A permanent magnet synchronous motor short circuit fault model, a fault simulation method and a traction system health diagnosis function test method

Abstract

This invention discloses a short-circuit fault model, fault simulation method, and traction system health diagnosis function testing method for a permanent magnet synchronous motor. The method includes constructing a mathematical model of short-circuit faults for both the inverter and the permanent magnet synchronous motor to simulate phase-to-phase short-circuit faults occurring within the windings. Based on the mathematical model, different parameters are set to simulate normal motor operation, inter-turn short-circuit faults, phase-to-phase short-circuit faults occurring within the windings, and phase-to-phase short-circuit faults occurring at the winding ends. This allows for arbitrary switching between various short-circuit fault states and simulation of fault severity. The short-circuit fault modeling technology of this invention quickly switches between simulating various faults by modifying the short-circuit turns ratio. This solves the problem of low testing efficiency caused by the inconsistency in modeling equations, which prevents the use of a unified model for testing various short-circuit faults and necessitates multiple model downloads for different short-circuit faults.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet synchronous motor technology, and relates to a short-circuit fault model, fault simulation method and traction system health diagnosis function test method for permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have become a top choice in modern high-performance motor drive systems due to their high efficiency, high power density, excellent control performance, and high reliability. In recent years, they have also been gradually adopted in rail transit vehicles. With the advancement of intelligent operation and maintenance technologies, health diagnosis of traction systems has become a core technology for traction control. For short-circuit faults in the windings of PMSMs that may occur during operation, the traction system needs to diagnose and handle them promptly. Otherwise, problems such as overheating and vibration may lead to more serious faults, affecting train operation safety. The feasibility of health diagnosis algorithms for traction systems requires extensive testing. However, traditional ground testing requires damaging the motor, which not only causes irreversible damage to the motor and other testing equipment and increases product development costs but also poses significant safety hazards. Therefore, it is imperative to develop a versatile, low-cost, and low-safety-hazard testing system.

[0003] Technical solution of existing technology 1

[0004] A finite element model of short-circuit fault in the winding of a permanent magnet synchronous motor was constructed using electromagnetic simulation software. A health diagnosis algorithm model for the traction system was built using MATLAB. The feasibility of the health diagnosis algorithm for the traction system was verified by joint simulation using electromagnetic simulation software and MATLAB software.

[0005] Disadvantages of existing technology 1 Although this method can simulate short-circuit faults at any location, its simulation step size is too large, around 100µs, which has a large error compared to the actual system's operating speed, making it impossible to accurately verify the traction system health diagnosis algorithm. At the same time, the use of electromagnetic simulation software makes the simulation run time very long (each simulation takes several hours to several days), resulting in low testing efficiency.

[0006] Technical solution of existing technology 2 To address the shortcomings of the first technique, a mathematical model of inter-turn short-circuit faults or phase-to-phase short-circuit faults occurring at the winding ends of a permanent magnet synchronous motor was built and downloaded to a simulator. This model was then connected to the physical traction control unit to construct a hardware-in-the-loop simulation platform. The hardware-in-the-loop simulation was used to verify the health diagnosis algorithm of the traction system running in the traction control unit.

[0007] Disadvantages of existing technology 2 While hardware-in-the-loop (HIL) simulation improves the accuracy and efficiency of testing, its testing scope is limited to the health diagnosis algorithms of the traction control unit for inter-turn short-circuit faults or phase-to-phase short-circuit faults occurring at the winding ends. It cannot verify the corresponding health diagnosis algorithms for phase-to-phase short-circuit faults occurring inside the winding, making the traction system health diagnosis algorithm test incomplete. In addition, the simulation of inter-turn short-circuit faults and phase-to-phase short-circuit faults occurring at the winding ends are conducted separately, and it is not possible to switch faults at any time to test the health diagnosis algorithms for multiple faults, which has a certain impact on testing efficiency. Summary of the Invention

