Powertrain having open-circuit fault tolerance function, and method and electric vehicle

Abstract

A powertrain having an open-circuit fault tolerance function. The powertrain comprises an electric motor controller (50) and a driving electric motor (60), wherein the driving electric motor is an interior permanent magnet synchronous electric motor, and the electric motor controller (50) comprises an inverter circuit (52) and a control apparatus (51). The control apparatus (51) is used for controlling, in response to any phase current of a driving current outputted by bridge arm midpoints of three-phase bridge arms becoming zero during the process of receiving a torque signal, bridge arm midpoints of two-phase bridge arms corresponding to the other two phase currents to respectively output a fault-tolerant current, wherein the fault-tolerant current is a pulsed alternating current, a current amplitude of the fault-tolerant current changes along with a change in a rotor angle of the driving electric motor (60), and the fault-tolerant current is used for controlling the average value of torques outputted by the driving electric motor (60) to be less than a torque indicated by the torque signal. A control method for a powertrain, which method is used for the powertrain. An electric vehicle, which comprises a vehicle control unit and the powertrain. By means of such configurations, when an open-circuit fault occurs, output torque pulsations of a driving electric motor can be reduced, and stable operation at a reduced power can be realized, thereby improving the availability of a driving system.

Description

Powertrain, method and electric vehicle with open circuit fault tolerance function

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 27, 2023, with application number 202311613153.9 and invention name “Powertrain, method and electric vehicle with open circuit fault tolerance function”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electric vehicles, and more particularly, to a powertrain, method and electric vehicle with open-circuit fault tolerance function. Background Art

[0003] Faced with the dual pressures of environmental crises and energy shortages, electric vehicles, with their outstanding advantages such as low energy consumption and low pollution, have become a key development direction for the automotive industry. Permanent magnet synchronous motors, with their high efficiency, high power density, and fast torque response, have become the primary development trend for electric vehicle drive motors. As a key component of electric vehicles, the safety and reliability of the electric drive system are crucial to the driver's property and life safety. If an open circuit fault occurs in any phase of the drive axle or in the drive motor during vehicle operation, the output torque will oscillate between positive and negative due to unbalanced output phase current, resulting in reduced motor control performance and even potential motor burnout over extended periods of operation.

[0004] At present, the fault-tolerant control for single-phase open-circuit faults of permanent magnet synchronous motors is mainly based on a method that combines hardware redundancy with control algorithms. However, the current fault-tolerant control algorithms are difficult to effectively control the large torque fluctuations of built-in permanent magnet synchronous motors after a phase loss fault occurs.

[0005] Summary of the Invention

[0006] The present application provides a powertrain, method and electric vehicle with open-circuit fault tolerance function, which realizes fault-tolerant control of open-circuit faults by reconstructing the reference current of the powertrain after the fault, thereby reducing the output torque pulsation of the drive motor, achieving stable operation with reduced power, and improving the availability of the motor drive system.

[0007] In the first aspect, the present application provides a powertrain, which includes a motor controller and a drive motor, the drive motor is an embedded permanent magnet synchronous motor, the motor controller includes an inverter circuit and a control device, the inverter circuit includes a three-phase bridge arm, the midpoint of each phase bridge arm in the three-phase bridge arm is used to connect one phase winding in the three-phase winding of the drive motor, the control device is used to receive a torque signal and control the midpoint of the three-phase bridge arm of the inverter circuit to output a drive current or a fault-tolerant current, and the drive current is a three-phase current; the control device is used to respond to the torque signal and control the inverter circuit The midpoint of each phase bridge arm outputs a driving current, and the driving current is used to control the torque indicated by the output torque signal of the drive motor; in response to any phase current of the driving current output from the midpoint of the bridge arm of the three-phase bridge arm becoming zero during the process of receiving the torque signal, the midpoints of the two phase bridge arms corresponding to the other two phase currents are controlled to output fault-tolerant currents respectively, and the fault-tolerant current is a pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the drive motor, and the fault-tolerant current is used to control the average value of the torque output by the drive motor to be less than the torque indicated by the torque signal.

[0008] When an open-circuit fault occurs in the powertrain, by controlling the current in the two-phase bridge arm, the average value of the torque output by the drive motor can be controlled to be less than the torque indicated by the torque signal, and the torque indicated by the torque signal can be output periodically. The current fault-tolerant control method is only applicable to surface-mounted drive motors, and does not take into account the scenario where the quadrature-axis inductance and the direct-axis inductance are not equal, that is, the embedded drive motor. The setting of the fault-tolerant current in the solution of the present application is applicable to embedded permanent magnet synchronous motors, and this fault-tolerant current can enable the drive motor with an open-circuit fault to output the torque indicated by the torque signal as much as possible, or the maximum torque that the drive motor can output at this time.

[0009] According to the solution of the present application, when an open circuit fault occurs in the three-phase bridge arm of the motor controller or in one phase of the three-phase winding of the drive motor, a fault-tolerant current is output. The magnitude of the fault-tolerant current is related to the difference between the direct-axis inductance and the quadrature-axis inductance of the drive motor, thereby reducing the output torque pulsation of the drive motor, achieving stable operation with reduced power, and improving availability.

[0010] In the present application, an open circuit fault in the powertrain may refer to an open circuit in the three-phase bridge arm of the motor controller, or an open circuit in the three-phase winding of the drive motor. It may be an open circuit fault that occurs suddenly during the operation of the electric vehicle, or it may be an open circuit fault that occurs before the electric vehicle is started and then started. Similar situations should be within the scope of protection of this application and will not be described in detail below.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the fault-tolerant current is used to control the drive motor to periodically output the torque indicated by the torque signal.

[0012] In combination with the first aspect, in certain implementations of the first aspect, each phase arm of the three-phase bridge arm includes two switching tubes, and the control device is used to control the two switching tubes of the bridge arm corresponding to any phase current to turn off.

