A five-phase motor single-phase short-circuit fault-tolerant control method based on decoupling matrix invariance

Abstract

The application relates to a five-phase motor single-phase short-circuit fault-tolerant control method based on decoupling matrix invariance, which comprises the following steps: calculating a current reference value of a q-axis of a five-phase motor by adopting a PI controller according to a speed error; converting reference currents of the motor on dq axes into reference currents on alpha-beta axes by using a decoupling matrix of the five-phase motor in a healthy state; determining the reference currents on the alpha-beta axes after a single-phase open-circuit fault in combination with a fault-tolerant coefficient; calculating secondary harmonic torque pulsation generated by a short-circuit current, and injecting an additional fundamental current to eliminate the obtained secondary harmonic torque pulsation; the method does not need to change the decoupling matrix, directly uses the decoupling matrix in the healthy state and the fault-tolerant coefficient to perform fault-tolerant control on the single-phase short circuit, reduces the complexity of the control process, simplifies the control process, realizes disturbance-free fault-tolerant operation of the motor under the single-phase short-circuit fault, and improves the stability of the motor.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a single-phase short-circuit fault-tolerant control method for a five-phase motor based on the invariance of the decoupling matrix. Background Technology

[0002] Currently, electrical systems are increasingly replacing traditional actuators in a growing number of applications, including aerospace, ship propulsion, and new energy vehicles. These applications have very high requirements for reliability and safety. In fact, once a fault occurs in a traditional three-phase motor, it needs to be diagnosed and resolved quickly. However, in operation, the timeliness of fault resolution is often not guaranteed, leading to irreparable losses. Therefore, five-phase motors, which can guarantee that in the event of a fault in one or two phases, only the control algorithm needs to be changed without adding additional power electronic components, are gaining increasing attention. Due to their greater degrees of freedom than traditional three-phase motors, high-quality fault-tolerant control methods for five-phase motors can compensate for the impact of faults, achieve smooth torque, and do not require additional hardware redundancy.

[0003] When a single-phase winding short-circuites, the presence of permanent magnets on the rotor generates an uncontrollable and uneliminable short-circuit current in the short-circuited phase. This significantly impacts the stability of motor operation and torque pulsation. Excessive short-circuit current can also cause severe overheating in that phase, leading to secondary motor malfunctions.

[0004] To address the impact of single-phase short-circuit current, current methods primarily involve shutting off the corresponding switch and using a reduced-order decoupling matrix to control the remaining four phases. However, the reduced-order decoupling matrix varies significantly depending on the location of the faulty phase, undoubtedly increasing the complexity of the control method. Furthermore, existing single-phase short-circuit fault-tolerant methods fail to adequately consider the handling of additional degrees of freedom. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a five-phase motor single-phase short-circuit fault-tolerant control method based on decoupling matrix invariance, which simplifies the control process, takes into account the additional degrees of freedom of the motor, thereby realizing the uninterrupted fault-tolerant operation of the motor under single-phase short-circuit faults and improving the stability of the motor.

[0006] The technical solution adopted in this invention is a single-phase short-circuit fault-tolerant control method for a five-phase motor based on an invariant decoupling matrix. This method includes the following steps:

[0007] S1. Use a rotary transformer or photoelectric encoder to collect the mechanical angle θ of the motor at the current moment. m The mechanical angle θ of the motor m Converted to the mechanical speed ω of the motor m The mechanical speed ω of the motor mWith the preset motor reference speed The motor speed error e is obtained by comparison. r According to the speed error e r The reference value of the q-axis current of the five-phase motor is calculated using a PI controller.

[0008] S2. The current along the d-axis of the five-phase motor is a given current, and the reference value for the current along the d-axis of the five-phase motor is 0. This is determined by the decoupling matrix T of the five-phase motor in a healthy state. Park Convert the motor's reference current on the dq axis to a reference current on the αβ axis.

[0009] S3. Treat the short-circuit phase as a superposition of a single-phase open-circuit fault and a single-phase short-circuit fault. Determine the motor's fault tolerance coefficient based on the single-phase open-circuit fault, and combine the fault tolerance coefficient to determine the reference current on the αβ axis after the single-phase open-circuit fault.