[0008] To address the issues of incomplete traction system health diagnosis algorithm testing due to the inability of current hardware-in-the-loop (HIL) simulation testing systems to simulate phase-to-phase short-circuit faults occurring within windings, and the need for multiple models to simulate different types of winding short-circuit faults in current HIL systems, which affects testing efficiency, this invention aims to improve the existing HIL system by resolving these two issues. This will completely replace existing technology one and thoroughly solve the problems of low simulation accuracy and low testing efficiency in the joint simulation testing method of using electromagnetic simulation software to construct short-circuit faults in permanent magnet synchronous motor windings for traction system health diagnosis algorithms. The technical solution adopted in this invention is: an inverter and permanent magnet synchronous motor short-circuit fault model, including: a permanent magnet synchronous motor short-circuit fault model based on the dq coordinate system, an inverter three-phase voltage solution model, a dq-axis voltage solution model, and an inverter three-phase current solution model. The short-circuit fault model of the permanent magnet synchronous motor based on the dq coordinate system includes a solution model for the dq axis current and short-circuit current, and a solution model for the voltage increment. The inverter three-phase voltage solution model is used to solve the three-phase voltage output by the inverter to the motor based on the three-phase PWM pulses, intermediate DC voltage and three-phase inverter current; The dq-axis voltage solution model is used to convert the three-phase motor voltage transmitted by the inverter three-phase voltage solution model into dq-axis voltage through 3s / 2r transformation, and then output it to the permanent magnet synchronous motor short-circuit fault model based on the dq coordinate system. The voltage increment solution model is used to solve the dq axis voltage increment caused by a short circuit fault; The dq-axis current and short-circuit current solution model is used to output the short-circuit current i on the short-circuit resistor based on the dq-axis voltage transmitted by the dq-axis voltage solution model and the dq-axis voltage increment caused by the short-circuit fault transmitted by the voltage increment solution model. f d-axis current, q-axis current; The inverter three-phase current model is used to convert the d-axis current and q-axis current output from the motor dq-axis current and short-circuit current solution model into three-phase current through a 2r / 3s transformation, and then output it to the inverter three-phase voltage solution model.

[0009] Furthermore, the modeling process for the inverter three-phase voltage solution model is as follows: When the upper arm of phase A is turned on, the voltage of phase A is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase A is conducting, the phase A voltage is 0. When neither the upper nor lower arm of phase A is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase A is freewheeling, the phase A voltage is taken as the voltage of the intermediate supporting capacitor. When the diode in the lower bridge arm of phase A freewheels, the voltage of phase A is 0. When the upper arm of phase B is turned on, the phase B voltage is taken as the voltage of the intermediate support capacitor. When the lower arm of phase B is conducting, the phase B voltage is 0. When neither the upper nor lower arm of phase B is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode of the upper arm of phase B is freewheeling, the phase B voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase B freewheels, and the phase B voltage is 0. When the upper arm of phase C is turned on, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase C is conducting, the phase C voltage is 0. When neither the upper nor lower arm of phase C is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase C is freewheeling, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase C freewheels, and the voltage of phase C is 0.

[0010] Furthermore, the formula for the dq-axis current calculation model is as follows:

[0011] in, , These are the dq axis voltages, , These are the dq-axis currents, respectively. , These are the d-q axis inductors, , These represent the dq-axis voltage increments caused by short-circuit faults; in this model formula, , It was obtained by solving the dq-axis voltage model; , The current is obtained through the voltage increment solution model, thereby determining the dq-axis current of the motor. , .

[0012] Furthermore: When phases B and C are short-circuited, the formula for the voltage increment solution model is as follows: in, The rotor position angle of the permanent magnet synchronous motor is obtained by integrating the rotational speed ω. The short-circuit current on the short-circuit resistor is obtained from the short-circuit current solution model, and m and n are the short-circuit ratios of the B-phase and C-phase windings, respectively.

[0013] When phases B and C are short-circuited, the formula for the short-circuit current calculation model is as follows:

[0014] in, , , and are the self-inductances of phase B and phase C windings, respectively. , , These are the mutual inductances of the three-phase windings.

[0015] Based on the aforementioned inverter and permanent magnet synchronous motor short-circuit fault model, simulation of different short-circuit faults for any two phase windings of the permanent magnet synchronous motor is achieved, including the following steps: Assume that the X-phase winding and Y-phase winding are internally connected by resistor R. f Short circuit, where X phase and Y phase are any two of phases a, b, and c; Let the ratio of the number of turns of the X-phase winding from the short-circuit point to the neutral point N to the total number of turns of the X-phase winding be the X-phase short-circuit ratio, denoted as m; and let the ratio of the number of turns of the Y-phase winding from the short-circuit point to the neutral point N to the total number of turns of the Y-phase winding be the Y-phase short-circuit ratio, denoted as n. By setting m and n to different values, different short-circuit faults or fault degrees can be simulated. Alternatively, different levels of fault can be simulated by changing the value of the short-circuit resistor Rf.