[0013] When an open circuit fault occurs in the powertrain, the current of one phase bridge arm of the motor controller will become zero, so the motor controller can control the switch tube of the phase bridge arm with the open circuit fault to disconnect.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the fault-tolerant currents outputted by the midpoints of the two-phase bridge arms corresponding to the other two-phase currents have the same current amplitude and opposite current directions.

[0015] When a phase failure occurs in any phase of the three-phase bridge arm, the current of the phase where the phase failure occurs is zero, and the absolute values ​​of the phase currents of the other two phases are equal and in opposite directions.

[0016] In combination with the first aspect, in certain implementations of the first aspect, each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period, and a fourth time period in sequence, wherein in the first time period and the third time period, the current amplitude of the fault-tolerant current has the same correspondence with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite; in the second time period and the fourth time period, the current amplitude of the fault-tolerant current has the same correspondence with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite; in the first time period and the second time period, the current amplitude of the fault-tolerant current has different correspondence with the rotor angle of the drive motor, and the direction of the fault-tolerant current is the same.

[0017] In combination with the first aspect, in certain implementations of the first aspect, each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period, and a fourth time period in sequence, wherein in the first time period and the third time period, the fault-tolerant current is a preset value; in the second time period and the fourth time period, the current amplitude of the fault-tolerant current has the same corresponding relationship with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite.

[0018] In combination with the first aspect, in certain implementations of the first aspect, the fault-tolerant current is used to control the drive motor to output the torque indicated by the torque signal in the second and fourth time periods, and the torque output in the first and third time periods is less than the torque indicated by the torque signal.

[0019] Based on the torque equation for the embedded drive motor and the equal absolute values ​​of the two-phase currents, the range of torque values ​​and the fault-tolerant current that can control the drive motor's output torque value indicated by the torque signal can be calculated. Specifically, during the second and fourth time periods, the fault-tolerant current has the same mapping relationship with the drive motor's rotor angle, or the same expression. When the drive motor is unable to output the torque value indicated by the torque signal, the fault-tolerant current can adopt a preset mapping relationship with the drive motor's rotor angle or a preset value. Specifically, during the first and third time periods, the fault-tolerant current has the same mapping relationship with the drive motor's rotor angle, or the fault-tolerant current has a preset value. For example, during the first and third time periods, the fault-tolerant current can be set to the current value corresponding to the drive motor's maximum torque output at that time. The fault-tolerant current and the drive motor's rotor angle have a certain corresponding relationship and are expressed in the same expression. Furthermore, for example, during the first and third time periods, the fault-tolerant current can be set to zero, controlling the drive motor to output no torque.

[0020] It should be understood that the first, second, third, and fourth periods described above are merely one possible division method within a cycle and do not imply that each cycle has four specific periods. Other division methods may also be used. A cycle may also begin with the second, third, or fourth period. The above is only one possible division method. Other situations can also refer to the above expression method and will not be repeated here.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the waveform corresponding to the torque output by the fault-tolerant current used to control the drive motor is a square wave.

[0022] In the second and fourth periods, the drive motor outputs the torque indicated by the torque signal, while in the first and third periods, the torque output by the drive motor is less than the torque indicated by the torque signal, so the torque waveform output by the drive motor can be a square wave.

[0023] In combination with the first aspect, in certain implementations of the first aspect, the frequency of the fault-tolerant current is the same as the fluctuation frequency of the torque.

[0024] The frequency of the fault-tolerant current is the number of periodic changes per unit time. Periodic changes can occur when the fault-tolerant current expression or direction changes. Whenever the fault-tolerant current expression or direction changes, the torque fluctuates, and the frequency of the two fluctuations is the same.

[0025] In combination with the first aspect, in certain implementations of the first aspect, the control device is used to receive a torque signal, and during the process of the inverter circuit outputting a fault-tolerant current, the torque output by the drive motor is less than or equal to the torque value indicated by the torque signal.

[0026] The fault-tolerant current is smaller than the maximum current that the motor controller can output and will not exceed the current corresponding to the torque value indicated by the torque signal. Thus, the torque output by the driving motor will not exceed the torque value indicated by the torque signal.

[0027] In combination with the first aspect, in certain implementations of the first aspect, during the process of the inverter circuit outputting the fault-tolerant current, the average value of the torque output by the drive motor is greater than or equal to 60% of the torque value indicated by the torque signal.

[0028] According to the solution of the present application, the powertrain can output an average torque of about 60% of the torque value indicated by the torque signal when the electric vehicle is running at a medium and low speed, which can ensure that the vehicle limps to a safe zone.

[0029] In combination with the first aspect, in certain implementations of the first aspect, the control device is configured to perform closed-loop control on the fault-tolerant current using any one of the two non-zero phase currents in the driving current as a closed-loop feedback current.

[0030] In combination with the first aspect, in certain implementations of the first aspect, the control device is configured to perform closed-loop control on the fault-tolerant current using any one of the two non-zero phase currents in the driving current as a closed-loop feedback current.

[0031] In combination with the first aspect, in certain implementations of the first aspect, the control device is used to perform closed-loop control on the fault-tolerant current at a compensation angle corresponding to the closed-loop feedback current.

[0032] In combination with the first aspect, in certain implementations of the first aspect, in response to the A-phase current in the driving current becoming zero, the control device is used to use the B-phase current as the closed-loop feedback current, and use a compensation angle of 0 to perform closed-loop control on the fault-tolerant current; in response to the B-phase current in the driving current becoming zero, the control device is used to use the C-phase current as the closed-loop feedback current, and use a compensation angle of 4π / 3 to perform closed-loop control on the fault-tolerant current; in response to the C-phase current in the driving current becoming zero, the control device is used to use the A-phase current as the closed-loop feedback current, and use a compensation angle of 2π / 3 to perform closed-loop control on the fault-tolerant current.

[0033] In combination with the first aspect, in certain implementations of the first aspect, the motor controller includes a proportional-integral (PI) closed-loop control module, which is used to perform closed-loop control on the fault-tolerant current.