[0010] S4. Calculate the torque T generated by the short-circuit current based on the short-circuit current of a single-phase short-circuit fault. sc ;

[0011] S5. Inject additional fundamental current to eliminate the torque T obtained in step S4. sc This allows us to obtain a new reference current for the motor on the αβ axis.

[0012] S6, Combining the decoupling matrix T of the motor in a healthy state Clarke The new reference current obtained in step S5 Converted to residual phase reference current

[0013] S7. Calculate the phase reference current. Compared with the phase current sensor measurement value (i a i b i c i d i e The difference between the phase voltage and the phase voltage is calculated by inputting the difference into the proportional resonant controller.

[0014] S8. Add the phase voltage value obtained in step S7 to the back electromotive force of the short-circuit phase to obtain the optimal short-circuit fault-tolerant phase voltage reference value.

[0015] S9. Input the optimal short-circuit fault-tolerant phase voltage reference value obtained in step S8 into the CPWM module to obtain the switching signals of the remaining phases; then input the obtained switching signals of the remaining phases into the inverter to control the motor and realize the short-circuit fault-tolerant control of the five-phase motor.

[0016] The beneficial effects of this invention are as follows: The above-mentioned method for single-phase short-circuit fault-tolerant control of a five-phase motor based on an invariant decoupling matrix does not require changing the decoupling matrix. It directly uses the decoupling matrix and fault-tolerant coefficient under healthy conditions to perform fault-tolerant control of single-phase short circuits, reducing the complexity and simplifying the control process. Furthermore, this method focuses on the additional degrees of freedom of the motor, using a proportional resonant controller to compensate for the effects of open-circuit and short-circuit currents by maintaining a fault-tolerant factor that keeps the torque unchanged before and after the fault. This achieves uninterrupted fault-tolerant operation of the motor under single-phase short-circuit faults, improving the motor's stability.

[0017] Preferably, in step S2, the decoupling matrix T of the five-phase motor in a healthy state... Park The expression is:

[0018]

[0019] Preferably, in step S3, the reference current of the current following the single-phase open-circuit fault on the αβ axis is... The expression is: Among them, K α3,α1 K α3,β1 K β3,α1 K β3,β1 K represents the fault tolerance factor of the motor. α3,α1 =-1,K α3,β1 =0, while K β3,α1 and K β3,β1 The value of K is determined by the constraints obtained from the additional degrees of freedom, which refer to equal amplitude or minimum copper loss; if the constraint obtained from the additional degrees of freedom is minimum copper loss, then K β3,α1 and K β3,β1 The value is K β3,α1 =0,K β3,β1 =0; if the additional degrees of freedom are constrained to have equal amplitudes, then K β3,α1 and K β3,β1 The value is K β3,α1 =0,K β3,β1 =0.236.

[0020] Preferably, in step S4, the torque T generated by the short-circuit current is calculated based on the short-circuit current. sc The specific process is as follows: Set the impedance of the short-circuited phase to remain constant. In the short-circuit loop, the impedance Z, composed of resistor R and inductor L, is... a Represented as: Where, ω e Indicates electric speed. The angle between the resultant impedance and resistance in the impedance vector diagram is represented by j, where j represents the imaginary unit, and |Z| represents the modulus of resistance. Combined with the back electromotive force of the short-circuit phase, the short-circuit current is expressed as: Where a represents the amplitude of the short-circuit current, b is the amplitude of the short-circuit current, and E a Let T represent the back electromotive force of the short-circuited phase, then the torque T caused by the short-circuit current is... sc Just for: Where, ψ m This represents the magnetomotive force flux linkage of the motor rotor.

