Motor controller, powertrain and control method for controlling driving motor

Abstract

Disclosed are a motor controller (11) for an electric vehicle (01), a powertrain (10) and a control method for controlling a driving motor. The powertrain comprises the motor controller and a driving motor (12). The motor controller is used for receiving a torque signal and controlling the driving motor to output a torque; and, in response to a reduction rate of the rotating speed of the driving motor being less than a preset rate and the rotating speed of the driving motor being less than a preset value, the motor controller is used for controlling the driving motor to output a second positive torque. Thus, under the action of the second positive torque, the braking speed or deceleration of a vehicle can be accurately adjusted, mitigating the trend of forward movement of the center of mass of the vehicle during braking and shaking of the vehicle after being stopped, thus improving the comfort of vehicles during braking.

Description

Motor controller, powertrain, and control method for driving motor

[0001] This application claims priority to the Chinese patent application with application number 202311126970.1 filed with the State Intellectual Property Office of China on August 31, 2023, and priority to the Chinese patent application with the invention name “Motor controller, powertrain and control method for driving motor”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electric vehicle power systems, and in particular to a motor controller, a powertrain, and a method for controlling a drive motor. Background Art

[0003] When the driver or the intelligent driving system brakes the vehicle, the vehicle typically experiences a "nodding / jerk" phenomenon. This jerking is particularly noticeable when the vehicle is about to stop. Optimizations to the vehicle's powertrain or suspension system are often employed to mitigate this "nodding / jerk" phenomenon, but it cannot be completely avoided.

[0004] In order to further avoid the "nodding / stuttering" phenomenon of the vehicle during braking and achieve a comfortable braking effect, the comfort braking algorithm of the existing technology will deliberately reduce the braking pressure in the later stage of braking during driving. However, the signal transmission path of the existing comfort braking algorithm is long, which leads to a longer response time of the braking system and thus increases the braking distance.

[0005] Summary of the Invention

[0006] During vehicle braking, the late braking phase refers to the period from when the vehicle's speed decreases from a very low level to zero, specifically from near a stop to a complete stop and no relative motion with the ground. During braking, the vehicle's suspension is compressed due to deceleration. After braking, even though the vehicle has actually stopped, the vehicle's body rebounds under the action of the suspension, causing vibration and "nodding" of the vehicle, which affects the driving experience. To address this issue, existing comfort braking algorithms release a certain amount of wheel-end braking force in the late braking phase to reduce the electric vehicle's deceleration, thereby alleviating the vibration and "nodding" phenomenon, thereby reducing braking jitter and improving driving comfort. However, existing comfort braking algorithms suffer from long signal transmission paths and latency, which can lead to reduced braking performance. To address this issue, embodiments of the present application provide a motor controller, powertrain, and method for controlling a drive motor. The motor controller provided herein is used to control the output torque of a drive motor during non-emergency braking of an electric vehicle to reduce the vehicle's braking force output, thereby improving the vehicle's braking performance. The motor controller, powertrain, and electric vehicle are described in detail below.

[0007] The operation of an electric vehicle includes driving and braking processes. The driving process refers to the process in which the electric vehicle's drive motor outputs positive torque to drive the wheels, allowing the electric vehicle to move. The braking process refers to the process in which the electric vehicle's braking system outputs friction braking force to the electric vehicle's wheels to gradually reduce the speed of the electric vehicle. During the braking process of an electric vehicle, the drive motor of an electric vehicle with energy recovery function can also output negative torque to convert the electric vehicle's kinetic energy into electrical energy, thereby generating an induced current. At the same time, the negative torque output by the drive motor can also be used to provide braking force for the electric vehicle. Among them, the drive motor outputs positive torque when the output direction of the drive motor is the same as the direction of the drive motor's speed. The drive motor outputs negative torque when the output direction of the drive motor is opposite to the direction of the drive motor's speed.

[0008] In a first aspect, an embodiment of the present application provides a motor controller for an electric vehicle. The motor controller includes an inverter circuit. The inverter circuit includes a multi-phase bridge arm, and the midpoint of the multi-phase bridge arm is used to connect the multi-phase winding of the drive motor. The motor controller is used to receive a torque signal and control the output torque of the drive motor. During the driving process of the electric vehicle, the motor controller is used to control the drive motor to generate a first positive torque, and the first positive torque is used to respond to the torque value indicated by the torque signal. Specifically, during the driving process of the electric vehicle, the vehicle controller calculates the vehicle torque demand and sends a torque signal to the motor controller according to the vehicle torque demand. The motor controller controls the drive motor to output torque according to the torque value indicated by the torque signal to drive the electric vehicle.

[0009] During braking of the electric vehicle, in response to a deceleration of the electric vehicle being less than a preset deceleration and a speed being less than a preset speed, the motor controller outputs a driving current at a midpoint of a plurality of bridge arms of the motor controller to cause the drive motor to output a second positive torque, wherein the second positive torque is greater than a torque value indicated by the torque signal.

[0010] During braking, the electric vehicle's deceleration is less than the preset deceleration, indicating that the electric vehicle's braking mode is non-emergency braking. In the non-emergency braking state, the electric vehicle's speed gradually decreases. When the electric vehicle's speed is less than the preset speed, indicating that the electric vehicle is in the late braking stage, the motor controller's inverter circuit outputs a drive current to cause the drive motor to output a second positive torque. Because the second positive torque is positive, it causes the electric vehicle to generate acceleration, thereby reducing the electric vehicle's deceleration. This, in turn, can alleviate the compression of the electric vehicle's tires and suspension, thereby reducing the electric vehicle's "nodding" and vibration, and improving the driving experience of the electric vehicle.

[0011] The motor controller provided herein can directly control the drive motor to output a second positive torque based on the braking state of the electric vehicle, thereby achieving comfortable braking for the electric vehicle. Because the motor controller can directly output the second positive torque rather than controlling the drive motor output torque based on the torque signal, the motor controller controls the drive motor to output a second positive torque that is greater than the torque value indicated by the torque signal.

[0012] For example, the electric vehicle's speed and deceleration can be derived by the motor controller from resolver signals obtained from a resolver sensor mounted on the drive motor. This improves the accuracy of the electric vehicle's speed and deceleration. Furthermore, because the resolver sensor has a high sampling frequency and the motor controller can directly access the resolver signal, the latency in obtaining the electric vehicle's speed and deceleration is reduced. This allows the motor controller to quickly determine the second positive torque based on the electric vehicle's speed and deceleration for braking intervention.