[0034] In the process of the motor controller controlling the output fault-tolerant current, any one of the two phases of the output fault-tolerant current, i.e., the two phases without open-circuit fault, can be used as the feedback current of the closed-loop control, and combined with the compensation angle, the magnitude and phase of the fault-tolerant current can be closed-loop controlled so that the fault-tolerant current can be accurately output within a controllable range.

[0035] According to the solution of the present application, the output current of the motor controller is controllable, reducing the risk of uncontrolled overcurrent and preventing the expansion of faults.

[0036] In combination with the first aspect, in some implementations of the first aspect, the phase current reference value I corresponding to the fault-tolerant current ref Satisfies the following formula:

[0037] a=2n p (L d -L q )sinθcosθ, c=-T e ;

[0038] Among them, I max is the maximum current amplitude of the motor controller, θ is the rotor angle of the drive motor, n p is the number of pole pairs of the driving motor, L d is the direct-axis inductance of the driving motor, L q is the quadrature-axis inductance of the driving motor, is the rotor flux of the drive motor, T e The torque indicated by the torque signal.

[0039] The magnitude of the fault-tolerant current can be determined by referring to the above formula. Based on this formula, the output torque ripple of the drive motor during an open-circuit fault can be reduced, achieving stable operation at reduced power and improving the availability of the motor drive system.

[0040] In the second aspect, the present application provides a control method for a powertrain, the powertrain includes a motor controller and a drive motor, the drive motor is an embedded drive motor, the motor controller includes an inverter circuit and a control device, the inverter circuit includes a three-phase bridge arm, the midpoint of each phase bridge arm in the three-phase bridge arm is used to connect one phase winding in the three-phase winding of the drive motor, the control method includes responding to the torque signal, outputting a drive current, the drive current is used to control the torque indicated by the output torque signal of the drive motor; in response to any phase current in the drive current becoming zero, controlling the two-phase bridge corresponding to the phase currents of the other two phases that are not zero The midpoints of the arms output fault-tolerant currents respectively. The fault-tolerant currents are pulsed alternating currents and the current amplitude of the fault-tolerant currents changes with the rotor angle of the drive motor. Each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period and a fourth time period in sequence. In the second time period and the fourth time period, the current amplitude of the fault-tolerant current has the same correspondence with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite. The fault-tolerant current is used to control the torque indicated by the output torque signal of the drive motor; the directions of the fault-tolerant current in the first time period and the third time period are opposite; the directions of the fault-tolerant current in the first time period and the second time period are the same.

[0041] In combination with the second aspect, in certain implementations of the second aspect, the fault-tolerant current is used to control the drive motor to output the torque indicated by the torque signal in the second and fourth time periods, and the torque output in the first and third time periods is less than the torque indicated by the torque signal.

[0042] In combination with the second aspect, in certain implementations of the second aspect, in the first time period and the third time period, the current amplitude of the fault-tolerant current has the same correspondence with the rotor angle of the drive motor; or, in the first time period and the third time period, the fault-tolerant current is a preset value.

[0043] In combination with the second aspect, in certain implementations of the second aspect, the method further includes performing closed-loop control on the fault-tolerant current by using any one of the two non-zero phase currents in the driving current as a closed-loop feedback current.

[0044] In the third aspect, the present application provides an electric vehicle, which includes a vehicle controller and a powertrain as in the first aspect and various implementations of the first aspect, wherein the motor controller is used to receive a torque signal from the vehicle controller, and the motor controller is used to control the midpoint of each phase bridge arm of the inverter circuit to output a driving current in response to the torque signal, and the driving current is used to control the torque indicated by the output torque signal of the drive motor; in response to any phase current of the driving current output from the midpoint of the bridge arm of the three-phase bridge arm during the process of receiving the torque signal becoming zero, the midpoints of the bridge arms of the two phase bridge arms corresponding to the other two phase currents are controlled to output fault-tolerant currents respectively, and the fault-tolerant current is a pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the drive motor, and the fault-tolerant current is used to control the average value of the torque output by the drive motor to be less than the torque indicated by the torque signal.

[0045] The beneficial effects in other aspects can refer to the beneficial effects described in the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0047] FIG2 is a schematic diagram of a possible motor controller implementation method provided by an embodiment of the present application;

[0048] FIG3 is a schematic diagram of a motor controller provided in an embodiment of the present application;

[0049] FIG4 is a schematic diagram of a control module provided in an embodiment of the present application;

[0050] FIG5 is a schematic diagram of a powertrain operation according to an embodiment of the present application;

[0051] FIG6 is a schematic diagram of another powertrain operation provided by an embodiment of the present application;

[0052] FIG7 is a schematic diagram of a motor control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0054] With the widespread use of electric vehicles, the safety issues of electric vehicles are attracting more and more attention.

[0055] FIG1 is a schematic diagram of an electric vehicle provided in an embodiment of the present application. As shown in FIG1 , the electric vehicle 10 includes a power battery 20, a powertrain 30, and a vehicle controller 40. The vehicle controller 40 can send instructions to the powertrain 30 to control the vehicle to perform driving and other operations. The powertrain 30 is used to drive the electric vehicle 10. The powertrain 30 includes a motor controller 50 and a drive motor 60. The motor controller 50 includes a control device 51 and an inverter circuit 52. The inverter circuit 52 can be a control circuit composed of insulated gate bipolar transistors (IGBTs). The on-off control signal of the IGBT in the inverter circuit 52 is provided by the above-mentioned control device 51. Taking the control of a three-phase motor as an example, by using 6 IGBTs to form an inverter control circuit, the DC current at the battery end is converted into a three-phase AC current, which is respectively provided to the three-phase windings (A, B, C) of the three-phase motor to control the speed or torque output of the three-phase motor. The motor controller 50 can generate a modulation voltage by turning on and off the internal power devices, thereby stimulating the three-phase windings of the motor to generate current.