[0016] Furthermore: By setting m and n to different values, different short-circuit faults or fault degrees can be simulated; or by changing the resistance value of the short-circuit resistor Rf, different fault degrees can be simulated. The specific settings are as follows: (1) When the short-circuit turns ratio m=0 and n=0, the normal operating state of the simulated motor is realized; (2) When the short-circuit turns ratio is 0 < m ≤ 1 and n = 0, the inter-turn short-circuit fault of the X phase winding is simulated. The larger m is, the more severe the inter-turn short-circuit fault of the X phase is. The most severe fault is reached when m = 1. (3) When the short-circuit turns ratio m=0 and 0<n≤1, the simulated inter-turn short-circuit fault of the Y-phase winding is realized. The larger n is, the more severe the inter-turn short-circuit fault of the Y-phase is. The most severe fault is reached when n=1. (4) When the short-circuit turns ratio is 0 < m < 1 and 0 < n < 1, the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings is simulated. Similarly, the larger the values ​​of m and n, the more severe the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings. (5) When the short-circuit turns ratio m=1 and n=1, the phase-to-phase short-circuit fault occurring at the ends of the X-phase and Y-phase windings is simulated. (6) When the short-circuit turns ratio m and n remain unchanged, the magnitude of the short-circuit resistance Rf is changed, that is, the degree of short-circuit fault is changed. The smaller Rf is, the more severe the fault is.

[0017] The traction system health diagnosis function test method based on the aforementioned short-circuit fault model of a permanent magnet synchronous motor includes the following steps: S11: The inverter six-way switching signal issued by the traction control unit, which is based on the traction system health diagnosis algorithm, is transmitted to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model running in the simulator through the digital hard-wire interface. S12: The inverter and permanent magnet synchronous motor short circuit fault model is calculated based on the six-way switching signals given by the traction control unit. The generated inverter three-phase current is fed back to the traction control unit through the analog hard-wired interface and used as the decision data source for the health diagnosis algorithm in the traction control unit. S13: The parameters of rotational speed w, inverter DC-side voltage Udc, permanent magnet motor dq-axis inductance Ld, Lq, rotor flux linkage Phai_f, short-circuit resistance Rf, and winding short-circuit ratio m, n are transmitted from the parameter setting unit to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model unit via Ethernet. Modifying Udc on the host computer allows for the replacement of inverters with different voltage levels, modifying Ld, Lq, and Phai_f allows for the replacement of different motors, modifying w changes the motor's different speed states, and modifying Rf, m, and n changes the type and severity of the motor short-circuit fault, thus realizing the health diagnosis function test of the traction system.

[0018] This invention provides a short-circuit fault model, fault simulation method, and traction system health diagnosis function testing method for permanent magnet synchronous motors. Utilizing the short-circuit fault modeling technology of this invention, it can simulate phase-to-phase short-circuit faults occurring within the windings, solving the problem of incomplete testing of traction system health diagnosis algorithms in current hardware-in-the-loop (HIL) simulation testing systems due to the lack of a mathematical model for phase-to-phase short-circuit faults within the windings. This application fills the gap in HIL simulation platforms for phase-to-phase short-circuit faults occurring within the windings and also solves the problem of low testing efficiency caused by the inability to use a unified model for testing various short-circuit faults due to inconsistent modeling equations, and the need to download models multiple times for different short-circuit faults.

[0019] The short-circuit fault modeling technology for permanent magnet synchronous motors of this invention enables the rapid switching between simulating normal operation, inter-turn short circuit in one phase, internal short circuit in two phase windings, and end short circuit in two phase windings within a single simulation model by modifying the short-circuit turns ratio. This solves the problem of low testing efficiency caused by the inability to use a unified model for fault testing due to inconsistent modeling equations and the need to download the model multiple times for different short-circuit faults.

