Motor controller and method for shortening emergency braking distance and electric vehicle

Abstract

The invention discloses a motor controller for shortening an emergency braking distance, a control method and an electric vehicle, relates to the field of new energy vehicles, and can be applied to pure electric vehicles and hybrid vehicles. The motor controller is used for the electric automobile, the motor controller is used for controlling a driving motor of the electric automobile to output forward torque to drive wheels of the electric automobile, the electric automobile further comprises an automatic emergency braking system, and the automatic emergency braking system is used for outputting braking force to brake the electric automobile after being triggered. The motor controller is further used for controlling the driving motor to output reverse torque after the automatic emergency braking system is triggered and before the automatic emergency braking system outputs braking force in the running process of the electric automobile, and the direction of the reverse torque is opposite to the rotating speed direction of the driving motor. According to the scheme, the AEB braking distance is shortened or the AEB intervention speed is increased under the condition that the AEB braking distance is not changed, the false triggering rate of the AEB is reduced, and the safety of the vehicle is improved.

Description

Technical Field

[0001] The present application relates to the field of new energy vehicles, and more specifically, to a motor controller, method and electric vehicle for shortening emergency braking distance. Background Art

[0002] Active safety configurations of vehicles are receiving more and more attention. The autonomous emergency braking (AEB) system uses the vehicle's perception system, such as cameras and radars, to measure the distance to the vehicle in front or obstacles, and then uses the data analysis module to compare the measured distance with the warning distance and the safety distance. When the measured distance is less than the warning distance, an alarm will be given, and when it is less than the safety distance, the AEB system will be activated, causing the car to brake automatically, thus ensuring safe travel.

[0003] The braking distance of AEB directly affects the safety of the car. At the same time, in order to prevent AEB from being triggered by mistake, the recognition distance is usually limited, which usually requires reducing the braking distance. In the traditional AEB architecture, the vehicle relies on the braking system to complete the entire AEB process, and the vehicle braking system requires the hydraulic system to build pressure so that the brake caliper clamps the brake disc and generates braking force for the entire vehicle. This process usually takes a certain amount of time, and the pressure building time is relatively long. Untimely braking will increase the AEB braking distance.

[0004] Therefore, how to shorten the emergency braking distance of electric vehicles is a problem that needs to be solved. Summary of the invention

[0005] The present application provides a motor controller, method and electric vehicle for shortening the emergency braking distance. When AEB is triggered, the drive motor responds quickly and outputs braking torque to reduce the vehicle speed within the time when the hydraulic braking force has not been fully established. The drive system and the braking system cooperate with each other, thereby shortening the AEB braking distance or increasing the AEB intervention speed while the AEB braking distance remains unchanged, reducing the false triggering rate of AEB and improving the safety of the vehicle.

[0006] In a first aspect, the present application provides a motor controller for shortening the emergency braking distance, the motor controller is used for an electric vehicle, the motor controller is used to control the drive motor of the electric vehicle to output a positive torque to drive the wheels of the electric vehicle, and the electric vehicle also includes an automatic emergency braking system, the automatic emergency braking system is used to output a braking force after being triggered to brake the electric vehicle. The motor controller is also used to control the drive motor to output a reverse torque after the automatic emergency braking system is triggered and before the automatic emergency braking system outputs the braking force during the driving process of the electric vehicle, and the direction of the reverse torque is opposite to the direction of the rotation speed of the drive motor.

[0007] The motor controller is suitable for electric vehicles or hybrid vehicles. The electric vehicles can be distributed motors or centralized motor architectures, with multiple drive motors and multiple motor controllers. The motor controller can be any one of the multiple motor controllers. The drive motor can be a wheel-side motor or a hub motor, and the drive motor can independently drive one wheel of the vehicle. The motor controller can output three-phase alternating current to the drive motor, thereby controlling the output torque of the drive motor. The drive motor includes a stator winding and a rotor. The motor controller can control the output torque of the motor by outputting alternating current to the three-phase stator winding. The motor controller can change the strength and direction of the stator magnetic field by adjusting the magnitude of the input stator winding current and the phase of the three-phase current, thereby changing the interaction force between the stator and the rotor, that is, controlling the torque output by the drive motor.

[0008] It should be understood that for electric vehicles with multiple drive motors, if AEB is triggered, the drive motors driving coaxial wheels, such as two drive motors driving two front wheels or two drive motors driving two rear wheels, should output equal reverse torques to avoid yaw torques that may cause the vehicle to lose control. Therefore, if it is an electric vehicle with multiple motor controllers controlling multiple drive motors respectively, the motor controllers need to control the reverse torque output by the drive motors to be equal to the reverse torque output by the drive motors driving the coaxial wheels.

[0009] The automatic emergency braking (AEB) system is an active safety feature of electric vehicles that can automatically brake in emergency situations. For example, the AEB system detects that the distance between the electric vehicle and an obstacle (pedestrians, vehicles, etc.) is less than the safe distance and automatically applies the brakes or increases the braking force when the driver does not apply enough brakes, thereby slowing down and braking the vehicle. The AEB system can be set up with a separate controller or integrated into the vehicle controller or advanced driver assistance systems (ADAS) controller. When the controller of the AEB system determines that the AEB system needs to be activated, it will send an AEB system enable signal to the vehicle controller and / or motor controller. The AEB system enable signal is used to indicate that the AEB is triggered for automatic braking.

