage-based methods, current-based methods do not require additional sensors and offer advantages such as simplicity, low cost, and high reliability. However, existing current-based methods generally only diagnose single-phase open-circuit faults in five-phase permanent magnet motor drive systems and are susceptible to motor load variations, exhibiting poor reliability and robustness. Therefore, this patent proposes a method for diagnosing phase loss faults in five-phase permanent magnet motor drive systems. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art; to this end, the present invention proposes a method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system, which solves the technical problem that the prior art is easily affected by the motor load and has poor reliability and robustness in the process of diagnosing phase loss faults in a five-phase permanent magnet motor drive system.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system, comprising:

[0006] S100: Collects the five-phase stator current of a five-phase permanent magnet motor;

[0007] S200: Perform Clarke transformation on the five-phase stator current to obtain the fundamental current component and the third harmonic current component; calculate the fault detection variable based on the fundamental current component and the third harmonic current component.

[0008] S300: Compare the fault detection variables with the set threshold to determine whether the five-phase permanent magnet motor has experienced a phase loss fault; if so, locate the faulty phase.

[0009] S400: The five-phase stator current is transformed into two spatial current vectors through spatial vector decomposition. Fault diagnosis variables are constructed based on the two spatial current vectors to realize fault phase location.

[0010] Preferably, the Clarke transformation of the five-phase stator current described in S200 to obtain the fundamental current component and the third harmonic current component includes:

[0011] The five-phase stator currents are labeled as is1, is2, is3, is4, and is5, respectively.

[0012] The fundamental current components iα and iβ, and the third harmonic current components iα3 and iβ3 are obtained through formulas 1 and 2; where formula 1 is... Formula 2 is

[0013] Preferably, the fault detection variables are calculated based on the fundamental current component and the third harmonic current component, including:

[0014] The fault detection variable F is calculated using Formula 3. fault Formula 3 is: in, p is the number of pole pairs of the motor, Ω(t) is the real-time rotor speed, and when the five-phase permanent magnet motor has an open circuit fault, the fault detection variable is greater than 0.

[0015] Preferably, the process of transforming the five-phase stator currents into two space current vectors through space vector decomposition in step S400 includes:

[0016] Through formula The five-phase stator currents are decomposed into two space vector currents; where ε = 1, 3, i η For phase current, Let be the current vector in the first plane. This is the current vector in the third plane.

[0017] Preferably, the fault diagnosis variables constructed based on two space current vectors as described in S400 include:

[0018] The zero-sequence current component is labeled as i0; where...

[0019] Combining the zero-sequence current component, the current i is represented by two space vector currents. η ,get

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention performs Clarke transformation on the five-phase stator current of the five-phase permanent magnet motor to obtain fault detection variables, and determines whether the five-phase permanent magnet motor is operating normally based on the fault detection variables; when the five-phase permanent magnet motor is operating abnormally, it performs spatial vector decomposition transformation on the five-phase stator current to obtain two spatial current vectors, and then constructs fault diagnosis variables to realize fault phase location; the present invention can effectively realize single-phase and two-phase phase loss fault detection and location of five-phase permanent magnet motors, and has the advantages of simplicity, high reliability, strong robustness, low cost and ease of implementation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram illustrating the principle and steps of the present invention;

[0023] Figure 2 This is a topology diagram of the five-phase permanent magnet motor of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figures 1-2 The first aspect of this invention provides a method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system, comprising:

[0026] S100: Collects the five-phase stator current of a five-phase permanent magnet motor;

[0027] S200: Perform Clarke transformation on the five-phase stator current to obtain the fundamental current component and the third harmonic current component; calculate the fault detection variable based on the fundamental current component and the third harmonic current component.

[0028] S300: Compare the fault detection variables with the set threshold to determine whether the five-phase permanent magnet motor has experienced a phase loss fault; if so, locate the faulty phase.

[0029] S400: The five-phase stator current is transformed into two spatial current vectors through spatial vector decomposition. Fault diagnosis variables are constructed based on the two spatial current vectors to realize fault phase location.

[0030] In S200, the five-phase stator current is subjected to a Clarke transformation as described in Formula 1 to obtain the fundamental current component and the third harmonic current component; specifically including:

[0031] The five-phase stator currents are labeled as is1, is2, is3, is4, and is5, respectively. The fundamental current components iα and iβ, as well as the third harmonic current components iα3 and iβ3, are obtained through formulas 1 and 2.

[0032] Formula 1 above is Formula 2 is

[0033] In S300, fault detection variables are calculated based on the fundamental current component and the third harmonic current component, including:

[0034] The fault detection variable F is calculated using Formula 3. fault Formula 3 is: in, p represents the number of pole pairs of the motor, and Ω(t) represents the real-time rotor speed. When the five-phase permanent magnet motor experiences an open-circuit fault, the fault detection variable is greater than 0. When the five-phase permanent magnet motor is running normally, the fault detection variable is 0. The corresponding set threshold σi is selected based on the actual parameters of the five-phase permanent magnet motor.