[0020] The present invention utilizes the short-circuit fault modeling technology for permanent magnet synchronous motors to build a model, and forms a semi-physical simulation test system for traction system health diagnosis function based on this model (real-time simulation with a step size of about 100ns, and each simulation takes about a few minutes). This system has high simulation accuracy and fast speed, and can completely replace the existing technology (with a step size of about 100us, and each simulation takes about several hours or even longer). It completely solves the problems of low simulation accuracy and low test efficiency in the joint simulation test method of traction system health diagnosis algorithm using electromagnetic simulation software to build a short-circuit fault model of permanent magnet synchronous motor windings. 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 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 short-circuit fault model diagram of a permanent magnet synchronous motor; Figure 2 Taking the short-circuit fault of phase B and phase C windings as an example, the main circuit diagram is shown when a phase-to-phase short circuit occurs inside the winding. Figure 3 This is an interface configuration model diagram; Figure 4 This is a functional test block diagram of the traction system health diagnosis algorithm; Figure 5 This is a schematic diagram of an embodiment of a hardware-in-the-loop simulation test system for the health diagnosis function of a traction system. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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] Figure 1 This is a short-circuit fault model diagram of an inverter and a permanent magnet synchronous motor; Figure 2 Taking the short-circuit fault of phase B and phase C windings as an example, the main circuit diagram is shown when a phase-to-phase short circuit occurs inside the winding. A mathematical model for short-circuit faults in inverters and permanent magnet synchronous motors includes a short-circuit fault model for permanent magnet synchronous motors based on the dq coordinate system, a three-phase voltage solution model for inverters, a dq-axis voltage solution model, and a three-phase current solution model for inverters. The short-circuit fault model of the permanent magnet synchronous motor based on the dq coordinate system includes a solution model for the dq axis current and short-circuit current, and a solution model for the voltage increment. The inverter three-phase voltage solution model is used to solve the three-phase voltage output by the inverter to the motor based on the three-phase PWM pulses, intermediate DC voltage and three-phase inverter current; The dq-axis voltage solution model is used to convert the three-phase motor voltage transmitted by the inverter three-phase voltage solution model into dq-axis voltage through 3s / 2r transformation, and then output it to the permanent magnet synchronous motor short-circuit fault model based on the dq coordinate system. The voltage increment solution model is used to solve the dq axis voltage increment caused by a short circuit fault; The dq-axis current and short-circuit current solution model is used to output the short-circuit current i on the short-circuit resistor based on the dq-axis voltage transmitted by the dq-axis voltage solution model and the dq-axis voltage increment caused by the short-circuit fault transmitted by the voltage increment solution model. f d-axis current, q-axis current; The inverter three-phase current model is used to convert the d-axis current and q-axis current output from the motor dq-axis current and short-circuit current solution model into three-phase current through a 2r / 3s transformation, and then output it to the inverter three-phase voltage solution model.

[0026] The Figure 1 In the model, the inverter's three-phase current , , Equal to the above Figure 2The three-phase current detected at the ends of the motor windings in the schematic diagram , , ; The modeling process for the inverter three-phase voltage solution model is as follows: When the upper arm of phase A is turned on, the voltage of phase A is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase A is conducting, the phase A voltage is 0. When neither the upper nor lower arm of phase A is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase A is freewheeling, the phase A voltage is taken as the voltage of the intermediate supporting capacitor. When the diode in the lower bridge arm of phase A freewheels, the voltage of phase A is 0. When the upper arm of phase B is turned on, the phase B voltage is taken as the voltage of the intermediate support capacitor. When the lower arm of phase B is conducting, the phase B voltage is 0. When neither the upper nor lower arm of phase B is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode of the upper arm of phase B is freewheeling, the phase B voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase B freewheels, and the phase B voltage is 0. When the upper arm of phase C is turned on, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase C is conducting, the phase C voltage is 0. When neither the upper nor lower arm of phase C is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase C is freewheeling, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase C freewheels, and the voltage of phase C is 0.

[0027] The formula for solving the dq-axis current is as follows:

[0028] in, , These are the dq axis voltages, , These are the dq-axis currents, respectively. , These are the d-q axis inductors, , These represent the d-q axis voltage increments caused by short-circuit faults. In this model formula, , It is obtained through the dq-axis voltage solution model; , The current is obtained through the voltage increment solution model, thereby determining the dq-axis current of the motor. , .

[0029] When phases B and C are short-circuited, the formula for the voltage increment solution model is as follows: in, The rotor position angle of the permanent magnet synchronous motor is obtained by integrating the rotational speed ω. The short-circuit current on the short-circuit resistor is obtained from the short-circuit current solution model, and m and n are the short-circuit ratios of the B-phase and C-phase windings, respectively.

[0030] When phases B and C are short-circuited, the formula for the short-circuit current calculation model is as follows:

[0031] in, , , and are the self-inductances of phase B and phase C windings, respectively. , , These are the mutual inductances of the three-phase windings.

[0032] This formula is the short-circuit loop equation; the short-circuit current can be calculated using the known flux linkage and three-phase currents. This outputs to the voltage increment solution model.