[0010] In the present application, the AEB system outputting braking force to the electric vehicle may refer to a controller integrated with the AEB system directly or indirectly controlling the braking system of the electric vehicle to output braking force, which will not be elaborated in the following text.

[0011] Reverse torque can also be called negative torque. During the forward driving of an electric vehicle, positive torque is used to drive the vehicle, and negative torque is used to brake the vehicle. During the reversing of an electric vehicle, positive torque is used to brake the vehicle, and negative torque is used to drive the vehicle. The motor controller can change the phase of the three-phase current output to the drive motor so that the rotor cuts the magnetic field generated by the stator winding, and the kinetic energy of the rotor is converted into electrical energy and input into the power battery. At this time, the drive motor outputs negative torque. The motor controller changes the size of the three-phase current output to the motor to increase or decrease the positive torque or negative torque output by the motor. It should be understood that the forward driving of an electric vehicle is used as an example for explanation in this application. Similar descriptions can be referred to in the scenario of reversing an electric vehicle. The direction of the torque output by the drive motor can be modified accordingly, and the function of the torque should remain consistent.

[0012] It should be understood that when AEB is activated, the electric vehicle will brake automatically, and the braking system of the electric vehicle will be controlled to output braking force to stop the electric vehicle. Usually, the braking system needs to build up pressure through the hydraulic system to output braking force, so it takes a certain amount of time for the braking system to build up hydraulic pressure and output braking force. During this period of time, the electric vehicle is not decelerated by the braking force. The drive motor does not need to build pressure, and the torque control response time is less than the time for the brake system to build pressure. Therefore, the drive motor can be controlled by the motor controller to output reverse torque during the period of brake system pressure building, thereby quickly braking the electric vehicle.

[0013] According to the solution of the present application, when AEB is triggered, a fast-response motor controller is used to control the drive motor to output reverse torque, thereby filling the lack of hydraulic braking force for a certain period of time. Without increasing the hardware cost of the vehicle, the braking distance of the vehicle in the AEB scenario is shortened, thereby improving the safety of the vehicle.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is used to control the drive motor to output reverse torque until the speed of the electric vehicle is reduced to zero.

[0015] In a possible embodiment, the motor control machine can control the drive motor to output reverse torque during the entire process from AEB triggering to automatic braking to stopping. Before the braking system outputs braking force, a larger reverse torque can be output to make up for the blank time of braking force, and after the braking system starts to output braking force, the reverse torque is reduced. If the electric controller is in full effect, the long-term operation capability of the drive motor itself and the kinetic energy recovery capability of the power battery must also be considered.

[0016] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario, so that the electric vehicle can quickly reach the target deceleration, shorten the emergency braking distance, and improve the safety of the vehicle.

[0017] In combination with the first aspect, in certain implementations of the first aspect, in the process of the motor controller controlling the drive motor to output reverse torque, the deceleration of the electric vehicle before the emergency braking system outputs braking force is less than the deceleration of the electric vehicle after the emergency braking system outputs braking force.

[0018] The reverse torque output by the drive motor should not be too large. After the emergency braking system starts to output braking force, the deceleration of the electric vehicle will increase rapidly. In order to prevent the wheels from locking and affecting the driving safety of the electric vehicle, the braking system should be the main braking force.

[0019] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario to shorten the emergency braking distance, and the braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is used to control the drive motor to stop outputting the reverse torque in response to the automatic emergency braking system outputting braking force and the deceleration of the electric vehicle being greater than or equal to a preset deceleration during the process of controlling the drive motor to output the reverse torque.

[0021] The motor controller can be connected to the braking system or vehicle controller signal. When the automatic emergency braking system starts to output braking force, the deceleration of the electric vehicle will increase rapidly. When the braking force output by the braking system causes the electric vehicle to have sufficient deceleration, the motor controller can control the drive motor to stop outputting reverse torque and exit braking in time to avoid overlap with the braking force output by the braking system, which may cause the wheels to lock.

[0022] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario to generate braking force in turn, so that the electric vehicle can quickly reach the target deceleration and shorten the emergency braking distance. The braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0023] In combination with the first aspect, in certain implementations of the first aspect, in a process in which the motor controller is used to control the drive motor to output a reverse torque before the automatic emergency braking system outputs braking force, the deceleration of the electric vehicle is less than a preset deceleration or the deceleration of the drive motor is less than a preset deceleration.

[0024] The deceleration of the drive motor can be understood as the deceleration of the motor speed. There is usually a corresponding relationship between the motor speed and the vehicle speed. Therefore, the deceleration of the electric vehicle can be calculated from the deceleration of the motor speed.

[0025] The reverse torque output by the drive motor should not be too large. After the emergency braking system starts to output braking force, the deceleration of the electric vehicle will increase rapidly. In order to prevent the wheels from locking and affecting the driving safety of the electric vehicle, the braking system should be the main braking force.

[0026] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario to shorten the emergency braking distance, and the braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0027] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is used to control the reverse torque output by the drive motor to decrease to zero when the braking force output by the automatic emergency braking system increases from zero.

