A fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC

Abstract

This invention discloses a fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC. After an inverter switch failure, this method connects the motor neutral point to the DC power supply midpoint and reconfigures the inverter into a two-phase four-switch fault-tolerant operating topology using the remaining switches. The control system adopts a dual-loop structure. The outer loop controls the motor speed through a PI regulator and provides torque and flux linkage reference values ​​to the inner loop based on the maximum torque-to-current ratio. The inner loop employs model predictive direct torque control, using the stator voltage equation and stator current prediction model to obtain predicted flux linkage and torque values. The optimal switching state of the inverter is obtained using a value function, and the remaining switches are controlled to achieve fault-tolerant operation of the motor after a switch failure. This invention enables stable system operation even after a switch failure without requiring control strategy switching, effectively improving the safety and reliability of permanent magnet synchronous motor operation.

Description

Technical Field

[0001] This invention relates to a two-phase four-switch fault-tolerant control method for permanent magnet synchronous motors based on MPC, belonging to the field of permanent magnet synchronous motor control technology. Background Technology

[0002] In recent years, permanent magnet synchronous motors have been widely used in the drive systems of new energy vehicles, and their excellent control performance is the foundation for the stable operation of electric vehicles. The inverter is a core component of the electric vehicle motor drive system; a failure in this system can lead to serious consequences such as a complete power outage, endangering driving safety. Inverter fault-tolerant control technology can effectively improve the operational reliability of the motor drive system and enhance vehicle safety.

[0003] Common fault-tolerant inverter topologies include three-phase four-arm fault-tolerant topologies, three-phase four-switch fault-tolerant topologies, and two-phase four-switch fault-tolerant topologies. Different fault-tolerant topologies have different characteristics. The three-phase four-arm fault-tolerant topology adds a redundant arm to the existing bridge arms, resulting in high voltage vector utilization and effective fault handling, but significantly increases the number of switching devices and cost. Compared to the four-arm topology, the three-phase four-switch fault-tolerant topology has the advantages of small size and low cost, but its effective voltage vector value is only half that of the inverter during normal operation, resulting in fewer selectable voltage vectors and larger output torque ripple. Furthermore, this topology can only tolerate single-phase faults in the inverter, limiting its application range. The two-phase four-switch fault-tolerant inverter, by directly discarding the faulty phase and connecting the motor neutral point to the DC power supply neutral point, can tolerate both single-phase faults in the inverter and the motor. Its fault-tolerant topology is simple, requires fewer additional devices, is low-cost, and small in size, offering greater advantages.

[0004] In terms of control technology, traditional vector-based permanent magnet synchronous motor (PMSM) control technology suffers from complex parameter calculations and slow dynamic response, increasingly failing to meet current demands. In recent years, scholars both domestically and internationally have conducted extensive research, proposing novel control schemes such as model predictive control, fuzzy control, and sliding mode control. These new control theories have improved the operating performance of motor systems under normal operating conditions, but research on the operating state of the system under inverter failure conditions is relatively limited. In particular, PMSM control technology based on model predictive control, which utilizes a value function to select the optimal voltage vector, offers advantages such as low torque ripple and fast dynamic response, effectively improving the dynamic response speed of motor control and becoming a current research hotspot in motor drive control technology. Summary of the Invention

[0005] To address the aforementioned technical issues, this invention proposes a fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC. This method combines fault-tolerant topology reconstruction with model predictive direct torque control strategy, enabling the system to possess a certain degree of fault tolerance and good steady-state and dynamic performance.

[0006] The technical solution adopted in this invention is:

[0007] A fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC includes the following steps:

[0008] (1) When a switch tube of a certain phase of the inverter fails, disconnect the faulty bridge arm, connect the motor neutral point to the DC power supply midpoint, and reconstruct the inverter into a two-phase four-switch fault-tolerant operation topology.

