An inverter single switch open-circuit fault tolerance control method

Abstract

The application provides a single-switch open-circuit fault tolerance control method of an inverter, and relates to the technical field of electric drive systems.The method comprises the following steps: in response to a single-switch open-circuit fault of a multi-phase inverter, determining the voltage output constraint of a fault phase under the single-switch open-circuit fault according to the fault switch position corresponding to the single-switch open-circuit fault and the phase current direction of the fault phase; when the original reference pole voltage of the fault phase does not satisfy the voltage output constraint, determining a zero-sequence compensation voltage according to the original reference pole voltage of the fault phase and the voltage output constraint; superimposing the zero-sequence compensation voltage on the original reference pole voltage of each phase of the multi-phase inverter respectively to obtain the compensation reference pole voltage of each phase of the multi-phase inverter, and generating a pulse width modulation signal for driving the multi-phase inverter according to the space vector modulation. The application can maintain the stable operation of a motor without adding additional hardware when a single-switch open-circuit fault occurs in the inverter.

Description

Technical Field

[0001] This invention relates to the field of electric drive system technology, and more specifically, to a fault-tolerant control method, device, equipment, and storage medium for an inverter with a single switch open-circuit fault. Background Technology

[0002] With the increasing demands for continuous operation of electric drive systems from new energy vehicles and industrial drive equipment, electric drive systems not only need to have power output capability under normal operating conditions, but also need to maintain a certain degree of controlled operation capability when some power devices fail.

[0003] Electric drive systems typically use multiphase inverters to drive motors. Taking a three-phase two-level inverter as an example, each phase arm of the inverter includes multiple switching transistors. When any switching transistor experiences an open-circuit fault, the range of pole voltages that the faulty phase can output will change due to the position of the faulty switch and the direction of the faulty phase current. This causes the actual voltage range that the inverter can operate under fault conditions to differ from that under normal conditions. If the inverter is still controlled according to the reference voltage before the fault occurred, the reference voltage may exceed the actual output capability under fault conditions, thereby affecting the stable operation of the motor.

[0004] In response to this, some related technologies involve blocking the inverter's drive signal after a fault occurs, causing the motor to stop operating. However, this can easily lead to a sudden power interruption, affecting the safety and stability of the electric drive system. Other solutions use a phase-loss energizing method to maintain motor operation. While this can keep the motor running to some extent, it alters the original multi-phase power supply relationship of the motor, making it difficult to maintain an ideal rotating magnetic field. This can easily lead to large torque pulsations, causing mechanical vibration and noise, and failing to meet the stable operation requirements of the motor and electric drive system. Still other solutions achieve fault tolerance by using additional hardware such as redundant bridge arms and neutral point leads. However, this increases the cost and structural complexity of the electric drive system and reduces system integration and power density. Summary of the Invention

[0005] The problem solved by this invention is: how to maintain stable motor operation without adding extra hardware when a single switch open circuit fault occurs in the inverter.

[0006] To address the aforementioned problems, this invention provides a fault-tolerant control method, device, equipment, and storage medium for single-switch open-circuit faults in inverters.

[0007] In a first aspect, the present invention provides a fault-tolerant control method for an inverter with a single switch open-circuit fault, applicable to an electric drive system including a multiphase inverter and a motor, comprising: In response to a single-switch open-circuit fault in the multiphase inverter, the voltage output constraint of the faulty phase under the current single-switch open-circuit fault is determined based on the fault switch position and the phase current direction of the faulty phase corresponding to the single-switch open-circuit fault. When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage of the faulty phase and the voltage output constraint. The zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. Space vector modulation is performed based on the compensated reference pole voltages of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

[0008] Optionally, the multiphase inverter includes a three-phase two-level voltage source inverter, which includes three phase bridge arms, each of which includes an upper bridge arm switch and a lower bridge arm switch; the single switch open circuit fault is an open circuit fault in the upper bridge arm switch or the lower bridge arm switch of any phase bridge arm in the three-phase two-level voltage source inverter.

[0009] Optionally, the motor includes an AC motor; the inverter single-switch open-circuit fault-tolerant control method further includes: Collect the stator current and rotor position of the AC motor; Based on the stator current, the rotor position, and the torque request corresponding to the AC motor, the AC motor is subjected to field-oriented control to generate the original reference pole voltage of each phase of the multiphase inverter.

[0010] Optionally, the inverter single-switch open-circuit fault-tolerant control method further includes: Obtain the single-switch open-circuit fault signal of the multiphase inverter; Based on the single switch open circuit fault signal, determine the faulty phase and the location of the faulty switch where the single switch open circuit fault occurred; The fault switch position is used to characterize the inverter phase in which the open-circuit fault occurs and the connection position of the switch in the corresponding bridge arm.

[0011] Optionally, determining the voltage output constraint of the faulty phase under the current single-switch open-circuit fault based on the fault switch position and phase current direction of the faulty phase corresponding to the single-switch open-circuit fault includes: Based on the location of the fault switch, determine the inverter switch state combination that cannot be executed normally due to the open circuit fault of the single switch tube; Based on the phase current direction of the faulty phase, the currently executable switching state combination is determined from multiple switching state combinations of the multiphase inverter; The voltage output constraint of the fault phase is determined based on the pole voltage output range corresponding to the current executable switch state combination. The voltage output constraint includes at least one of the following: upper voltage limit, lower voltage limit, voltage range, voltage boundary, and voltage feasible region.

[0012] Optionally, when the fault switch position is the upper bridge arm position of the fault phase, and the phase current direction of the fault phase causes the pole voltage of the fault phase output toward the positive DC bus to depend on the upper bridge arm switch that has an open-circuit fault, the voltage output constraint is used to limit the pole voltage of the fault phase output toward the positive DC bus. When the fault switch is in the lower arm position of the faulty phase, and the phase current direction of the faulty phase causes the pole voltage of the faulty phase output toward the negative DC bus to depend on the lower arm switch that has an open-circuit fault, the voltage output constraint is used to limit the pole voltage of the faulty phase output toward the negative DC bus.

[0013] Optionally, when the original reference pole voltage of the faulty phase does not satisfy the voltage output constraint, determining the zero-sequence compensation voltage based on the original reference pole voltage of the faulty phase and the voltage output constraint includes: Determine the voltage polarity corresponding to the original reference pole voltage of the faulty phase; When the voltage polarity is the same as the voltage polarity restricted by the single-switch open-circuit fault, and the original reference pole voltage of the fault phase exceeds the target voltage boundary corresponding to the voltage output constraint, it is determined that the original reference pole voltage of the fault phase does not meet the voltage output constraint. Based on the original reference pole voltage of the fault phase and the voltage output constraint, the zero-sequence compensation voltage is determined.

[0014] Optionally, determining the zero-sequence compensation voltage based on the original reference pole voltage of the faulty phase and the voltage output constraint includes: Determine the voltage difference between the target voltage boundary corresponding to the voltage output constraint and the original reference pole voltage of the fault phase; The zero-sequence compensation voltage is determined based on the voltage difference so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint.

[0015] Optionally, the zero-sequence compensation voltage is the minimum amplitude compensation voltage required to make the compensation reference pole voltage of the faulty phase meet the voltage output constraint; And / or, the zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter with the same voltage value to obtain the corresponding compensation reference pole voltage of the multiphase inverter.

[0016] Optionally, the inverter single-switch open-circuit fault-tolerant control method further includes: When the original reference pole voltage of the fault phase satisfies the voltage output constraint, it is determined that no zero-sequence compensation is required under the current single-switch open-circuit fault, and the conventional zero-sequence modulation voltage is determined according to the preset zero-sequence modulation strategy. The conventional zero-sequence modulation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the modulation reference pole voltage of each phase of the multiphase inverter. Space vector modulation is performed based on the modulation reference pole voltage of each phase of the multiphase inverter. The conventional zero-sequence modulation voltage includes a saddle-wave zero-sequence voltage.

[0017] Optionally, the inverter single-switch open-circuit fault-tolerant control method further includes: Based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, determine the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault. Based on the voltage output limiting parameters, determine the output limiting parameters of the motor under the current single-switch open-circuit fault. The output control parameters of the motor are limited according to the output limiting parameters.

[0018] Optionally, the multiphase inverter includes a three-phase two-level voltage-source inverter, and the voltage output limiting parameters include the upper limit of the allowable output phase voltage fundamental amplitude. The step of determining the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault, based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, includes: Determine the maximum absolute value of the zero-sequence compensation voltage within the preset control range; The upper limit of the phase voltage fundamental amplitude is determined based on the difference between the maximum single-sided voltage output capability corresponding to the DC bus voltage and the maximum absolute value.

[0019] Optionally, the motor includes an AC motor, and the output limiting parameters include at least one of a combination of maximum permissible torque and permissible current; The step of determining the output limit parameters of the motor under the current single-switch open-circuit fault based on the voltage output limit parameters includes: Based on the upper limit of the phase voltage fundamental amplitude and at least one of the motor speed, temperature and current limits, determine the permissible combination of the direct-axis current reference value and the quadrature-axis current reference value that satisfies the upper limit of the phase voltage fundamental amplitude. The maximum permissible torque is determined based on the permissible combination; The allowed combinations are determined by at least one of the following methods: maximum torque-current ratio strategy, maximum torque-voltage ratio strategy, analytical calculation, and preset mapping relationship.

[0020] Optionally, the output control parameters include at least one of torque request, direct-axis current reference value, and quadrature-axis current reference value; The step of limiting the motor's output control parameters according to the output limiting parameters includes: When the torque request exceeds the maximum permissible torque, the torque request is limited to no more than the maximum permissible torque; And / or, limit the direct-axis current reference value and the quadrature-axis current reference value according to the permitted combination.

[0021] Optionally, the step of performing space vector modulation based on the compensated reference pole voltages of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter includes: The executable space voltage vector set is determined based on the number of phases and the number of voltage levels of the multiphase inverter, as well as the executable switch state combination under the current single switch open circuit fault. The target voltage vector is determined based on the compensation reference pole voltage of each phase of the multiphase inverter; Determine at least one space voltage vector and its corresponding application time from the executable space voltage vector set for synthesizing the target voltage vector; The pulse width modulation signal is generated based on the at least one spatial voltage vector and the corresponding action time.

[0022] Secondly, the present invention provides a fault-tolerant control device for an inverter single-switch open-circuit fault, comprising: The constraint determination module is used to determine the voltage output constraint of the faulty phase under the current single switch open circuit fault in response to the occurrence of a single switch open circuit fault in the multiphase inverter, based on the fault switch position and phase current direction of the faulty phase corresponding to the single switch open circuit fault. The compensation determination module is used to determine the zero-sequence compensation voltage based on the original reference pole voltage of the faulty phase and the voltage output constraint when the original reference pole voltage of the faulty phase does not meet the voltage output constraint. The voltage compensation module is used to superimpose the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. The drive modulation module is used to perform space vector modulation based on the compensation reference pole voltage of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

[0023] Thirdly, the present invention provides an electronic device, including a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the inverter single-switch open-circuit fault-tolerant control method as described in the first aspect when executing the computer program.

[0024] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when read and executed by a processor, implements the inverter single-switch open-circuit fault-tolerant control method as described in the first aspect.

[0025] The beneficial effects of the inverter single-switch open-circuit fault-tolerant control method of the present invention are as follows: After detecting a single-switch open-circuit fault, the present invention can determine the voltage output constraint of the faulty phase under the current fault state according to the fault switch position and the current direction of the faulty phase, thereby determining the actual voltage output limit of the faulty phase caused by the single-switch open-circuit fault; furthermore, for the case where the original reference pole voltage does not meet the voltage output constraint, a zero-sequence compensation voltage is determined, and by superimposing the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter, the compensation reference pole voltage of the faulty phase meets the voltage output constraint; and a pulse width modulation signal for driving the multiphase inverter is generated based on the compensated reference pole voltage. Therefore, this invention, without adding redundant bridge arms, neutral point leads, or other additional hardware, identifies the actual output voltage capability of the faulty phase under a single-switch open-circuit fault condition and adjusts the reference pole voltage of each phase based on zero-sequence compensation. This fully utilizes the remaining voltage output capability of the non-faulty power devices, enabling the multiphase inverter to adapt to voltage output capability changes caused by a single-switch open-circuit fault. Consequently, the electric drive system can transition from the traditional shutdown protection mode after a fault to a limited operation mode based on the remaining hardware capability. Simultaneously, by modulating based on the executable space voltage vector set under the fault condition, it avoids generating unexecutable switching states dependent on the faulty switch, thereby maintaining controlled motor operation without sudden power interruption and improving the operational continuity, safety, and reliability of the electric drive system under fault conditions. Furthermore, compared to the single-phase operation method adopted in related technologies after a single-switch open-circuit fault, the present invention does not need to change the original multi-phase power supply relationship of the motor. Instead, it determines the voltage output constraint under fault conditions and adjusts the zero-sequence compensation, so that the inverter can continue to output multi-phase AC voltage that meets the control requirements within the remaining hardware capacity range. This avoids the change in power supply state caused by single-phase operation and the resulting current imbalance and torque fluctuation problems, thereby improving the stability of motor operation under fault conditions. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a fault-tolerant control method for an inverter single-switch open-circuit fault in an embodiment of the present invention. Figure 2 This is a flowchart illustrating a fault-tolerant control method for an inverter single-switch open-circuit fault in another embodiment of the present invention. Figure 3 This is a schematic diagram of the normal operating current path of any phase arm of the multiphase inverter in different phase current directions in an embodiment of the present invention. Figure 4 This is a schematic diagram of the control structure corresponding to the inverter single-switch open-circuit fault-tolerant control method in this embodiment of the invention; Figure 5This is a schematic diagram of the boundary of the output area of ​​the space voltage vector in the normal state and the single-switch open-circuit fault state in an embodiment of the present invention; Figure 6 This is a schematic diagram of the current, voltage, and torque control waveforms corresponding to the inverter single-switch open-circuit fault-tolerant control method in an embodiment of the present invention. Figure 7 This is a structural block diagram of the inverter single-switch open-circuit fault-tolerant control device in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] Combination Figure 1 As shown, this embodiment of the invention provides a fault-tolerant control method for an inverter with a single switch open-circuit fault, applicable to an electric drive system including a multiphase inverter and a motor.

