A three-phase permanent magnet synchronous motor drive system open-circuit fault tolerance control method

Abstract

The application discloses a kind of three-phase permanent magnet synchronous motor drive system open-circuit fault tolerance control method, it is related to synchronous motor fault tolerance control field.In the fault occurs, by introducing the average copper loss of a current fundamental period to optimize fault tolerance current reference value to realize copper loss constraint, motor current commutation and reduce torque ripple.Finally, by calculating average copper loss to detect whether the average copper loss of motor exceeds the maximum copper loss threshold value specified to update the fault tolerance reference current of motor in real time, and then improve the fault tolerance capability of three-phase permanent magnet synchronous motor drive system, current tracking accuracy, reduce torque ripple and copper loss of fault tolerance operation.

Description

Technical Field

[0001] This invention belongs to the field of fault-tolerant control technology for synchronous motors, specifically a fault-tolerant control method for open-circuit faults in a three-phase permanent magnet synchronous motor drive system. Background Technology

[0002] Phase loss faults and open circuit faults of switching transistors are common electrical faults in motors. When a motor experiences a phase loss fault or an open circuit fault of a switching transistor, the motor will not stop immediately, but the motor will produce a series of motor fault characteristics, such as torque pulsation and motor overheating. If no post-fault handling is performed, it may even lead to secondary faults and eventually cause the motor drive system to collapse.

[0003] To improve the fault-tolerant control performance of motors, auxiliary circuitry is used in three-phase motor drive systems. This increases the current flow path by altering the system's topology, thereby enhancing fault-tolerant control. Simultaneously, open-winding systems are widely used, allowing independent control of each phase's current and significantly improving the fault-tolerant control performance of three-phase motors.

[0004] To reduce torque and flux control errors, existing research has established a mathematical model of the motor after a phase loss fault by analyzing the characteristics of the motor after a fault, and proposed a predictive control method to control the motor after the fault. This greatly improves the fault-tolerant control performance of the motor and reduces the motor torque output and flux control errors.

[0005] However, existing technologies still have shortcomings. First, these auxiliary circuit facilities and open winding facilities may still fail, increasing system cost and complexity, which is not conducive to the promotion and use of the method. Second, current research mainly focuses on a certain fault-tolerant control method for phase loss faults and open circuit faults of switching transistors. Moreover, these methods do not take into account the copper loss factor after motor failure. It is possible that using the above-mentioned fault-tolerant control methods will increase the copper loss of the motor and reduce the motor operating efficiency under fault conditions. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a fault-tolerant control method for open-circuit faults in a three-phase permanent magnet synchronous motor drive system. This method achieves fault-tolerant control for both phase-loss faults and open-circuit faults by reconstructing the reference current of the motor drive system after a fault. Under a phase-loss fault, the reference current is determined using the motor torque command and the motor torque formula. Then, the average copper loss of the motor over one current fundamental cycle is calculated to obtain a new reference current that considers current commutation and motor copper loss. This fault-tolerant control method can reduce motor torque ripple and current tracking errors, and limit the average copper loss of the motor to below the target value. For open-circuit faults, based on the fault-tolerant control for phase-loss faults, the current reference value remains unchanged during normal operation. During fault operation, the current reference value for motor fault-tolerant control is the same as the current reference value for phase-loss fault-tolerant control.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A fault-tolerant control method for open-circuit faults in a three-phase permanent magnet synchronous motor drive system includes:

[0011] Open circuit faults in a three-phase permanent magnet synchronous motor drive system refer to phase loss faults and switching transistor open circuit faults. This is based on the dq-axis current expression during phase loss fault operation, the torque formula for surface-mounted permanent magnet synchronous motors, current suppression requirements, and motor torque commands. By obtaining the phase current reference value during phase-loss fault-tolerant operation, and then using the coordinate transformation of the dq-axis current expression, a new dq-axis fault-tolerant current reference value can be obtained, thus achieving the theoretical minimum torque ripple during phase-loss fault-tolerant operation.

[0012] Considering that current commutation cannot be completed instantaneously, the angle required for current commutation is calculated by calculating the time required for minimum current commutation, and the current reference value that satisfies current commutation is obtained. Substituting this into the phase current reference value, the phase current reference value considering current commutation under the new phase loss fault-tolerant operation condition is obtained.