[0009] (2) The three-phase stator current i of the permanent magnet synchronous motor is collected by a current Hall sensor. a i b i c The electrical angle θ and actual rotational speed n of the motor rotor are calculated using a photoelectric encoder; based on the electrical angle θ of the motor rotor, the three-phase stator current i... a i b i c After rotational coordinate transformation, the dq-axis current components i in the two-phase synchronous rotating coordinate system are obtained. d i q ;

[0010] (3) Speed ​​outer loop design based on PI regulator, the actual motor speed n and the given speed n * The difference is calculated, and the electromagnetic torque reference value T is obtained through a PI controller. e * According to the electromagnetic torque reference value T e * The stator flux reference value |Ψ is obtained by the maximum torque-current ratio control method. s * |;

[0011] (4) Discretize the mathematical model of the permanent magnet synchronous motor in the two-phase synchronous rotating coordinate system, and obtain the predicted value of the stator current at time (k+1) based on the difference equation of the stator current.

[0012] (5) By using the relationship between stator flux linkage, electromagnetic torque and stator current, stator flux linkage and electromagnetic torque prediction models are constructed respectively. Using the predicted value of stator current at time (k+1) in step (4), the predicted value of stator flux linkage and electromagnetic torque of motor at time (k+1) can be obtained.

[0013] (6) The inner loop adopts a model predictive direct torque control strategy, which uses the reference and predicted values ​​of electromagnetic torque and stator flux linkage to construct a value function. The optimal switching state of the inverter is obtained through the value function. The inverter controls the switching tube to operate according to the optimal switching state, so as to realize the fault-tolerant operation of the permanent magnet synchronous motor.

[0014] A further improvement to the technical solution of this invention is as follows: In step (1), the neutral point of the permanent magnet synchronous motor needs to be brought out, and two capacitors are connected in series on the DC side of the inverter. The middle tap of the two capacitors serves as the DC power supply midpoint and is connected to the neutral point of the permanent magnet synchronous motor through a bidirectional thyristor. When a fault is detected in a certain phase switch of the inverter, the connection between that phase bridge arm and the motor is disconnected, and the bidirectional thyristor is closed to connect the motor neutral point to the DC power supply midpoint. The remaining switch is used to reconstruct the inverter into a two-phase four-switch fault-tolerant operating topology.

[0015] A further improvement to the technical solution of the present invention is that: in step (3), the electromagnetic torque reference value T e * The formula for obtaining it is:

[0016]

[0017] In the formula k p and k i These are the proportional gain and integral gain in the PI controller, respectively.

[0018] The stator flux reference value |Ψ is obtained using the maximum torque-current ratio control method. s * The formula is as follows:

[0019]

[0020] In the formula L s For stator inductance, its expression is: p n Ψ represents the number of pole pairs of a permanent magnet synchronous motor. f It is a permanent magnet flux linkage.

[0021] A further improvement of the technical solution of the present invention is that, in step (4), after the mathematical model of the permanent magnet synchronous motor is discretized, the resulting stator current differential equation is as follows:

[0022]

[0023] In the above formula, U d (k) and U q (k) represents the d-axis and q-axis components of the reference voltage vector applied to the motor by the inverter at time k in the two-phase synchronous rotating coordinate system, respectively. d (k) and iq (k) represents the d-axis and q-axis components of the motor stator current at time k in the two-phase synchronous rotating coordinate system, respectively. d and L q ω represents the d-axis and q-axis components of the equivalent inductance of the stator winding, respectively, R is the resistance of the motor stator winding, and ω is the resistance of the stator winding. e T is the electric angular velocity of the motor rotor. s Sampling time;

[0024] Predicted stator current i of the motor at time (k+1) d (k+1) and i q (k+1) can be obtained from the above formula.

[0025] A further improvement of the technical solution of the present invention is that, in step (5), based on the relationship between stator flux linkage and stator current in the motor model, a stator flux linkage prediction model can be constructed as follows:

[0026]

[0027] Substituting the predicted value of the stator current at time (k+1) into the above equation, we obtain the predicted value of the stator flux linkage at time (k+1) |Ψ s (k+1)|;

[0028] Similarly, the electromagnetic torque prediction model can be constructed as shown in the following equation:

[0029]

[0030] The predicted electromagnetic torque T of the motor at time (k+1) e (k+1) can be obtained from the above formula.

[0031] A further improvement of the technical solution of the present invention is that: in step (6), the reference values ​​and predicted values ​​of electromagnetic torque and stator flux linkage are used to construct a value function, as shown in the following formula:

[0032]

[0033] Under fault-tolerant operation of the system, since the inverter only has two bridge arms and four switching transistors to control the motor, there are only four switching states. Based on the model predictive control strategy, the predicted values ​​of electromagnetic torque and stator flux linkage at time (k+1) under the four different switching states can be obtained. The switching state that minimizes the value function J is selected as the optimal switching state of the inverter. The inverter controls the switching transistors to operate according to the optimal switching state, which can realize fault-tolerant operation of the permanent magnet synchronous motor.