[0013] In one implementation of the first aspect, the motor controller controls the drive motor to reduce output of the negative torque in response to the drive motor outputting a negative torque during braking of the electric vehicle, the deceleration of the electric vehicle being less than a preset deceleration, and the speed of the electric vehicle being less than a preset speed. The drive motor rotating means that the wheels of the electric vehicle drive the drive motor to rotate during braking of the electric vehicle.

[0014] Electric vehicles typically feature energy recovery. During braking, the motor controller controls the drive motor to generate electricity, converting the vehicle's kinetic energy into electricity to charge the battery. During this energy recovery process, the drive motor outputs negative torque, providing regenerative braking force for the vehicle. In the later stages of braking, the motor controller can control the drive motor to reduce negative torque output, thereby reducing the braking force applied to the vehicle and improving braking comfort and the driving experience.

[0015] In an implementation of the first aspect, the motor controller controls the drive motor to reduce the negative torque output, and the negative torque value outputted is smaller than the negative torque value indicated by the torque signal.

[0016] As mentioned above, during the braking process, the motor controller can directly control the drive motor to reduce the negative torque output according to the braking state of the electric vehicle. Therefore, the negative torque value output by the motor controller during the process of controlling the drive motor to reduce the negative torque output is less than the negative torque value indicated by the torque signal.

[0017] In an implementation of the first aspect, in response to a pedal stroke of the brake pedal being less than a preset value and a speed of the electric vehicle being less than a preset value, the motor controller controls the drive motor to output a second positive torque.

[0018] In this example, the pedal travel of the brake pedal is less than the preset value, indicating that the electric vehicle is in non-emergency braking at this time, and the motor controller controls the drive motor to output the second positive torque.

[0019] In one implementation of the first aspect, the motor controller is used to control the drive motor to output a torque value indicated by a torque signal in response to the deceleration of the electric vehicle being greater than a preset deceleration or the brake pedal stroke indicated by the pedal stroke signal being greater than a preset value during braking.

[0020] During the braking process of an electric vehicle, when the deceleration of the electric vehicle is greater than the preset deceleration or the brake pedal stroke is greater than the preset value, it indicates that the braking mode of the electric vehicle is emergency braking, that is, the speed of the electric vehicle needs to be reduced quickly. When the braking mode of the electric vehicle is emergency braking, the braking response speed of the electric vehicle is prioritized rather than braking comfort. Therefore, at this time, the motor controller will not control the drive motor to output the second positive torque or reduce the negative torque output by the drive motor, but will control the drive motor to output the torque value according to the indication of the torque signal to ensure the braking speed of the electric vehicle.

[0021] In one implementation of the first aspect, the magnitude of the second positive torque output by the motor controller is positively correlated with the pedal stroke of the brake pedal. That is, the greater the pedal stroke indicated by the pedal stroke signal, the greater the required braking force, and accordingly, the greater the second positive torque value output by the motor controller. The smaller the pedal stroke indicated by the pedal stroke signal, the smaller the required braking force, and accordingly, the smaller the second positive torque value output by the motor controller.

[0022] In one implementation of the first aspect, the magnitude of the second positive torque output by the motor controller is positively correlated with the speed of the electric vehicle. That is, the greater the speed of the electric vehicle, the greater the braking force required during braking, and accordingly, the greater the value of the second positive torque output by the motor controller. The lower the speed of the electric vehicle, the smaller the braking force required during braking, and accordingly, the smaller the value of the second positive torque output by the motor controller.

[0023] In one implementation of the first aspect, the motor controller is configured to control the drive motor to output a second positive torque in response to a rate of decrease in the drive motor speed being less than a preset rate and a speed of the drive motor being less than a preset speed. During braking of the electric vehicle, the deceleration of the electric vehicle corresponds to the rate of decrease in the drive motor speed, and the speed of the electric vehicle corresponds to the speed of the drive motor. Therefore, the motor controller may also use the rate of decrease in the drive motor speed and the speed of the drive motor as criteria for determining whether to output the second positive torque to improve braking comfort of the electric vehicle.

[0024] In one implementation of the first aspect, the motor controller is used to control the drive motor to reduce the negative torque output in response to the fact that the speed reduction rate of the drive motor during the process of outputting negative torque is greater than a preset rate and the speed of the drive motor is less than a preset speed.

[0025] In one implementation of the first aspect, the motor controller is used to control the drive motor to output a second positive torque in response to the pedal stroke of the brake pedal being less than a preset value, the speed reduction rate of the drive motor being greater than a preset rate, and the speed of the drive motor being less than a preset speed.

[0026] In an implementation of the first aspect, the motor controller is used to connect to a motor speed sensor, and the motor speed sensor is used to detect the speed of the drive motor.

[0027] In one implementation of the first aspect, in response to the drive motor ceasing to output the second positive torque or negative torque, the motor controller is configured to control the torque output by the drive motor to be the torque value indicated by the torque signal. The motor controller provided herein can directly adjust the torque output by the drive motor based on the operating state of the electric vehicle during the final braking phase of the electric vehicle to reduce the braking force of the electric vehicle and thereby improve braking comfort. When the drive motor ceases to output the second positive torque or negative torque, the motor controller returns to normal operation, i.e., the motor controller controls the torque output by the drive motor to be the torque value indicated by the torque signal output by the vehicle controller.

[0028] In a second aspect, embodiments of the present application provide a powertrain. The powertrain includes a motor controller and a drive motor. The motor controller is configured to receive a torque signal and control the drive motor to output torque. During driving of the electric vehicle, the motor controller is configured to control the drive motor to generate a first positive torque in response to a torque value indicated by the torque signal. During braking of the electric vehicle, the motor controller controls the drive motor to generate a second positive torque or to reduce the negative torque generated by the drive motor in response to the electric vehicle's deceleration being less than a preset deceleration and the electric vehicle's speed being less than a preset speed.

[0029] During the braking process of an electric vehicle, the rate of decrease of the drive motor speed is greater than the preset rate and the speed of the drive motor is less than the preset value, indicating that the deceleration of the electric vehicle is small and the vehicle speed is small, that is, the braking mode of the electric vehicle is non-emergency braking and the electric vehicle is in the final stage of braking. At this time, the motor controller controls the drive motor to output a second positive torque to offset the braking force of the electric vehicle, thereby reducing the braking force of the electric vehicle to alleviate the "nodding" and vibration of the electric vehicle and improve the driving experience.

[0030] In one implementation of the second aspect, the second positive torque is greater than the positive torque value indicated by the torque signal, and the negative torque is less than the negative torque value indicated by the torque signal.