[0029] This embodiment of the method can be applied to electric drive systems including multiphase inverters and motors, such as electric drive systems for vehicles or corresponding industrial drive equipment, to achieve fault-tolerant control for single-switch open-circuit faults in the inverter. This allows the vehicle or corresponding industrial drive equipment to maintain controlled operation even when a single-switch open-circuit fault occurs in the inverter, improving the operational continuity and reliability of the electric drive system under fault conditions. A multiphase inverter refers to a voltage-type inverter with multiple phase output terminals, capable of adjusting the output voltage of each phase independently. Multiphase inverters can include three-phase inverters, five-phase inverters, or other inverters with multiple phase output terminals.

[0030] A multiphase inverter in an electric drive system generates multiphase AC power to drive a motor according to control commands. For example, the multiphase inverter may include multiple phase arms, each including multiple switching transistors (or power devices such as IGBTs or SiC MOSFETs). Each switching transistor is turned on or off according to a corresponding drive signal to form different switching states and output corresponding phase voltages. The motor can be electrically connected to the output terminals of each phase of the multiphase inverter to operate based on the AC power output by the multiphase inverter.

[0031] During the operation of an electric drive system, an open-circuit fault may occur in a multiphase inverter due to aging of the switching transistors, overcurrent, thermal stress, or other abnormal factors. When an open-circuit fault occurs in a switching transistor, the voltage output state of a portion of the corresponding phase bridge arm is limited, causing a change in the actual output pole voltage range of that phase. Furthermore, since the space voltage vector is determined by the combination of switching states corresponding to each phase bridge arm of the multiphase inverter, when some switching state combinations cannot be executed due to the open-circuit fault, the space voltage vector corresponding to those switching state combinations cannot be output normally, causing a change in the set of space voltage vectors that the multiphase inverter can achieve under fault conditions. In other words, a single open-circuit fault not only affects the pole voltage output range of the faulty phase but also causes a contraction in the overall output space voltage region of the inverter. If the original reference pole voltage generated before the fault is still used to control the inverter operation, the original reference pole voltage may exceed the actual output range under fault conditions, resulting in the inaccurate execution of the reference voltage. Based on this, the method in this embodiment adjusts the reference voltage according to the fault state after a single switch open-circuit fault occurs, so that the inverter can continue to output a drive voltage that meets the fault state constraints.

[0032] The fault-tolerant control method for single-switch open-circuit faults in inverters includes the following steps: Step 100: In response to a single-switch open-circuit fault in the multiphase inverter, determine the voltage output constraint of the faulty phase under the current single-switch open-circuit fault based on the fault switch position and the phase current direction of the faulty phase.

[0033] Specifically, when a single-switch open-circuit fault is detected in a multiphase inverter, the location of the fault switch corresponding to the faulty switch is determined. The fault switch location characterizes the inverter phase in which the faulty switch is located and the switch's position within that phase. For example, the fault switch location may include information about the faulty phase to which the faulty switch belongs, and whether the faulty switch is located on the upper or lower side of the corresponding bridge arm. Simultaneously, the direction of the phase current corresponding to the fault is obtained. Since the impact of a switch open-circuit fault on the voltage output capability of the faulty phase is related to the current flow direction, the same fault switch location may correspond to different voltage output limitation states under different phase current directions.

[0034] Therefore, the method in this embodiment can determine the actual voltage range that the faulty phase can output under the current fault state based on the location of the faulty switch and the direction of the phase current of the faulty phase. Specifically, based on the location of the faulty switch, the affected switching state caused by the open circuit of the switching transistor can be determined; based on the direction of the phase current of the faulty phase, the voltage output state that the faulty phase can achieve using the remaining switching devices under the current conditions can be determined. It should be noted that the same open circuit fault may correspond to different actual voltage output capabilities under different phase current directions. For example, when the direction of the faulty phase current changes, the faulty phase current may form a freewheeling path through different power devices, allowing the pole voltage corresponding to some switching states to still be achieved. Therefore, the voltage output range of the faulty phase cannot be accurately determined based solely on the location of the faulty switch; it is necessary to combine the phase current direction at the time of the fault to jointly determine the voltage output constraint. Based on the above information, the voltage output constraint corresponding to the fault is determined. The voltage output constraint is used to characterize the range of pole voltages that the faulty phase can output under the current single open circuit fault (state). For example, the voltage output constraint can be expressed as the maximum value, minimum value, or target voltage boundary of the pole voltage of the faulty phase.

[0035] Therefore, by following the above steps, the dynamic voltage output capability of the faulty phase is determined based on the specific fault location and current state, rather than simply treating the inverter after the fault as operating with a single phase, thereby improving the accuracy of subsequent compensation control.

[0036] Step 210: When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, determine the zero-sequence compensation voltage based on the original reference pole voltage and voltage output constraint of the faulty phase.

[0037] Specifically, after determining the voltage output constraint corresponding to the fault, the original reference pole voltages of each phase of the inverter within the current control cycle are obtained. These original reference pole voltages are the reference voltage commands for each phase determined based on the motor operating status, motor control objectives, and the normal operating status of the inverter, without considering the impact of a single switch open-circuit fault.

[0038] The original reference pole voltage corresponding to the fault is compared with the voltage output constraint to determine whether the original reference pole voltage is within the executable range under the fault condition.

[0039] When the original reference pole voltage of the faulty phase meets the voltage output constraint, it indicates that under the current fault condition, the original reference pole voltage of the faulty phase is still within the voltage range that the multiphase inverter can actually output. The faulty phase does not have a voltage execution limitation problem caused by the reference pole voltage exceeding the voltage output constraint. Therefore, it is not necessary to determine the zero-sequence compensation voltage based on the voltage output constraint.

[0040] When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, it indicates that under the current fault condition, the original reference pole voltage of the faulty phase exceeds the actual voltage output range corresponding to the fault. If the multiphase inverter is directly controlled according to the original reference pole voltage, the faulty phase may not be able to accurately execute the corresponding voltage command. Therefore, it is necessary to compensate and adjust the original reference pole voltage. Specifically, a zero-sequence compensation voltage is determined based on the deviation between the original reference pole voltage of the faulty phase and the voltage output constraint. The zero-sequence compensation voltage is used to adjust the overall offset of the reference pole voltage of each phase of the multiphase inverter relative to the reference potential, so that the compensated reference pole voltage corresponding to the fault enters the executable range corresponding to the voltage output constraint. For example, when the original reference pole voltage of the faulty phase exceeds the target voltage boundary corresponding to the voltage output constraint, a zero-sequence compensation voltage corresponding to the voltage deviation direction can be determined based on the voltage deviation between the original reference pole voltage and the target voltage boundary to adjust the reference pole voltage of the faulty phase, so that the compensated reference pole voltage after superimposing the zero-sequence compensation voltage meets the voltage output constraint.

[0041] Step 310: Superimpose the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint.

[0042] Specifically, after determining the zero-sequence compensation voltage, the zero-sequence compensation voltage is superimposed onto the corresponding original reference pole voltages of the multiphase inverter.

[0043] For example, for any phase output of a multiphase inverter, the compensation reference pole voltage after superimposing the zero-sequence compensation voltage can be expressed as: V x，new =V x，ref +V0; Among them, V x，ref V represents the original reference pole voltage of the corresponding phase, V0 represents the zero-sequence compensation voltage, V x，new This represents the compensation reference pole voltage after the zero-sequence compensation voltage is superimposed on the corresponding phase.

[0044] Since the zero-sequence compensation voltage acts simultaneously on the reference pole voltages of each phase, the reference pole voltages of each phase shift relative to the overall reference potential. This allows for adjustment of the reference pole voltage of the faulty phase without altering the relative relationship between the phase reference pole voltages. By uniformly shifting the original reference pole voltages of each phase, the compensated reference pole voltage of the faulty phase can meet the voltage output constraints corresponding to the current fault state without changing the required inter-phase voltage relationship of the motor. Specifically, after the zero-sequence compensation voltage is superimposed on the reference pole voltages of each phase, the voltage difference between any two phases remains unchanged. Because the zero-sequence compensation voltage is superimposed on the reference pole voltages of each phase with the same voltage value, the difference between any two phase reference pole voltages remains unchanged at the reference command level. For multi-phase AC motors without a neutral point, this inter-phase voltage relationship can characterize the voltage relationship at the motor winding ends. Therefore, zero-sequence compensation mainly adjusts the distribution position of the reference pole voltages of each phase relative to the DC bus reference potential, without changing the reference voltage difference relationship between the phases.

[0045] Therefore, after zero-sequence compensation, the faulty phase no longer requires the inverter to execute a voltage state that it cannot achieve, thereby reducing control errors caused by voltage command out-of-bounds errors.

[0046] Step 410: Perform space vector modulation based on the compensation reference pole voltage of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

[0047] Specifically, after obtaining the corresponding compensation reference pole voltages for each phase of the multiphase inverter, space vector modulation is performed based on these voltages. The space vector modulation determines the target voltage vector based on the compensation reference pole voltages for each phase and generates a corresponding pulse width modulation (PWM) signal based on the currently executable switching state of the multiphase inverter. This PWM signal drives the switches in the multiphase inverter, ensuring that the inverter outputs an AC voltage that matches the compensation reference pole voltages. Because the space vector modulation input uses the fault-compensated reference pole voltages, even if a single switch in the inverter has an open-circuit fault, the generated drive signal can still enable the inverter to output a voltage that meets the fault constraints as much as possible.

[0048] In summary, the method of this embodiment can determine the voltage output constraint of the faulty phase under the current fault state based on the fault switch position and the current direction of the faulty phase after detecting a single switch open circuit fault, thereby determining the actual voltage output limit of the faulty phase caused by the single switch open circuit fault; furthermore, it determines the zero-sequence compensation voltage for cases where the original reference pole voltage does not meet the voltage output constraint, and superimposes the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter so that the compensation reference pole voltage of the faulty phase meets the voltage output constraint; and generates a pulse width modulation signal for driving the multiphase inverter based on the compensated reference pole voltage. Therefore, this embodiment of the method, without adding redundant bridge arms, neutral point leads, or other additional hardware, identifies the actual output voltage capability of the faulty phase under a single-switch open-circuit fault state and adjusts the reference pole voltage of each phase based on zero-sequence compensation. It fully utilizes the remaining voltage output capability corresponding to the non-faulty power devices, enabling the multiphase inverter to adapt to the voltage output capability changes caused by a single-switch open-circuit fault. This allows the electric drive system to transform from the traditional shutdown protection mode after a fault to a limited operation mode based on the remaining hardware capability. At the same time, by modulating based on the executable space voltage vector set under the fault state, it avoids generating unexecutable switching states dependent on the faulty switch, thereby maintaining controlled motor operation without sudden power interruption and improving the operational continuity, safety, and reliability of the electric drive system under fault states. Furthermore, compared to the single-phase operation method adopted in related technologies after a single-switch open-circuit fault, the method in this embodiment does not need to change the original multi-phase power supply relationship of the motor. Instead, it determines the voltage output constraint under the fault state and adjusts the zero-sequence compensation, so that the inverter can continue to output multi-phase AC voltage that meets the control requirements within the remaining hardware capability range. This avoids the change in power supply state caused by single-phase operation and the resulting current imbalance and torque fluctuation problems, thereby improving the stability of motor operation under fault state.

[0049] Optionally, the multiphase inverter includes a three-phase two-level voltage source inverter, which includes three phase bridge arms, each phase bridge arm including an upper bridge arm switch and a lower bridge arm switch; a single switch open circuit fault is an open circuit fault in the upper bridge arm switch or the lower bridge arm switch of any phase bridge arm in the three-phase two-level voltage source inverter.