[0034] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0035] This invention combines a three-phase four-switch inverter with a permanent magnet synchronous motor with a neutral point. Only one additional fast bidirectional thyristor is needed to switch between normal and fault-tolerant operation, resulting in a simple structure. Using the motor's electromagnetic torque and stator flux linkage as control variables, and stator current as an intermediate variable, model predictive torque control is employed. The optimal vector is directly selected from the value function, leading to rapid system response. Furthermore, model predictive control effectively suppresses electromagnetic torque pulsation, resulting in smoother motor operation and improved reliability and fault-tolerant operation of the motor drive system. Attached Figure Description

[0036] Figure 1 A block diagram for predictive torque control of a two-phase four-switch fault-tolerant inverter driving a permanent magnet synchronous motor with a neutral point.

[0037] Figure 2 This is a flowchart of the fault-tolerant control process;

[0038] Figure 3 This is a schematic diagram of an open circuit for the switching transistor;

[0039] Figure 4 This is a schematic diagram of a two-phase four-switch fault-tolerant reconfiguration.

[0040] Figure 5 This is a diagram showing the correspondence between the inverter output voltage vector and the switching status variables under fault conditions.

[0041] Figure 6 The waveform of the motor output speed under a fault-tolerant control system;

[0042] Figure 7 This is a waveform diagram of the torque output of the motor under a fault-tolerant control system. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to embodiments:

[0044] This invention is a fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC. It is a fault-tolerant direct torque control method for a two-phase four-switch permanent magnet synchronous motor based on model predictive control. The specific control block diagram is as follows: Figure 1As shown in the diagram. When an open-circuit fault occurs in the inverter switching transistor, the connection between the motor port and the faulty arm of the inverter is first disconnected, and the motor neutral point is connected to the power supply neutral point. The remaining switching transistors are used to perform fault-tolerant reconfiguration of the system topology. The outer loop of the controller is a speed loop based on a PI regulator design. The given torque is output through the PI regulator, and the reference stator flux is provided by maximum torque-to-current ratio control (MTPA). The inner loop adopts a model predictive direct torque control strategy. Based on the stator voltage equation and the stator current prediction model, the predicted values ​​of stator flux and electromagnetic torque are obtained. The optimal switching state of the inverter is obtained using the value function, and the remaining switching transistors are controlled to achieve fault-tolerant operation of the motor. The control flowchart is shown in the diagram. Figure 2 As shown, the system can still ensure safe and stable operation even in the event of a switching transistor failure, maintaining good steady-state and dynamic performance.

[0045] In this invention, the neutral point of the permanent magnet synchronous motor needs to be brought out. Two capacitors are connected in series on the DC side of the inverter. The center tap of these two capacitors serves as the DC power supply midpoint and is connected to the neutral point of the permanent magnet synchronous motor via a bidirectional thyristor. When an open-circuit fault occurs in a phase switch of the inverter, for example, if the A-phase switch S1 of the inverter has an open-circuit fault, ... Figure 3 As shown. First, disconnect the connection between the motor port and the faulty arm of the inverter. Simultaneously, close the bidirectional thyristor and connect the motor neutral point to the power supply neutral point. Use the remaining switching transistors to reconfigure the inverter into a two-phase four-switch fault-tolerant operating topology, as shown. Figure 4 As shown.

[0046] The three-phase stator current i of a permanent magnet synchronous motor a i b i c The electrical angle θ and actual rotational speed n of the motor rotor are acquired by a current Hall sensor and calculated using a photoelectric encoder. Based on the electrical angle value of the motor rotor, the three-phase stator current is transformed into the dq-axis current component i in a two-phase synchronous rotating coordinate system. d i q .

[0047] The outer loop of the controller is a speed loop based on a PI controller. The given torque is output through the PI controller, and the reference stator flux is provided by maximum torque-to-current ratio control (MTPA). The actual speed n and the given reference speed n are... * The difference is calculated, and the reference torque value T is obtained through a PI controller. e * The formula is:

[0048]

[0049] In the formula k p and k iThese are the proportional gain and integral gain in the PI controller, respectively.