[0033] Based on the aforementioned inverter and permanent magnet synchronous motor short-circuit fault model, simulation of short-circuit faults in any two phase windings of a permanent magnet synchronous motor is achieved, characterized by the following steps: S11: Assume that the X-phase winding and Y-phase winding are internally connected by resistor R. f Short circuit, where X phase and Y phase are any two of phases a, b, and c; S12: Let the ratio of the number of turns in the X-phase winding from the short-circuit point to the neutral point N to the total number of turns in the X-phase winding be the X-phase short-circuit ratio, denoted as m; let the ratio of the number of turns in the Y-phase winding from the short-circuit point to the neutral point N to the total number of turns in the Y-phase winding be the Y-phase short-circuit ratio, denoted as n. By setting m and n to different values, different short-circuit faults or fault degrees can be simulated. In addition, changing the short-circuit resistance Rf can also simulate different fault degrees, as detailed below: (1) When the short-circuit turns ratio m=0 and n=0, the normal operating state of the simulated motor is realized; (2) When the short-circuit turns ratio is 0 < m ≤ 1 and n = 0, the inter-turn short-circuit fault of the X phase winding is simulated. The larger m is, the more severe the inter-turn short-circuit fault of the X phase is. The most severe fault is reached when m = 1. (3) When the short-circuit turns ratio m=0 and 0<n≤1, the simulated inter-turn short-circuit fault of the Y-phase winding is realized. The larger n is, the more severe the inter-turn short-circuit fault of the Y-phase is. The most severe fault is reached when n=1. (4) When the short-circuit turns ratio is 0 < m < 1 and 0 < n < 1, the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings is simulated. Similarly, the larger the values ​​of m and n, the more severe the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings. (5) When the short-circuit turns ratio m=1 and n=1, the phase-to-phase short-circuit fault occurring at the ends of the X-phase and Y-phase windings is simulated. (6) When the short-circuit turns ratio m and n remain unchanged, the magnitude of the short-circuit resistance Rf is changed, that is, the degree of short-circuit fault is changed. The smaller Rf is, the more severe the fault is.

[0034] A method for testing the health diagnosis function of a traction system based on short-circuit fault modeling of a permanent magnet synchronous motor includes the following steps: S21: The six inverter switching signals sent by the traction control unit where the traction system health diagnosis algorithm is located: PWM_A_high, PWM_A_low, PWM_B_high, PWM_B_low, PWM_C_high, PWM_C_low, are transmitted to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model running in the simulator through the digital hard-wire interface. S22: The inverter and permanent magnet synchronous motor short circuit fault model is calculated based on the six switching signals given by the traction control unit. The generated inverter three-phase currents ia_inv, ib_inv, and ic_inv are fed back to the traction control unit through the analog hard-wire interface and used as the decision data source for the health diagnosis algorithm in the traction control unit. S23: The parameters of rotational speed w, inverter DC-side voltage Udc, permanent magnet motor dq-axis inductance Ld, Lq, rotor flux linkage Phai_f, short-circuit resistance Rf, and winding short-circuit ratio m, n are transmitted from the parameter setting unit to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model unit via Ethernet. Modifying Udc on the host computer allows for the replacement of inverters with different voltage levels, modifying Ld, Lq, and Phai_f allows for the replacement of different motors, modifying w changes the motor's different speed states, and modifying Rf, m, and n changes the type and severity of the motor short-circuit fault, thus realizing the health diagnosis function test of the traction system.

[0035] Steps S21 / S22 / S23 are executed sequentially; Example 1 To model the fault topology of the permanent magnet synchronous motor described above, the three-phase voltage equations of the motor are first constructed as follows:

[0036] in, , , These are the phase voltages of the three-phase windings. and These are the voltages formed across the resistances of the B-phase winding and the C-phase winding respectively by the short-circuit current. , and These are the three-phase winding flux linkages under normal operating conditions. , and These are magnetic chains formed by permanent magnets. , and These are the magnetic flux linkages formed by the short-circuit current on the inductance of the three-phase windings A, B, and C.

[0037] The three sets of flux linkage equations are as follows: (1) Three-phase winding flux linkage formed by the three-phase current of the stator:

[0038] (2) Three-phase magnetic flux formed by the rotor permanent magnet:

[0039] (3) Three-phase winding flux linkage formed by short-circuit current:

[0040] in, , , , , , These are the self-inductance and mutual inductance of the three-phase windings, respectively. It is a permanent magnet flux linkage. This is the short-circuit current across the short-circuit resistor. θ represents the rotor position angle of the permanent magnet synchronous motor, and m and n are the short-circuit ratios of the B-phase and C-phase windings, respectively.

[0041] From the three-phase flux linkage formed by the short-circuit current, we can see that when m=0 and n=0, the flux linkage formed by the short-circuit current is also 0, corresponding to the normal operation of the motor; when 0<m≤1 and n=0, the flux linkage formed by the short-circuit current only includes the turn linkage between each phase and the short-circuit winding of phase B, corresponding to the state where there is only a short-circuit fault between phase B turns; when m=0 and 0<n≤1, the flux linkage formed by the short-circuit current only includes the turn linkage between each phase and the short-circuit winding of phase C, corresponding to the state where there is only a short-circuit fault between phase C turns; when 0<m<1 and 0<n<1, the flux linkage formed by the short-circuit current includes both the turn linkage between each phase and the short-circuit winding of phase B and the short-circuit winding of phase C, corresponding to the state where there is a short-circuit fault between phases occurring within the windings of phases B and C; when m=1 and n=1, the flux linkage formed by the short-circuit current in each phase is linked with the full turns of the winding of phase B and the full turns of the winding of phase C, corresponding to the state where there is a short-circuit fault between the ends of the windings of phases B and C.