[0013] By calculating the average copper loss power and mechanical power, the expression for the copper loss factor is obtained. The copper loss factor is positively correlated with the average copper loss. Then, using the torque formula and the copper loss formula, the phase current reference value considering copper loss can be obtained. By changing the copper loss factor, the phase current reference value is changed, thereby changing the average copper loss. This is then compared with the torque command. By combining the obtained phase current reference values ​​under phase loss fault tolerance operation, the phase current reference values ​​under phase loss fault tolerance operation considering copper loss can be obtained.

[0014] By combining the current commutation angle, an expression for the copper loss factor considering current commutation can be obtained. This expression is used as the initial value of the phase current reference value under the fault-tolerant operation condition of phase loss considering the magnitude of copper loss. Thus, this phase current reference value becomes the initial value of the phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and the magnitude of copper loss.

[0015] Considering the maximum upper limit of copper loss in the motor, a PI controller is introduced to calculate the optimal copper loss factor. The maximum value of this copper loss factor is the copper loss factor considering current commutation. When the average copper loss exceeds its upper limit, the copper loss factor will decrease to reduce the average copper loss until it is equal to the upper limit of the average copper loss. At this point, the copper loss factor is the optimal copper loss factor. Substituting it into the phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and copper loss, the optimal phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and copper loss can be obtained.

[0016] For open-circuit faults of switching transistors, a two-mode fault-tolerant control method is implemented based on the phase current reference value during fault-tolerant operation of phase loss faults to achieve fault-tolerant control.

[0017] Furthermore, based on the expression for the dq-axis current during single-phase fault operation, the torque formula for the surface-mounted permanent magnet synchronous motor is as follows: Where it is assumed that phase A is a phase loss fault phase, i B Indicates the B-phase current; i d i q These are represented as d-axis and q-axis currents, respectively; N p Indicates the number of pole pairs of the motor; T e Indicates motor torque; ψ f It is the amplitude of the permanent magnet flux linkage; θ e This indicates the electrical angular position information of the motor rotor.

[0018] Furthermore, based on the expression for the dq-axis current during single-phase fault operation, the torque formula for surface-mounted permanent magnet synchronous motors, current suppression requirements, and motor torque commands... The specific reference values ​​for the phase current during fault-tolerant operation with a phase loss fault are as follows: in To consider only the motor torque command The obtained phase current reference value during fault-tolerant operation under phase loss fault; This refers to the reference value of the phase current during fault-tolerant operation with added current suppression requirements for phase-loss faults; I max This represents the maximum current amplitude of the motor.

[0019] Furthermore, the minimum time required for the current commutation is specifically as follows: Where T ct L represents the minimum commutation time.s For the stator inductance of the motor; U dc This is the DC bus voltage.

[0020] Furthermore, the current commutation angle is specifically: θ c =ω e T ct ;where θ c ω is the current commutation angle. e It is the electric angular velocity of the motor.

[0021] Furthermore, the specific phase current reference value considering current commutation is as follows:

[0022] in The phase current reference value is taken into account for current commutation; To meet the current reference value for current commutation; The current inflection point is the increase in the phase current reference value after considering the current commutation.

[0023] Furthermore, by using the average copper loss power and mechanical power, the expression for the copper loss factor is obtained, specifically: Where P cu P Te These are the average copper loss power and mechanical power, respectively; R s R is the stator resistance of the motor; n is the motor speed; Cu This is the copper loss factor.

[0024] Furthermore, the phase current reference value under the fault-tolerant operation condition of a phase loss fault, considering copper loss and current commutation, is specifically as follows: in The phase current reference value is taken into account for copper losses; The phase current reference value is provided for a phase-loss fault-tolerant operation that takes into account copper losses and current commutation.

[0025] Furthermore, the average copper loss under phase loss fault-tolerant operation is specifically as follows: in These are the turning points for the phase current reference values ​​after considering copper losses.