[0050] The stator flux reference value |Ψ is obtained using the maximum torque-current ratio control method. s * The formula is as follows:

[0051]

[0052] In the formula L s For stator inductance, its expression is: p n Ψ represents the number of pole pairs of a permanent magnet synchronous motor. f It is a permanent magnet flux linkage.

[0053] The mathematical model of the permanent magnet synchronous motor in a two-phase synchronous rotating coordinate system is discretized. Based on the difference equation of the stator current, the predicted value of the stator current at time (k+1) can be obtained as shown in the following formula:

[0054]

[0055] In the above formula, U d (k) and U q (k) represents the d-axis and q-axis components of the reference voltage vector applied to the motor by the inverter at time k in the two-phase synchronous rotating coordinate system, respectively. d (k) and i q (k) represents the d-axis and q-axis components of the motor stator current at time k in the two-phase synchronous rotating coordinate system, respectively. d and L q ω represents the d-axis and q-axis components of the equivalent inductance of the stator winding, respectively, R is the resistance of the motor stator winding, and ω is the resistance of the stator winding. e T is the electric angular velocity of the motor rotor. s Sampling time.

[0056] Predicted stator current i of the motor at time (k+1) d (k+1) and i q (k+1) can be obtained from the above formula.

[0057] By using the relationship between stator flux linkage, electromagnetic torque and stator current, stator flux linkage and electromagnetic torque prediction models are constructed respectively. Using the predicted value of stator current at time (k+1) in step (4), the predicted values ​​of stator flux linkage and electromagnetic torque of the motor at time (k+1) can be obtained.

[0058] Based on the relationship between stator flux linkage and stator current in the motor model, the stator flux linkage prediction model can be constructed as follows:

[0059]

[0060] Substituting the predicted value of the stator current at time (k+1) into the above equation, we obtain the predicted value of the stator flux linkage at time (k+1) |Ψ s (k+1)|;

[0061] Similarly, the electromagnetic torque prediction model can be constructed as shown in the following equation:

[0062]

[0063] The predicted electromagnetic torque T of the motor at time (k+1) e (k+1) can be obtained from the above formula.

[0064] The inner loop of the controller employs a model predictive direct torque control strategy, constructing a value function using reference and predicted values ​​of electromagnetic torque and stator flux linkage, as shown in the following equation:

[0065]

[0066] By finding the minimum value of the value function, the optimal voltage vector for the next moment is selected, and then the switching state corresponding to the optimal voltage vector is output to control the remaining switching transistors, so as to achieve fault-tolerant operation.

[0067] In fault-tolerant operation, since the inverter only has two bridge arms and four switching transistors controlling the motor, there are only four switching states. The combination method of the switching states and the corresponding voltage vectors in fault-tolerant operation are as follows:

[0068] Assuming a fault occurs in the A-phase bridge arm switch, the fuse blows rapidly, isolating the A-phase bridge arm. Since the inverter only has four switches left to control the motor, there are four possible switch state combinations: M0(0,0), M1(0,1), M2(1,0), and M3(1,1). Figure 5 As shown, the numbers in parentheses represent the states of the switches in phases B and C of the bridge arm. "1" indicates that the upper switch in the same bridge arm is on and the lower switch is off; "0" indicates that the upper and lower switches in the same bridge arm are off, the opposite of "1". When a fault occurs in the A-phase switch of the inverter, the A-phase bridge arm is isolated, and the bidirectional thyristor TR is simultaneously turned on, connecting the neutral point N of the permanent magnet synchronous motor to the midpoint of the DC-side capacitor to construct a new topology for the motor control system under fault conditions. The inverter outputs a three-phase voltage U. AN U BN U CN The expression is shown in formula (7), where U DC This is the DC source voltage.

[0069]

[0070] Transforming the phase voltages in the three-phase stationary coordinate system into voltages in the two-phase stationary coordinate systems α and β, we obtain the voltage expressions as follows:

[0071]

[0072] Similarly, by transforming the phase voltages in the three-phase coordinate system to the stationary coordinate system under the other switching states, the correspondence between the switching states and voltage vectors of the three-phase four-switch inverter is shown in Table 1:

[0073] Table 1. Switching states and voltage vectors under fault-tolerant control during phase A fault.