[0050] For example, the following explanation uses a three-phase two-level voltage source inverter as an example to illustrate the voltage output limitation mechanism under single-switch open-circuit fault conditions.

[0051] A three-phase two-level voltage source inverter comprises three phase arms, each corresponding to a one-phase AC output terminal. Each phase arm includes an upper and a lower bridge arm switch connected in series between the positive and negative terminals of the DC bus. The connection point between the upper and lower bridge arm switches serves as the output terminal of the corresponding phase, used to output AC voltage to the corresponding phase winding of the motor. During normal operation of the three-phase two-level voltage source inverter, different switching states can be formed by controlling the upper and lower bridge arm switches in each phase arm to alternately turn on or off. Corresponding drive signals are generated according to a space vector modulation strategy to ensure that the three-phase two-level voltage source inverter outputs three-phase AC power that meets the motor's operating requirements.

[0052] When an open-circuit fault occurs in the upper or lower bridge arm switch of any phase arm in a three-phase two-level voltage source inverter, some switching states of the corresponding phase arm cannot be executed normally, causing a change in the range of pole voltages that the faulty phase can output. An open-circuit fault can include an open-circuit fault in either the upper or lower bridge arm switch of any phase arm. Since different switch positions correspond to different voltage output limits, and the direction of the phase current in the faulty phase affects the actual voltage state that can be formed under the fault condition, in this embodiment, the voltage output constraint corresponding to the faulty phase under the current open-circuit fault state can be determined based on the position of the switch with the open-circuit fault and the direction of the phase current in the faulty phase, and subsequent zero-sequence compensation control is performed based on the voltage output constraint.

[0053] Optionally, the motor may include an AC motor.

[0054] Specifically, the motor in this embodiment can be an AC motor, which operates based on the multiphase AC power output from the multiphase inverter. The AC motor can include AC motors capable of torque control through stator current adjustment, such as permanent magnet synchronous motors and induction motors.

[0055] The fault-tolerant control method for single-switch open-circuit faults in inverters also includes: Collect the stator current and rotor position of the AC motor; Based on the stator current, rotor position, and torque request of the AC motor, field-oriented control is performed on the AC motor to generate the original reference pole voltages of each phase of the multiphase inverter.

[0056] Specifically, since the electric drive system uses an AC motor, the stator current and rotor position of the AC motor can be collected during its operation. The stator current characterizes the current operating state of the AC motor, and the rotor position characterizes the spatial position of the AC motor rotor. For example, the stator current may include the phase current corresponding to each phase winding of the AC motor; for instance, for a three-phase AC motor, the stator current may include all three phase stator currents.

[0057] The torque request for the AC motor is used to characterize the target torque expected to be output by the AC motor within the current control cycle. Specifically, during AC motor operation, the electric drive system's corresponding control system generates a corresponding torque request based on the current operating conditions and determines the torque control target for the AC motor based on the torque request. For example, in a vehicle driving scenario, the torque request can be determined by the vehicle controller based on the driver's acceleration needs, vehicle operating status, etc., and is used to characterize the driving torque currently expected to be output by the AC motor. In industrial drive equipment application scenarios, the torque request can also be determined based on the equipment operating status and target operating requirements, and is used to characterize the driving torque currently required to be output by the AC motor.

[0058] Based on the collected stator current, rotor position, and corresponding torque request of the AC motor, field-oriented control is performed on the AC motor. Specifically, field-oriented control can perform coordinate transformation on the stator current of the AC motor. For example, for a three-phase AC motor, the stator current in the three-phase stationary coordinate system can be converted into current components in the two-phase stationary coordinate system using Clarke transformation, and based on the rotor position of the AC motor, the current components in the two-phase stationary coordinate system can be converted into direct-axis and quadrature-axis current components in the synchronous rotating coordinate system using Park transformation. Further, the corresponding current control target is determined in conjunction with the torque request. For example, the direct-axis current reference value and quadrature-axis current reference value can be determined based on the torque request, and current closed-loop control is performed based on the direct-axis current reference value, quadrature-axis current reference value, and the collected actual current state. Further, the voltage control quantity used to drive the AC motor is determined based on the current closed-loop control result, and the corresponding original reference pole voltages of the multiphase inverter are determined based on the voltage control quantity. In some embodiments, after the current closed-loop control generates the direct-axis voltage control quantity and the quadrature-axis voltage control quantity in the synchronous rotating coordinate system, the original reference pole voltages of each phase of the multiphase inverter can be determined through Park inverse transformation and Clarke inverse transformation, or other equivalent coordinate transformation methods. The original reference pole voltages represent the expected phase reference voltages output by the multiphase inverter to meet the current torque request and operating state requirements of the AC motor, without considering the impact of a single switch open-circuit fault. In other words, the original reference pole voltages are reference voltage commands determined based on the normal electric drive control process, and do not include compensation adjustments for single switch open-circuit faults.

[0059] In subsequent processes, when a single-switch open-circuit fault occurs in the multiphase inverter, the original reference pole voltage can be compared with the voltage output constraint determined based on the fault state. The comparison result determines whether zero-sequence compensation should be performed, ensuring the multiphase inverter can still output a drive voltage that meets the constraint requirements under fault conditions. Specifically, when the original reference pole voltage meets the voltage output constraint, it indicates that the current reference voltage is still within the actual output range of the faulty phase under the single-switch open-circuit fault state, and a corresponding modulation reference voltage can be generated according to a preset modulation strategy. When the original reference pole voltage does not meet the voltage output constraint, it indicates that the current reference voltage exceeds the inverter's actual voltage output capability under fault conditions, requiring the determination of a zero-sequence compensation voltage based on the voltage output constraint, and adjustment of the reference pole voltages for each phase.

[0060] For example, the AC motor can be a permanent magnet synchronous motor. In applications such as new energy vehicles, permanent magnet synchronous motors are typically driven by inverters. The corresponding controller can generate corresponding reference voltage commands through field-oriented control based on the stator current, rotor position, and target torque request of the permanent magnet synchronous motor, and further convert them to obtain the original reference pole voltages of each phase of the multiphase inverter.

[0061] For AC motors using three-phase AC power supply and field-oriented control, the three-phase stator windings have a preset phase difference in space. When the three-phase stator currents remain balanced and satisfy the corresponding phase relationship, a continuous rotating magnetic field can be formed in the motor air gap, which helps to smoothly output electromagnetic torque. The direct-axis current component is mainly used for flux linkage control, while the quadrature-axis current component is mainly used for torque control. Therefore, maintaining continuous control of the stator current under single-switch open-circuit fault conditions helps reduce torque fluctuations during fault operation.

[0062] Furthermore, in this embodiment, when adjusting the reference pole voltage of each phase through zero-sequence compensation, the zero-sequence compensation voltage is simultaneously superimposed on the reference pole voltage of each phase, thus not changing the line voltage difference between any two phases. For example, for any two phases a and b: (V a,ref +V0)-(V b,ref +V0)=V a,ref -V b,ref , Among them, V a,ref and V b,ref V1 and V2 represent the original reference pole voltages of phase a and phase b of the multiphase inverter, respectively, and V0 represents the zero-sequence compensation voltage.

[0063] Therefore, zero-sequence compensation can adjust the absolute position of the reference pole voltage of each phase relative to the DC bus without changing the phase-to-phase voltage relationship of the motor, thus providing a basis for avoiding reference voltage overshooting under fault conditions.

[0064] For example, such as Figure 4 As shown, the electric drive system in this embodiment may include a controller, a multiphase inverter, and an AC motor. The multiphase inverter is electrically connected to the AC motor and is used to output multiphase AC voltage according to the pulse width modulation signal generated by the controller to drive the AC motor. The controller is used to acquire the operating status information of the AC motor and the fault status information of the multiphase inverter, and to control the multiphase inverter.

[0065] Figure 4The speed regulator, current PI regulator, zero-sequence voltage dynamic compensation control, and space vector modulation module shown can all be functional components of the controller, categorized according to control functions. Specifically, the speed regulator and current PI regulator perform closed-loop control of the AC motor; the zero-sequence voltage dynamic compensation control, located between the current PI regulator and the space vector modulation module, compensates for the original reference pole voltage based on the fault status information of the multiphase inverter; and the space vector modulation module generates pulse width modulation signals to control the operation of the multiphase inverter based on the corresponding reference pole voltage. These functional components can be implemented by the same controller or by multiple control units working together; this embodiment does not limit their specific hardware or software implementation.

[0066] Specifically, the speed regulator determines the direct-axis current reference value based on the operating status of the AC motor and the corresponding control objective. and cross-axis current reference value The direct-axis current reference value and the quadrature-axis current reference value are input to the current PI regulator. The current PI regulator performs closed-loop adjustment based on the direct-axis current reference value, the quadrature-axis current reference value, and the acquired actual current state to generate the corresponding original reference pole voltage V. x，ref .

[0067] Under normal operating conditions of the multiphase inverter, or when a single-switch open-circuit fault does not cause the original reference pole voltage to exceed the voltage output constraint, the original reference pole voltage V x，ref The input can be directly to the SVPWM module, or it can be modulated by conventional zero-sequence modulation and used as the modulation reference pole voltage. The SVPWM module then generates pulse width modulation signals based on the original reference pole voltage to control the on / off state of each switch in the multiphase inverter, thereby driving the AC motor.

[0068] When a single-switch open-circuit fault occurs in a multiphase inverter, the zero-sequence voltage dynamic compensation control adjusts the original reference pole voltage based on the fault state information. This fault state information includes the fault switch position, the direction of the fault phase current, and voltage output constraints determined based on these information. Specifically, the zero-sequence voltage dynamic compensation control determines whether the current original reference pole voltage meets the voltage output constraints under the fault state. When the original reference pole voltage does not meet the voltage output constraints, the zero-sequence compensation voltage is determined based on the deviation between the original reference pole voltage and the voltage output constraints. This zero-sequence compensation voltage is then superimposed onto the original reference pole voltages of each phase of the multiphase inverter to obtain the compensated reference pole voltage. Furthermore, the SVPWM module compensates for the reference pole voltage. The corresponding pulse width modulation signal is generated and the inverter output drive voltage is controlled so that the AC motor can still maintain controlled operation under the single switch open circuit fault condition.

[0069] Therefore, the method in this embodiment does not require changing the original motor control architecture, nor does it require adding additional hardware such as redundant bridge arms or neutral point leads. It only requires adding a zero-sequence voltage dynamic compensation control process between the current closed-loop control output and SVPWM modulation to adjust the reference pole voltage according to the fault state, thereby improving the continuity and reliability of the electric drive system under the single-switch open-circuit fault state.

[0070] Optionally, the fault-tolerant control method for open-circuit faults of a single switch in the inverter also includes: Acquire the open-circuit fault signal of a single switch in a multiphase inverter; Based on the single-switch open-circuit fault signal, determine the faulty phase and the location of the faulty switch where the single-switch open-circuit fault occurred; The fault switch position is used to characterize the inverter phase in which the switch tube that has experienced an open-circuit fault is located, as well as the connection position of the switch tube in the corresponding bridge arm.

[0071] Specifically, during the operation of a multiphase inverter, the operating status of each switch in the multiphase inverter can be detected to determine whether an open-circuit fault exists. When an open-circuit fault is detected in a switch, a corresponding single-switch open-circuit fault signal can be generated. This single-switch open-circuit fault signal characterizes a fault state in the multiphase inverter where a single switch cannot conduct normally, and can indicate the location of the open-circuit fault switch, the corresponding faulty phase, and the fault type. For example, a corresponding fault diagnosis module can detect the operating status of each switch in the multiphase inverter to determine whether an open-circuit fault exists. When the fault diagnosis module detects an open-circuit fault in a switch, it can generate a corresponding single-switch open-circuit fault signal and feed it back to the corresponding controller. After receiving the single-switch open-circuit fault signal, the controller can determine the location of the faulty switch based on the fault signal and further execute subsequent voltage output constraint determination, zero-sequence compensation, and modulation control processes under the fault state.

[0072] Based on the single-switch open-circuit fault signal, the faulty phase and the location of the fault switch can be determined. The faulty phase represents the inverter phase to which the faulty switch belongs; the fault switch location represents the connection position of the faulty switch within the corresponding phase arm. For example, the fault switch location can be used to distinguish between different switch positions within the same phase arm, such as the upper and lower arm switch positions within the same phase arm. Since the voltage output state that the corresponding phase arm can form after an open-circuit fault occurs at different switch positions, different fault switch locations may correspond to different voltage output constraints.

[0073] After determining the faulty phase and the location of the fault switch, the voltage output constraint of the faulty phase under the current single-switch open-circuit fault state can be further determined by combining the phase current direction of the faulty phase. This constraint can then be used for subsequent zero-sequence compensation control. Since the actual output voltage state of the faulty phase after a single-switch open-circuit fault is related not only to the location of the fault switch but also to the current phase current direction of the faulty phase, determining the voltage output constraint by comprehensively considering the fault switch location and the phase current direction can more accurately reflect the actual voltage output capability of the faulty phase under the fault state.