[0026] Furthermore, the initial value of the copper loss factor is specifically as follows: Where C cu_in This is represented as the initial value of the copper loss factor;

[0027] During the fault-tolerant control operation of phase loss fault, a PI controller is introduced to calculate the optimal copper loss factor. The maximum value of this copper loss factor is the copper loss factor considering current commutation. When the average copper loss exceeds its upper limit, the copper loss factor will decrease to reduce the average copper loss until it is equal to the upper limit of the average copper loss. At this time, the copper loss factor is the optimal copper loss factor.

[0028] The described two-mode fault-tolerant control method for open-circuit faults of switching transistors; assuming a fault occurs in the upper transistor of phase A, the current reference value remains unchanged in normal operation mode, and in fault operation mode, the current reference value is equal to the fault-tolerant current reference value for a phase loss fault, specifically: in These are the dq-axis reference currents during fault-tolerant operation with open-circuit faults in the switching transistor; sinθ e >0 indicates that the motor is operating normally; sinθ e <0 indicates that the motor is in fault-tolerant operation;

[0029] For switching transistor failures: During fault-tolerant operation, the average copper loss will not exceed its threshold, therefore the optimal copper loss factor is equal to the initial value of the copper loss factor.

[0030] The principle of this invention lies in the following: Firstly, it provides a fault-tolerant control method for open-circuit faults in a three-phase permanent magnet synchronous motor drive system, comprising:

[0031] Expression for dq-axis current after phase loss fault: Assume that a phase loss fault occurs in phase A, so the current in phase A is 0, and the current in phase B is the opposite of the current in phase A.

[0032] The expression for motor torque after a phase loss fault is as follows:

[0033] The phase current reference value for fault-tolerant operation is obtained through motor torque command: It takes into account the maximum current amplitude that the motor can withstand and can achieve the minimum torque pulsation theoretically required when the motor is running under a phase loss fault; however, it does not take into account current commutation, resulting in poor current tracking accuracy and negative torque output.

[0034] Considering the minimum current commutation time:

[0035] Considering the minimum current commutation angle: θ c =ω e T ct .

[0036] Phase current reference value considering current commutation: By taking current commutation factors into account, the current tracking accuracy of the motor in fault-tolerant operation with phase loss faults can be greatly improved, and the torque output performance can be improved. However, the motor copper loss is not taken into account, which reduces the motor efficiency.

[0037] Average copper loss power and mechanical power of the motor:

[0038] Motor copper loss factor:

[0039] Phase current reference value considering only copper losses:

[0040] Phase current reference values ​​under fault-tolerant operation conditions considering copper loss and current commutation in a single-phase fault: By adjusting the copper loss factor, current commutation and the average copper loss of the motor can be achieved.

[0041] Average copper loss under phase loss fault-tolerant operation:

[0042]

[0043] Initial value of copper loss factor: Current commutation can be achieved by substituting the initial value of the copper loss factor into the phase current reference value.

[0044] Optimal Copper Loss Factor Solution: The initial value of the copper loss factor is taken as its maximum value. When the calculated average copper loss is less than a specified value, the optimal copper loss factor equals the initial value. When the calculated average copper loss is greater than the specified value, the copper loss factor should be reduced. To solve for the optimal copper loss factor, a PI controller is introduced to solve for it, and its maximum output value is taken as the initial value. When the average copper loss is less than the specified value, the PI controller outputs the initial value of the copper loss factor as the optimal value. When the calculated average copper loss is greater than the specified value, the PI controller outputs the copper loss factor, which gradually decreases until the average copper loss equals the specified value.

[0045] Two-mode fault-tolerant control for open-circuit faults in switching transistors: Assuming a fault occurs in the upper tube of phase A, the current reference value remains unchanged during normal operation. During fault operation, the current reference value is equal to the fault-tolerant current reference value for a phase loss fault.

[0046] The present invention has the following beneficial effects:

[0047] The proposed fault-tolerant control method for open-circuit fault-tolerant control of a three-phase permanent magnet synchronous motor drive system, based on current reference value reconstruction, achieves fault-tolerant control simply by changing the current reference value of the motor drive system. The control framework of the motor drive control system under normal operating conditions can still be used for fault-tolerant operation. This method eliminates the need for any auxiliary circuitry, reducing economic costs. It reduces current tracking errors caused by the inability to immediately complete current commutation. By introducing a copper loss factor, copper losses during fault-tolerant operation are constrained, ensuring that the maximum copper loss limit is not exceeded. The stability of fault-tolerant operation is improved by introducing a PI controller to optimize the reference current in real time. The optimized fault-tolerant reference current satisfies current commutation requirements, reduces current tracking errors, eliminates negative torque, and achieves a good balance between motor copper losses and output torque. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the three-phase motor drive control system used.