[0074]

[0075] By adopting the model predictive direct torque control strategy, the predicted values ​​of electromagnetic torque and stator flux linkage at time (k+1) can be obtained under the above four different switching states. The switching state that minimizes the value function J of equation (6) is selected as the optimal switching state of the inverter. The inverter controls the operation of the switching tube according to the optimal switching state, which can realize the fault-tolerant operation of the permanent magnet synchronous motor.

[0076] To illustrate the fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC of this invention, which can achieve stable operation of the inverter under open-circuit faults while maintaining normal system operation and improve the fault-tolerant operation capability of the system, the proposed fault-tolerant control method was simulated and verified on MATLAB / Simulink software. The simulation results are presented and analyzed in detail.

[0077] The parameters of the permanent magnet synchronous motor used in the simulation are as follows: rated voltage U N =220V, AC and DC axis inductance L d =L q =5.25×10 -3 H, pole pair number p n =4, stator resistance R s =1.2Ω, permanent magnet flux linkage Ψ f =0.0796Wb, moment of inertia J =0.0027kg·m 2 The sampling period is 25ms.

[0078] At the start of the simulation, the given speed was 600 r / min and the input torque was 2 N·m. The inner loop adopted direct torque control based on model prediction. All the inverter switches were operating normally. At 0.2 s, the A-phase switch failed. The control system disconnected the A-phase bridge arm and connected the motor neutral point to the DC power supply neutral point, so that the system could continue to operate in the two-phase four-switch fault-tolerant mode.

[0079] Figure 6This is a waveform of the motor's output speed when switching from normal operation to fault-tolerant operation mode after a fault in phase A switch. At 0s, with a given speed of 600 r / min, the motor speed reaches the given value at 0.07s, at which point the motor reaches a steady state. At t=0.2s, the system experiences a fault and switches to fault-tolerant operation mode. The motor speed follows the given speed well, and the system quickly reaches a steady state after the fault. As shown in the enlarged graph, the speed pulsation increases to 0.6 r / min in fault-tolerant operation mode, slightly higher than in normal mode, but still maintains good steady-state performance.

[0080] Figure 7 This is a waveform diagram of the electromagnetic torque output by the motor when switching from normal state to fault-tolerant operation mode after a fault in phase A switch. At 0s, the given torque is 2 N·m, and the system reaches a steady state 0.07s after startup. At t=0.2s, the phase A fault enters the fault-tolerant operation mode, and the torque pulsation of the motor output increases from the original 0.1 N·m to 0.3 N·m. The waveform does not have obvious jump fluctuations and can quickly enter a steady state. The electromagnetic torque maintains good steady-state and dynamic performance.

[0081] As can be seen from the above, the two-phase four-switch fault-tolerant control method for permanent magnet synchronous motors based on MPC proposed in this invention can maintain good steady-state and dynamic performance under inverter switching tube failure, enabling the system to have a certain fault-tolerant operation capability and improving the system's stability and robustness.

[0082] The examples described above are merely preferred embodiments of the present invention and have been described in detail, rather than being limitations on the technical methods. It should be noted that for those skilled in the art, several improvements or equivalent substitutions can be made without departing from the basic principles of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC, characterized in that: Includes the following steps: (1) When a switch in one phase of the inverter fails, disconnect the faulty bridge arm, connect the motor neutral point to the DC power supply neutral point, and reconfigure the inverter into a two-phase four-switch fault-tolerant operation topology. (2) The three-phase stator current i of the permanent magnet synchronous motor is collected by the current Hall sensor a 、 b 、 c The electrical angle θ and the actual speed n of the motor rotor are calculated by using the photoelectric encoder; according to the electrical angle θ of the motor rotor, the three-phase stator current i a 、 b 、 c After the rotation coordinate transformation, the dq-axis current components i d 、 q in the two-phase synchronous rotation coordinate system are obtained (3) Based on the PI regulator speed outer ring design, the actual speed of the motor n and the given speed n * The difference is obtained by the PI controller to get the electromagnetic torque reference value T e * ; According to the electromagnetic torque reference value T e * , the maximum torque current ratio control method is obtained. The stator flux reference value |Ψ s * |; (4) Discretize the mathematical model of the permanent magnet synchronous motor in the two-phase synchronous rotating coordinate system, and obtain the predicted value of the stator current at time (k+1) based on the difference equation of the stator current. (5) By using the relationship between stator flux linkage, electromagnetic torque and stator current, stator flux linkage and electromagnetic torque prediction models are constructed respectively. Using the predicted value of stator current at time (k+1) in step (4), the predicted value of stator flux linkage and electromagnetic torque of motor at time (k+1) can be obtained. (6) The inner loop adopts a model predictive direct torque control strategy, which uses the reference and predicted values ​​of electromagnetic torque and stator flux linkage to construct a value function. The optimal switching state of the inverter is obtained through the value function. The inverter controls the switching tube to operate according to the optimal switching state, so as to realize the fault-tolerant operation of the permanent magnet synchronous motor.