[0074] Optionally, based on the fault switch position corresponding to the single-switch open-circuit fault and the phase current direction of the fault phase, the voltage output constraint of the fault phase under the current single-switch open-circuit fault is determined, including: Based on the location of the fault switch, determine the inverter switch state combination that cannot be executed normally due to a single switch open circuit fault; Based on the direction of the phase current of the faulty phase, the currently executable switching state combination is determined from multiple switching state combinations of the multiphase inverter. Determine the voltage output constraint of the fault phase based on the pole voltage output range corresponding to the current executable switch state combination; The voltage output constraint includes at least one of the following: upper voltage limit, lower voltage limit, voltage range, voltage boundary, and voltage feasible region.

[0075] Specifically, after a single-switch open-circuit fault occurs in a multiphase inverter, the inverter switching state combinations that cannot be implemented according to the preset control logic due to the single-switch open-circuit fault can be determined first based on the location of the faulty switch. The switching state combination characterizes the combination relationship of the conduction states of the switches in each phase arm of the multiphase inverter; different switching state combinations correspond to different arm output states and corresponding pole voltage output states. The faulty switch location characterizes the inverter phase where the open-circuit faulty switch is located and the connection position of the switch in the corresponding phase arm.

[0076] Because a switch with an open-circuit fault cannot perform the conduction operation normally according to the control command, some switch state combinations related to the conduction state of the faulty switch cannot be implemented according to the preset control logic. For example, when an open-circuit fault occurs in the upper bridge arm switch of a phase bridge arm, the switch state combination including the conduction state of the upper bridge arm switch cannot be executed normally; when an open-circuit fault occurs in the lower bridge arm switch of a phase bridge arm, the switch state combination including the conduction state of the lower bridge arm switch cannot be executed normally. It should be noted that the switch state combinations that cannot be executed normally are used to characterize the state combinations that the switch cannot implement according to the preset control logic, and do not mean that the corresponding pole voltage cannot necessarily be formed under the fault state. The actual output pole voltage state still needs to be further determined by combining the direction of the fault phase current and the current path.

[0077] Furthermore, based on the phase current direction of the faulty phase, the executable switching state combination under the current single-switch open-circuit fault state is determined from multiple switching state combinations of the multiphase inverter.

[0078] Specifically, under a single-switch open-circuit fault condition, the faulty phase does not necessarily completely lose its corresponding voltage output capability. The actual pole voltage state that the faulty phase can form is also related to the current direction of the phase current. When the phase current direction of the faulty phase is different, the faulty phase current can flow through the conduction path corresponding to the unfaulty switch or the freewheeling path corresponding to the freewheeling device, thus allowing some of the affected pole voltage states to still be formed. Therefore, by combining the limited switch state combinations corresponding to the faulty switch position and the current direction of the current in the faulty phase, multiple switch state combinations of the multiphase inverter can be screened to determine the actually executable switch state combinations under the current fault condition.

[0079] For example, such as Figure 3 As shown, taking any phase arm in a multiphase inverter as an example, the phase arm includes an upper bridge arm switch Sa1, a lower bridge arm switch Sa2, and freewheeling diodes Da1 and Da2 connected in anti-parallel to the upper bridge arm switch Sa1 and the lower bridge arm switch Sa2, respectively. Figure 3 (a) and Figure 3 As shown in (b), when the direction of the phase current ia and the switching state of the phase bridge arm are different, the phase current ia can form corresponding current paths through the corresponding switching transistors or freewheeling diodes. Therefore, whether the same combination of switching states can form the corresponding pole voltage depends not only on the conduction state of the switching transistors, but also on the current phase current direction and the corresponding current path. Therefore, under the single-switch open-circuit fault state, it is necessary to combine the fault switch position and the fault phase current direction to determine the actual executable switching state combination.

[0080] Furthermore, the voltage output constraint of the fault phase is determined based on the pole voltage output range corresponding to the current executable switch state combination. Specifically, after determining the current executable switch state combination, the actual voltage range that the fault phase can output under the current single-switch open-circuit fault state can be determined based on the fault phase pole voltage corresponding to each executable switch state combination. The voltage output constraint characterizes the actual voltage output capability limitation of the fault phase under the current fault state and can include at least one of the following: upper voltage limit, lower voltage limit, voltage range, voltage boundary, and voltage feasible region. For example, the voltage output range corresponding to the fault can be determined based on the maximum and minimum values ​​of the fault phase pole voltages corresponding to multiple current executable switch state combinations; or, the voltage range that the fault phase can output under the current single-switch open-circuit fault state can be determined based on the pole voltage boundary corresponding to the current executable switch state combination.

[0081] Therefore, the voltage output constraint is not set in advance, but is dynamically determined according to the actual switch position and the direction of the phase current when the fault occurs. This can more accurately reflect the actual voltage output capability of the faulty phase after a single switch open circuit fault, and provide a basis for subsequent zero-sequence compensation based on voltage output constraints.

[0082] Optionally, when the fault switch is in the upper arm position of the fault phase, and the phase current direction of the fault phase causes the pole voltage of the fault phase output toward the positive DC bus to depend on the upper arm switch that has an open-circuit fault, the voltage output constraint is used to limit the pole voltage of the fault phase output toward the positive DC bus. When the fault switch is in the lower arm position of the faulty phase, and the phase current direction of the faulty phase causes the pole voltage of the faulty phase output toward the negative DC bus to depend on the lower arm switch that has an open-circuit fault, the voltage output constraint is used to limit the pole voltage of the faulty phase output toward the negative DC bus.

[0083] Specifically, when determining the voltage output constraint corresponding to the fault, the restricted pole voltage direction of the fault phase can also be determined based on the fault switch position and the phase current direction of the fault phase.

[0084] In a multiphase inverter, each phase arm typically includes multiple switching devices connected between the positive and negative terminals of the DC bus. By controlling the on / off state of the corresponding switching devices, the output terminal of that phase can be electrically connected to either the positive or negative terminal of the DC bus, thereby forming pole voltages of different polarities.

[0085] When the fault switch is in the upper arm position of the faulty phase, if the pole voltage state of the faulty phase output towards the positive DC bus depends on the upper arm switch that is experiencing an open-circuit fault, then the pole voltage state of the faulty phase output towards the positive DC bus is restricted because the upper arm switch cannot conduct normally. In this case, the corresponding voltage output constraint can be determined based on the restricted positive pole voltage state to limit the pole voltage of the faulty phase output towards the positive DC bus.

[0086] Similarly, when the fault switch is in the lower arm position of the faulty phase, if the pole voltage state of the faulty phase output towards the negative DC bus depends on the open-circuit faulty lower arm switch, then the pole voltage state of the faulty phase output towards the negative DC bus is restricted because the lower arm switch cannot conduct normally. In this case, the corresponding voltage output constraint can be determined based on the restricted negative pole voltage state to limit the pole voltage of the faulty phase output towards the negative DC bus.

[0087] It should be noted that the pole voltage state that the faulty phase can output depends not only on the position of the switch that experienced the open-circuit fault, but also on the direction of the phase current in the current faulty phase. By simultaneously considering the position of the faulty switch and the direction of the phase current, the actual restricted pole voltage direction under the current fault state can be determined, thereby more accurately determining the voltage output constraint corresponding to the fault.

[0088] Optionally, when the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage of the faulty phase and the voltage output constraint, including: Determine the voltage polarity corresponding to the original reference pole voltage of the faulty phase; When the voltage polarity is the same as the voltage polarity limited by the single-switch open-circuit fault, and the original reference pole voltage of the fault phase exceeds the target voltage boundary corresponding to the voltage output constraint, it is determined that the original reference pole voltage of the fault phase does not meet the voltage output constraint. Based on the original reference pole voltage of the fault phase and the voltage output constraint, the zero-sequence compensation voltage is determined.

[0089] Specifically, when determining whether the original reference pole voltage of the faulty phase meets the voltage output constraint, further judgment can be made based on the voltage polarity corresponding to the original reference pole voltage and the restricted voltage polarity corresponding to the single-switch open-circuit fault. Specifically, after a single-switch open-circuit fault occurs in the faulty phase, the output capability of different polarities of the faulty phase may be limited due to different fault switch positions and different phase current directions. Therefore, not all reference pole voltages exceeding the normal operating range need compensation; instead, it is necessary to determine whether the current original reference pole voltage is located in the restricted direction caused by the single-switch open-circuit fault. Therefore, the voltage polarity corresponding to the original reference pole voltage of the faulty phase can be determined first. The voltage polarity characterizes the direction of the pole voltage expected to be output from the faulty phase, such as a pole voltage towards the positive terminal of the DC bus or a pole voltage towards the negative terminal of the DC bus. Further, the voltage polarity corresponding to the original reference pole voltage is compared with the voltage polarity restricted by the single-switch open-circuit fault. When the voltage polarity corresponding to the original reference pole voltage differs from the voltage polarity restricted by the single-switch open-circuit fault, it indicates that the output direction corresponding to the current reference pole voltage is not the restricted direction caused by the fault. The faulty phase may still achieve the corresponding voltage output through other switching states, so there is no need to determine the zero-sequence compensation voltage based on this voltage state. However, when the voltage polarity corresponding to the original reference pole voltage is the same as the voltage polarity restricted by the single-switch open-circuit fault, it is further determined whether the original reference pole voltage exceeds the target voltage boundary corresponding to the voltage output constraint. When the original reference pole voltage of the faulty phase exceeds the target voltage boundary, it indicates that the target output state corresponding to the current original reference pole voltage exceeds the actual output range of the faulty phase under the fault state, that is, the original reference pole voltage does not meet the voltage output constraint. At this time, the corresponding zero-sequence compensation voltage can be determined based on the deviation between the original reference pole voltage and the target voltage boundary.

[0090] The zero-sequence compensation voltage is used to shift the original reference pole voltage of each phase of the multiphase inverter as a whole, so that the compensation reference pole voltage corresponding to the fault is adjusted from the restricted area to the range allowed by the voltage output constraint.

[0091] For example, when a single-switch open-circuit fault limits the output pole voltage of the faulty phase toward the positive terminal of the DC bus, and the current original reference pole voltage also requires the output pole voltage toward the positive terminal of the DC bus and exceeds the corresponding target voltage boundary, the zero-sequence compensation voltage can be determined based on the voltage deviation between the two to reduce the reference pole voltage corresponding to the fault so that it meets the voltage output constraint under the current fault state.

[0092] Therefore, ineffective compensation in unrestricted voltage directions can be avoided, and zero-sequence compensation can be adjusted only for the voltage output limitation actually caused by a single switch open circuit fault, thereby improving the accuracy of fault compensation.

[0093] For example, such as Figure 5 As shown, under normal operating conditions, a multiphase inverter can utilize a complete set of space voltage vectors to form a corresponding space voltage output region, such as... Figure 5 As shown in (a); at this time, the reference voltage trajectory generated based on the normal motor control process is located within the space voltage output region, and the multiphase inverter can perform space vector modulation according to the reference voltage trajectory. When a single switch open-circuit fault occurs in the multiphase inverter, due to the inability to execute some switching state combinations, the corresponding space voltage vector set changes, thus limiting the actual output space voltage range of the multiphase inverter, such as... Figure 5 As shown in (b), if the reference voltage command under normal conditions is still used for control, some of the original reference pole voltages may exceed the executable range under fault conditions. Based on this, the method in this embodiment determines the zero-sequence compensation voltage according to the voltage output constraint corresponding to the fault state, and simultaneously superimposes the zero-sequence compensation voltage onto the original reference pole voltages of each phase, causing the reference pole voltages of each phase to shift relative to the DC bus reference potential as a whole, thereby ensuring that the compensation reference pole voltage of the fault phase meets the voltage output constraint under fault conditions. It should be noted that zero-sequence compensation does not change the difference between any two phase reference pole voltages at the reference command level; it is mainly used to adjust the distribution position of the phase reference pole voltages within the DC bus voltage range.

[0094] Optionally, the zero-sequence compensation voltage is determined based on the original reference pole voltage and voltage output constraints of the faulty phase, including: Determine the voltage difference between the target voltage boundary corresponding to the voltage output constraint and the original reference pole voltage of the fault phase; The zero-sequence compensation voltage is determined based on the voltage difference so that the compensation reference pole voltage of the faulty phase meets the voltage output constraint.

[0095] Specifically, the zero-sequence compensation voltage can be determined based on the original reference pole voltage of the faulty phase and the target voltage boundary corresponding to the voltage output constraint.

[0096] If the original reference pole voltage of the faulty phase does not meet the voltage output constraint, it indicates that the expected output reference pole voltage of the current faulty phase exceeds the actual output range corresponding to the single-switch open-circuit fault state. At this time, it is necessary to adjust the reference pole voltage of the faulty phase to the range allowed by the voltage output constraint by shifting the reference pole voltage of each phase as a whole.