[0042] The three-phase voltage equations are transformed using the following two coordinate transformation matrices:

[0043]

[0044] After coordinate transformation, the three-phase voltage equations are obtained in the dq coordinate system as follows:

[0045] in, , These are the dq axis voltages, , These are the dq-axis currents, respectively. , These are the d-q axis inductors, , These represent the voltage increments on the d and q axes caused by short-circuit faults.

[0046] In the voltage equation above, the dq-axis voltage, dq-axis inductance, and the dq-axis voltage increment caused by a short circuit fault are used as inputs to solve for the dq-axis current of the three-phase motor.

[0047] dq axis voltage , ; by three-phase phase voltage , , Obtained through 3s / 2r transformation Three-phase voltage , , The voltage of the intermediate supporting capacitor is determined by the states of the six switching transistors of the inverter. The switching rules between 0 and 0 are as follows: When the upper arm of phase A is turned on, the voltage of phase A is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase A is conducting, the phase A voltage is 0. When neither the upper nor lower arm of phase A is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase A is freewheeling, the phase A voltage is taken as the voltage of the intermediate supporting capacitor. When the diode in the lower bridge arm of phase A freewheels, the voltage of phase A is 0. When the upper arm of phase B is turned on, the phase B voltage is taken as the voltage of the intermediate support capacitor. When the lower arm of phase B is conducting, the phase B voltage is 0. When neither the upper nor lower arm of phase B is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode of the upper arm of phase B is freewheeling, the phase B voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase B freewheels, and the phase B voltage is 0. When the upper arm of phase C is turned on, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase C is conducting, the phase C voltage is 0. When neither the upper nor lower arm of phase C is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase C is freewheeling, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase C freewheels, and the voltage of phase C is 0.

[0048] The specific formula for the dq axis voltage increment caused by a short circuit fault is as follows: in, The rotor position angle of the permanent magnet synchronous motor can be obtained by integrating the rotational speed w. denoted as , where is the short-circuit current across the short-circuit resistor, and m and n are the short-circuit ratios of the B-phase and C-phase windings, respectively.

[0049] in It can be obtained from the short-circuit loop equation, by... , , , , The equations for the short-circuit loop are as follows:

[0050] in, , , and are the self-inductances of phase B and phase C windings, respectively. , , These are the mutual inductances of the three-phase windings.

[0051] Figure 3 The interface configuration model is shown below.

[0052] Figure 4 This is a functional test block diagram of the traction system health diagnosis algorithm; After constructing the short-circuit fault model of the permanent magnet synchronous motor based on the above equations, the constructed model body can be combined with the parameter given and fault injection model and the traction system health diagnosis algorithm to jointly test the function of the traction system health diagnosis algorithm.

[0053] A method for testing the health diagnosis function of a traction system based on short-circuit fault modeling of a permanent magnet synchronous motor includes the following steps: Among them, PWM_A_high, PWM_A_low, PWM_B_high, PWM_B_low, PWM_C_high, and PWM_C_low are the six-channel switching signals of the inverter issued by the traction control unit where the traction system health diagnosis algorithm is located. They are transmitted to the permanent magnet synchronous motor short-circuit fault simulation model running in the simulator through the digital hard-wire interface. ia_inv, ib_inv, and ic_inv are the inverter three-phase currents obtained by the motor model calculation based on the switching signals given by the traction control unit. They are fed back to the traction control unit through the analog hard-wired interface and used as the decision data source for the health diagnosis algorithm in the traction control unit. Parameters such as w, Udc, Ld, Lq, Phai_f, Rf, m, and n are transmitted from the parameter setting unit to the simulation unit via Ethernet and applied to the simulation model. Modifying Udc on the host computer allows you to change the inverter to a different voltage level, modifying Ld, Lq, and Phai_f allows you to change the motor to a different speed, modifying w allows you to change the motor's speed state, and modifying Rf, m, and n allows you to change the type and severity of the motor's short-circuit fault.

[0054] According to the functional test block diagram of the traction system health diagnosis algorithm described in the technical solution of the present invention, the following can be constructed: Figure 5 The embodiment shown demonstrates a hardware-in-the-loop simulation test of the traction system health diagnosis algorithm function.