[0049] Figure 2 This is a flowchart of an open-circuit fault-tolerant control method for a permanent magnet synchronous motor drive system according to the present invention.

[0050] Figure 3 Based on torque command The obtained phase current reference value diagram for fault-tolerant operation under phase loss fault.

[0051] Figure 4 This is a diagram of phase current reference values ​​for use during fault-tolerant operation with consideration of current commutation in the event of a phase loss fault.

[0052] Figure 5 This is a fault-tolerant performance diagram of phase current reference values ​​with different copper loss factors during phase loss fault fault-tolerant operation.

[0053] Figure 6 This is a fault-tolerant performance diagram of the two-mode fault-tolerant control method when the switching transistor is in an open-circuit fault condition. Detailed Implementation

[0054] The technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0055] like Figure 1As shown, this embodiment relates to a three-phase permanent magnet synchronous motor drive system, including: a current command generation unit, a reference voltage generation unit, a signal generation unit, a power drive unit, a current detection and conversion unit, and a position and speed detection unit, wherein: the current command generation unit generates a current command based on a torque command. Obtain the reference current The reference voltage generation unit generates the reference voltage based on the reference current. and feedback i d i q Calculated voltage command The signal generation unit generates signals based on the reference voltage. The drive signal is obtained through modulation; the power drive unit drives the motor according to the drive signal; the current detection and transformation unit acquires the current signal and performs coordinate transformation; the position and speed detection unit is used to obtain the motor's position information θ and speed information ω. e .

[0056] like Figure 2 As shown, this embodiment illustrates the open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system based on the aforementioned system, specifically including:

[0057] S1: Assuming a phase loss fault occurs in phase A, under fault-tolerant operation, based on torque command... Obtain the phase current reference value for fault-tolerant operation:

[0058] like Figure 3 As shown, based on torque command The phase current reference value obtained during phase loss fault tolerance operation requires the current to be reversed immediately during current commutation, which will increase the current tracking error of the motor and deteriorate the torque output performance of the motor.

[0059] S2: Based on torque command To achieve the theoretical minimum torque ripple, the phase current reference value for fault-tolerant operation must ensure that the motor current can instantly commutate during commutation, which is impossible in actual motor systems. Therefore, the commutation angle must be considered during fault-tolerant motor operation. This is achieved by solving for the commutation time: The reversal angle can also be solved: θ c =ω e T ct By solving for the commutation angle, the fault-tolerant control reference current considering current commutation can be calculated: By taking current commutation factors into account, the current tracking accuracy of the motor in fault-tolerant operation with phase loss faults can be greatly improved, and the torque output performance can be improved. However, the motor copper loss is not taken into account, which reduces the motor efficiency.

[0060] like Figure 4 As shown: Compared with torque command-based Compared to the phase current reference value obtained during phase loss fault tolerance operation, the current commutation time is extended when using the phase current reference value that takes current commutation into account during phase loss fault tolerance operation, and the motor starts commutation at an earlier angle.

[0061] S3: By introducing copper losses and mechanical power: The copper loss factor of the motor can be expressed as: Then, using the torque formula: And coordinate transformation formula: The reference value of the phase current considering only copper losses can then be obtained: As can be seen from the formula, the copper loss of the motor can be changed by altering the copper loss factor. Therefore, in order to reduce copper loss... It should also be selected as the phase current reference value and should be as small as possible. Therefore and Values ​​with smaller absolute values ​​should be given priority as reference values. Therefore, the reference value of the phase current under the fault-tolerant operation condition of a phase loss fault, considering copper losses and current commutation, can be expressed as follows: By adjusting the copper loss factor, current commutation and the average copper loss of the motor can be achieved.

[0062] like Figure 5 As shown: By changing the copper loss factor, the reference value of the phase current during fault-tolerant operation of the motor is altered. Simultaneously, current commutation can also be achieved by changing the copper loss factor. By changing the copper loss factor, the average copper loss of the motor can be altered; the smaller the copper loss factor, the smaller the average copper loss of the motor.