[0028] Since the braking system of electric vehicles needs a certain amount of time to build up hydraulic pressure to output braking force, during this period, the motor controller needs to control the drive motor to output reverse torque for compensation. When the braking system of the electric vehicle builds up braking force, the output braking force gradually increases, and the reverse torque of the drive motor can gradually stop, and the braking system continues to brake to complete the remaining emergency braking process. The braking is smoothly transitioned from the drive system braking to the braking.

[0029] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario, and the reverse torque output by the drive system smoothly transitions to the braking force output by the braking system, thereby shortening the emergency braking distance and improving vehicle safety.

[0030] In combination with the first aspect, in some implementations of the first aspect, the motor controller is used to control the drive motor to stop outputting torque after the drive motor outputs reverse torque for a preset time period. The deceleration of the electric vehicle within the preset time period is less than the deceleration of the electric vehicle during the process of the automatic emergency braking system outputting braking force after the preset time period.

[0031] Since the braking system of an electric vehicle needs a certain amount of time to build up hydraulic pressure to output braking force, during this period the motor controller needs to control the drive motor to output reverse torque for compensation. The motor controller controls the drive motor to stop outputting torque after controlling the drive motor to output reverse torque for a preset period of time.

[0032] It should be understood that the preset time length may be equal to the time for the brake system to build pressure, that is, the time length from receiving the AEB system enable signal to the brake system outputting the braking force. The preset time length may be calibrated according to the performance of the vehicle's brake system.

[0033] The motor controller does not need to be connected to the brake system signal. The motor controller does not need to detect when the brake system completes the pressure buildup and outputs the braking force. It only needs to control the drive motor to output reverse torque within a preset time after receiving the AEB system enable signal. After the reverse torque is output for a preset time, the drive motor is controlled to stop outputting torque to avoid overlap with the braking force output by the brake system.

[0034] In a possible embodiment, the preset duration is less than or equal to 500 milliseconds.

[0035] Electric vehicles rely on the braking system to complete the entire AEB process. The braking system requires the hydraulic system to build pressure so that the brake caliper clamps the brake disc to generate the braking force of the entire vehicle. This pressure building process usually takes 200 to 500 milliseconds, and the pressure building time is relatively long. During this period, the motor controller can control the drive motor to output reverse torque to brake the electric vehicle. Therefore, in one possible setting, the preset duration is less than or equal to 500 milliseconds.

[0036] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario to generate braking force in turn, so that the electric vehicle can quickly reach the target deceleration and shorten the emergency braking distance. The braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0037] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is used to control the magnitude of the reverse torque output by the drive motor to be less than or equal to the torque limit.

[0038] The torque limit is the maximum reverse torque that the drive motor can output when AEB is triggered. The torque limit is related to the hardware capability and the safety value of the reverse torque output by the drive motor under the condition of ensuring the safety of the hardware and the vehicle at the vehicle speed. The torque limit can be obtained based on the vehicle performance calibration and can be preset.

[0039] According to the solution of the present application, in the scenario where AEB is triggered, the motor controller controls the drive motor to output reverse torque as much as possible to brake the electric vehicle, so that the electric vehicle can quickly reach the target deceleration while ensuring the safety of the electric vehicle as much as possible, shortening the emergency braking distance and improving safety.

[0040] In combination with the first aspect, in certain implementations of the first aspect, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs braking force during the driving process of the electric vehicle, the motor controller is used to receive a reverse torque signal, and the reverse torque indicated by the reverse torque signal is a preset value. The motor controller is used to control the drive motor to output the reverse torque indicated by the reverse torque signal in response to the reverse torque indicated by the reverse torque signal being less than or equal to the torque limit. The motor controller is used to control the drive motor to output the reverse torque corresponding to the torque limit in response to the reverse torque indicated by the reverse torque signal being greater than the torque limit.

[0041] The motor controller is used to receive the reverse torque signal from the vehicle controller, and the reverse torque signal is used to indicate the target torque.

[0042] When AEB is triggered, the controller integrated with the AEB system will send the AEB system enable signal and the required total braking force to the vehicle controller and the brake system controller. After receiving the AEB system enable signal and the total braking force, the vehicle controller will pass it to the motor controller. After the motor controller receives the reverse torque signal sent by the vehicle controller, the reverse torque signal indicates the braking force that needs to be allocated to the drive system. The motor controller will determine the size of the reverse torque that needs to be output based on the reverse torque signal.

[0043] When the absolute value of the target torque is greater than the absolute value of the torque limit, the motor controller outputs the reverse torque corresponding to the torque limit. When the absolute value of the target torque is less than or equal to the absolute value of the torque limit, the motor controller outputs the target torque indicated by the reverse torque signal.

[0044] Regardless of the speed of the electric vehicle, when AEB is triggered, it is usually hoped that the deceleration generated during emergency braking is as large as possible. Therefore, the target torque is a preset value, which can correspond to the adhesion coefficient of the wheel contact. When the drive motor outputs the reverse torque corresponding to the preset value, the electric vehicle can obtain the largest possible braking force and deceleration.