[0021] Preferably, in step S5, the specific process of injecting additional fundamental current to eliminate the torque obtained in step S4 is as follows: injecting the fundamental current into the reference current of the β1 axis of the motor. In this process, the fundamental current is injected into the reference current of the motor's β3 axis. In the middle, the torque T generated by the injected fundamental current β1c To counteract the torque T obtained in step S4 sc That is, T β1c =-T sc The torque T is obtained. β1c The expression is: Among them, E β I represents the back electromotive force of the motor along the β axis. β1c I represents the compensation current of the motor on the β axis. bβ1c I cβ1c I dβ1c I eβ1c E represents the compensation current on the β-axis for the four phases other than the short-circuit phase. b E c E d E e This represents the back electromotive force (EMF) of the four phases other than the short-circuited phase on the β axis, where p represents the number of pole pairs and k represents the number of pole pairs. csc and k ssc ψ represents the compensation coefficient. m This represents the magnetomotive force flux linkage of the motor rotor.

[0022] Preferably, in step S6, the decoupling matrix T of the motor in a healthy state is... Clarke The expression is:

[0023] Attached Figure Description

[0024] Figure 1 The flowchart is a method for single-phase short-circuit fault-tolerant control of a five-phase motor based on decoupling matrix invariance according to the present invention.

[0025] Figure 2 This is the control structure diagram corresponding to the single-phase short-circuit fault-tolerant control method for a five-phase motor based on the invariance of the decoupling matrix according to the present invention;

[0026] Figure 3A comparison diagram of current and torque of a five-phase motor under healthy and fault conditions;

[0027] Figure 4 The current and torque diagrams obtained after using the method of this invention in a fault state;

[0028] Figure 5 The current and torque diagrams for sudden torque increase after applying the method of the present invention with equal amplitude constraints in a fault state;

[0029] Figure 6 The diagram shows the current and torque when the speed suddenly increases after applying the method of the present invention with equal amplitude constraints in a fault state. Detailed Implementation

[0030] The invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description. The scope of protection of the invention is not limited to these specific embodiments.

[0031] This invention relates to a single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance. The invariance of the decoupling matrix means that the traditional decoupling matrix used in the motor is not reduced in order; the traditional decoupling matrix is ​​maintained. Figure 1 As shown, the method includes the following steps:

[0032] S1. Use a rotary transformer or photoelectric encoder to collect the mechanical angle θ of the motor at the current moment. m The mechanical angle θ of the motor m Converted to the mechanical speed ω of the motor m The mechanical speed ω of the motor m With the preset motor reference speed The motor speed error e is obtained by comparison. r According to the speed error e r The reference value of the q-axis current of the five-phase motor is calculated using a PI controller.

[0033] S2. The current along the d-axis of the five-phase motor is a given current, and the reference value for the current along the d-axis of the five-phase motor is 0. This is determined by the decoupling matrix T of the five-phase motor in a healthy state. Park Convert the motor's reference current on the dq axis to a reference current on the αβ axis. The decoupling matrix T of the five-phase motor in a healthy state Park Let be the PARK transformation matrix of the five-phase motor in a healthy state, and its expression is:

[0034] S3. Since all the switching transistors corresponding to the short circuit will be turned off, the short circuit phase is considered as a superposition of a single-phase open circuit fault and a single-phase short circuit fault. The fault tolerance coefficient of the motor is determined based on the single-phase open circuit fault, and the reference current on the αβ axis after the single-phase open circuit fault is determined in combination with the fault tolerance coefficient. Reference current The expression is: Among them, K α3,α1 K α3,β1 K β3,α1 K β3,β1 The fault tolerance coefficient K represents the motor's tolerance factor. To ensure the consistency of the magnetomotive force before and after a fault, the fault tolerance factor K is... α3,α1 and K α3,β1 The value of K is determined to be: α3,α1 =-1,K α3,β1 =0, while K β3,α1 and K β3,β1 The value of K is determined by the constraints obtained from the additional degrees of freedom, which refer to equal amplitude or minimum copper loss; if the constraint obtained from the additional degrees of freedom is minimum copper loss, then K β3,α1 and K β3,β1 The value is K β3,α1 =0,K β3,β1 =0; if the additional degrees of freedom are constrained to have equal amplitudes, then K β3,α1 and K β3,β1 The value is K β3,α1 =0,K β3,β1 =0.236;

[0035] S4. Calculate the torque T generated by the short-circuit current based on the short-circuit current of a single-phase short-circuit fault. sc ;