[0031] In one embodiment, the motor controller is configured to control the drive motor to reduce the negative torque in response to the fact that the speed reduction rate of the drive motor is greater than a preset rate and the speed of the drive motor is less than a preset value during the process of the drive motor outputting negative torque.

[0032] In one embodiment, the motor controller is used to control the drive motor to output a second positive torque in response to the pedal stroke indicated by the pedal stroke signal being less than a preset value, the reduction rate of the drive motor's speed being greater than a preset rate, and the speed of the drive motor being less than a preset speed.

[0033] In one embodiment, the powertrain further includes a rotary transformer, which is used to detect the rotation speed and rotor position of the drive motor.

[0034] In a third aspect, an embodiment of the present application provides a control method for controlling a drive motor. The control method includes:

[0035] receiving a torque signal, where the torque signal is used to indicate a torque requirement of a drive motor to drive the electric vehicle;

[0036] During driving of the electric vehicle, controlling the drive motor to generate a first positive torque, the first positive torque being used in response to a torque value indicated by the torque signal;

[0037] During the braking process of the electric vehicle, in response to the deceleration of the electric vehicle being less than the preset deceleration and the speed of the electric vehicle being less than the preset speed, the drive motor is controlled to generate a second positive torque or the negative torque generated by the drive motor is reduced.

[0038] In one implementation of the third aspect, the second positive torque is greater than the positive torque value indicated by the torque signal, and the negative torque is less than the negative torque value indicated by the torque signal.

[0039] In one implementation of the third aspect, the control method includes:

[0040] During the braking process of the electric vehicle, in response to the reduction rate of the driving motor speed being greater than the preset reduction rate and the driving motor speed being less than the preset speed, the driving motor is controlled to output a second positive torque or the negative torque generated by the driving motor is reduced.

[0041] The motor controller provided in the first aspect of this application and the motor controller in the powertrain of the second aspect can be used to execute this control method. This control method can improve the braking performance, braking comfort, and driving experience of electric vehicles. The specific beneficial effects are as described in any of the motor controllers in the first aspect or any of the powertrains in the second aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic diagram of an electric vehicle 01 provided in an embodiment of the present application;

[0043] FIG2 is a schematic diagram of a powertrain 10 provided in an embodiment of the present application;

[0044] FIG3 is a schematic diagram of a motor controller 11 provided in an embodiment of the present application;

[0045] FIG4 is a schematic diagram of a braking system 30 provided in an embodiment of the present application;

[0046] FIG5 is a schematic diagram of an energy recovery implementation according to an embodiment of the present application;

[0047] FIG6 is a schematic diagram of an electric vehicle braking process according to an embodiment of the present application;

[0048] FIG7 is a schematic diagram of another braking process of an electric vehicle provided in an embodiment of the present application;

[0049] FIG8 is another schematic diagram of the braking process of an electric vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the embodiments of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0051] With the development of electric vehicles, the driving experience has received increasing attention. Among them, the braking performance of a vehicle is a key factor affecting the driving experience. During the braking process, the late braking phase refers to the period from when the vehicle's speed decreases from a very low level to zero, that is, the period from when the vehicle is nearly stopped to when it is completely stopped and there is no relative motion with the ground. During the braking process, the vehicle's suspension is compressed under the action of deceleration. After the braking process is completed, although the vehicle has actually stopped, the vehicle body rebounds under the action of the suspension, causing the vehicle to vibrate and "nod," affecting the driving experience. To address this problem, conventional comfort braking algorithms release a certain amount of wheel-end braking force in the late braking phase to reduce the electric vehicle's deceleration, thereby alleviating the vehicle's vibration and "nod," thereby reducing braking jitter and improving driving comfort. However, existing comfort braking algorithms have long signal transmission paths and long time delays, which can lead to reduced braking performance. Based on this, embodiments of the present application provide a motor controller, powertrain, and electric vehicle. The motor controller provided herein is used to control the output torque of a drive motor during non-emergency braking of an electric vehicle to reduce the electric vehicle's braking force output, thereby improving the electric vehicle's braking performance. The motor controller, the powertrain, and the electric vehicle will be described in detail below with reference to specific embodiments.

[0052] Referring to FIG. 1 , FIG. 1 is a schematic diagram of an electric vehicle 01 provided in an embodiment of the present application. As shown in FIG. 1 , electric vehicle 01 includes a powertrain 10 and a power battery 20 connected to powertrain 10. Powertrain 10 is used to drive electric vehicle 01. Power battery 20 is used to provide electrical energy to powertrain 10. Powertrain 10 is used to receive power from power battery 20 and provide power to electric vehicle 01. Electric vehicle 01 also includes a braking system 30, which is used to provide braking force to electric vehicle 01 when electric vehicle 01 is in a braking state.

[0053] The operating states of electric vehicle 01 include a driving state and a braking state. When electric vehicle 01 is in the driving state, powertrain 10 outputs torque to drive wheels 40, for example, to rotate. When electric vehicle 01 is in the braking state, powertrain 10 stops driving wheels 40, and braking system 30 provides braking force to wheels 40, thereby reducing the speed of electric vehicle 01. The driving state refers to the process in which the drive motor 12 of electric vehicle 01 outputs positive torque to drive wheels 40, thereby enabling electric vehicle 01 to move. The braking state refers to the process in which the braking system 30 of electric vehicle 01 outputs friction braking force to wheels 40 of electric vehicle 01, thereby gradually reducing the speed of electric vehicle 01. In the braking state, the drive motor 12 of electric vehicle 01, which has an energy recovery function, can also output negative torque to convert the kinetic energy of electric vehicle 01 into electrical energy, thereby generating an induced current. This negative torque output by the drive motor 12 can also be used to provide braking force for electric vehicle 01. The positive torque output by the drive motor 12 refers to the direction in which the output of the drive motor 12 is in the same direction as the rotational speed of the drive motor 12. The negative torque output by the drive motor 12 means that the output direction of the drive motor 12 is opposite to the rotational speed direction of the drive motor 12 .

[0054] Figure 2 is a schematic diagram of a powertrain 10 provided in an embodiment of the present application. The powertrain 10 includes a motor controller 11 and a drive motor 12. During the driving process of the electric vehicle 01, the motor controller 11 converts the direct current (DC) from the power battery 20 into three-phase alternating current (AC), which is used to drive the drive motor 12 to generate torque. The drive motor 12 is in driving connection with the wheels 40 of the electric vehicle 01, and the torque generated by the drive motor 12 is transmitted to the wheels 40 to drive the wheels 40 to rotate.