[0056] This application is primarily applicable to electric vehicles, which can be any of a variety of vehicles, including sedans, trucks, and passenger buses. They can also be transport devices for carrying people or goods, such as tricycles, two-wheeled vehicles, and trains, or other types of vehicles powered by power batteries. Electric vehicles include, but are not limited to, pure electric vehicles (pure EV / battery EV), hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), and new energy vehicles (NEV).

[0057] The drive motor 60 in the embodiment of the present application comprises a three-phase embedded permanent magnet synchronous motor. The drive motor 60 in the embodiment of the present application has the same structure as a conventional motor, including a rotor, a stator core, and stator windings. Common cooling methods for drive motors include oil cooling, water cooling, or air cooling.

[0058] The power battery in the embodiment of the present application can be a lithium-ion battery, a lithium metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-sulfur battery, a lithium-air battery or a sodium-ion battery, etc., which are not limited here. In terms of scale, the power battery in the embodiment of the present application can be a single cell, or a battery module or a battery pack, which are not limited here. In terms of application scenarios, the power battery can be used in power devices such as automobiles and ships. For example, it can be applied to power vehicles to power the motor of the power vehicle and serve as a power source for electric vehicles. The power battery can also power other electrical devices in electric vehicles, such as in-car air conditioners, car players, etc. For the sake of ease of description, the application scheme of the present application will be described below by taking the application of power batteries in electric vehicles (or new energy vehicles) as an example.

[0059] As a key component of electric vehicles, the safety and reliability of the powertrain are crucial to the driver's property and life safety. Permanent magnet synchronous motors (PMSMs) are categorized into surface-mount and embedded types based on the mounting of the permanent magnets. Surface-mount motors have tile-shaped permanent magnets attached to the outer surface of the rotor core, resulting in equal quadrature-axis and direct-axis inductances. Embedded PMSMs, however, have permanent magnets located within the rotor, resulting in a smaller direct-axis inductance than the quadrature-axis inductance. In comparison, embedded PMSMs offer lower harmonics, lower torque ripple, higher torque and power density, and a wider speed range, making them widely used in electric vehicle drive systems.

[0060] During vehicle operation, if an open circuit fault occurs in the upper and lower tubes of any phase of the drive axle in the inverter circuit 52 in the motor controller 50 or an open circuit fault occurs in the drive motor 60, the output torque will oscillate between positive and negative due to the imbalance of the output phase current, resulting in a decrease in the motor control performance, and the drive motor may even be burned out during long-term operation.

[0061] At present, fault-tolerant control for single-phase open-circuit faults in permanent magnet synchronous motors is mainly based on a method that combines hardware redundancy with control algorithms. However, this method changes the mechanical structure of power devices and other components, resulting in problems such as increased costs and increased size of the drive system.

[0062] In one possible implementation, fault-tolerant control for open-circuit faults can be achieved by reconstructing the reference current of the motor drive system after the fault. Under an open-circuit fault, the reference current is determined using the motor torque command and the motor torque formula. The average motor copper loss over one fundamental current cycle is then calculated to generate a new reference current that takes current commutation and motor copper loss into account. This fault-tolerant control method can reduce motor torque ripple and current tracking error, while limiting the average motor copper loss to below the target value.

[0063] in To consider only the motor torque command The obtained phase current reference value during open circuit fault tolerance operation; It is the phase current reference value during open circuit fault tolerant operation with current suppression requirement added; I max is the maximum current amplitude of the motor current.

[0064] It should be understood that this implementation method only supports surface-mounted permanent magnet synchronous motor types. When applied to built-in permanent magnet synchronous motors, the software will experience periodic zero-crossing oscillations due to the magnetic resistance torque component, and cannot be effectively applied, as it is limited by the motor type.

[0065] In another possible implementation, as shown in Figure 2, a three-phase, four-bridge-arm topology can be used as hardware redundancy to achieve fault tolerance for synchronous motors. When the powertrain is operating normally, the fourth bridge-arm circuit is not operational. If a single-phase fault occurs during operation of the three-phase AC motor, the bridge arm connected to the faulty phase is disconnected, and the fourth bridge arm is operational. In this case, the drive circuit uses the two-phase, three-bridge-arm drive circuit used for single-phase motors, and the control method is switched to that of single-phase motors. This allows the three-phase AC motor, with one phase open, to operate stably.

[0066] It should be understood that this implementation is not restricted by the motor type and control method, but requires additional redundant circuits, which increases system cost and complexity.

[0067] Based on the above problems, the present application provides a powertrain, method and electric vehicle with open-circuit fault tolerance function. Without increasing hardware costs, when an open-circuit fault occurs in the motor controller or drive motor, fault-tolerant control of the open-circuit fault is achieved by reconstructing the reference current after the fault. This can effectively reduce the powertrain output torque pulsation, achieve stable operation with reduced power, and improve system availability. It is suitable for embedded three-phase permanent magnet synchronous motors.

[0068] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set", "install", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. The term "including" used in this application should not be interpreted as being limited to the contents listed thereafter; it does not exclude other elements or steps. Therefore, it should be interpreted as specifying the existence of the mentioned features, wholes, steps or parts, but does not exclude the existence or addition of one or more other features, wholes, steps or parts and groups thereof. Therefore, the expression "a device comprising means A and B" should not be limited to a device consisting only of parts A and B.

[0069] To facilitate understanding of the embodiments of the present application, first, a brief introduction to the concepts and technologies involved in the embodiments of the application is given.

[0070] It should be understood that the relevant terms and explanations in the following text are common to all embodiments throughout the text. Different embodiments can be used independently or in combination based on certain internal or external connections. Different implementation methods in the embodiments can be used independently or in combination.

[0071] 1. Synchronous motor

[0072] A type of AC motor that generates a rotating magnetic field by passing symmetrical current through the stator winding. The rotor is equipped with permanent magnets or excitation windings. The rotor magnetic field rotates synchronously with the stator rotating magnetic field due to the magnetic pull of the stator magnetic field, and generates torque externally.

[0073] According to the different installation methods of permanent magnets, they can be divided into two structures: surface mount and embedded.