[0063] S4: Calculate the average copper loss over one fundamental current cycle:

[0064] Then, a PI controller is introduced to solve for the optimal copper loss factor. The upper limit of the motor copper loss is used as the reference value for the PI controller, and the initial value of the copper loss factor that can satisfy current commutation is set as follows: The average copper loss is the maximum value output by the PI controller. When the average copper loss is less than the specified value, the PI controller outputs the initial value of the copper loss factor as the optimal value. When the calculated average copper loss is greater than the specified value, the PI controller outputs the copper loss factor gradually decreasing until the average copper loss equals the specified value.

[0065] S5: Substitute the obtained optimal copper loss factor into... The optimal fault-tolerant control phase current reference value can then be obtained under a phase loss fault.

[0066] S6: The optimal fault-tolerant control phase current reference value under phase loss fault operation can be obtained by coordinate transformation. The optimal fault-tolerant control dq axis current reference value under phase loss fault operation can be obtained by substituting the optimal fault-tolerant control dq axis current reference value into the control system to complete the fault-tolerant control operation.

[0067] For open-circuit faults in the switching transistor, a two-mode fault-tolerant control method is adopted: Assuming a fault occurs in phase A, the current reference value remains unchanged during normal operation. In fault operation mode, the current reference value is equal to the fault-tolerant current reference value for a phase loss fault. Fault-tolerant control can be achieved by substituting the obtained dq-axis current reference values ​​into the control system.

[0068] like Figure 6 As shown, the current reference value for an open-circuit fault in the switching transistor is only changed during fault operation. Through this fault-tolerant control method, the remaining healthy switching transistors are fully utilized to control the motor.

[0069] In the above steps, torque ripple, current tracking accuracy, and motor copper loss factors during fault-tolerant operation of the motor are all considered in the proposed fault-tolerant control. The proposed open-circuit fault-tolerant control method for the three-phase permanent magnet synchronous motor drive system can effectively reduce motor torque ripple, current tracking accuracy error, and average motor copper loss during fault-tolerant operation, thereby improving the safety and reliability of the system.

Claims

1. A fault-tolerant control method for open-circuit faults in a three-phase permanent magnet synchronous motor drive system, characterized in that, include: Open circuit faults in a three-phase permanent magnet synchronous motor drive system refer to phase loss faults and switching transistor open circuit faults. This is based on the dq-axis current expression during phase loss fault operation, the torque formula for surface-mounted permanent magnet synchronous motors, current suppression requirements, and motor torque commands. By obtaining the phase current reference value during phase-loss fault-tolerant operation, and then using the coordinate transformation of the dq-axis current expression, a new dq-axis fault-tolerant current reference value can be obtained, thus achieving the theoretical minimum torque ripple during phase-loss fault-tolerant operation. Considering that current commutation cannot be completed instantaneously, the angle required for current commutation is calculated by calculating the time required for minimum current commutation, and the current reference value that satisfies current commutation is obtained. Substituting this into the phase current reference value, the phase current reference value considering current commutation under the new phase loss fault-tolerant operation condition is obtained. By calculating the average copper loss power and mechanical power, the expression for the copper loss factor is obtained. The copper loss factor is positively correlated with the average copper loss. Then, using the torque formula and the copper loss formula, the phase current reference value considering copper loss can be obtained. By changing the copper loss factor, the phase current reference value is changed, thereby changing the average copper loss. This is then compared with the torque command. By combining the obtained phase current reference values ​​under phase loss fault tolerance operation, the phase current reference values ​​under phase loss fault tolerance operation considering copper loss can be obtained. By combining the current commutation angle, an expression for the copper loss factor considering current commutation can be obtained. This expression is used as the initial value of the phase current reference value under the fault-tolerant operation condition of phase loss considering the magnitude of copper loss. Thus, this phase current reference value becomes the initial value of the phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and the magnitude of copper loss. Considering the maximum upper limit of copper loss in the motor, a PI controller is introduced to calculate the optimal copper loss factor. The maximum value of this copper loss factor is the copper loss factor considering current commutation. When the average copper loss exceeds its upper limit, the copper loss factor will decrease to reduce the average copper loss until it is equal to the upper limit of the average copper loss. At this point, the copper loss factor is the optimal copper loss factor. Substituting it into the phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and copper loss, the optimal phase current reference value under the fault-tolerant operation condition of phase loss considering current commutation and copper loss can be obtained. For open-circuit faults of switching transistors, a two-mode fault-tolerant control method is implemented based on the phase current reference value during phase-loss fault-tolerant operation to achieve fault-tolerant control. When a fault occurs in the upper transistor of phase A, the current reference value remains unchanged in normal operation mode, and in fault operation mode, the current reference value is equal to the phase-loss fault-tolerant current reference value, specifically: ;in , These are the dq-axis reference currents during fault-tolerant operation with open-circuit faults in the switching transistor; sinθ e >0 indicates that the motor is operating normally; sinθ e <0 indicates that the motor is in fault-tolerant operation; θ e This indicates the electrical angular position information of the motor rotor; The phase current reference value is provided for a phase-loss fault-tolerant operation that takes into account copper losses and current commutation.

2. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 1, characterized in that: The specific expressions for the dq-axis current and the torque formula for the surface-mounted permanent magnet synchronous motor during single-phase fault operation are as follows: ; When phase A is a phase loss fault phase, i B Indicates the B-phase current; i d i q These are represented as d-axis and q-axis currents, respectively; N p Indicates the number of pole pairs of the motor; T e ψ represents the motor torque; f It is the amplitude of the permanent magnet flux linkage.

3. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 2, characterized in that: Based on the expression for the dq-axis current during single-phase fault operation, the torque formula for a surface-mounted permanent magnet synchronous motor, current suppression requirements, and motor torque commands. The specific reference values ​​for the phase current during fault-tolerant operation with a phase loss fault are as follows: ; ;in To consider only the motor torque command The obtained phase current reference value during fault-tolerant operation under phase loss fault; This refers to the reference value of the phase current during fault-tolerant operation with added current suppression requirements for phase loss faults; I max This represents the maximum current amplitude of the motor.

4. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 3, characterized in that: The specific time required for the minimum current commutation is as follows: ; where T ct L represents the minimum commutation time. s For the stator inductance of the motor; U dc This is the DC bus voltage.

5. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 4, characterized in that: The current commutation angle is specifically: ;where θ c ω is the current commutation angle. e It is the electric angular velocity of the motor.

6. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 5, characterized in that: The specific phase current reference value considering current commutation is as follows: ; ; ;in The phase current reference value is taken into account for current commutation; To meet the current reference value for current commutation; , , , The power inflection point is the increase in the phase current reference value after considering the current commutation.

7. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 6, characterized in that: The expression for the copper loss factor is obtained by using the average copper loss power and mechanical power, as follows: ; ;where P cu P Te These are the average copper loss power and mechanical power, respectively; R s R is the stator resistance of the motor; n is the motor speed; Cu This is the copper loss factor.

8. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 7, characterized in that: The phase current reference value under the fault-tolerant operation condition of phase loss fault considering copper loss and current commutation is specifically as follows: ; ;in The phase current reference value is taken into account for copper losses.

9. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 8, characterized in that: The average copper loss under phase loss fault-tolerant operation is specifically as follows: ; ;in , , , , , , , These are the turning points for the phase current reference values ​​after considering copper losses.

10. The open-circuit fault-tolerant control method for a three-phase permanent magnet synchronous motor drive system according to claim 9, characterized in that: The initial value of the copper loss factor is specifically as follows: ; where C cu_in This is represented as the initial value of the copper loss factor; During the fault-tolerant control operation of phase loss fault, a PI controller is introduced to calculate the optimal copper loss factor. The maximum value of this copper loss factor is the copper loss factor considering current commutation. When the average copper loss exceeds its upper limit, the copper loss factor will decrease to reduce the average copper loss until it is equal to the upper limit of the average copper loss. At this time, the copper loss factor is the optimal copper loss factor. For switching transistor failures: During fault-tolerant operation, the average copper loss will not exceed its threshold, therefore the optimal copper loss factor is equal to the initial value of the copper loss factor.

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