[0097] Further, the voltage difference between the target voltage boundary and the original reference pole voltage of the fault phase is determined. This voltage difference characterizes the degree to which the current original reference pole voltage exceeds the executable range of the fault state. The target voltage boundary characterizes the critical voltage value that the fault phase is allowed to output under the current single-switch open-circuit fault state. For example, when the voltage output constraint is used to limit the pole voltage of the fault phase output towards the positive terminal of the DC bus, the target voltage boundary can be the maximum permissible positive pole voltage corresponding to the fault; when the voltage output constraint is used to limit the pole voltage of the fault phase output towards the negative terminal of the DC bus, the target voltage boundary can be the minimum permissible negative pole voltage corresponding to the fault.

[0098] The zero-sequence compensation voltage is determined based on the voltage difference. Unlike conventional zero-sequence modulation methods that are determined according to a preset zero-sequence modulation strategy, the zero-sequence compensation voltage in this embodiment is dynamically determined based on the actual voltage output capability of the fault phase under the current fault state. It is used to actively adjust the distribution position of the reference pole voltage of each phase relative to the DC bus reference potential, so that the compensation reference pole voltage of the fault phase enters the executable range corresponding to the fault state. Specifically, the zero-sequence compensation voltage is a directional voltage compensation amount, the direction of which is used to offset the deviation of the original reference pole voltage of the fault phase relative to the target voltage boundary, so that the compensation reference pole voltage of the fault phase after superimposing the zero-sequence compensation voltage enters the allowable range corresponding to the voltage output constraint. The positive and negative signs of the zero-sequence compensation voltage are used to characterize the overall offset direction of the reference pole voltage of each phase, and the absolute value of the zero-sequence compensation voltage is used to characterize the voltage offset amount required. For example, when the original reference pole voltage of the fault phase exceeds the target voltage boundary corresponding to the voltage output constraint, the direction of the zero-sequence compensation voltage is used to move the compensation reference pole voltage of the fault phase towards the target voltage boundary; when the original reference pole voltage of the fault phase is lower than the target voltage boundary, the direction of the zero-sequence compensation voltage is reversed. When the zero-sequence compensation voltage is superimposed on the original reference pole voltage of the faulty phase, the compensation reference pole voltage corresponding to the faulty phase no longer exceeds the target voltage boundary, thus satisfying the voltage output constraint.

[0099] In this embodiment, the zero-sequence compensation voltage is determined based on the deviation between the actual output capability of the faulty phase under fault conditions and the target reference voltage, rather than using a preset fixed compensation amount. This allows the zero-sequence compensation amount to be adjusted according to changes in the fault switch position, phase current direction, and current reference voltage requirements, thereby improving the accuracy of reference voltage adjustment under fault conditions.

[0100] Optionally, the zero-sequence compensation voltage is the minimum amplitude compensation voltage required to make the compensation reference pole voltage of the faulty phase meet the voltage output constraint.

[0101] In this embodiment, the zero-sequence compensation voltage can be the minimum amplitude compensation voltage required to make the compensation reference pole voltage of the faulty phase meet the voltage output constraint.

[0102] Specifically, when determining the zero-sequence compensation voltage based on the voltage difference between the original reference pole voltage of the fault phase and the target voltage boundary corresponding to the voltage output constraint, the amplitude of the zero-sequence compensation voltage can be further limited so that the zero-sequence compensation voltage has a minimum amplitude while satisfying the voltage output constraint of the fault phase.

[0103] If the amplitude of the zero-sequence compensation voltage is too small, the compensation reference pole voltage of the fault phase after superimposing the zero-sequence compensation voltage may still exceed the voltage output range under the current fault state, causing the inverter to be unable to accurately execute the corresponding voltage command. If the amplitude of the zero-sequence compensation voltage is too large, it will cause the original reference pole voltage of each phase of the multiphase inverter to have an excessive overall offset, causing the compensation reference pole voltage of the healthy phase (or normal phase, i.e., other phases besides the fault phase) to occupy more DC bus voltage margin, reducing the overall voltage utilization capability of the inverter.

[0104] Therefore, the method in this embodiment determines a zero-sequence compensation voltage with minimum amplitude based on the voltage difference between the original reference pole voltage of the faulty phase and the target voltage boundary, so that the compensated reference pole voltage of the faulty phase after superimposing the zero-sequence compensation voltage reaches the target voltage boundary; or, with a preset safety margin, it brings it into the allowable range corresponding to the voltage output constraint. For example, when the original reference pole voltage of the faulty phase exceeds the target voltage boundary, the amplitude of the zero-sequence compensation voltage can be determined based on the difference between the original reference pole voltage and the target voltage boundary, so that the compensated reference pole voltage of the faulty phase reaches the target voltage boundary or enters the allowable range of the voltage output constraint.

[0105] Therefore, while ensuring that the fault phase compensation reference pole voltage meets the voltage output constraint under fault conditions, the impact of zero-sequence compensation on the reference pole voltage of other phases is reduced, the additional voltage margin consumption is reduced, and the DC bus voltage utilization rate is improved.

[0106] Optionally, the zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter with the same voltage value to obtain the corresponding compensation reference pole voltage of each phase of the multiphase inverter.

[0107] In this embodiment, after determining the zero-sequence compensation voltage, the zero-sequence compensation voltage can be superimposed on the original reference pole voltages of the corresponding multiphase inverters to obtain the corresponding compensation reference pole voltages.

[0108] Specifically, during normal operation of a multiphase inverter, the original reference pole voltage of each phase is used to characterize the expected output pole voltage of the corresponding phase arm. Due to a single switch open-circuit fault, the switching state of some faulty phases cannot be executed, thus limiting the range of pole voltages that the faulty phase can output. Therefore, this embodiment introduces a zero-sequence compensation voltage to shift the overall reference pole voltage of each phase of the multiphase inverter.

[0109] The zero-sequence compensation voltage is a single voltage value, which is superimposed on the original reference pole voltage of each phase of the multiphase inverter. For example, the compensation reference pole voltage of any phase in the multiphase inverter can be determined according to the following relationship: V x，new =V x，ref +V0, Among them, V x，ref V represents the original reference pole voltage of any phase, V0 represents the zero-sequence compensation voltage, V x，new This represents the compensation reference pole voltage after the zero-sequence compensation voltage is superimposed on the corresponding phase.

[0110] Since the zero-sequence compensation voltage applies the same voltage value to each phase, under ideal modulation conditions, the reference pole voltages of each phase shift in the same direction as a whole, while the reference voltage difference between any two phases remains unchanged. In other words, after zero-sequence compensation: (V a，new V b，new )=(V a，ref V b，ref ), This allows for the adjustment of the reference pole voltage of the faulty phase without altering the phase-to-phase voltage relationship corresponding to the output voltage of the multiphase inverter, thus reducing the risk of changes in motor control performance caused by adjusting the reference pole voltage of the faulty phase alone.

[0111] For example, when the original reference pole voltage of the faulty phase exceeds the voltage boundary allowed to be output under the current fault condition, the zero-sequence compensation voltage in the corresponding direction is determined and simultaneously superimposed on the original reference pole voltage of the faulty phase and other phases, so that the compensation reference pole voltage of the faulty phase enters the voltage output constraint range, while maintaining the original voltage difference relationship between each phase.

[0112] Therefore, the method in this embodiment does not require additional hardware. It can adapt to the change in the output capability of the fault phase voltage caused by the open circuit fault of a single switch by simply shifting the reference pole voltage uniformly. While ensuring the executability of the fault phase voltage, it reduces the impact on the normal operation control of the motor and improves the continuity and reliability of the electric drive system under fault conditions.

[0113] Optionally, combined Figure 2 As shown, the fault-tolerant control method for single-switch open-circuit faults in inverters also includes: Step 220: When the original reference pole voltage of the fault phase meets the voltage output constraint, it is determined that no fault zero-sequence compensation based on voltage output constraint is required under the current single-switch open-circuit fault state, and the conventional zero-sequence modulation voltage is determined according to the preset zero-sequence modulation strategy. Step 320: Superimpose the conventional zero-sequence modulation voltage onto the original reference pole voltage of each phase of the multiphase inverter to obtain the modulation reference pole voltage of each phase of the multiphase inverter. Step 420: Perform space vector modulation based on the modulation reference pole voltages of each phase of the multiphase inverter; Among them, the conventional zero-sequence modulation voltage includes the saddle wave zero-sequence voltage.

[0114] In this embodiment, after determining the voltage output constraint based on the fault switch position and the phase current direction of the fault phase, it can be further determined whether the original reference pole voltage of the fault phase meets the voltage output constraint. Based on the determination result, different control paths can be selected. When the original reference pole voltage does not meet the voltage output constraint, a zero-sequence compensation voltage is determined based on the aforementioned embodiment to adjust the reference pole voltage under fault conditions. However, when the original reference pole voltage meets the voltage output constraint, no fault zero-sequence compensation is required, and the corresponding modulation reference pole voltage can be determined according to the conventional modulation process.

[0115] Specifically, when the original reference pole voltage of the faulty phase meets the voltage output constraint, it indicates that the current original reference pole voltage is within the actual output range of the faulty phase under a single-switch open-circuit fault condition, and the faulty phase does not need to adjust the reference pole voltage through fault zero-sequence compensation. In this case, to improve the voltage utilization of the multiphase inverter, a conventional zero-sequence modulation voltage can be determined according to a preset zero-sequence modulation strategy. The conventional zero-sequence modulation voltage is used to shift the overall reference pole voltage of each phase without changing the line voltage relationship between the phases of the multiphase inverter, thereby improving the DC bus voltage utilization. The preset zero-sequence modulation strategy can be pre-set according to the modulation method, operating state, and voltage utilization requirements of the multiphase inverter. For example, the conventional zero-sequence modulation voltage may include a saddle-wave zero-sequence voltage.

[0116] It should be noted that the aforementioned zero-sequence compensation voltage has a different function from the conventional zero-sequence modulation voltage used under fault constraints. The conventional zero-sequence modulation voltage is used to improve the DC bus voltage utilization during normal modulation and is usually determined according to a preset modulation strategy. In contrast, the zero-sequence compensation voltage is used to adapt to voltage output constraint changes caused by a single-switch open-circuit fault. It is not generated based on a fixed preset waveform, but rather dynamically determined based on the deviation between the original reference pole voltage of the fault phase and the voltage output constraint under fault conditions. By simultaneously adjusting the reference pole voltages of each phase, the reference pole voltage of the fault phase is brought into the actual executable range of the inverter.

[0117] Furthermore, the conventional zero-sequence modulation voltage is superimposed onto the original reference pole voltage of each phase of the multiphase inverter to obtain the corresponding modulation reference pole voltage.

[0118] Specifically, for any phase of a multiphase inverter, the modulation reference pole voltage can be determined according to the following relationship: V x，mod =V x，ref +V 0n , Among them, V x，ref V represents the original reference pole voltage of the corresponding phase. 0n This represents the conventional zero-sequence modulation voltage, V x，mod This represents the modulation reference pole voltage after the corresponding phase is superimposed with the conventional zero-sequence modulation voltage.

[0119] Since the conventional zero-sequence modulation voltage acts on the reference pole voltage of each phase simultaneously, the reference pole voltage of each phase can be shifted as a whole without changing the voltage difference relationship between the phases, thereby improving the DC bus voltage utilization rate.

[0120] After obtaining the corresponding modulation reference pole voltages of each multiphase inverter, space vector modulation can be performed based on the modulation reference pole voltages. Pulse width modulation signals are generated according to the corresponding space voltage vectors and the action time to control the on and off of each switch in the multiphase inverter, so as to drive the multiphase inverter to output the corresponding AC voltage.

[0121] Therefore, when a single switch open-circuit fault does not cause the current reference pole voltage to exceed the limit, the inverter voltage utilization capability can still be improved by using the conventional zero-sequence modulation method; while when the fault causes the reference pole voltage to exceed the limit, the reference voltage is adjusted by the aforementioned zero-sequence compensation method, thereby achieving adaptive control under different operating conditions in fault state.

[0122] Optionally, the fault-tolerant control method for open-circuit faults of a single switch in the inverter also includes: Based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, determine the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault. Based on the voltage output limiting parameters, determine the motor's output limiting parameters under the current single-switch open-circuit fault. The output control parameters of the motor are limited according to the output limit parameters.

[0123] After determining the zero-sequence compensation voltage, the method in this embodiment can further determine the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter. The voltage margin occupied by the zero-sequence compensation voltage characterizes the degree of occupancy of the DC bus voltage regulation space when the overall reference voltage is shifted to meet the voltage output constraints of the faulty phase. For example, it can be determined based on the amplitude, maximum amplitude, or other characterizing quantities of the zero-sequence compensation voltage within a preset control cycle.

[0124] Specifically, under a single-switch open-circuit fault condition, in order to ensure that the compensation reference pole voltage of the faulty phase meets the voltage output constraint, it is necessary to shift the original reference pole voltage of each phase as a whole through a zero-sequence compensation voltage. Since the zero-sequence compensation voltage changes the distribution of the reference pole voltage of each phase relative to the DC bus voltage, it will occupy part of the voltage regulation margin that the multiphase inverter can provide based on the DC bus voltage.