[0036] Although the faulty phase is isolated by opening the circuit, this does not completely cut off the short-circuit current of the faulty phase. Therefore, the short-circuit current still affects the operation of the motor. Thus, the impedance of the short-circuited phase is kept constant. In the short-circuit loop, the impedance Z, composed of resistor R and inductor L, is... a Represented as: Where, ω e Indicates electric speed. The angle between the resultant impedance and resistance in the impedance vector diagram is represented by j, where j represents the imaginary unit, and |Z| represents the modulus of resistance. Combined with the back electromotive force of the short-circuit phase, the short-circuit current is expressed as: Where a represents the amplitude of the sine component of the short-circuit current, and b is the amplitude of the cosine component of the short-circuit current, then the torque T caused by the short-circuit current... sc Just for: Where, ψ m The magnetomotive force flux linkage of the motor rotor;

[0037] S5. Inject additional fundamental current to eliminate the torque obtained in step S4, and obtain a new reference current for the motor on the αβ axis. The specific process of injecting additional fundamental current to eliminate the torque obtained in step S4 is as follows: inject the fundamental current into the reference current of the β1 axis of the motor. In order to ensure that the magnetomotive force is not affected after the fundamental current is injected, it is also necessary to inject the fundamental current into the reference current of the β3 axis of the motor. In the middle, the torque T generated by the injected fundamental current β1c To counteract the torque T obtained in step S4 sc That is, T β1c =-T sc The torque T is obtained. β1c The expression is: Among them, E β I represents the back electromotive force of the motor along the β axis. β1c I represents the compensation current of the motor on the β axis. bβ1c I cβ1c I dβ1c I eβ1c E represents the compensation current on the β-axis for the four phases other than the short-circuit phase. b E c E d E e This represents the back electromotive force (EMF) of the four phases other than the short-circuited phase on the β axis, where p represents the number of pole pairs and k represents the number of pole pairs. csc and k ssc Indicates the compensation coefficient;

[0038] S6, Combining the decoupling matrix T of the motor in a healthy state Clarke The new reference current obtained in step S5 Converted to residual phase reference current

[0039] S7. Calculate the phase reference current. Compared with the phase current sensor measurement value (i a i b i c i d i e The difference between the phase voltage and the phase voltage is calculated by inputting the difference into the proportional resonant controller.

[0040] The transfer function of the proportional resonant controller used for quasi-proportional resonant regulation is: Among them, K p Kr represents the proportional coefficient of the proportional resonant controller, and ω represents the resonant coefficient of the proportional resonant controller. c Indicates the resonant frequency;

[0041] S8. Add the phase voltage value obtained in step S7 to the back electromotive force of the short-circuit phase to obtain the optimal short-circuit fault-tolerant phase voltage reference value.

[0042] S9. Input the optimal short-circuit fault-tolerant phase voltage reference value obtained in step S8 into the CPWM module to obtain the switching signals of the remaining phases; then input the obtained switching signals of the remaining phases into the inverter to control the motor and realize the short-circuit fault-tolerant control of the five-phase motor.

[0043] The above-mentioned single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance is adopted. This method analyzes the short-circuit fault mechanism and proposes a calculation method for the short-circuit current and its caused torque ripple. Applying this algorithm after a single-phase short circuit ensures that the torque ripple after the fault is consistent with the torque ripple under healthy conditions, achieving disturbance-free operation. Utilizing additional degrees of freedom, the control performance under two constraints—minimum copper loss and equal phase current amplitude—can be obtained. Furthermore, under this fault-tolerant control method, such as... Figure 5 and Figure 6 As shown, the dynamic performance of the control system was verified by trying sudden torque increase and speed change respectively. The experiment verified that the dynamic performance of the method is good.