[0055] Figure 3 is a schematic diagram of the motor controller 11 provided in an embodiment of the present application. As shown in Figure 3, the motor controller 11 is connected to the power battery 20 and the drive motor 12. The motor controller 11 includes a control device 111 and an inverter circuit 112. The inverter circuit 112 includes three switch tube bridge arms. Each switch tube bridge arm includes an upper bridge arm switch tube and a lower bridge arm switch tube, and the two ends of each switch tube bridge arm are used to receive direct current from the power battery 20, and the midpoint of each switch tube bridge arm is used to connect a phase winding of the drive motor 12. When the electric vehicle 01 is in the driving state, the upper bridge arm switch tube and the lower bridge arm switch tube of the three switch tube bridge arms of the inverter circuit 112 are alternately turned on. The inverter circuit 112 is used to convert the direct current from the power battery 20 into alternating current and power the drive motor 12.

[0056] In one embodiment, the drive motor 12 is a six-phase motor including six-phase windings, and the inverter circuit 112 of the motor controller 11 includes six parallel-connected bridge arms. The midpoints of the six bridge arms of the inverter circuit 112 are used to connect the six-phase windings of the drive motor 12.

[0057] The control device 111 is a module with computing capabilities. For example, the control device 111 may include one or more of a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic devices, or discrete hardware components.

[0058] Exemplarily, the control device 111 may be a microcontroller unit (MCU). Optionally, the control device 111 may be a device in which a microcontroller MCU and a vehicle control unit (VCU) are integrated into one. This solution does not impose any limitation on this.

[0059] In some possible implementations, the control device 111 can be connected to the first communication bus, for example, the control device 111 can include a communication terminal, which can be connected to the first communication bus. The control device 111 can establish communication with other components in the electric vehicle 01 through the first communication bus, that is, the control device 111 can directly obtain signals through the first communication bus. For example, one or more of the vehicle speed, torque signal and brake signal can be obtained. Furthermore, the control device 111 can also upload signals to the first communication bus, such as one or more signals such as the output torque of the drive motor 12 or the current of the inverter circuit 112. Exemplarily, the first communication bus can be a controller area network (CAN) bus, such as the chassis CAN bus of the electric vehicle 01.

[0060] In one possible implementation, the control device 111 can be connected to a speed detection device. For example, the control device 111 includes an input terminal for receiving a signal from a sensor, and the input terminal can be connected to a speed detection device. The speed detection device can be provided on the drive motor 12 (for example, provided on the rotor of the motor). In this case, the control device 111 can receive a rotary signal and a speed signal of the drive motor 12 from the speed detection device. Exemplarily, the speed detection device can be a rotary transformer (i.e., a rotary transformer sensor), a motor speed sensor, etc. The rotary transformer is used to detect the speed and rotor position of the drive motor. The motor speed sensor is used to detect the speed of the drive motor. Exemplarily, the structure of the powertrain 10 also includes the rotary transformer.

[0061] In one embodiment, the control device 111 can determine the speed of the electric vehicle, the acceleration (or deceleration) of the electric vehicle, etc. based on the resolver signal of the drive motor 12. The control device 111 can determine the speed of the drive motor based on the speed signal of the drive motor 12. Of course, other methods can also be used to determine other parameters, and this solution does not limit this.

[0062] FIG4 is a schematic diagram of a braking system 30 provided in an embodiment of the present application. The braking system 30 includes a brake pedal 31, a brake controller 32, and four actuators 33. When the driver steps on the brake pedal 31, the brake controller 32 generates a brake control signal according to the travel of the brake pedal 31, and the four actuators 33 output a braking force to the corresponding wheels 40 according to the instructions of the brake control signal to reduce the speed of the electric vehicle 01. During the braking process of the electric vehicle 01, the greater the travel of the brake pedal 31, the greater the braking force indicated by the brake signal, the greater the braking force output by the four actuators 33, and the faster the speed of the electric vehicle 01 decreases.

[0063] The electric vehicle 01 provided in the embodiment of the present application also has an energy recovery function. Energy recovery means that when the electric vehicle 01 is in a braking state, the wheel 40 drives the drive motor 12 to rotate, the drive motor 12 operates in a power generation state and outputs negative torque, and the drive motor 12 converts the kinetic energy of the electric vehicle 01 into electrical energy. While generating electricity, the drive motor 12 can also provide feedback braking force for the electric vehicle 01. Figure 5 is a schematic diagram of the execution principle of energy recovery. As shown in Figure 5, when the driver steps on the brake pedal 31, the vehicle controller 50 is used to receive the braking control signal from the brake controller 32 and send an energy recovery instruction to the motor controller 11, and the motor controller 11 controls the drive motor 12 to operate in a power generation state. The drive motor 12 rotates with the wheel 40 and outputs three-phase alternating current. The motor controller 11 receives the three-phase alternating current output by the drive motor 12, converts the three-phase alternating current into direct current, and charges the power battery 20.

[0064] Braking for electric vehicle 01 is categorized into emergency braking and non-emergency braking. Emergency braking can be understood as a braking process that rapidly decelerates electric vehicle 01. During emergency braking, the deceleration of electric vehicle 01 is relatively high. Non-emergency braking can be understood as a braking process that gradually decelerates electric vehicle 01. During non-emergency braking, the deceleration of electric vehicle 01 is relatively low. Whether electric vehicle 01 is in emergency braking mode or non-emergency braking mode can be determined based on the deceleration of electric vehicle 01, brake pedal travel, or the speed reduction rate of the drive motor.

[0065] In one embodiment, if the deceleration of the electric vehicle 01 during braking is greater than the preset deceleration, the braking mode of the electric vehicle 01 is the emergency braking mode. If the deceleration of the electric vehicle 01 during braking is less than or equal to the preset deceleration, the braking mode of the electric vehicle 01 is the non-emergency braking mode. For example, the preset deceleration is 5 m / s 2 .

[0066] In one embodiment, if the pedal stroke of the electric vehicle 01 is greater than a preset value during the braking process of the electric vehicle 01, the braking mode of the electric vehicle 01 is the emergency braking mode. If the pedal stroke of the electric vehicle 01 is less than or equal to the preset value during the braking process of the electric vehicle 01, the braking mode of the electric vehicle 01 is the non-emergency braking mode.

[0067] In one embodiment, if the deceleration rate of the drive motor 12 during braking of the electric vehicle 01 is greater than a preset rate, the braking mode of the electric vehicle 01 is an emergency braking mode. If the deceleration rate of the drive motor 12 during braking of the electric vehicle 01 is less than or equal to a preset rate, the braking mode of the electric vehicle 01 is a non-emergency braking mode.