[0045] When the motor controller receives the AEB system enable signal, it immediately controls the drive motor to generate a reverse torque that does not exceed the total braking force determined by the AEB system. The reverse torque is the minimum of the drive motor's maximum reverse torque capacity and the absolute value of the total braking force. When the absolute value of the target torque indicated by the vehicle controller is greater than the absolute value of the torque limit, it means that the drive motor cannot achieve the target indicated by the vehicle controller and can only output reverse torque as much as possible. At this time, the motor controller controls the drive motor to output the reverse torque corresponding to the torque limit. When the absolute value of the target torque indicated by the vehicle controller is less than or equal to the absolute value of the torque limit, it means that the drive motor is capable of completing the target braking force assigned by the vehicle controller. At this time, it only needs to output the target torque assigned by the vehicle controller. At this time, the motor controller controls the drive motor to output the target torque indicated by the reverse torque signal.

[0046] According to the solution of the present application, reverse torque is output within the capability of the drive system, so that the electric vehicle can quickly reach the target deceleration while ensuring the safety of the electric vehicle as much as possible, shortening the emergency braking distance and improving safety.

[0047] In combination with the first aspect, in certain implementations of the first aspect, when the motor controller is used to control the drive motor to output a reverse torque, the magnitude of the reverse torque output by the drive motor does not change with the opening of the accelerator pedal of the electric vehicle.

[0048] The motor controller is used to control the drive motor to output a torque indicated by the opening of the electric vehicle's accelerator pedal during the driving process of the electric vehicle. The motor controller controls the drive motor to output a torque different from the torque indicated by the opening of the accelerator pedal in response to an AEB system enable signal.

[0049] When the AEB system is not triggered, the motor controller will control the output torque of the drive motor according to the torque indicated by the opening of the accelerator pedal, and the electric vehicle will drive normally. When the AEB system is triggered, the motor controller responds to the AEB system enable signal to perform AEB braking control, and no longer responds to the opening of the accelerator pedal to control the drive motor, but directly adjusts the torque output by the drive motor. In an emergency, the driver may not react and still step on the accelerator pedal. If AEB is not triggered, the motor controller responds to the opening of the accelerator pedal to control the drive motor to output positive torque, and the electric vehicle will still drive forward and cause an accident. Therefore, when AEB is triggered, the motor controller controls the drive motor to output a torque that is different from the torque indicated by the opening of the accelerator pedal, and controls the drive motor to output a reverse torque.

[0050] According to the solution of the present application, the motor controller directly performs control during emergency braking, with low communication latency and rapid response time, thereby improving the safety of the electric vehicle.

[0051] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is used to control the drive motor to increase the output reverse torque within a preset time period in response to the actual deceleration of the drive motor indicated by the resolver sensor being less than the target deceleration.

[0052] When the motor controller receives the AEB trigger signal, it obtains the target deceleration indicated by the vehicle controller, and obtains the actual deceleration of the drive motor according to the resolver signal sent by the resolver sensor, and then performs closed-loop control on the target deceleration of the drive motor and the actual deceleration of the drive motor, adjusts the drive motor torque, and continues closed-loop control during emergency braking. When the actual deceleration of the drive motor indicated by the resolver sensor is less than the target deceleration indicated by the vehicle controller, the motor controller increases the output current to control the drive motor to increase the output reverse torque. When the actual deceleration of the drive motor indicated by the resolver sensor is greater than the target deceleration indicated by the vehicle controller, the motor controller reduces the output current to control the drive motor to reduce the output reverse torque.

[0053] In the present application, increasing the output reverse torque can be understood as increasing the absolute value of the reverse torque, and decreasing the output reverse torque can be understood as decreasing the absolute value of the reverse torque.

[0054] According to the solution of the present application, the torque output by the drive motor is precisely controlled in a closed loop through the signal of the resolver sensor, so that when the braking force of the brake system is established, the closed-loop control of the motor controller can quickly stop the reverse torque, so that the braking force output by the drive system and the brake system are smoothly connected, thereby improving the safety of the vehicle.

[0055] In combination with the first aspect, in certain implementations of the first aspect, the motor controller is further used to control the drive motor to stop outputting reverse torque in response to the automatic emergency braking system being turned off during the process of the drive motor outputting reverse torque.

[0056] When the motor controller is driving the motor to output reverse torque, if the AEB process ends prematurely, the motor controller will control the drive motor to stop outputting reverse torque.

[0057] In a possible embodiment, the reverse torque output by the driving motor reduces the speed of the electric vehicle to zero or to a safe range, and the electric vehicle will not collide. Then, the AEB system will be turned off and the AEB system stop signal will be activated.

[0058] In a possible embodiment, when the motor controller drives the motor to output reverse torque, the controller integrated with the AEB system performs further detection, and when it is detected that the AEB is falsely triggered, an AEB system stop signal is sent, thereby terminating the AEB process. This application does not limit how to detect false triggering.

[0059] According to the solution of the present application, when AEB is triggered, the drive system first outputs reverse torque to brake the vehicle, which can reserve confirmation time for AEB, reduce the AEB false trigger rate, and improve vehicle safety.

[0060] In a second aspect, the present application provides a method for shortening the emergency braking distance of an electric vehicle, the method comprising: during the driving process of the electric vehicle, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs a braking force, the drive motor of the electric vehicle outputs a reverse torque. In response to the deceleration of the electric vehicle after the automatic emergency braking system outputs the braking force being greater than or equal to a preset deceleration, the drive motor stops outputting the reverse torque.