[0055] Specifically: After constructing a short-circuit fault model of a permanent magnet synchronous motor, the model can be downloaded to the simulation unit hardware via Ethernet for execution. This simulation unit can be any simulator supporting simulation steps of 100ns or smaller (such as HiGale simulators, dSPACE simulators, etc.). To enable arbitrary switching of fault types and severity, a host computer can be used as a parameter input unit, connected to the simulation unit via Ethernet. This allows for the configuration of inverter and motor parameters of the model running in the simulation unit, enabling the test system to quickly adapt to traction system tests of different power and voltage levels. It also allows for rapid injection of short-circuit fault types and severity into the model, thus achieving efficient and comprehensive testing of traction system health diagnosis functions for various short-circuit faults in permanent magnet synchronous motors.

[0056] The short-circuit fault modeling method for permanent magnet synchronous motors described in this invention can be applied not only in hardware-in-the-loop (HIL) simulation test platforms but also in any simulation test platform that uses mathematical formulas as a prototype. For example, in the MATLAB environment, the mathematical equations of this technical solution can be used to model short-circuit faults in permanent magnet synchronous motors and to model the traction system health diagnosis algorithm. Both can be simulated together to verify the function and performance of the traction system health diagnosis algorithm. However, the simulation step size of this implementation is only on the order of 100µs, and its accuracy and efficiency are far inferior to the constructed hardware-in-the-loop (HIL) simulation test system embodiment for traction system health diagnosis.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A short-circuit fault model for an inverter and a permanent magnet synchronous motor, characterized in that: include: Short-circuit fault model of permanent magnet synchronous motor, three-phase voltage solution model of inverter, dq axis voltage solution model and three-phase current solution model of inverter based on dq coordinate system; The short-circuit fault model of the permanent magnet synchronous motor based on the dq coordinate system includes a solution model for the dq axis current and short-circuit current, and a solution model for the voltage increment. The inverter three-phase voltage solution model is used to solve the three-phase voltage output by the inverter to the motor based on the three-phase PWM pulses, intermediate DC voltage and three-phase inverter current; The dq-axis voltage solution model is used to convert the three-phase motor voltage transmitted by the inverter three-phase voltage solution model into dq-axis voltage through 3s / 2r transformation, and then output it to the permanent magnet synchronous motor short-circuit fault model based on the dq coordinate system. The voltage increment solution model is used to solve the dq axis voltage increment caused by a short circuit fault; The dq-axis current and short-circuit current solution model is used to output the short-circuit current i on the short-circuit resistor based on the dq-axis voltage transmitted by the dq-axis voltage solution model and the dq-axis voltage increment caused by the short-circuit fault transmitted by the voltage increment solution model. f d-axis current, q-axis current; The inverter three-phase current solution model is used to convert the d-axis current and q-axis current output from the motor dq-axis current and short-circuit current solution model into three-phase current through a 2r / 3s transformation, and then output it to the inverter three-phase voltage solution model.

2. The short-circuit fault model for an inverter and permanent magnet synchronous motor according to claim 1, characterized in that: The modeling process for the inverter three-phase voltage solution model is as follows: When the upper arm of phase A is turned on, the voltage of phase A is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase A is conducting, the phase A voltage is 0. When neither the upper nor lower arm of phase A is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase A is freewheeling, the phase A voltage is taken as the voltage of the intermediate supporting capacitor. When the diode in the lower bridge arm of phase A freewheels, the voltage of phase A is 0. When the upper arm of phase B is turned on, the phase B voltage is taken as the voltage of the intermediate support capacitor. When the lower arm of phase B is conducting, the phase B voltage is 0. When neither the upper nor lower arm of phase B is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode of the upper arm of phase B is freewheeling, the phase B voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase B freewheels, and the phase B voltage is 0. When the upper arm of phase C is turned on, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. When the lower arm of phase C is conducting, the phase C voltage is 0. When neither the upper nor lower arm of phase C is conducting, the voltage is determined based on the freewheeling current of the corresponding diodes. If the diode in the upper arm of phase C is freewheeling, the phase C voltage is taken as the voltage of the intermediate supporting capacitor. The lower bridge arm diode of phase C freewheels, and the voltage of phase C is 0.

3. The short-circuit fault model for an inverter and permanent magnet synchronous motor according to claim 1, characterized in that: The formula for solving the dq-axis current is as follows: in, , These are the dq axis voltages, , These are the dq-axis currents, respectively. , These are the d-q axis inductors, , These represent the dq-axis voltage increments caused by short-circuit faults; in this model formula, , It was obtained by solving the dq-axis voltage model; , The current is obtained through the voltage increment solution model, thereby determining the dq-axis current of the motor. , .