[0035] 1) When the motor is running in good health

[0036] The five-phase stator current is given by formula 4. Formula 4: Combining Formula 1, we obtain Formula 5, which is as follows: The calculated fault detection variable is F. fault =0.

[0037] 2) Single-phase failure (taking phase A as an example)

[0038] The five-phase stator current is given by formula 6. Formula 6: Combining Formula 1, we can obtain Formula 7 and Formula 8. Formula 7 is as follows: Formula 8 is specifically as follows The calculated fault detection variable is F. fault =0.118.

[0039] 3) When two adjacent phases fail (taking phase AB as an example)

[0040] The five-phase stator current is given by formula 9. Formula 9: Combining Formula 1, we can obtain Formula 10 and Formula 11. Formula 10 is as follows: Specifically, Equation 11 is Then the calculated fault detection variable is F fault = 0.3185.

[0041] 4) When two non - adjacent phases are open - circuited (taking phases A and C as an example)

[0042] The five - phase stator current is as shown in Equation 12. Equation 12: Combining Equation 1 gives Equations 13 and 14. Specifically, Equation 13 is: Specifically, Equation 14 is Then the calculated fault detection variable is F fault = 0.178.

[0043] In S400, the five - phase stator current is transformed through space vector decomposition to obtain two space current vectors, and the fault diagnosis variable ρ is calculated according to Equation 15 η , and Equation 15 is: When an open - circuit fault occurs in a certain phase, the corresponding fault diagnosis variable ρ η = 1, thus achieving the location of the fault phase. In theory, it is necessary to judge whether ρ η is equal to 1. However, in simulation and experiments, it is impossible to perfectly converge to 1. Therefore, the added judgment condition is M1 < ρ η < M2, where M1 and M2 are two set thresholds. M1 is slightly less than 1, and M2 is slightly greater than 1. The values of M1 and M2 are specifically determined by the parameters of the motor itself. The judgment condition makes ρ η roughly converge around 1.

[0044] Decompose the five - phase stator current by space vector to obtain two space vector currents, including:

[0045] Through Equation Decompose the five - phase stator current by space vector to obtain two space vector currents; where ε = 1, 3, i η is the phase current, is the current vector in the first plane, which is related to energy conversion and torque generation; is the current vector in the third plane, which is related to copper loss.

[0046] Under normal operating conditions, the third - harmonic vector is almost zero when the input current is sinusoidal. The zero - sequence current component is:

[0047] When an open - circuit fault occurs in the motor, the harmonic current of the motor changes significantly. Using VSD inverse transformation, the phase current is represented by space current vectors: Among them, the operator · means multiplying the real parts of two vectors and the imaginary parts of two vectors respectively, and then summing them.

[0048] Taking a star-connected five-phase permanent magnet motor as an example, its zero-sequence current component is 0, that is: i0 = 0; therefore, we get

[0049] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system, characterized in that, include: S100: Collects the five-phase stator current of a five-phase permanent magnet motor; S200: Perform Clarke transformation on the five-phase stator current to obtain the fundamental current component and the third harmonic current component; Calculate the fault detection variables based on the fundamental current component and the third harmonic current component; S300: Compares the fault detection variables with the set threshold to determine whether the five-phase permanent magnet motor has experienced a phase loss fault; If yes, then proceed with fault phase location; S400: The five-phase stator current is transformed into two spatial current vectors through spatial vector decomposition. Fault diagnosis variables are constructed based on the two spatial current vectors to realize fault phase location. Fault detection variables are calculated based on the fundamental current component and the third harmonic current component, including: The fault detection variable is calculated using Formula 3. Formula 3 is: ;in, , p This represents the number of pole pairs of the motor. Ω(t) The real-time rotor speed is the value of the fault detection variable when the five-phase permanent magnet motor has an open circuit fault. The method described in S400, which transforms the five-phase stator currents into two space current vectors through space vector decomposition, includes: Through formula The five-phase stator currents are decomposed into two space vector currents; where ε = 1 and 3. For phase current, = ; The current vector in the first plane, The current vector in the third plane; The fault diagnosis variables are calculated according to Formula 15. Formula 15 is: The judgment condition is: , Set two thresholds, Slightly less than 1 Slightly greater than 1 The specific value is determined by the parameters of the motor itself, and the judgment condition makes... It roughly converges to around 1, thus achieving fault phase localization.

2. The method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system according to claim 1, characterized in that, The Clarke transformation of the five-phase stator current described in S200 yields the fundamental current component and the third harmonic current component, including: The five-phase stator currents are respectively labeled as , , , , ; The fundamental current component is obtained using Equations 1 and 2. , and the third harmonic current component , ; where, Formula 1 is Formula 2 is .

3. The method for diagnosing phase loss faults in a five-phase permanent magnet motor drive system according to claim 1, characterized in that, The fault diagnosis variables constructed based on two space current vectors as described in S400 include: The zero-sequence current component is labeled as ;in, ; Combining the zero-sequence current component, the current is represented by two space vector currents. ,get .

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