[0061] In combination with the second aspect, in certain implementations of the second aspect, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs braking force, the deceleration of the electric vehicle during the process in which the drive motor outputs reverse torque is less than the deceleration of the electric vehicle after the automatic emergency braking system outputs braking force.

[0062] The target deceleration of the electric vehicle caused by the reverse torque output by the driving motor is smaller than the deceleration of the electric vehicle caused by the braking force output by the braking system. The purpose of this treatment is to give priority to the braking system and avoid the locking of the electric vehicle caused by the braking force generated by the driving motor and the braking force output by the braking system at the same time, thereby improving the safety of the vehicle.

[0063] In a third aspect, the present application provides an electric vehicle, the electric vehicle comprising a motor controller, a drive motor, and an automatic emergency braking system as described in the first aspect and various implementations thereof, wherein during the driving of the electric vehicle, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs a braking force, the drive motor of the electric vehicle outputs a reverse torque. In response to the deceleration of the electric vehicle being greater than or equal to a preset deceleration after the automatic emergency braking system outputs a braking force, the drive motor stops outputting the reverse torque.

[0064] The vehicle controller is used to control the drive system to output reverse torque and control the brake system to output target braking force in response to the automatic emergency braking AEB system enable signal during the driving process of the electric vehicle. The AEB system enable signal is used to indicate the start of the AEB system. Among them, the simultaneous control of the drive system to output reverse torque and the control of the brake system to output target braking force includes: the brake system starts to increase the hydraulic pressure to increase the output braking force to the target braking force. The motor controller is used to control the drive motor to output reverse torque before the brake system output reaches the target braking force. The direction of the reverse torque is opposite to the direction of rotation of the rotor of the drive motor. After the brake system output reaches the target braking force, the motor controller is used to control the drive motor to stop outputting torque.

[0065] The electric vehicle includes a sensor for detecting the distance between the electric vehicle and a front obstacle, and the vehicle controller is used to send an alarm prompt in response to the distance between the electric vehicle and the front obstacle detected by the sensor being less than the alarm distance and greater than or equal to the distance threshold. The vehicle controller is used to control the drive system to output a reverse torque and the brake system to output a target braking force in response to the distance between the electric vehicle and the front obstacle detected by the sensor being less than the distance threshold.

[0066] The beneficial effects of other aspects can refer to the beneficial effects described in the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is a schematic diagram of an electric vehicle system architecture provided by an embodiment of the present application;

[0068] Figure 2 The present application provides a schematic diagram of an electric vehicle;

[0069] Figure 3 is a schematic diagram of AEB control provided in an embodiment of the present application;

[0070] Figure 4 is another AEB control schematic diagram provided in an embodiment of the present application;

[0071] Figure 5 This is a schematic diagram of an electric vehicle driving provided by an embodiment of the present application;

[0072] Figure 6 It is a schematic diagram of the AEB control process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The following will describe the technical solution in the present application in conjunction with the accompanying drawings. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0074] The automatic emergency braking (AEB) system is a very important safety feature. It uses radar and cameras to monitor the vehicles and pedestrians ahead. If a potential collision risk is detected, the system will take corresponding warning and braking measures to avoid a collision or reduce the degree of collision damage. When the measured distance is less than the alarm distance, an alarm will be given, and when it is less than the safe distance, the AEB system will start, causing the car to brake automatically, thus ensuring safe travel. In order to prevent false triggering of AEB, the recognition distance is usually limited, which usually requires reducing the braking distance.

[0075] In a possible implementation, AEB control completes the emergency parking process through the hydraulic braking system. The execution process is as follows: In the AEB triggering scenario, when the advanced driver assistance systems (ADAS) determines that the distance to the front vehicle or obstacle is less than the safe distance, the ADAS controller sends the AEB system enable signal, target deceleration or target braking force to the braking system, and then the braking system executes the AEB process according to the target deceleration or target braking force sent by ADAS to control the vehicle to stop in an emergency.

[0076] It should be understood that the above method of using the electric vehicle hydraulic brake system to complete AEB control requires the hydraulic system to build pressure so that the brake caliper clamps the brake disc and generates braking force for the entire vehicle. This process usually takes about 200 to 500 milliseconds, and the pressure building time is relatively long. Untimely braking will increase the AEB braking distance. Taking a vehicle speed of 80km / h as an example, if it takes 200 milliseconds to build pressure, the running distance of the vehicle without braking during this period is 4.5m.

[0077] Based on the above problems, the present application provides a motor controller, method and electric vehicle for shortening the emergency braking distance. When the hydraulic braking force is not fully established when AEB is triggered, the drive motor responds quickly and outputs braking torque to reduce the vehicle speed. The drive system and the braking system cooperate with each other, thereby shortening the AEB braking distance or increasing the AEB intervention speed while the AEB braking distance remains unchanged, reducing the false triggering rate of AEB and improving the safety of the vehicle.

[0078] Figure 1 and Figure 2 Schematic diagram of the electric vehicle 10 architecture provided in an embodiment of the present application.