[0074] The permanent magnets of surface-mount motors are tile-shaped on the outer surface of the rotor core. The quadrature-axis inductance and the direct-axis inductance are equal. The surface-mount type can also be called surface-mount type, surface-protruding type, and other names.

[0075] The permanent magnet of the embedded permanent magnet synchronous motor is located inside the rotor, and the direct-axis inductance is smaller than the quadrature-axis inductance. The embedded type can also be called built-in type, convex machine type, buried type and other names.

[0076] 2. Torque

[0077] The torque output by the motor shaft of a synchronous motor is called electromagnetic torque, which is composed of synchronous torque and reluctance torque. The torque generated by the interaction between the stator's rotating magnetic field and the rotor's rotating magnetic field is called synchronous torque.

[0078] The inconsistency in the equivalent air gap thickness between the direct-axis and quadrature-axis magnetic circuits in a synchronous motor results in unequal magnetic resistance. Since magnetic flux always prefers the path with the least magnetic resistance, this mismatch between the direct-axis and quadrature-axis magnetic resistances can bias the magnetic flux in its path selection, generating an additional torque known as reluctance torque.

[0079] 3. Vector control

[0080] A control method applicable to motors with rotating magnetic fields can equate the three-phase stator current coefficients to an orthogonal two-phase system, decomposing the motor's rotor space vector into two rectangular coordinate components: the magnetic field direction component and the rotor electromotive force direction component. These two components are independently controlled, enabling direct control of the motor's magnetic flux and electromotive force, thereby precisely controlling the motor's torque and speed. Specifically, Clark and Park transformations can be used to convert physical quantities between a three-axis, two-dimensional stator stationary coordinate system and a two-axis rotating coordinate system. Taking the vector control method of a permanent magnet synchronous motor as an example, the rotor magnetic field direction is the direct axis (d-axis) and its leading direction by 90° is the quadrature axis (q-axis), forming a rotating coordinate system. The three-phase currents can be converted into currents on the d-axis and q-axis. The magnetic field direction formed by the current vector Is, which is synthesized by a given direct-axis current Id and quadrature-axis current Iq, forms an angle with the rotor magnetic field direction. A suitable angle maximizes the torque generated by the interaction between the magnetic fields, thereby increasing the motor's output torque.

[0081] The present application provides a powertrain 30 .

[0082] As shown in Figure 3, the powertrain 30 in the embodiment of the present application includes a motor controller 50 and a drive motor 60. In the embodiment of the present application, the drive motor 60 can be an embedded drive motor, so the direct-axis inductance and quadrature-axis inductance of the drive motor 60 are different.

[0083] The motor controller 50 includes an inverter circuit 52 and a control device 51. The inverter circuit 52 is composed of IGBTs, and the on / off control signals for the IGBTs in the inverter circuit 52 can be provided by the control device 51. Taking the control of a three-phase motor as an example, by using six IGBTs to form the inverter circuit 52, current from the power battery 20 is passed into the drive motor, providing current to the three-phase windings of the three-phase motor to control the speed or torque output of the three-phase motor.

[0084] The inverter circuit 52 includes three-phase bridge arms in parallel, one end of each phase bridge arm is used to connect to the positive pole of the power battery 20, the other end of each phase bridge arm is used to connect to the negative pole of the power battery 20, and the midpoint of each phase bridge arm is used to connect to one phase winding of the three-phase winding of the drive motor 60.

[0085] The midpoint of the three-phase bridge arm is used to output a driving current or a fault-tolerant current, and the control device 51 is used to receive a torque signal and control the inverter circuit 52 to output a driving current or a fault-tolerant current.

[0086] The control device 51 is used to control the midpoint of each phase bridge arm of the inverter circuit 52 to output a driving current in response to the torque signal. The driving current is used to control the drive motor 60 to output the torque indicated by the torque signal.

[0087] The motor controller 50 can be used to detect a phase loss fault in the three-phase bridge arm in the inverter circuit 52. When a phase loss fault occurs in any phase of the three-phase bridge arm, the motor controller 50 can be used to output a fault-tolerant current to the drive motor 60. The direct-axis inductance and the quadrature-axis inductance of the drive motor 60 are different, so the magnitude of the fault-tolerant current is related to the difference between the direct-axis inductance and the quadrature-axis inductance of the drive motor 60.

[0088] The control device 51 is used to respond to any phase current in the driving current output from the midpoint of the bridge arm of the three-phase bridge arm becoming zero, and control the midpoints of the two-phase bridge arms corresponding to the other two phase currents in the driving current to output fault-tolerant current respectively. The fault-tolerant current is pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the drive motor 60. The fault-tolerant current is used to control the average value of the torque output by the drive motor to be less than the torque indicated by the torque signal. The fault-tolerant current is used to control the drive motor 60 to periodically output the torque indicated by the torque signal.

[0089] When an open circuit fault occurs in any phase of the three-phase bridge arm in the inverter circuit 52 or an open circuit fault occurs in any phase winding of the three-phase winding of the drive motor 60, the corresponding phase current in the drive current becomes zero, and the phase currents of the other two phases have equal amplitudes and opposite directions.

[0090] In a possible embodiment, the control device is used to control the two switching tubes corresponding to the bridge arm with zero output current to turn off in response to any phase current of the driving current output from the bridge arm midpoint of the three-phase bridge arm becoming zero.

[0091] For the phase bridge arm where an open circuit fault occurs in the inverter circuit 52 , the switch tube can be disconnected.

[0092] As shown in FIG4 , the open circuit fault tolerance control of the motor controller 50 mainly includes an open circuit detection module, a reference current calculation module, a feedback current and conversion angle selection module, a PI control module, and a wave voltage calculation module.

[0093] In one possible embodiment, the open circuit detection module is used to detect the three-phase bridge arm. When a phase failure is detected in the three-phase bridge arm, the motor controller 50 can switch between the normal torque mode and the fault-tolerant control mode according to the detection result of the open circuit detection module, that is, switch between the output drive current and the fault-tolerant current.