2. The method for fault-tolerant control of a two-phase four-switch permanent magnet synchronous motor based on MPC according to claim 1, characterized in that: In step (1), the neutral point of the permanent magnet synchronous motor needs to be brought out. Two capacitors are connected in series on the DC side of the inverter. The middle tap of the two capacitors serves as the DC power supply midpoint and is connected to the neutral point of the permanent magnet synchronous motor through a bidirectional thyristor. When a fault is detected in a certain phase switch of the inverter, the connection between the phase bridge arm and the motor is disconnected. At the same time, the bidirectional thyristor is closed to connect the motor neutral point to the DC power supply midpoint. The remaining switch is used to reconstruct the inverter into a two-phase four-switch fault-tolerant operating topology.

3. The method for fault-tolerant control of a two-phase four-switch permanent magnet synchronous motor based on MPC according to claim 1, characterized in that: In step (3), the electromagnetic torque reference value T e * The formula for obtaining it is: In the formula k p and k i These are the proportional gain and integral gain in the PI controller, respectively. The stator flux reference value |Ψ is obtained using the maximum torque-current ratio control method. s * The formula is as follows: In the formula L s For stator inductance, its expression is: p n Ψ represents the number of pole pairs in a permanent magnet synchronous motor. f It is a permanent magnet flux linkage.

4. The fault-tolerant control method for a two-phase four-switch permanent magnet synchronous motor based on MPC according to claim 1, characterized in that: In step (4), after discretizing the mathematical model of the permanent magnet synchronous motor, the resulting stator current differential equation is shown in the following equation: In the above formula, U d (k) and U q (k) represents the d-axis and q-axis components of the reference voltage vector applied to the motor by the inverter at time k in the two-phase synchronous rotating coordinate system, respectively. d (k) and i q (k) represents the d-axis and q-axis components of the motor stator current at time k in the two-phase synchronous rotating coordinate system, respectively. d and L q ω represents the d-axis and q-axis components of the equivalent inductance of the stator winding, respectively, R is the resistance of the motor stator winding, and ω is the resistance of the stator winding. e T is the electric angular velocity of the motor rotor. s Sampling time; Predicted stator current i of the motor at time (k+1) d (k+1) and i q (k+1) can be obtained from the above formula.

5. The method for fault-tolerant control of a two-phase four-switch permanent magnet synchronous motor based on MPC according to claim 1, characterized in that: In step (5), based on the relationship between stator flux linkage and stator current in the motor model, the stator flux linkage prediction model can be constructed as follows: Substituting the predicted value of the stator current at time (k+1) into the above equation, we obtain the predicted value of the stator flux linkage at time (k+1) |Ψ s (k+1)|; Similarly, the electromagnetic torque prediction model can be constructed as shown in the following equation: The predicted electromagnetic torque T of the motor at time (k+1) e (k+1) can be obtained from the above formula.

6. The method for fault-tolerant control of a two-phase four-switch permanent magnet synchronous motor based on MPC according to claim 1, characterized in that: In step (6), the reference and predicted values ​​of electromagnetic torque and stator flux linkage are used to construct a value function, as shown in the following equation: Under fault-tolerant operation of the system, since the inverter only has two bridge arms and four switching transistors to control the motor, there are only four switching states. Based on the model predictive control strategy, the predicted values ​​of electromagnetic torque and stator flux linkage at time (k+1) under the four different switching states can be obtained. The switching state that minimizes the value function J is selected as the optimal switching state of the inverter. The inverter controls the switching transistors to operate according to the optimal switching state, which can realize fault-tolerant operation of the permanent magnet synchronous motor.

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