[0079] like Figure 1 As shown, the electric vehicle 10 includes a vehicle controller 20, a drive system 30 and a brake system 40. The drive system 30 includes a motor controller 50 and a drive motor 60. The motor controller 50 is used to output current to the drive motor 60 to control the drive motor 60 to output a positive torque to drive the electric vehicle 10. The brake system 40 is used to brake the electric vehicle 10 by establishing a hydraulic output braking force.

[0080] The electric vehicle 10 may be a wheel-side four-drive motor drive architecture, where the drive motor 60 is arranged on the side of the driven wheel and is controlled by a separate motor controller 50. The electric vehicle 10 may also be a centralized drive motor drive architecture, where two motors for driving two front wheels or two rear wheels are arranged together.

[0081] There may be one or more motor controllers 50 . The motor controllers 50 and the drive motors 60 may correspond one to one, or one motor controller 50 may correspond to multiple drive motors 60 . The motor controller 50 is used to control one or more drive motors 60 to output torque to drive the electric vehicle 10 .

[0082] The motor controller provided in the implementation of the present application may be any one of a plurality of motor controllers. The following embodiments only take one motor controller as an example, and the actions of other motor controllers may be similarly understood by referring to the description.

[0083] In one embodiment, the motor controller 50 includes a signal interface, and the motor controller 50 is connected to the vehicle controller 20 and other motor controllers 50 through the signal interface. The vehicle controller 20 is connected to the accelerator pedal signal, and the vehicle controller 20 calculates the vehicle torque demand according to the opening of the accelerator pedal during the driving of the electric vehicle 10, and sends a torque signal to the motor controller 50 according to the vehicle torque demand. Each motor controller 50 controls the corresponding drive motor 60 to output torque to drive the corresponding wheel according to the indication of the torque signal.

[0084] In one embodiment, the motor controller 50 is connected to a resolver sensor via a signal interface. The resolver sensor is used to detect the rotation speed of the drive motor 60 controlled by the motor controller 50 . The motor controller 50 is used to receive a signal from the resolver sensor.

[0085] The resolver sensor can accurately detect the position, direction and speed of the motor rotor, is responsible for monitoring and extracting the rotation speed of the drive motor, has a high sampling rate, and is directly connected to the motor controller 50 by signal.

[0086] like Figure 2 As shown, the brake system 40 includes a brake controller 70 and a plurality of hydraulic brake devices 80, and the brake controller 70 is connected to the brake pedal 120 by signal. The brake controller 70 can be used to determine the braking force according to the opening of the brake pedal 120. During the driving process, when the electric vehicle 10 needs to brake, the driver steps on the brake pedal, and the brake controller 70 receives the brake pedal signal from the brake pedal 120 and outputs a braking force distribution signal to the hydraulic brake device 80. The hydraulic brake device 80 is used to receive the braking force distribution signal and establish hydraulic pressure according to the instruction of the braking force distribution signal and output a clamping force to the brake disc, thereby generating a friction braking force, so that the electric vehicle 10 is braked.

[0087] In one embodiment, the vehicle controller 20 is connected to the brake pedal 120. The vehicle controller 20 calculates the vehicle braking demand based on the brake pedal opening of the electric vehicle 10 during driving and sends a braking signal to the brake controller 70 based on the vehicle braking demand. The brake controller 70 controls the corresponding hydraulic brake device to brake the corresponding wheel according to the indication of the braking signal.

[0088] The electric vehicle also includes an automatic emergency braking (AEB) system, which is used to output a braking force to brake the electric vehicle after being triggered. The AEB system can be provided with a separate controller, or it can be integrated into the vehicle controller 20 or the advanced driver assistance system (ADAS) controller. When the controller integrated with the AEB system determines that the AEB system is triggered, it will send an AEB system enable signal to the vehicle controller 20 and / or the motor controller 50. The AEB system enable signal is used to indicate the activation of AEB for automatic braking.

[0089] The controller integrated with the AEB system sends relevant signals to the motor controller 50, and communication can be performed via a controller area network (CAN) or other communication methods.

[0090] In one embodiment, the electric vehicle 10 includes a sensor for detecting the distance between the electric vehicle 10 and a front obstacle, and the vehicle controller 20 is used to send an alarm prompt in response to the distance between the electric vehicle 10 and the front obstacle detected by the sensor being less than the alarm distance and greater than or equal to the distance threshold. The vehicle controller 20 is used to control the drive system 30 to output a reverse torque and the brake system 40 to output a target braking force in response to the distance between the electric vehicle 10 and the front obstacle detected by the sensor being less than the distance threshold.

[0091] Figure 3 It is a flow chart of shortening the emergency braking distance provided by an embodiment of the present application.

[0092] like Figure 3 As shown, the vehicle controller 20 is used to respond to an automatic emergency braking AEB system enable signal during the driving process of the electric vehicle 10, and simultaneously control the drive system 30 to output reverse torque and the brake system 40 to output target braking force. The AEB system enable signal is used to indicate that the AEB system is triggered.

[0093] A controller integrated with the AEB system, such as an ADAS controller, sends the AEB system enable signal and the target braking force or target deceleration to the braking system 40 and the driving system 30 simultaneously.

[0094] The controller integrated with the AEB system sends relevant signals to the motor controller 50, and can use conventional CAN communication or other faster communication methods to reduce communication delay and further reduce the AEB braking distance.