[0094] In a possible embodiment, a proportional-integral (PI) closed-loop control module is used to perform closed-loop control on the fault-tolerant current.

[0095] For a three-phase embedded permanent magnet synchronous motor, its direct-axis inductance is smaller than the quadrature-axis inductance (L d <L q ), the torque equation is as follows

[0096] Where T e is the output torque, n p is the number of motor pole pairs, L d is the direct-axis inductance of the driving motor, L q is the quadrature-axis inductance of the driving motor, is the rotor flux, i d is the direct axis current, i q is the quadrature axis current.

[0097] When the open circuit detection module detects an open circuit fault in the system, it needs to switch to the open circuit fault tolerant control mode and calculate the output reference current in real time.

[0098] For example, taking the U phase failure as an example, i a =0,i b =-i c According to Clark and Park transformation calculations, the expressions of direct-axis current and quadrature-axis current in open-circuit operation are as follows:

[0099] According to formula (1), for the embedded drive motor, L d <L q :

[0100] It can be seen from the above formula (3) that the output torque can be controlled by performing specific strategy control on the B-phase current.

[0101] In a possible embodiment, the frequency of the fault-tolerant current is the same as the fluctuation frequency of the output torque.

[0102] It should be understood that when a phase loss fault occurs, the drive motor 60 cannot stably output the torque indicated by the torque signal as it does during normal operation. During certain times, the torque that the drive motor 60 can output is limited by the faulty hardware. During these times, the torque can be controlled by performing specific strategies on the phase current so that the drive motor 60 outputs a preset torque.

[0103] In a possible embodiment, each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period and a fourth time period in sequence, wherein in the first time period and the third time period, the current amplitude of the fault-tolerant current has the same corresponding relationship with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite; in the second time period and the fourth time period, the current amplitude of the fault-tolerant current has the same corresponding relationship with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite; in the first time period and the second time period, the current amplitude of the fault-tolerant current has different corresponding relationship with the rotor angle of the drive motor, and the direction of the fault-tolerant current is the same.

[0104] For example, at this time, the phase current reference value I corresponding to the fault-tolerant current of phase B is ref Conforms to the following formula:

[0105] Where: a = 2n p (L d -L q )sinθcosθ, c=-T e .

[0106] In the above equation, θ is the rotor angle of the drive motor, I ref is the phase current reference value corresponding to the fault-tolerant current, I max is the maximum current amplitude of the motor controller.

[0107] It should be understood that I max According to the device and implementation capabilities of the motor controller, is the current reversing point.

[0108] Based on the above implementation ref The reference current given control can achieve stable control of the output torque. As shown in Figure 5, in the first and third periods, the mapping relationship between the fault-tolerant current and the rotor angle of the drive motor is the same. When the B-phase current is the fault-tolerant current, the drive motor can output the maximum torque that can be output when an open-circuit fault occurs. In the second and fourth periods, the mapping relationship between the fault-tolerant current and the rotor angle of the drive motor is the same: It can be seen that after switching to the open-loop fault-tolerant control strategy, the output torque is an approximate square wave, and the torque output by the driving motor fluctuates at a 2-fold frequency in each output cycle.

[0109] In the actual system, the motor output torque is connected to the wheels through the half-shaft. The transmission system is an inertia link. The high-frequency torque pulses are basically smooth after filtering and have little impact on the driving experience.

[0110] In another possible embodiment, each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period and a fourth time period in sequence, wherein in the first time period and the third time period, the fault-tolerant current is a preset value; in the second time period and the fourth time period, the current amplitude of the fault-tolerant current has the same corresponding relationship with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite.

[0111] For example, the preset value may be 0, in which case the phase current reference value I corresponding to the fault-tolerant current of phase B is ref Conforms to the following formula:

[0112] a=2n p (L d -L q )sinθcosθ, c=-T e ;

[0113] As shown in Figure 6, the difference from the previous implementation is that in b 2 ≤4ac range will refer to the current I ref The given setting is 0, and the corresponding output reference current and output torque waveforms are shown in Figure 6. The driving motor torque is a square wave with twice the output frequency.

[0114] The fault-tolerant current is used to control the drive motor to output the torque indicated by the torque signal in the second and fourth time periods, and the torque output in the first and third time periods is less than the torque indicated by the torque signal.

[0115] The control device 51 is configured to receive a torque signal. During the process of the inverter circuit outputting a fault-tolerant current, the torque output by the drive motor 60 is configured to be less than or equal to the torque value indicated by the torque signal. The average value of the torque output by the drive motor may be greater than or equal to 60% of the torque value indicated by the torque signal.

[0116] According to the solution of the present application, the output current of the motor controller is controllable, reducing the risk of uncontrolled overcurrent and preventing the expansion of faults. The output torque of the drive motor is a high-frequency square wave, which can solve the problem of torque oscillation in an uncontrollable state. The average output torque of the drive motor at medium and low speeds can reach about 60% of the given value, which can ensure that the vehicle limps to a safe area.

[0117] The motor controller 50 may perform closed-loop control on the fault-tolerant current through a PI closed-loop control module.

[0118] In a possible embodiment, the control device 51 is configured to perform closed-loop control on the fault-tolerant current by using any one of the two non-zero phase currents in the driving current as a closed-loop feedback current.

[0119] In a possible embodiment, the control device 51 is configured to perform closed-loop control on the fault-tolerant current at a compensation angle corresponding to the closed-loop feedback current.

[0120] After an open circuit fault occurs in different phases, the closed-loop feedback current and compensation angle used by the control device 51 are different. The control device 51 can obtain the open circuit position through the open circuit detection module, thereby determining which specific phase current to select as the closed-loop feedback current and performing closed-loop control on the fault-tolerant current.

[0121] Exemplarily, in response to the A-phase current in the driving current becoming zero, that is, an open circuit fault occurs in the A-phase in the three-phase bridge arm, the control device 51 is used to use the current in the B-phase bridge arm as the closed-loop feedback current and use a compensation angle of 0 to perform closed-loop control on the fault-tolerant current.