[0068] If the braking mode of the electric vehicle 01 is emergency braking, the braking efficiency and braking safety of the electric vehicle 01 must be prioritized, that is, when the braking mode of the electric vehicle 01 is emergency braking, the electric vehicle 01 must be stopped quickly according to the braking force indicated by the brake controller 32. If the braking mode of the electric vehicle 01 is non-emergency braking, the braking comfort and driving experience of the electric vehicle 01 must be considered, that is, the "nodding" and vibration phenomena of the electric vehicle 01 at the end of braking must be reduced as much as possible. The motor controller 11 provided in the embodiment of the present application controls the drive motor 12 to output a second positive torque at the end of braking of the electric vehicle 01 to reduce the total braking force of the electric vehicle 01 and thereby improve braking comfort. The comfortable braking solution provided in the present application is applicable to non-emergency braking scenarios.

[0069] During the braking process of an electric vehicle, the final braking phase refers to the process from when the speed of the electric vehicle 01 decreases from very low to completely zero. During the early and middle stages of braking, the suspension and tires of the electric vehicle 01 are compressed by the braking deceleration. At the final braking phase, the suspension and tires rebound, causing the electric vehicle to "nod" and vibrate. In one embodiment, during the braking process of an electric vehicle, the speed of the electric vehicle is less than a preset speed, and the electric vehicle is at the final braking phase. In another embodiment, during the braking process of an electric vehicle, the speed of the drive motor is less than a preset speed, and the electric vehicle is at the final braking phase.

[0070] The above describes the architecture of the embodiment of the present application. The following is an illustrative description of how the motor controller specifically considers multiple factors to control the drive motor to achieve comfortable braking, with reference to the accompanying drawings.

[0071] The following first introduces a solution for controlling the drive motor to achieve comfortable braking by taking deceleration and vehicle speed into consideration.

[0072] In one embodiment, during the driving process of the electric vehicle, the motor controller 11 is configured to control the drive motor 12 to generate a first positive torque, which is responsive to the torque value indicated by the torque signal. Specifically, during the driving process of the electric vehicle 01, the vehicle controller 50 calculates the vehicle torque demand and sends a torque signal to the motor controller 11 based on the vehicle torque demand. The motor controller 11 then controls the drive motor to output torque based on the torque value indicated by the torque signal to drive the electric vehicle 01.

[0073] In one embodiment, in response to the deceleration of the electric vehicle 01 being less than a preset deceleration and the speed of the electric vehicle 01 being less than a preset speed during braking of the electric vehicle 01, the motor controller 11 outputs a driving current at the midpoint of the multiple bridge arms of the inverter circuit 112 to cause the drive motor 12 to output a second positive torque, wherein the second positive torque is greater than the torque value indicated by the torque signal and the second positive torque is a positive torque.

[0074] During the braking process of the electric vehicle, the motor controller 11 responds to the deceleration of the electric vehicle 01 being less than the preset deceleration and the speed of the electric vehicle 01 being less than the preset speed, and the midpoints of the multiple bridge arms of the motor controller output driving current to enable the drive motor to output a second positive torque.

[0075] Specifically, during the braking process of electric vehicle 01, control device 111 is configured to receive a braking signal from brake controller 32, a vehicle speed signal from a vehicle speed sensor, and a deceleration signal from a deceleration sensor. During the braking process, if the deceleration of electric vehicle 01 is less than a preset deceleration, this indicates that electric vehicle 01 is in non-emergency braking mode. In this non-emergency braking state, the speed of electric vehicle 01 gradually decreases. When the speed of electric vehicle 01 is less than the preset speed, indicating that the electric vehicle is in the late braking stage, the inverter circuit of motor controller 11 outputs a drive current to cause drive motor 12 to output a second positive torque. Since the second positive torque is positive, it generates acceleration in electric vehicle 01, thereby reducing the deceleration of electric vehicle 01. This, in turn, reduces the compression of the tires and suspension of electric vehicle 01, thereby alleviating the "nodding" and vibration of the electric vehicle and improving the driving experience of electric vehicle 01.

[0076] During the driving process of electric vehicle 01, electric vehicle 01 outputs torque according to the torque value indicated by the torque signal output by vehicle controller 50. However, during the process of motor controller 11 outputting the second positive torque, motor controller 11 outputs the second positive torque according to the speed and deceleration of electric vehicle 01, rather than according to the torque signal indicated by vehicle controller 50. Therefore, the second positive torque output by motor controller 11 is inconsistent with the torque signal indicated by the torque signal. Generally, during the braking process of an electric vehicle, it is necessary to control drive motor 12 to stop outputting positive torque. The torque value indicated by the torque signal output by vehicle controller 50 is extremely small, so the second positive torque is greater than the torque value indicated by the torque signal.

[0077] For example, as shown in FIG6 , during the driving process of an electric vehicle, the vehicle is traveling normally, the vehicle deceleration is zero, the torque value indicated by the torque signal output by the vehicle controller is zero, and the torque output by the drive motor is also zero. In the early stages of vehicle braking, when the driver depresses the brake pedal, the braking system outputs a braking force to reduce the speed of the electric vehicle, increasing the deceleration of the electric vehicle. During this process, the torque value indicated by the torque signal output by the vehicle controller is zero, and the torque output by the drive motor is also zero. As the electric vehicle approaches a stop, in the later stages of vehicle braking, when the deceleration of the electric vehicle is less than a preset deceleration and the speed of the electric vehicle is less than a preset speed, the electric vehicle's braking mode is non-emergency braking. As shown in period ① in FIG6 , the inverter circuit of the motor controller outputs a drive current to cause the drive motor to output a second positive torque, which is a positive torque. As the speed and deceleration of the electric vehicle continue to decrease until the deceleration reaches zero and the vehicle stops, the inverter circuit of the motor controller stops outputting the drive current, causing the drive motor to stop outputting the second positive torque. At this point, the torque output by the drive motor is zero. During the entire braking process, the torque value indicated by the torque signal output by the vehicle controller 50 is 0.

[0078] The following describes how the motor controller 11 determines the magnitude of the second positive torque.

[0079] In one embodiment, the motor controller 11 determines the second positive torque according to the speed and / or deceleration of the electric vehicle 01 .