[0095] The vehicle controller 20 is used to send a reverse torque signal to the motor controller 50 . The reverse torque signal is used to indicate a target torque. The reverse torque indicated by the reverse torque signal is a preset value.

[0096] The vehicle controller 20 is used to send a braking signal to the braking system 40 , and the braking signal is used to indicate a target braking force.

[0097] It should be understood that no matter how fast the electric vehicle 10 is, when AEB is triggered, it is generally desired that the deceleration generated during emergency braking is as large as possible. The target torque and target braking force may correspond to the adhesion coefficient of the wheel contact and may be obtained by calibration. When the drive motor outputs the target torque or the brake system outputs the target braking force, the electric vehicle 10 may obtain the largest possible braking force and deceleration.

[0098] After the AEB is triggered, that is, the braking system 40 receives the AEB system enable signal, the braking system 40 starts to increase the hydraulic pressure to increase the output braking force to the target braking force.

[0099] The brake controller 70 controls the hydraulic brake device to start building up hydraulic pressure. The piston in the master cylinder is pushed to compress the brake fluid in the brake booster. After the brake fluid is compressed, hydraulic pressure is generated. This pressure is transmitted to the brake cylinder of each wheel through the brake line. After the brake cylinder (also called the brake cylinder or wheel cylinder) is subjected to hydraulic pressure, it pushes the piston in the cylinder to move outward. The movement of the cylinder piston will push the brake components in the brake (such as the brake pads in the brake caliper) to contact the brake disc, generating braking force. The friction between the brake pads and the brake disc generates braking force, which acts on the wheels to slow down or stop the wheels from rotating.

[0100] During this process, the brake system 40 is unable to output braking force or unable to output target braking force.

[0101] The motor controller 50 is used to increase the output current to control the drive motor 60 to output a reverse torque within a preset time period before the brake system output reaches the target braking force. The direction of the reverse torque is opposite to the rotor rotation direction of the drive motor 60.

[0102] During the driving process of the electric vehicle 10, the motor controller 50 is used to control the drive motor 60 to output a reverse torque after the automatic emergency braking system is triggered and before the automatic emergency braking system outputs the braking force, and the direction of the reverse torque is opposite to the rotational speed direction of the drive motor.

[0103] The motor controller 50 can output three-phase alternating current to the drive motor, thereby controlling the output torque of the drive motor 60. The drive motor 60 includes a stator winding and a rotor. The motor controller 50 can control the output torque of the drive motor 60 by outputting alternating current to the three-phase stator winding. The motor controller 50 can change the stator magnetic field strength and direction by adjusting the magnitude of the input stator winding current and the phase of the three-phase current, thereby changing the interaction force between the stator and the rotor, that is, controlling the torque output by the drive motor 60. Reverse torque can also be called negative torque. Positive torque is used to drive the vehicle, and negative torque is used to brake the vehicle. The motor controller 50 can change the phase of the three-phase current output to the drive motor 60 so that the rotor cuts the magnetic field generated by the stator winding, and the kinetic energy of the rotor is converted into electrical energy and input into the power battery. At this time, the drive motor 60 outputs negative torque. The motor controller 50 changes the magnitude of the three-phase current output to the drive motor 60, and the positive torque or negative torque output by the motor can be increased or decreased.

[0104] It should be understood that for an electric vehicle 10 with multiple drive motors, if AEB is triggered, the drive motors 60 driving the coaxial wheels, for example, the two drive motors 60 driving the two front wheels or the two rear wheels, should output the same reverse torque to avoid yaw torque and vehicle loss of control. Therefore, if the electric vehicle 10 has multiple motor controllers 50 controlling the multiple drive motors 60, the motor controllers 50 need to control the reverse torque output by the drive motors 60 to be equal to the reverse torque output by the drive motors 60 driving the coaxial wheels.

[0105] It takes a certain amount of time for the brake system 40 to build up hydraulic pressure and output braking force. During this period of time, the electric vehicle 10 is not decelerated by the braking force. However, the drive motor 60 does not need to build up pressure, and the torque control response time is shorter than the time for the brake system 40 to build up pressure. Therefore, the motor controller 50 can be used to control the drive motor to output reverse torque during the period when the brake system 40 builds pressure, thereby quickly braking the electric vehicle 10.

[0106] In one embodiment, the motor controller is used to control the drive motor to stop outputting torque after the drive motor outputs reverse torque for a preset time period. The deceleration of the electric vehicle 10 within the preset time period is less than the deceleration of the electric vehicle 10 during the process of the automatic emergency braking system outputting braking force after the preset time period.

[0107] In some possible embodiments, the preset time length may be equal to the time it takes for the brake system to build pressure, that is, the time length from when the AEB system enable signal is received to when the brake system outputs the braking force. The preset time length may be calibrated according to the performance of the vehicle's brake system.

[0108] It should be understood that the preset time length may be equal to the time for the brake system to build pressure, that is, the time length from receiving the AEB system enable signal to the brake system outputting the braking force. The preset time length may be calibrated according to the performance of the vehicle's brake system.