[0122] As another example, in response to the B-phase current in the driving current becoming zero, that is, an open circuit fault occurs in the B-phase in the three-phase bridge arm, the control device 51 is used to use the current in the C-phase bridge arm as the closed-loop feedback current and use a compensation angle of 4π / 3 to perform closed-loop control on the fault-tolerant current.

[0123] As another example, in response to the C-phase current in the driving current becoming zero, that is, an open circuit fault occurs in the C-phase in the three-phase bridge arm, the control device 51 is used to use the current in the A-phase bridge arm as the closed-loop feedback current and use a compensation angle of 2π / 3 to perform closed-loop control on the fault-tolerant current.

[0124] Taking the case of an open circuit in phase A as an example, the upper and lower tube drivers of phase A are turned off during operation, and no current is output. Phase B current is used for closed-loop control, and the current of phase C is equal to that of phase B and in the opposite direction. Similarly, when other phases are open circuited, the closed-loop current and conversion angle selection are as follows:

[0125] Table 1. Closed-loop feedback current and compensation angle

[0126] It should be understood that the closed-loop current and compensation angle in the above table are only examples, and other corresponding relationships can also be used to control the fault-tolerant current, which is not limited in this application.

[0127] The present application provides a motor control method.

[0128] The control method is applied to an electric vehicle 10 , which includes a power battery 20 and the powertrain 30 described above.

[0129] The control method includes:

[0130] In response to the torque signal, a driving current is output, and the driving current is used to control the drive motor 60 to output the torque indicated by the torque signal.

[0131] In response to any phase current in the drive current becoming zero, the midpoints of the two phase bridge arms corresponding to the other two phase currents that are not zero are controlled to output a fault-tolerant current. The fault-tolerant current is a pulsed alternating current, and the current amplitude of the fault-tolerant current varies with the rotor angle of the drive motor. Each cycle of the fault-tolerant current includes a first period, a second period, a third period, and a fourth period in sequence. In the second and fourth periods, the current amplitude of the fault-tolerant current has the same correspondence with the rotor angle of the drive motor, and the direction of the fault-tolerant current is opposite. The fault-tolerant current is used to control the torque indicated by the output torque signal of the drive motor. The direction of the fault-tolerant current is opposite in the first and third periods. The direction of the fault-tolerant current is the same in the first and second periods.

[0132] In a possible embodiment, the fault-tolerant current is used to control the drive motor to output the torque indicated by the torque signal in the second and fourth time periods, and the torque output in the first and third time periods is less than the torque indicated by the torque signal.

[0133] In a possible embodiment, in the first period and the third period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is the same; or, in the first period and the third period, the fault-tolerant current is a preset value.

[0134] In a possible embodiment, the method further includes performing closed-loop control on the fault-tolerant current by using any one of the two non-zero phase currents in the driving current as a closed-loop feedback current.

[0135] FIG7 is a schematic diagram of a specific process flow when outputting a fault-tolerant current. As shown in FIG7 , the control method may specifically include:

[0136] It should be noted that, unless otherwise stated, in the various embodiments of the present application, the serial numbers of the processes, such as S110, S120, etc., do not mean the order of execution. The order of execution of the processes should be determined by their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0137] S110, detecting an open circuit fault and the open circuit position.

[0138] If the open circuit detection module detects that a single-phase open circuit fault occurs, the operating mode of the motor controller 50 is switched to the fault-tolerant control mode.

[0139] S120, selecting a closed-loop feedback current and a wave-generating conversion angle according to the open-circuit position.

[0140] The closed-loop feedback current and the compensation angle corresponding to the closed-loop feedback current are determined according to any phase current of the two-phase currents that are not zero in the driving current.

[0141] In a possible embodiment, the closed-loop feedback current is output to the PI control module, and the conversion angle is output to the wave voltage conversion module.

[0142] S130, calculating a fault-tolerant reference current according to the target torque, the rotor position, and the motor parameters.

[0143] The calculation of the fault-tolerant current can refer to the calculation method in the previous article and will not be repeated here.

[0144] In one possible implementation, the PI control module performs closed-loop control based on the target torque, the rotor position, and the capacitor fault current.

[0145] S140, the phase current PI control obtains the output voltage as the input of the wave voltage module.

[0146] S150, calculating the wave voltage according to the output voltage and the conversion angle.

[0147] The motor controller 50 is controlled to output a fault-tolerant current to the drive motor 60 so that the drive motor 60 periodically outputs the torque indicated by the torque signal. The magnitude of the fault-tolerant current is related to the difference between the direct-axis inductance and the quadrature-axis inductance of the drive motor.

[0148] This solution achieves fault-tolerant control for open-circuit faults by reconstructing the powertrain's reference current after a fault. This reduces the pulsation of the drive motor's output torque, enabling stable operation at reduced power and improving the availability of the motor drive system. The average output torque of the drive motor at low and medium speeds can reach approximately 60% of the target torque, ensuring the vehicle can limp to a safe zone.

[0149] The present application provides an electric vehicle 10 .

[0150] The electric vehicle 10 includes a power battery 20 and the powertrain 30 as described above.

[0151] The power battery 20 provides current to the powertrain 30 .

[0152] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0153] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0154] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0155] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0156] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A powertrain with open circuit fault tolerance function, characterized in that: The powertrain includes a motor controller and a drive motor, the drive motor is an embedded permanent magnet synchronous motor, the motor controller includes an inverter circuit and a control device, the inverter circuit includes a three-phase bridge arm, the midpoint of each phase of the three-phase bridge arm is used to connect one phase of the three-phase winding of the drive motor, the control device is used to receive a torque signal and control the midpoint of the three-phase bridge arm of the inverter circuit to output a drive current or a fault-tolerant current, and the drive current is a three-phase current; The control device is used to: In response to the torque signal, controlling the midpoint of each phase bridge arm of the inverter circuit to output the drive current, wherein the drive current is used to control the drive motor to output the torque indicated by the torque signal; In response to any phase current of the driving current outputted from the midpoint of the bridge arm of the three-phase bridge arm becoming zero during the process of receiving the torque signal, the midpoints of the bridge arms of the two phases corresponding to the other two phases of the current are controlled to output the fault-tolerant current respectively. The fault-tolerant current is a pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the driving motor. The fault-tolerant current is used to control the average value of the torque outputted by the driving motor to be less than the torque indicated by the torque signal.