[0080] Specifically, the motor controller 11 can determine the second positive torque based on the comfort braking curve corresponding to the electric vehicle 01 as a reference curve. The motor controller 11 predetermines the comfort braking curve for the electric vehicle. For example, by recording the speed curve and / or deceleration curve of the electric vehicle 01 as the brake pedal is gradually released during braking, and allowing the electric vehicle 01 to smoothly stop, multiple tests can be performed to plot an ideal speed curve and / or deceleration curve for the electric vehicle 01, which is the comfort braking curve. Using these speed curves and / or deceleration curves as a control basis, the electric vehicle 01 is braked as closely as possible according to the comfort braking curve. By determining the speed or deceleration of the electric vehicle 01 based on the speed curve and / or deceleration curve, the second positive torque of the electric vehicle 01 can be determined.

[0081] In another embodiment, the motor controller 11 calculates the second positive torque based on parameters such as the deceleration of the electric vehicle, the mass of the electric vehicle 01, the transmission ratio of the power system, and the rolling radius of the tire. Using the formula F = m*a, T = m*a*r, the total torque T used to offset the current deceleration braking of the electric vehicle can be estimated. Among them, F is the total braking force of the electric vehicle 01, m is the mass of the electric vehicle, a is the current deceleration of the electric vehicle 01 (the deceleration is obtained based on the resolver signal), r is the rolling radius of the tire of the electric vehicle 01, and T is the second positive torque of the wheel end of the electric vehicle 01 for comfort braking. Then using T = Te*i, the second positive torque of the motor that offsets the current deceleration braking of the electric vehicle 01 can be calculated, Te is the second positive torque of the motor for comfort braking of the electric vehicle, and i is the transmission ratio of the electric vehicle.

[0082] Of course, other methods can also be used to calculate the second positive torque, and this solution does not limit this.

[0083] In a specific implementation, the motor controller 11 can receive a torque signal from the vehicle controller 50. Based on the resolver signal of the drive motor 12, the motor controller 11 can obtain the speed of the electric vehicle 01. By performing differential processing based on the speed of the electric vehicle 01, the deceleration of the electric vehicle 01 can be obtained. Of course, the deceleration can also be obtained based on a deceleration sensor, etc. When the deceleration of the electric vehicle 01 during braking is less than the preset deceleration and the speed of the electric vehicle 01 is less than the preset speed, the motor controller 11 calculates the second positive torque. For example, when the speed v of the electric vehicle 01 satisfies v1>v and the deceleration satisfies a>a1, the second positive torque is calculated. Wherein, v1 is the preset speed and a1 is the preset deceleration. Of course, other conditions can also be used, such as the speed v satisfies v1>v>v2 and the deceleration satisfies a>a1, etc., and v2 is also the preset speed. This solution does not limit this.

[0084] Furthermore, the motor controller 11 may output a first control signal based on the second positive torque to control the inverter circuit to drive the drive motor to output the second positive torque.

[0085] In this example, braking intervention is performed based on the second positive torque generated by drive motor 12. This second positive torque precisely adjusts the vehicle's braking speed or deceleration, ensuring no noticeable "nodding" during braking, thereby enhancing braking comfort. This approach mitigates the tendency of the vehicle's center of mass to shift forward during braking and reduces vehicle sway after stopping, improving braking comfort while effectively reducing control delay and braking distance.

[0086] Furthermore, by obtaining a resolver signal from a resolver sensor mounted on drive motor 12 and then determining the electric vehicle's speed and deceleration based on the resolver signal, the accuracy of the speed and deceleration of electric vehicle 01 can be improved. Furthermore, because the resolver sensor has a high sampling frequency and the motor controller can directly obtain the resolver signal, the time delay in obtaining the electric vehicle's speed and deceleration is reduced. This allows the motor controller to quickly determine the second positive torque based on the electric vehicle's speed and deceleration for braking intervention.

[0087] In one embodiment, in response to the speed reduction rate of the drive motor 12 being less than a preset rate and the speed of the drive motor 12 being less than a preset speed, the motor controller 11 controls the drive motor 12 to output a second positive torque.

[0088] Specifically, during the braking process of the electric vehicle 01, the motor controller 11 is used to receive the braking signal from the brake controller 32 and the speed signal (rotational signal) from the motor speed sensor. For example, the motor controller is connected to the motor speed sensor. The motor speed sensor is used to detect the speed of the drive motor. Furthermore, the motor controller can receive the speed signal of the drive motor from the motor speed sensor to obtain the speed of the drive motor. During the braking process, the speed of the drive motor 12 decreases as the speed of the electric vehicle 01 decreases, and the deceleration of the electric vehicle 01 corresponds to the speed reduction rate of the drive motor 12. Therefore, during the braking process of the electric vehicle 01, when the speed reduction rate of the drive motor 12 is less than the preset rate and the speed of the drive motor 12 is less than the preset speed, the motor controller 11 is used to control the drive motor 12 to output a second positive torque.

[0089] In one possible embodiment, the motor controller 11 is used to control the drive motor 12 to reduce the negative torque output in response to the electric vehicle 01 driving the motor 12 to output negative torque as it rotates during braking, the deceleration of the electric vehicle 01 is less than a preset deceleration, and the speed of the electric vehicle 01 is less than a preset speed.

[0090] If the energy recovery function is activated during the braking process of electric vehicle 01, the braking system 30 of electric vehicle 01 and the energy recovery system jointly provide braking force for the electric vehicle 01. Specifically, the four actuators 33 of braking system 30 provide mechanical braking force for electric vehicle 01. During the energy recovery process, the drive motor 12 operates in a power generation state and outputs negative torque to provide feedback braking force for electric vehicle 01. During non-emergency braking of electric vehicle 01, in the late braking phase, that is, when the speed of electric vehicle 01 is less than a preset speed, the motor controller 11 controls the drive motor 12 to reduce the negative torque output, thereby reducing the total braking force of electric vehicle 01 and mitigating the nodding and vibration phenomena during the braking process of electric vehicle 01, thereby improving braking comfort and driving experience.

[0091] Figure 7 is a schematic diagram illustrating how motor controller 11 controls drive motor 12 to reduce negative torque output during energy recovery. As shown in Figure 7, during braking of electric vehicle 01, motor controller 11 controls drive motor 12 to output negative torque based on the torque indicated by the torque signal. At time ① in the late braking phase, motor controller 11 controls drive motor 12 to reduce negative torque output, thereby reducing the overall braking force of electric vehicle 01.