Claims

1. A single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance, characterized in that: The method includes the following steps: S1. Use a rotary transformer or photoelectric encoder to collect the mechanical angle of the motor at the current moment. The mechanical angle of the motor Converted to the mechanical speed of the motor ; The mechanical speed of the motor With the preset motor reference speed The motor speed error was obtained by comparison. According to the speed error The reference value of the q-axis current of the five-phase motor is calculated using a PI controller. ; S2. The current along the d-axis of the five-phase motor is a given current, and the reference value for the current along the d-axis of the five-phase motor is 0. This is achieved through the decoupling matrix of the five-phase motor in a healthy state. Convert the motor's reference current on the dq axis to... Reference current on the shaft ; S3. Treat the short-circuit phase as a superposition of a single-phase open-circuit fault and a single-phase short-circuit fault. Determine the motor's fault tolerance coefficient based on the single-phase open-circuit fault, and combine the fault tolerance coefficient to determine the current after a single-phase open-circuit fault. Reference current on the shaft ; S4. Calculate the torque generated by the short-circuit current based on the short-circuit current of a single-phase short-circuit fault. ; S5. Inject fundamental current to eliminate the torque obtained in step S4. The motor is obtained New reference current on the axis The specific process is as follows: the fundamental current is injected into the reference current of the motor's β1 axis. In this process, the fundamental current is injected into the reference current of the motor's β3 axis. In the middle, the torque generated by the injected fundamental current To counteract the torque obtained in step S4 ,Right now To obtain torque The expression is: ;in, Indicates that the motor is in The back electromotive force of the shaft, Indicates that the motor is in Shaft compensation current, , , , This indicates that the other four phases, excluding the short-circuit phase, are in Shaft compensation current, , , , This indicates that the other four phases, excluding the short-circuit phase, are in The back electromotive force of the shaft, Represents the extreme logarithm. and Indicates the compensation coefficient. The magnetomotive force flux linkage of the motor rotor; S6. Decoupling matrix of the motor in a healthy state The new reference current obtained in step S5 Convert to reference current ; S7. Calculate the reference current. With phase current sensor measurement value The difference is obtained and input into the proportional resonant controller, which calculates the phase voltage value. S8. Add the phase voltage value obtained in step S7 to the back electromotive force of the short-circuit phase to obtain the optimal short-circuit fault-tolerant phase voltage reference value. S9. Input the optimal short-circuit fault-tolerant phase voltage reference value obtained in step S8 into the CPWM module to obtain the switching signals of the remaining phases; then input the obtained switching signals of the remaining phases into the inverter to control the motor and realize the short-circuit fault-tolerant control of the five-phase motor.

2. The single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance as described in claim 1, characterized in that: In step S2, the decoupling matrix of the five-phase motor in a healthy state The expression is: 。 3. The method for single-phase short-circuit fault-tolerant control of a five-phase motor based on decoupling matrix invariance as described in claim 2, characterized in that: In step S3, the current after the single-phase open-circuit fault is... Reference current on the shaft The expression is: ,in, , , , This represents the motor's fault tolerance factor. ,and and The value of is determined by the constraints obtained from the additional degrees of freedom, which refer to equal amplitude or minimum copper loss; if the constraint obtained from the additional degrees of freedom is minimum copper loss, then and The value is If the additional degrees of freedom are constrained to have equal amplitudes, then and The value is .

4. The single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance as described in claim 3, characterized in that: In step S4, the torque generated by the short-circuit current is calculated based on the short-circuit current. The specific process is as follows: Set the impedance of the short-circuited phase to remain constant. In the short-circuit loop, the resistor... and inductor The impedance of the composition Represented as: ,in, Indicates electric speed. The angle between the resultant impedance and resistance in the impedance vector diagram is represented by j, where j represents the imaginary unit, and |Z| represents the modulus of resistance. Combined with the back electromotive force of the short-circuit phase, the short-circuit current is expressed as: Where a represents the amplitude of the sinusoidal component of the short-circuit current, and b represents the amplitude of the cosine component of the short-circuit current. The torque caused by the short-circuit current represents the back electromotive force of the short-circuit phase. Just for: in, This represents the magnetomotive force flux linkage of the motor rotor.

5. The single-phase short-circuit fault-tolerant control method for a five-phase motor based on decoupling matrix invariance as described in claim 1, characterized in that: In step S6, the decoupling matrix of the motor in a healthy state The expression is: 。

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