[0125] Furthermore, based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, the voltage output limiting parameters of the multiphase inverter under the current fault state are determined. These voltage output limiting parameters characterize the remaining voltage output capability of the multiphase inverter under the current single-switch open-circuit fault state. For example, when the amplitude of the zero-sequence compensation voltage increases, it indicates that more voltage margin is needed under the current fault state to ensure that the reference pole voltage of the faulty phase meets the voltage output constraint. Correspondingly, the remaining voltage range that the multiphase inverter can use to output motor drive voltage decreases. Therefore, by combining the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage, the remaining voltage output capability of the inverter under fault state can be evaluated more accurately.

[0126] Furthermore, based on the voltage output limiting parameters, the output limiting parameters of the motor under the current single-switch open-circuit fault are determined. For example, for a permanent magnet synchronous motor, the combination of direct-axis current reference values ​​and quadrature-axis current reference values ​​that satisfy the voltage constraints can be determined based on the current motor speed, motor temperature, current limit, and the upper limit of the allowable phase voltage fundamental amplitude. The current combination can be determined using maximum torque-to-current ratio control, maximum torque-to-voltage ratio control, analytical calculation, or a preset mapping relationship, and the maximum allowable output torque under the current fault condition can be calculated based on the current combination.

[0127] Specifically, the motor is powered by a multiphase inverter, and the voltage output capability of the multiphase inverter directly affects the operating range of the motor. When the remaining voltage output capability of the multiphase inverter decreases, the maximum control voltage that the motor can obtain under corresponding speed, load, and other operating conditions is limited. Therefore, based on the voltage output limit parameters and the motor's current operating state, the corresponding output limit parameters for the motor under the current fault condition can be determined.

[0128] Among them, the output limit parameters can be used to characterize the motor's allowable output capability, such as the maximum allowable torque, the maximum allowable current, or other control parameters that can reflect the motor's output capability.

[0129] Furthermore, the output control parameters of the motor are limited according to the output limit parameters.

[0130] Specifically, during motor control, when the received output request exceeds the allowable output capacity under the current single-switch open-circuit fault state, the output control parameters are limited according to the output limit parameters so that the motor operating state corresponding to the limited output control parameters is within the range achievable under the current fault state.

[0131] For example, when the target torque request of the motor exceeds the maximum allowable torque, the target torque request can be limited to no more than the maximum allowable torque; or, the corresponding current control command can be limited according to the allowable current range to avoid generating control demands that exceed the inverter's remaining voltage output capacity during motor control.

[0132] Therefore, the method in this embodiment can not only adjust the reference pole voltage of the faulty phase through zero-sequence compensation, enabling the inverter to adapt to the voltage output limitation caused by a single switch open circuit fault, but also further assess the remaining output capacity of the inverter under fault conditions based on the voltage margin change during the compensation process, and limit the motor output demand accordingly, thereby avoiding the motor operating point from exceeding the actual power supply capacity of the faulty inverter, and improving the stability and reliability of the electric drive system operation under single switch open circuit fault conditions.

[0133] Optionally, the multiphase inverter includes a three-phase two-level voltage-source inverter, and the voltage output limiting parameters include the upper limit of the allowable output phase voltage fundamental amplitude. Based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, determine the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault, including: Determine the maximum absolute value of the zero-sequence compensation voltage within the preset control range; The upper limit of the phase voltage fundamental amplitude is determined based on the difference between the maximum single-sided voltage output capability corresponding to the DC bus voltage and the maximum absolute value.

[0134] Specifically, this explanation uses a three-phase two-level voltage-type inverter as an example. A three-phase two-level voltage-type inverter provides voltage output capability to each phase arm via the DC bus voltage and drives the AC motor by adjusting the output voltage of each phase arm. Under normal operating conditions, the inverter determines the maximum output phase voltage range based on the DC bus voltage and the corresponding modulation strategy to meet the different speed and torque requirements of the motor.

[0135] After a single-switch open-circuit fault occurs, in order to ensure that the compensation reference pole voltage of the faulty phase meets the corresponding voltage output constraint, it is necessary to shift the original reference pole voltage of each phase as a whole based on the zero-sequence compensation voltage. Since the zero-sequence compensation voltage changes the distribution of the reference pole voltage of each phase relative to the DC bus voltage, it will occupy part of the voltage margin that the inverter could originally use to output the motor drive voltage, thus reducing the maximum voltage capability that the inverter can provide to the motor under fault conditions.

[0136] Therefore, in order to avoid the motor control requirements exceeding the actual voltage output capability of the inverter under fault conditions, the voltage output limit parameters of the inverter under fault conditions can be determined based on the voltage margin occupied by the zero-sequence compensation voltage and the current DC bus voltage.

[0137] Specifically, the zero-sequence compensation voltages corresponding to multiple control cycles within a preset control range can be obtained, and the absolute values ​​of each zero-sequence compensation voltage can be determined. The preset control range can be set according to actual control requirements, and may include, for example, a control range corresponding to one control cycle, multiple consecutive control cycles, or a preset time length.

[0138] Furthermore, the maximum absolute value of the zero-sequence compensation voltage within the preset control interval is determined. This maximum absolute value characterizes the maximum voltage margin required to meet the output voltage constraint of the faulty phase under the current single-switch open-circuit fault condition. The maximum absolute value of the zero-sequence compensation voltage serves as the maximum voltage margin required for the zero-sequence compensation process.

[0139] After determining the maximum absolute value of the zero-sequence compensation voltage, the upper limit of the allowable output phase voltage fundamental amplitude is determined based on the difference between the maximum single-sided voltage output capability corresponding to the DC bus voltage and the maximum absolute value. Since the AC motor is actually driven by the fundamental AC voltage output by the inverter, and the inverter bridge arm pole voltage determines the range of the synthesized phase voltage fundamental, the upper limit of the phase voltage fundamental amplitude corresponding to the AC motor can be determined based on the output capability of the remaining pole voltage.

[0140] The maximum single-sided voltage output capability is used to characterize the maximum output voltage capability of the inverter bridge arm pole voltage relative to the reference potential under the current DC bus voltage conditions. When the absolute maximum value of the zero-sequence compensation voltage increases, it indicates that the inverter needs to use more voltage margin to adapt to fault conditions, thus reducing the remaining capacity available for outputting motor drive voltage, and correspondingly reducing the upper limit of the allowable phase voltage fundamental amplitude.

[0141] For example, under ideal conditions where the on-state voltage drop of power devices, dead-time effects, and modulation margin are ignored, the upper limit of the fundamental amplitude of the output phase voltage can be estimated according to the following relationship: V ph，max =V dc，max |V 0，max |, Among them, V ph，max This indicates the upper limit of the allowed output phase voltage fundamental amplitude; V dc，max This represents the maximum single-sided voltage output capability of the multiphase inverter bridge arm pole voltage relative to the reference potential under the current DC bus voltage conditions. For example, for a three-phase two-level voltage-source inverter, the maximum single-sided voltage output capability is the DC bus voltage V of the multiphase inverter. dc Half of, i.e., V dc，max =V dc / 2;∣V 0，max | represents the maximum absolute value of the zero-sequence compensation voltage within the preset control range. It should be noted that the above relationship is only an exemplary calculation method. In practical applications, the relationship between the maximum single-sided voltage output capability and the voltage margin occupied by the zero-sequence compensation voltage can be adaptively adjusted according to the inverter topology, modulation method, and motor control requirements.

[0142] Therefore, the method in this embodiment can dynamically evaluate the remaining voltage output capability of a three-phase two-level inverter under a single-switch open-circuit fault state based on the actual voltage margin occupied during the fault compensation process, and further determine the upper limit of the allowable phase voltage fundamental amplitude, providing a basis for subsequently limiting the motor output capability, thereby avoiding the motor control demand from exceeding the actual power supply capability of the inverter under fault state and improving fault operation stability.

[0143] Furthermore, since the zero-sequence compensation process consumes part of the DC bus voltage margin, the maximum control voltage that the inverter can provide to the AC motor under fault conditions is reduced. Based on this, the method in this embodiment further determines the remaining voltage output capability based on the voltage margin consumed by the zero-sequence compensation, and accordingly limits the corresponding current reference value and torque request of the AC motor. Compared to directly shutting down the machine or using a single-phase operation mode after a fault occurs, the method in this embodiment utilizes the unfaulty switching transistors and the remaining hardware voltage output capability, enabling the AC motor to maintain multi-phase controlled operation, and adaptively reducing the output capability to prevent the control target from exceeding the actual capability of the inverter under fault conditions.

[0144] Optionally, the motor includes an AC motor, and the output limiting parameters include at least one of a combination of maximum permissible torque and permissible current; Based on the voltage output limiting parameters, determine the motor's output limiting parameters under the current single-switch open-circuit fault condition, including: Based on the upper limit of the phase voltage fundamental amplitude and at least one of the motor speed, temperature and current limits, determine the permissible combination of direct-axis current reference values ​​and quadrature-axis current reference values ​​that satisfy the upper limit of the phase voltage fundamental amplitude. Determine the maximum permissible torque based on the permissible combinations; Among them, the combination can be determined by at least one of the following methods: maximum torque-current ratio strategy, maximum torque-voltage ratio strategy, analytical calculation, and preset mapping relationship.

[0145] Specifically, after determining the upper limit of the phase voltage fundamental amplitude of the multiphase inverter under the current single-switch open-circuit fault, the corresponding output limiting parameters of the motor can be further determined based on the upper limit of the phase voltage fundamental amplitude.

[0146] The motor can be an AC motor, such as a permanent magnet synchronous motor or other motors driven by AC power. AC motors typically achieve torque output by controlling the stator current. The direct-axis current reference value and the quadrature-axis current reference value are used to characterize the motor's flux linkage control component and torque control component, respectively. By adjusting the direct-axis current reference value and the quadrature-axis current reference value, the output torque and operating state of the AC motor can be changed.

[0147] Under a single-switch open-circuit fault condition, the voltage output capability of the multiphase inverter is limited by the upper limit of the phase voltage fundamental amplitude, thus constraining the maximum control voltage that the AC motor can obtain. Therefore, to avoid the motor control target exceeding the actual voltage capability that the inverter can provide under fault conditions, it is necessary to further determine the allowable current control range for the AC motor based on the upper limit of the phase voltage fundamental amplitude.

[0148] Specifically, based on the upper limit of the fundamental amplitude of the phase voltage and the current operating parameters of the motor, the permissible combination of direct-axis current reference values ​​and quadrature-axis current reference values ​​that meet the upper limit requirement of the fundamental amplitude of the phase voltage can be determined. The current operating parameters of the motor can include at least one of motor speed, temperature, and current limits. Motor speed characterizes the current back electromotive force level of the motor, temperature characterizes the thermal limiting state of the motor or electric drive system, and the current limit characterizes the maximum permissible current output capability of the motor and inverter. When the motor speed increases, the motor back electromotive force increases, and under the same DC bus voltage conditions, the voltage margin available for current control decreases; when the motor temperature increases or the current reaches the limit condition, further constraints on the current output are required. Therefore, by comprehensively considering the above factors, the range of direct-axis current reference values ​​and quadrature-axis current reference values ​​that meet the voltage constraints under the current fault condition can be determined.

[0149] For example, the current combination that satisfies the upper limit of the fundamental amplitude of the phase voltage can be determined based on the voltage constraint relationship corresponding to the AC motor: ( , )∈Ω, Where Ω represents the permissible combination of direct-axis current reference value and quadrature-axis current reference value that meets the voltage limit, current limit and other operating constraints under the current single-switch open-circuit fault condition. This represents the direct-axis current reference value, used to characterize the flux linkage control target of an AC motor; This represents the reference value of the quadrature axis current, used to characterize the torque control target of an AC motor.

[0150] Furthermore, the maximum permissible torque is determined based on the permissible combinations.

[0151] Specifically, the output torque of an AC motor is related to the quadrature-axis component of the stator current. Therefore, the maximum torque that the motor can output under the current fault condition can be determined based on the current state corresponding to the permissible combination. For example, the direct-axis current reference value and the quadrature-axis current reference value corresponding to the maximum torque output can be selected from the permissible combination to determine the corresponding maximum permissible torque.