[0092] In an embodiment of the present application, the motor controller 11 directly controls the drive motor 12 to output negative torque based on the speed and deceleration of the electric vehicle 01 during braking to reduce control response time, rather than controlling the drive motor 12 to output negative torque based on the torque signal indicated by the vehicle controller 50. Therefore, the negative torque value output by the drive motor 12 during the process of reducing negative torque output is less than the negative torque value indicated by the torque signal. As can be seen from Figure 7, from time t1 to time t2 when the speed of the electric vehicle 01 is reduced to zero, the negative torque value output by the drive motor 12 is less than the negative torque value indicated by the torque signal. The motor controller 11 provided in this application directly controls the torque output of the drive motor 12 during the braking process of the electric vehicle 01, rather than controlling the torque output of the drive motor 12 based on the torque signal output by the vehicle controller 50. The motor controller 11 provided in this application can shorten the control path of the torque control of the drive motor 12 and thereby increase the torque control speed, thereby improving the control efficiency and response speed of comfortable braking.

[0093] In one embodiment, the motor controller 11 controls the drive motor 12 to reduce the negative torque output in response to the drive motor 12 having a speed reduction rate less than a preset rate and a speed less than a preset speed during the drive motor 12 outputting negative torque. As previously described, during braking of the electric vehicle 01, the speed reduction rate of the drive motor 12 corresponds to the deceleration of the electric vehicle 01, while the speed of the drive motor 12 corresponds to the speed of the electric vehicle 01.

[0094] In one embodiment, the motor controller 11 is configured to control the drive motor to output a second positive torque in response to the travel of the brake pedal 31 of the electric vehicle 01 being less than a preset value and the speed of the electric vehicle 01 being less than a preset value during braking.

[0095] Specifically, during the braking process of electric vehicle 01, the driver depresses brake pedal 31, and brake controller 32 converts the pedal travel into a pedal travel signal. During the braking process, the pedal travel indicated by the pedal travel signal of electric vehicle 01 is less than a preset value, indicating that the braking mode of electric vehicle 01 is non-emergency braking. During the non-emergency braking state of electric vehicle 01, the speed of electric vehicle 01 gradually decreases. When the speed of electric vehicle 01 is less than the preset speed, indicating that electric vehicle 01 is in the late braking stage, the inverter circuit 112 of motor controller 11 outputs a drive current to cause drive motor 12 to output the second positive torque. Since the second positive torque is positive torque, the second positive torque causes electric vehicle 01 to generate acceleration, thereby reducing the deceleration of electric vehicle 01 and, in turn, reducing the braking force of electric vehicle 01. This, in turn, reduces the compression of the tires and suspension of electric vehicle 01, thereby alleviating the "nodding" and vibration of the electric vehicle and improving the driving experience of electric vehicle 01.

[0096] In one embodiment, the motor controller 11 controls the drive motor 12 to output the torque value indicated by the torque signal in response to the deceleration of the electric vehicle 01 being greater than a preset deceleration or the pedal stroke indicated by the pedal stroke signal being greater than a preset value during braking.

[0097] Specifically, during the braking process of electric vehicle 01, the motor controller is used to receive a braking control signal from the brake controller 32, or a deceleration signal from the deceleration sensor. If, during the braking process, the deceleration of electric vehicle 01 is greater than a preset deceleration, this indicates that the braking mode of electric vehicle 01 is emergency braking. Alternatively, during the braking process, the pedal travel indicated by the pedal travel signal of electric vehicle 01 is greater than a preset value, indicating that the braking mode of electric vehicle 01 is emergency braking. When electric vehicle 01 is in an emergency braking state, when the driver depresses the brake pedal 31, the brake controller 32 generates a braking control signal based on the brake pedal travel. At this point, the inverter circuit of motor controller 11 outputs a drive current to cause the drive motor 12 to output the torque value indicated by the torque signal.

[0098] That is, when the deceleration of the electric vehicle during braking is greater than a preset deceleration or the pedal travel indicated by the pedal travel signal is greater than a preset value, it indicates that the braking mode of electric vehicle 01 is emergency braking. When the braking mode of electric vehicle 01 is emergency braking, in order to ensure the braking efficiency and braking safety of electric vehicle 01, it is necessary to ensure that the braking force of electric vehicle 01 during braking always remains at the braking force indicated by brake controller 32. In emergency braking mode, the comfort braking solution provided in this application for reducing the braking force of electric vehicle 01 at the end of braking will not be effective. Therefore, the torque value output by motor controller 11 to drive motor 12 is the torque value indicated by vehicle controller 50.

[0099] Figure 8 is a schematic diagram of the braking process of an electric vehicle in emergency braking mode. As shown in Figure 8, in emergency braking mode, during the entire braking process, the torque output by the drive motor 12 is the same as the torque value indicated by the torque signal.

[0100] In another embodiment, the magnitude of the second positive torque output by the motor controller is positively correlated with the pedal travel indicated by the pedal travel signal.

[0101] The greater the pedal stroke indicated by the pedal stroke signal, the greater the required braking force, and accordingly, the greater the second positive torque value output by the motor controller. The smaller the pedal stroke indicated by the pedal stroke signal, the smaller the required braking force, and accordingly, the smaller the second positive torque value output by the motor controller.

[0102] In yet another embodiment, the magnitude of the second positive torque output by the motor controller 11 is positively correlated with the speed of the electric vehicle 01. Specifically, the greater the speed of the electric vehicle 01, the greater the braking force required during braking, and accordingly, the greater the value of the second positive torque output by the motor controller 11. The lower the speed of the electric vehicle 01, the smaller the braking force required during braking, and accordingly, the smaller the value of the second positive torque output by the motor controller 11.

[0103] In one embodiment, in response to the drive motor 12 stopping outputting the second positive torque or the negative torque, the motor controller 11 is configured to control the torque value output by the drive motor 12 to be the torque value indicated by the torque signal.

[0104] The motor controller 11 provided in this embodiment of the present application can directly adjust the torque output by the drive motor 12 according to the operating state of the electric vehicle 01 when the electric vehicle 01 is at the end of braking, thereby reducing the braking force of the electric vehicle 01 and improving braking comfort. When the drive motor 12 stops outputting the second positive torque or the negative torque, the motor controller 11 returns to normal operation, i.e., the torque value output by the drive motor 12 controlled by the motor controller 11 is the torque value indicated by the torque signal output by the vehicle controller 50.

[0105] In one embodiment, there may be one drive motor in the electric vehicle 01. The motor controller 11 may control one drive motor 12 to generate the second positive torque. Alternatively, there may be multiple drive motors 12 in the electric vehicle 01. The motor controller 11 may control one drive motor among the multiple drive motors 12 to generate the second positive torque. The motor controller 11 may also control at least two drive motors 12 among the multiple drive motors 12 to generate torque according to a preset ratio, and the sum of the torques generated by the at least two drive motors is the second positive torque. The at least two drive motors 12 may be any motor among the multiple drive motors 12. The preset ratio may be set arbitrarily. For example, the at least two drive motors may evenly distribute torque, or randomly distribute torque, etc., which is not limited in this solution. In this way, the flexibility of motor control can be improved.