4. The short-circuit fault model for an inverter and a permanent magnet synchronous motor according to claim 1, characterized in that: When phases B and C are short-circuited, the formula for the voltage increment solution model is as follows: in, The rotor position angle of the permanent magnet synchronous motor is obtained by integrating the rotational speed ω. The short-circuit current on the short-circuit resistor is obtained from the short-circuit current solution model, and m and n are the short-circuit ratios of the B-phase and C-phase windings, respectively.

5. The short-circuit fault model for an inverter and a permanent magnet synchronous motor according to claim 1, characterized in that: When phases B and C are short-circuited, the formula for the short-circuit current calculation model is as follows: in, , , and are the self-inductances of phase B and phase C windings, respectively. , , These are the mutual inductances of the three-phase windings.

6. The inverter and permanent magnet synchronous motor short-circuit fault model according to claims 1-5, which realizes the simulation of different short-circuit faults of any two phase windings of the permanent magnet synchronous motor, is characterized in that: Includes the following steps: Assume that the X-phase winding and Y-phase winding are internally connected by resistor R. f Short circuit, where X phase and Y phase are any two of phases a, b, and c; Let the ratio of the number of turns of the X-phase winding from the short-circuit point to the neutral point N to the total number of turns of the X-phase winding be the X-phase short-circuit ratio, denoted as m; and let the ratio of the number of turns of the Y-phase winding from the short-circuit point to the neutral point N to the total number of turns of the Y-phase winding be the Y-phase short-circuit ratio, denoted as n. By setting m and n to different values, different short-circuit faults or fault degrees can be simulated. Alternatively, different levels of fault can be simulated by changing the value of the short-circuit resistor Rf.

7. The fault simulation method for a short-circuit fault model of an inverter and a permanent magnet synchronous motor according to claim 6, characterized in that: By setting m and n to different values, different short-circuit faults or fault degrees can be simulated; or by changing the resistance value of the short-circuit resistor Rf, different fault degrees can be simulated. The specific settings are as follows: (1) When the short-circuit turns ratio m=0 and n=0, the normal operating state of the simulated motor is realized; (2) When the short-circuit turns ratio is 0 < m ≤ 1 and n = 0, the inter-turn short-circuit fault of the X phase winding is simulated. The larger m is, the more severe the inter-turn short-circuit fault of the X phase is. The most severe fault is reached when m = 1. (3) When the short-circuit turns ratio m=0 and 0<n≤1, the simulated inter-turn short-circuit fault of the Y-phase winding is realized. The larger n is, the more severe the inter-turn short-circuit fault of the Y-phase is. The most severe fault is reached when n=1. (4) When the short-circuit turns ratio is 0 < m < 1 and 0 < n < 1, the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings is simulated. Similarly, the larger the values ​​of m and n, the more severe the phase-to-phase short-circuit fault occurring inside the X-phase and Y-phase windings. (5) When the short-circuit turns ratio m=1 and n=1, the phase-to-phase short-circuit fault occurring at the ends of the X-phase and Y-phase windings is simulated. (6) When the short-circuit turns ratio m and n remain unchanged, the magnitude of the short-circuit resistance Rf is changed, that is, the degree of short-circuit fault is changed. The smaller Rf is, the more severe the fault is.

8. A traction system health diagnosis function test method based on the short-circuit fault model of a permanent magnet synchronous motor as described in claims 1-5, characterized in that: Includes the following steps: S11: The inverter six-way switching signal issued by the traction control unit, which is based on the traction system health diagnosis algorithm, is transmitted to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model running in the simulator through the digital hard-wire interface. S12: The inverter and permanent magnet synchronous motor short circuit fault model is calculated based on the six-way switching signals given by the traction control unit. The generated inverter three-phase current is fed back to the traction control unit through the analog hard-wired interface and used as the decision data source for the health diagnosis algorithm in the traction control unit. S13: The parameters of rotational speed w, inverter DC-side voltage Udc, permanent magnet motor dq-axis inductance Ld, Lq, rotor flux linkage Phai_f, short-circuit resistance Rf, and winding short-circuit ratio m, n are transmitted from the parameter setting unit to the inverter and permanent magnet synchronous motor short-circuit fault mathematical model unit via Ethernet. Modifying Udc on the host computer allows for the replacement of inverters with different voltage levels, modifying Ld, Lq, and Phai_f allows for the replacement of different motors, modifying w changes the motor's different speed states, and modifying Rf, m, and n changes the type and severity of the motor short-circuit fault, thus realizing the health diagnosis function test of the traction system.

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