[0152] The allowed combinations can be determined in various ways, including but not limited to maximum torque current ratio control, maximum torque voltage ratio control, analytical calculation, and preset mapping relationships. For example, in one implementation, based on maximum torque-to-current ratio control, within the range satisfying the upper limit of the phase voltage fundamental amplitude and the current limit, the allowable combination of the corresponding direct-axis current reference value and quadrature-axis current reference value can be determined to obtain a higher torque output capability under constrained conditions. In another implementation, based on maximum torque-to-voltage ratio control, according to the upper limit of the phase voltage fundamental amplitude and the current operating state of the motor, the allowable combination of the direct-axis current reference value and quadrature-axis current reference value satisfying the voltage limit conditions can be determined to improve the utilization of the limited voltage output capability under fault conditions. In yet another implementation, the allowable combination of the direct-axis current reference value and quadrature-axis current reference value satisfying the upper limit of the phase voltage fundamental amplitude under the current fault condition can be determined by analytical calculation based on the voltage equation, torque equation, and corresponding voltage and current limits of the AC motor. In yet another implementation, a mapping relationship between different motor operating states, voltage output limit parameters, and allowable current combinations can be pre-established, and the corresponding allowable current combination can be obtained from the mapping relationship based on the upper limit of the phase voltage fundamental amplitude corresponding to the current fault condition and the current operating state of the motor. The above different methods can be used individually or in combination according to the motor operating area or fault condition.

[0153] Therefore, the method in this embodiment can further map the change in inverter voltage output capability caused by a single switch open circuit fault to the motor output capability limit, dynamically adjust the allowable output torque or current range of the motor according to the fault state, avoid the motor control target from exceeding the actual power supply capacity of the inverter, and maintain the stable operation of the electric drive system without adding additional hardware.

[0154] Optionally, the output control parameters include at least one of torque request, direct-axis current reference value, and quadrature-axis current reference value; The output control parameters of the motor are limited according to the output limit parameters, including: When the torque request exceeds the maximum permissible torque, the torque request will be limited to no more than the maximum permissible torque; And / or, limit the direct-axis current reference value and the quadrature-axis current reference value according to the allowed combination.

[0155] Specifically, after determining the output limiting parameters of the motor under the current single-switch open-circuit fault state, the method of this embodiment can further limit the output control parameters of the motor based on the output limiting parameters. The output limiting parameters characterize the maximum output capacity that the motor is allowed to reach under the current fault state, such as the maximum allowable torque and the allowable current combination that satisfies constraints such as voltage and current. The output control parameters characterize the target control quantity actually issued by the motor control system to the motor control loop, such as at least one of torque request, direct-axis current reference value, and quadrature-axis current reference value.

[0156] Under normal operating conditions, the motor control system can determine the corresponding torque request based on vehicle demand or external control commands, and further generate corresponding current control commands to control the AC motor to output the target torque. However, after a single-switch open-circuit fault occurs in the multiphase inverter, the actual voltage output capability that the multiphase inverter can provide to the AC motor is reduced because the voltage output capability of the faulty phase is limited. If control is still performed according to the torque request or current reference value before the fault occurred, the voltage command corresponding to the motor control may exceed the actual voltage output capability that the inverter can provide under the current fault condition, resulting in increased current control error, current waveform distortion, or even failure to achieve the target operating state.

[0157] Therefore, in this embodiment, the output control parameters corresponding to the motor can be limited based on the output limit parameters determined under the current single-switch open-circuit fault state, so that the motor control target is within the actual power supply capacity range of the inverter under the fault state.

[0158] Specifically, when the output control parameters include a torque request, the current torque request can be compared with the maximum permissible torque.

[0159] When the torque request does not exceed the maximum allowable torque, it indicates that the current torque demand is within the allowable output range of the motor under the single switch open circuit fault condition, and the subsequent motor control process can be executed according to the current torque request.

[0160] When the torque request exceeds the maximum permissible torque, it indicates that the current torque demand exceeds the maximum output capacity that the motor can achieve under fault conditions. Therefore, the torque request is limited to no more than the maximum permissible torque. Furthermore, current control calculations can be recalculated based on the limited torque request to generate corresponding direct-axis current reference values ​​and quadrature-axis current reference values, so that subsequent motor control processes meet the voltage output limits under the current fault conditions.

[0161] And / or, when the output control parameters include direct-axis current reference values ​​and quadrature-axis current reference values, the direct-axis current reference values ​​and quadrature-axis current reference values ​​can be limited according to the allowed combinations.

[0162] Specifically, the permissible combination is used to characterize the feasible range of direct-axis and quadrature-axis current reference values ​​that satisfy the upper limit of the fundamental amplitude of the phase voltage, current limit, and other operating constraints under the current single-switch open-circuit fault condition. When the current operating point corresponding to the current direct-axis and quadrature-axis current reference values ​​is within the feasible range corresponding to the permissible combination, the current current control command can be maintained; when the current operating point exceeds the feasible range corresponding to the permissible combination, the direct-axis and / or quadrature-axis current reference values ​​can be adjusted to the feasible range corresponding to the permissible combination.

[0163] For example, the motor torque output requirement can be reduced by adjusting the quadrature axis current reference value, or the combination relationship between the direct axis current reference value and the quadrature axis current reference value can be re-determined according to the current operating state of the motor, so that the motor operating state corresponding to the adjusted current control command meets the voltage limit requirements under the current fault state.

[0164] Therefore, the method in this embodiment can further transmit the change in inverter voltage output capability caused by a single switch open-circuit fault to the motor control stage. It dynamically limits the motor torque request or current reference value based on the fault state, ensuring that the motor control target remains within the actual power supply capacity that the inverter can provide under fault conditions. This avoids current runaway or operational instability caused by control demands exceeding the inverter's output capacity. Furthermore, this embodiment eliminates the need for additional fault-tolerant hardware such as redundant bridge arms or neutral point leads. Instead, it improves the continuity, safety, and reliability of the electric drive system under fault conditions by assessing the inverter's remaining voltage output capability and coordinating and limiting the motor-side output capability.

[0165] Optionally, space vector modulation is performed based on the compensated reference pole voltages of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter, including: The set of executable space voltage vectors is determined based on the number of phases and the number of levels of the multiphase inverter, as well as the executable switching state combinations under the current single-switch open-circuit fault. The target voltage vector is determined based on the compensation reference pole voltage of each phase of the multiphase inverter. Determine at least one space voltage vector and its corresponding application time from the executable set of space voltage vectors for synthesizing the target voltage vector; A pulse width modulation signal is generated based on at least one space voltage vector and its corresponding duration.

[0166] In this embodiment, after obtaining the corresponding compensation reference pole voltages of the multiphase inverter, it is necessary to perform space vector modulation on the compensation reference pole voltages based on the executable space voltage vector set under the current single-switch open-circuit fault state, so as to generate a pulse width modulation signal for driving the multiphase inverter.

[0167] Specifically, in the case of a single open-circuit fault, the faulty switch cannot conduct normally according to the control command, making some switching state combinations in the multiphase inverter unrealizable. Since the space voltage vector is mapped from the switching state combinations corresponding to each phase arm, when some switching state combinations cannot be executed due to a fault, the space voltage vector corresponding to those combinations also cannot be actually output by the inverter. From the perspective of space voltage vector modulation, a single open-circuit fault is equivalent to rendering part of the inverter's original space voltage vector invalid, causing a change in the set of space voltage vectors corresponding to the normal state. This leads to a contraction in the voltage output boundary that can be used for space vector modulation relative to the normal state. Therefore, if space vector modulation is still performed based on the complete set of space voltage vectors under normal operating conditions, the space voltage vector implemented by the faulty switch may be selected. This results in the generated pulse width modulation signal failing to achieve the target voltage state corresponding to the actual output of the inverter, thus causing a deviation between the actual output voltage and the expected reference voltage.

[0168] For example, in a three-phase two-level inverter, under normal operating conditions, the switching state combinations of each phase arm can form a complete set of space voltage vectors. For instance, if each of the three phase arms has two switching states, multiple basic switching state combinations can be formed and mapped to corresponding space voltage vectors. These space voltage vectors collectively define the range of space voltages that the inverter can output under normal conditions. When a switch experiences an open-circuit fault, some switching state combinations related to the on-state of that switch become unavailable, causing the corresponding space voltage vector to be lost, resulting in a change in the actual output space voltage range of the inverter. Therefore, when performing space vector modulation under fault conditions, it is necessary to re-determine the set of executable space voltage vectors based on the currently executable switching state combinations, rather than continuing to use the complete set of space voltage vectors under normal operating conditions.

[0169] Based on this, the method of this embodiment first determines the set of executable space voltage vectors according to the number of phases, the number of levels of the multiphase inverter and the executable switch state combination under the current single switch open-circuit fault state.

[0170] The executable switch state combination is used to characterize the actual conduction state combinations that each switch in the multiphase inverter can achieve under the current fault state. Specifically, under normal operation of the multiphase inverter, each switch can form a complete switch state combination according to control commands, and correspondingly generate a complete set of space voltage vectors. However, when a single switch open-circuit fault occurs, since the faulty switch cannot conduct normally according to the control commands, some switch state combinations related to the conduction state of the faulty switch cannot be realized. It should be noted that under the single switch open-circuit fault state, whether the pole voltages corresponding to some switch state combinations can actually be formed also depends on the current direction of the faulty phase. This is because the faulty phase current may form a current path through other power devices, allowing some pole voltages determined by the switch state combinations to still be realized.

[0171] Therefore, the method in this embodiment first determines the switch state combinations that cannot be executed normally due to the fault based on the location of the faulty switch, and then filters other switch state combinations based on the phase current direction of the faulty phase to determine the actual executable switch state combinations under the current fault state. Further, based on the output voltage of each phase bridge arm corresponding to the executable switch state combinations, the set of executable space voltage vectors that can be used for space vector modulation under the current single-switch open-circuit fault state is determined. Through the above method, when performing space vector modulation under the fault state, the modulation vector is selected only from the set of executable space voltage vectors under the current fault state, avoiding the generation of unexecutable voltage states that depend on the faulty switch. The set of executable space voltage vectors is used to characterize the set of space voltage vectors that the multiphase inverter can actually realize under the current fault state.

[0172] After determining the set of executable space voltage vectors, the target voltage vector is determined based on the compensation reference pole voltage of each phase of the multiphase inverter.

[0173] Specifically, the compensated reference pole voltage is used to characterize the desired output voltage of each phase after zero-sequence compensation. By calculating the space voltage vector based on the compensated reference pole voltage of each phase, the corresponding target voltage vector can be determined. The compensated reference pole voltage serves as the reference input for space vector modulation, characterizing the voltage state of the inverter's desired output within the current control cycle. The target voltage vector characterizes the desired voltage state determined based on the compensated reference pole voltage within the current control cycle.

[0174] Further, at least one space voltage vector and its corresponding application time are determined from the executable set of space voltage vectors for synthesizing the target voltage vector.

[0175] Specifically, based on the positional relationship between the target voltage vector and each spatial voltage vector in the executable spatial voltage vector set, one or more spatial voltage vectors that can approximate or synthesize the target voltage vector can be selected, and based on the correspondence between the target voltage vector and the selected spatial voltage vectors, the duration of action of each spatial voltage vector in the current control cycle can be determined.

[0176] The duration of action is used to characterize the duration of the corresponding space voltage vector within a modulation cycle. By reasonably configuring the duration of action of different space voltage vectors, the actual output voltage of the multiphase inverter can be made as close as possible to the target voltage vector within the range that can be achieved under fault conditions, while avoiding output voltage states that cannot be achieved by the inverter under fault conditions.

[0177] Finally, a pulse width modulation signal is generated based on at least one space voltage vector and its corresponding duration.

[0178] Specifically, based on the determined sequence of action of the space voltage vectors and the corresponding action time of each space voltage vector, the turn-on and turn-off timing of each switch is determined, and a pulse width modulation signal is generated to control the on / off state of each switch in the multiphase inverter. This pulse width modulation signal drives each switch in the multiphase inverter, causing the multiphase inverter to output an AC voltage corresponding to the compensation reference pole voltage.

[0179] Since the method in this embodiment does not use all space voltage vectors under normal operating conditions during space vector modulation, but modulates based on the set of space voltage vectors that can actually be executed under the single-switch open-circuit fault condition, it can avoid generating control commands that cannot be implemented by the inverter under fault conditions during the modulation process. At the same time, since the modulation input uses the compensation reference pole voltage after zero-sequence compensation, the generated pulse width modulation signal can simultaneously meet the fault phase voltage output constraints and motor operation requirements.

[0180] Therefore, without adding redundant bridge arms, neutral point leads or other additional hardware, the inverter output capability changes caused by single switch open circuit faults can be adapted to by software control, so as to achieve stable motor operation under fault conditions and improve the continuity, safety and reliability of electric drive system operation under fault conditions.