2. The powertrain according to claim 1, characterized in that: Each phase bridge arm of the three-phase bridge arm includes two switch tubes, and the control device is used for: The two switch tubes of the corresponding bridge arm of any phase current are controlled to be turned off.

3. The powertrain according to claim 1 or 2, characterized in that: The fault-tolerant currents respectively outputted from the midpoints of the bridge arms of the two-phase bridge arms corresponding to the other two-phase currents have the same current amplitude and opposite current directions.

4. The powertrain according to any one of claims 1 to 3, characterized in that: The fault-tolerant current is a current that changes periodically, and each change cycle of the fault-tolerant current includes a first time period, a second time period, a third time period, and a fourth time period in sequence, wherein: In the first time period and the third time period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is the same, and the directions of the fault-tolerant current are opposite; In the second period and the fourth period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is the same, and the directions of the fault-tolerant current are opposite; In the first time period and the second time period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is different, and the directions of the fault-tolerant current are the same.

5. The powertrain according to any one of claims 1 to 3, characterized in that: Each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period and a fourth time period in sequence, wherein: In the first time period and the third time period, the fault-tolerant current is a preset value; In the second time period and the fourth time period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is the same, and the directions of the fault-tolerant current are opposite.

6. The powertrain according to claim 4 or 5, characterized in that: The fault-tolerant current is used to control the drive motor to output the torque indicated by the torque signal in the second time period and the fourth time period, and the torque output in the first time period and the third time period is less than the torque indicated by the torque signal.

7. The powertrain according to claim 4 or 5, characterized in that: The waveform corresponding to the torque output by the drive motor controlled by the fault-tolerant current is a square wave.

8. The powertrain according to any one of claims 1 to 7, characterized in that: The frequency of the fault-tolerant current is the same as the fluctuation frequency of the torque.

9. The power assembly according to any one of claims 1 to 8, characterized in that: The control device is used to receive a torque signal. During the process in which the inverter circuit outputs the fault-tolerant current, the torque output by the drive motor is less than or equal to the torque value indicated by the torque signal.

10. The power assembly according to any one of claims 1 to 9, characterized in that: During the process in which the inverter circuit outputs the fault-tolerant current, the average value of the torque output by the drive motor is greater than or equal to 60% of the torque value indicated by the torque signal.

11. The powertrain according to any one of claims 1 to 10, characterized in that: The phase current reference value I corresponding to the fault-tolerant current ref Satisfies the following formula: Among them, I max is the maximum current amplitude of the motor controller, θ is the rotor angle of the drive motor, n p is the number of pole pairs of the drive motor, L d is the direct axis inductance of the drive motor, L q is the quadrature-axis inductance of the driving motor, is the rotor flux of the drive motor, T e is the torque indicated by the torque signal.

12. A control method for a powertrain, characterized in that: The powertrain includes a motor controller and a drive motor, the drive motor is an embedded permanent magnet synchronous motor, the motor controller includes an inverter circuit and a control device, the inverter circuit includes a three-phase bridge arm, and the midpoint of each phase of the three-phase bridge arm is used to connect one phase winding of the three-phase winding of the drive motor. The control method includes: In response to the torque signal, output a driving current, wherein the driving current is used to drive the driving motor to output the torque indicated by the torque signal; In response to any phase current of the driving current becoming zero, the midpoints of the two-phase bridge arms corresponding to the other two phase currents that are not zero are controlled to output fault-tolerant currents respectively, wherein the fault-tolerant current is a pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the driving motor, and each cycle of the fault-tolerant current includes a first time period, a second time period, a third time period and a fourth time period in sequence, wherein: In the second period and the fourth period, the current amplitude of the fault-tolerant current has the same corresponding relationship with the rotor angle of the drive motor, the directions of the fault-tolerant current are opposite, and the fault-tolerant current is used to drive the drive motor to output the torque indicated by the torque signal; The directions of the fault-tolerant current in the first time period and the third time period are opposite; The direction of the fault-tolerant current in the first time period and the second time period is the same.

13. The method according to claim 12, characterized in that The fault-tolerant current is used to drive the drive motor to output the torque indicated by the torque signal in the second time period and the fourth time period, and the torque output in the first time period and the third time period is less than the torque indicated by the torque signal.

14. The method according to claim 12, characterized in that In the first time period and the third time period, the corresponding relationship between the current amplitude of the fault-tolerant current and the rotor angle of the drive motor is the same; or, In the first time period and the third time period, the fault-tolerant current is a preset value.

15. An electric vehicle, characterized in that: The electric vehicle comprises a vehicle controller and a powertrain as claimed in any one of claims 1 to 11, wherein the motor controller is used to receive a torque signal from the vehicle controller, and the motor controller is used to: In response to the torque signal, controlling the midpoint of each phase bridge arm of the inverter circuit to output the drive current, wherein the drive current is used to control the drive motor to output the torque indicated by the torque signal; In response to any phase current of the driving current outputted from the midpoint of the bridge arm of the three-phase bridge arm becoming zero during the process of receiving the torque signal, the midpoints of the bridge arms of the two phases corresponding to the other two phases of the current are controlled to output the fault-tolerant current respectively. The fault-tolerant current is a pulsed alternating current and the current amplitude of the fault-tolerant current changes with the rotor angle of the driving motor. The fault-tolerant current is used to control the average value of the torque outputted by the driving motor to be less than the torque indicated by the torque signal.

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