[0106] This embodiment of the present application uses the speed, deceleration, drive motor speed, and pedal travel signal of electric vehicle 01 as examples to illustrate control of the drive motor. Other conditions, such as the electric vehicle's gear position and driving mode, can also be incorporated. For example, if the electric vehicle's driving mode is the economical intelligent driving mode, the electric vehicle's gear position is forward, and the electric vehicle's speed during braking is less than a preset speed, the drive motor is controlled to output the aforementioned second positive torque. This solution does not impose any limitations on this.

[0107] It should be noted that in the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between the various embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0108] It should be understood that in the description of this application, unless otherwise specified, " / " indicates that the objects associated with each other are in an "or" relationship. For example, A / B can mean A or B; where A and B can be singular or plural. Also, in the description of this application, unless otherwise specified, "multiple" means two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural. In addition, to facilitate the clear description of the technical solutions of the embodiments of this application, in the embodiments of this application, words such as "first" and "second" are used to distinguish between identical or similar items with substantially the same functions and effects. Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity or execution order, and words such as "first" and "second" do not necessarily mean different. At the same time, in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A motor controller, characterized in that: The motor controller receives the torque signal and is used to; During the driving process of the electric vehicle, controlling the driving motor to generate a first positive torque, wherein the first positive torque is used to respond to the torque value indicated by the torque signal; During the braking process of the electric vehicle, in response to the deceleration of the electric vehicle being less than a preset deceleration and the vehicle speed of the electric vehicle being less than a preset vehicle speed, the drive motor is controlled to generate a second positive torque or to reduce the negative torque generated by the drive motor during rotation.

2. The motor controller according to claim 1, characterized in that: During the braking process of the electric vehicle, the second positive torque is greater than the positive torque value indicated by the torque signal, and the negative torque is less than the negative torque value indicated by the torque signal.

3. The motor controller according to any one of claims 1 to 2, characterized in that: The motor controller includes an inverter circuit, the inverter circuit includes a plurality of bridge arms, the midpoints of the bridge arms are used to connect the multi-phase windings of the drive motor, and the inverter circuit is used to output alternating current to enable the drive motor to output the second positive torque; or, The inverter circuit is used to receive the induced current generated by the rotation of the drive motor and control the negative torque value output by the drive motor.

4. The motor controller according to any one of claims 1 to 3, characterized in that: The motor controller is used to: During the braking process of the electric vehicle, in response to the travel of the brake pedal being less than a preset value and the speed of the electric vehicle being less than a preset value, the drive motor is controlled to output the second positive torque.

5. The motor controller according to any one of claims 1 to 4, characterized in that: The motor controller is used to: During the braking process of the electric vehicle, in response to the deceleration of the electric vehicle being greater than a preset deceleration or the travel of the brake pedal being greater than a preset value, the drive motor is controlled to output the torque value indicated by the torque signal.

6. The motor controller according to claim 4 or 5, characterized in that: The motor controller controls the magnitude of the second positive torque output by the drive motor to be positively correlated with the travel of the brake pedal; or, The motor controller controls the magnitude of the second positive torque output by the drive motor to be positively correlated with the speed of the electric vehicle.

7. The motor controller according to any one of claims 1 to 6, characterized in that: The motor controller is used to: During the braking process of the electric vehicle, in response to a reduction rate of the rotation speed of the drive motor being greater than a preset reduction rate and a rotation speed of the drive motor being less than a preset rotation speed, the drive motor is controlled to output the second positive torque.

8. The motor controller according to any one of claims 1 to 7, characterized in that: The motor controller is used to: During the braking process of the electric vehicle, in response to the fact that the speed reduction rate of the drive motor during the process of outputting the negative torque is less than a preset rate and the speed of the drive motor is less than a preset speed, the drive motor is controlled to reduce the negative torque output.

9. The motor controller according to any one of claims 4 to 8, characterized in that: The motor controller is used to: During the braking process of the electric vehicle, in response to the travel of the brake pedal being less than a preset value, the speed reduction rate of the drive motor being less than a preset rate, and the speed of the drive motor being less than the preset speed, the drive motor is controlled to output the second positive torque.

10. The motor controller according to any one of claims 1 to 9, characterized in that: The motor controller is used to: In response to the drive motor stopping outputting the second positive torque or the negative torque, the drive motor is controlled to output a torque value indicated by the torque signal.

11. A powertrain, characterized in that: The powertrain includes a motor controller and a drive motor, wherein the motor controller is used to receive a torque signal and control the drive motor to output torque, and the motor controller is used to: During the driving process of the electric vehicle, controlling the driving motor to generate a first positive torque, wherein the first positive torque is used to respond to a torque value indicated by the torque signal; During the braking process of the electric vehicle, in response to the deceleration of the electric vehicle being less than a preset deceleration and the vehicle speed of the electric vehicle being less than a preset vehicle speed, the drive motor is controlled to generate a second positive torque or to reduce the negative torque generated by the drive motor during rotation.

12. The powertrain according to claim 11, characterized in that: The second positive torque is greater than a positive torque value indicated by the torque signal, and the negative torque is less than a negative torque value indicated by the torque signal.

13. A control method for controlling a driving motor, characterized in that: The control method comprises: receiving a torque signal, wherein the torque signal is used to indicate a torque requirement of a drive motor to drive the electric vehicle; During the driving process of the electric vehicle, controlling the driving motor to generate a first positive torque, wherein the first positive torque is used to respond to a torque value indicated by the torque signal; During the braking process of the electric vehicle, in response to the deceleration of the electric vehicle being less than a preset deceleration and the vehicle speed of the electric vehicle being less than a preset vehicle speed, the drive motor is controlled to generate a second positive torque or to reduce the negative torque generated by the drive motor during rotation.

14. The control method according to claim 13, characterized in that: The second positive torque is greater than a positive torque value indicated by the torque signal, and the negative torque is less than a negative torque value indicated by the torque signal.

15. The control method according to claim 13 or 14, characterized in that: The control method further comprises: During the braking process of the electric vehicle, in response to the reduction rate of the driving motor speed being greater than a preset reduction rate and the driving motor speed being less than a preset speed, the driving motor is controlled to output the second positive torque or to reduce the negative torque generated by the driving motor.

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