[0181] For example, such as Figure 6 As shown, Figure 6The diagram illustrates the changes in control waveforms before and after a single-switch open-circuit fault in a multiphase inverter, according to the method described in this embodiment. The horizontal axis represents control time, and the vertical axis represents the zero-sequence (compensation) voltage, three-phase (stator) current, and (motor) electromagnetic torque, respectively. Before the fault, the multiphase inverter is in normal operation. The corresponding control system can generate a corresponding reference voltage command based on the motor's operating requirements and drive the AC motor using normal modulation. At this time, the zero-sequence compensation voltage is in normal modulation, the three-phase stator current maintains a corresponding sinusoidal relationship, and the electromagnetic torque remains at the target output level before the fault. When a single-switch open-circuit fault is detected, the corresponding control system determines the corresponding voltage output constraint based on the fault switch position and the direction of the fault phase current, and determines the zero-sequence compensation voltage based on the deviation between the original reference pole voltage and the voltage output constraint. Figure 6 As shown, after a fault occurs, the zero-sequence compensation voltage is dynamically adjusted according to the current fault state to ensure that the reference pole voltage corresponding to the fault enters the actual output range of the inverter. Simultaneously, because a single open-circuit fault limits the inverter's voltage output capability, the control system can adaptively adjust the motor output capability based on the remaining voltage output capability under the fault state, adjusting the three-phase stator current amplitude and motor output torque to a range matching the current fault state. Figure 6 It can be seen that, through the above control method, the AC motor can still maintain controlled operation after a single switch open circuit fault occurs, avoiding motor shutdown due to direct blocking of inverter drive signal, and reducing current distortion and torque fluctuation caused by insufficient voltage output capability under fault conditions.

[0182] Combination Figure 7 As shown, another embodiment of the present invention provides a fault-tolerant control device for an inverter single-switch open-circuit fault, comprising: The constraint determination module is used to respond to a single-switch open-circuit fault in the multiphase inverter and determine the voltage output constraint of the faulty phase under the current single-switch open-circuit fault based on the fault switch position and the phase current direction of the faulty phase. The compensation determination module is used to determine the zero-sequence compensation voltage based on the original reference pole voltage and voltage output constraint of the faulty phase when the original reference pole voltage of the faulty phase does not meet the voltage output constraint. The voltage compensation module is used to superimpose the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase meets the voltage output constraint. The drive modulation module is used to perform space vector modulation based on the compensation reference pole voltage of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

[0183] The inverter single-switch open-circuit fault-tolerant control device of this embodiment is used to implement the above-mentioned inverter single-switch open-circuit fault-tolerant control method. Its advantages over the prior art are the same as those of the above-mentioned inverter single-switch open-circuit fault-tolerant control method over the prior art, and will not be repeated here.

[0184] Combination Figure 8 As shown, another embodiment of the present invention provides an electronic device, including a memory 801 and a processor 802; Memory 801 is used to store computer programs; The processor 802 is used to implement the above-described inverter single-switch open-circuit fault-tolerant control method when executing a computer program.

[0185] Alternatively, an electronic device includes a memory 801 and a processor 802 coupled to the memory 801; the memory 801 is configured to store a computer program; the processor 802 is configured to perform the following operations when the computer program is executed: In response to a single-switch open-circuit fault in a multiphase inverter, the voltage output constraint of the faulty phase under the current single-switch open-circuit fault is determined based on the fault switch position and the phase current direction of the faulty phase. When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage and voltage output constraint of the faulty phase. The zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. Space vector modulation is performed based on the compensation reference pole voltages of each phase of the multiphase inverter to generate pulse width modulation signals for driving the multiphase inverter.

[0186] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is read and executed by a processor, it implements the above-described inverter single-switch open-circuit fault-tolerant control method.

[0187] Alternatively, a non-volatile computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the following operations: In response to a single-switch open-circuit fault in a multiphase inverter, the voltage output constraint of the faulty phase under the current single-switch open-circuit fault is determined based on the fault switch position and the phase current direction of the faulty phase. When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage and voltage output constraint of the faulty phase. The zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. Space vector modulation is performed based on the compensation reference pole voltages of each phase of the multiphase inverter to generate pulse width modulation signals for driving the multiphase inverter.

[0188] The technical solutions of the embodiments of the present invention, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of the embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, external hard drives, ROM, RAM, magnetic disks, or optical disks.

[0189] The computer-readable storage medium of this embodiment can be used to implement the above-described inverter single-switch open-circuit fault-tolerant control method. Its advantages over the prior art are the same as those of the above-described inverter single-switch open-circuit fault-tolerant control method over the prior art, and will not be repeated here.

[0190] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A fault-tolerant control method for an inverter with a single open-circuit switch, applied to an electric drive system including a multiphase inverter and a motor, characterized in that, include: In response to a single-switch open-circuit fault in the multiphase inverter, the voltage output constraint of the faulty phase under the current single-switch open-circuit fault is determined based on the fault switch position and the phase current direction of the faulty phase corresponding to the single-switch open-circuit fault. When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage of the faulty phase and the voltage output constraint. The zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. Space vector modulation is performed based on the compensated reference pole voltages of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

2. The inverter single-switch open-circuit fault-tolerant control method as described in claim 1, characterized in that, The multiphase inverter includes a three-phase two-level voltage source inverter, which includes three phase bridge arms. Each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The single switch open circuit fault is an open circuit fault in the upper bridge arm switch or the lower bridge arm switch of any phase bridge arm in the three-phase two-level voltage source inverter.

3. The inverter single-switch open-circuit fault-tolerant control method as described in claim 1, characterized in that, The motor includes an AC motor; the inverter single-switch open-circuit fault-tolerant control method further includes: Collect the stator current and rotor position of the AC motor; Based on the stator current, the rotor position, and the torque request corresponding to the AC motor, the AC motor is subjected to field-oriented control to generate the original reference pole voltage of each phase of the multiphase inverter.

4. The inverter single-switch open-circuit fault-tolerant control method as described in claim 1, characterized in that, Also includes: Obtain the single-switch open-circuit fault signal of the multiphase inverter; Based on the single switch open circuit fault signal, determine the faulty phase and the location of the faulty switch where the single switch open circuit fault occurred; The fault switch position is used to characterize the inverter phase in which the open-circuit fault occurs and the connection position of the switch in the corresponding bridge arm.

5. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, The step of determining the voltage output constraint of the faulty phase under the current single-switch open-circuit fault based on the fault switch position and phase current direction of the faulty phase corresponding to the single-switch open-circuit fault includes: Based on the location of the fault switch, determine the inverter switch state combination that cannot be executed normally due to the open circuit fault of the single switch tube; Based on the phase current direction of the faulty phase, the currently executable switching state combination is determined from multiple switching state combinations of the multiphase inverter; The voltage output constraint of the fault phase is determined based on the pole voltage output range corresponding to the current executable switch state combination. The voltage output constraint includes at least one of the following: upper voltage limit, lower voltage limit, voltage range, voltage boundary, and voltage feasible region.

6. The inverter single-switch open-circuit fault-tolerant control method as described in claim 5, characterized in that, When the fault switch position is the upper bridge arm position of the fault phase, and the phase current direction of the fault phase causes the pole voltage of the fault phase output toward the positive DC bus to depend on the upper bridge arm switch that has an open circuit fault, the voltage output constraint is used to limit the pole voltage of the fault phase output toward the positive DC bus. When the fault switch is in the lower arm position of the faulty phase, and the phase current direction of the faulty phase causes the pole voltage of the faulty phase output toward the negative DC bus to depend on the lower arm switch that has an open-circuit fault, the voltage output constraint is used to limit the pole voltage of the faulty phase output toward the negative DC bus.

7. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, When the original reference pole voltage of the faulty phase does not meet the voltage output constraint, the zero-sequence compensation voltage is determined based on the original reference pole voltage of the faulty phase and the voltage output constraint, including: Determine the voltage polarity corresponding to the original reference pole voltage of the faulty phase; When the voltage polarity is the same as the voltage polarity restricted by the single-switch open-circuit fault, and the original reference pole voltage of the fault phase exceeds the target voltage boundary corresponding to the voltage output constraint, it is determined that the original reference pole voltage of the fault phase does not meet the voltage output constraint. Based on the original reference pole voltage of the fault phase and the voltage output constraint, the zero-sequence compensation voltage is determined.

8. The inverter single-switch open-circuit fault-tolerant control method according to claim 7, characterized in that, The step of determining the zero-sequence compensation voltage based on the original reference pole voltage of the faulty phase and the voltage output constraint includes: Determine the voltage difference between the target voltage boundary corresponding to the voltage output constraint and the original reference pole voltage of the fault phase; The zero-sequence compensation voltage is determined based on the voltage difference so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint.

9. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, The zero-sequence compensation voltage is the minimum amplitude compensation voltage required to make the compensation reference pole voltage of the faulty phase meet the voltage output constraint. And / or, the zero-sequence compensation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter with the same voltage value to obtain the corresponding compensation reference pole voltage of the multiphase inverter.

10. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, Also includes: When the original reference pole voltage of the fault phase satisfies the voltage output constraint, it is determined that no zero-sequence compensation is required under the current single-switch open-circuit fault, and the conventional zero-sequence modulation voltage is determined according to the preset zero-sequence modulation strategy. The conventional zero-sequence modulation voltage is superimposed on the original reference pole voltage of each phase of the multiphase inverter to obtain the modulation reference pole voltage of each phase of the multiphase inverter. Space vector modulation is performed based on the modulation reference pole voltage of each phase of the multiphase inverter. The conventional zero-sequence modulation voltage includes a saddle-wave zero-sequence voltage.

11. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, Also includes: Based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, determine the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault. Based on the voltage output limiting parameters, determine the output limiting parameters of the motor under the current single-switch open-circuit fault. The output control parameters of the motor are limited according to the output limiting parameters.

12. The inverter single-switch open-circuit fault-tolerant control method according to claim 11, characterized in that, The multiphase inverter includes a three-phase two-level voltage-source inverter, and the voltage output limiting parameters include the upper limit of the allowable output phase voltage fundamental amplitude. The step of determining the voltage output limiting parameters of the multiphase inverter under the current single-switch open-circuit fault, based on the voltage margin occupied by the zero-sequence compensation voltage and the DC bus voltage of the multiphase inverter, includes: Determine the maximum absolute value of the zero-sequence compensation voltage within the preset control range; The upper limit of the phase voltage fundamental amplitude is determined based on the difference between the maximum single-sided voltage output capability corresponding to the DC bus voltage and the maximum absolute value.

13. The inverter single-switch open-circuit fault-tolerant control method according to claim 12, characterized in that, The motor includes an AC motor, and the output limiting parameters include at least one of a combination of maximum permissible torque and permissible current. The step of determining the output limit parameters of the motor under the current single-switch open-circuit fault based on the voltage output limit parameters includes: Based on the upper limit of the phase voltage fundamental amplitude and at least one of the motor speed, temperature and current limits, determine the permissible combination of the direct-axis current reference value and the quadrature-axis current reference value that satisfies the upper limit of the phase voltage fundamental amplitude. The maximum permissible torque is determined based on the permissible combination; The allowed combinations are determined by at least one of the following methods: maximum torque-current ratio strategy, maximum torque-voltage ratio strategy, analytical calculation, and preset mapping relationship.

14. The inverter single-switch open-circuit fault-tolerant control method according to claim 13, characterized in that, The output control parameters include at least one of torque request, direct-axis current reference value, and quadrature-axis current reference value; The step of limiting the motor's output control parameters according to the output limiting parameters includes: When the torque request exceeds the maximum permissible torque, the torque request is limited to no more than the maximum permissible torque; And / or, limit the direct-axis current reference value and the quadrature-axis current reference value according to the permitted combination.

15. The inverter single-switch open-circuit fault-tolerant control method according to any one of claims 1-4, characterized in that, The step of performing space vector modulation based on the compensated reference pole voltages of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter includes: The executable space voltage vector set is determined based on the number of phases and the number of voltage levels of the multiphase inverter, as well as the executable switch state combination under the current single switch open circuit fault. The target voltage vector is determined based on the compensation reference pole voltage of each phase of the multiphase inverter; Determine at least one space voltage vector and its corresponding application time from the executable space voltage vector set for synthesizing the target voltage vector; The pulse width modulation signal is generated based on the at least one spatial voltage vector and the corresponding action time.

16. A fault-tolerant control device for open-circuit faults of a single switch transistor in an inverter, characterized in that, include: The constraint determination module is used to determine the voltage output constraint of the faulty phase under the current single switch open circuit fault in response to the occurrence of a single switch open circuit fault in the multiphase inverter, based on the fault switch position and phase current direction of the faulty phase corresponding to the single switch open circuit fault. The compensation determination module is used to determine the zero-sequence compensation voltage based on the original reference pole voltage of the faulty phase and the voltage output constraint when the original reference pole voltage of the faulty phase does not meet the voltage output constraint. The voltage compensation module is used to superimpose the zero-sequence compensation voltage onto the original reference pole voltage of each phase of the multiphase inverter to obtain the compensation reference pole voltage of each phase of the multiphase inverter, so that the compensation reference pole voltage of the faulty phase satisfies the voltage output constraint. The drive modulation module is used to perform space vector modulation based on the compensation reference pole voltage of each phase of the multiphase inverter to generate a pulse width modulation signal for driving the multiphase inverter.

17. An electronic device, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is configured to implement, when executing the computer program, the inverter single-switch open-circuit fault-tolerant control method as described in any one of claims 1-15.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which is read and executed by a processor to implement the inverter single-switch open-circuit fault-tolerant control method as described in any one of claims 1-15.

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