[0109] The motor controller 50 does not need to be connected to the brake system 40 signal. The motor controller 50 does not need to detect when the brake system 40 completes the pressure buildup and outputs the braking force. It only needs to control the drive motor 60 to output the reverse torque within a preset time after receiving the AEB system enable signal. After the reverse torque is output for a preset time, the drive motor 60 is controlled to stop outputting the torque to avoid overlap with the braking force output by the brake system 40.

[0110] In a possible setting manner, the preset duration is less than or equal to 500 milliseconds.

[0111] The electric vehicle 10 relies on the braking system 40 to complete the entire AEB process. The braking system 40 requires the hydraulic system to build pressure so that the brake caliper clamps the brake disc to generate the braking force of the entire vehicle. The pressure building process usually takes 200 to 500 milliseconds, and the pressure building time is relatively long. During this period of time, the motor controller 50 can control the drive motor 60 to output reverse torque to brake the electric vehicle 10. Therefore, the preset time length can be less than or equal to 500 milliseconds.

[0112] In some other possible embodiments, the preset duration may also be equal to the entire AEB automatic braking time, that is, the time from receiving the AEB system enable signal to the electric vehicle 10 stopping. If the electric controller is fully functional, the reverse torque will decrease after the braking system outputs the braking force. At the same time, the long-term operating capability of the drive motor itself and the kinetic energy recovery capability of the power battery must also be considered.

[0113] In one embodiment, the motor controller 50 is configured to control the drive motor 60 to output reverse torque until the speed of the electric vehicle 10 is reduced to zero.

[0114] The motor control machine 50 can control the drive motor 60 to output reverse torque during the entire process from AEB triggering to automatic braking to stopping. Before the braking system outputs braking force, a larger reverse torque can be output to make up for the blank time of the braking force, and after the braking system 40 starts to output braking force, the reverse torque is reduced. If the electric controller 50 is in full effect, the long-term operation capability of the drive motor itself and the kinetic energy recovery capability of the power battery must also be considered.

[0115] In the process that the motor controller 50 controls the driving motor to output the reverse torque, the deceleration of the electric vehicle 10 before the emergency braking system outputs the braking force is smaller than the deceleration of the electric vehicle 10 after the emergency braking system outputs the braking force.

[0116] The reverse torque output by the drive motor 60 should not be too large. After the emergency brake system starts to output braking force, the deceleration of the electric vehicle 10 will increase rapidly. In order to prevent the wheels from locking and affecting the driving safety of the electric vehicle 10, the braking system should be used as the main braking force.

[0117] According to the solution of the present application, the drive system and the braking system work together in the AEB scenario to shorten the emergency braking distance, and the braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0118] In one embodiment, the motor controller 50 is used to control the drive motor 60 to stop outputting the reverse torque in response to the automatic emergency braking system outputting a braking force and the deceleration of the electric vehicle 10 being greater than or equal to a preset deceleration during the process of controlling the drive motor 60 to output the reverse torque.

[0119] The motor controller 50 can be connected to the brake system 40 or the vehicle controller 20 signal. When the automatic emergency braking system starts to output braking force, the deceleration of the electric vehicle 10 will increase rapidly. When the braking force output by the brake system 40 causes the electric vehicle 10 to have sufficient deceleration, the motor controller 50 can control the driving motor to stop outputting reverse torque and exit braking in time to avoid overlap with the braking force output by the brake system 40, which would cause the wheels to lock.

[0120] According to the solution of the present application, the drive system and the brake system work together in the AEB scenario to generate braking force in turn, so that the electric vehicle 10 can quickly reach the target deceleration and shorten the emergency braking distance. The braking system is given priority to avoid simultaneous action that may cause wheel locking, thereby improving vehicle safety.

[0121] In one embodiment, before the automatic emergency braking system outputs braking force, during the process in which the motor controller 50 is used to control the drive motor 60 to output reverse torque, the deceleration of the electric vehicle 10 is less than the preset deceleration or the deceleration of the drive motor is less than the preset deceleration.

[0122] The deceleration of the driving motor can be understood as the deceleration of the motor speed. The motor speed and the vehicle speed usually have a corresponding relationship. Therefore, the deceleration of the electric vehicle 10 can be calculated from the deceleration of the motor speed. The reverse torque output by the driving motor 60 should not be too large. After the emergency braking system starts to output braking force, the deceleration of the electric vehicle 10 will increase rapidly. In order to prevent the wheels from locking and affecting the driving safety of the electric vehicle 10, the braking of the braking system 40 should be the main focus.

[0123] In one embodiment, the motor controller 50 is configured to control the reverse torque output by the drive motor 60 to decrease to zero when the braking force output by the automatic emergency braking system increases from zero.

[0124] Since the brake system 40 of the electric vehicle 10 needs a certain period of time to build up hydraulic pressure to output braking force, during this period, the motor controller 50 needs to control the drive motor 60 to output reverse torque for compensation. When the brake system 40 of the electric vehicle 10 builds up braking force, the output braking force gradually increases, and the reverse torque of the drive motor 60 can gradually stop, and the brake system 40 continues to brake to complete the remaining emergency braking process. The braking is smoothly transitioned from the driving system braking to the braking.

[0125] The motor controller 50 is used to control the magnitude of the reverse torque output by the drive motor 60 to be less than or equal to the torque limit.

[0126] The torque limit is the maximum reverse torque capacity that the drive motor 60 can output when the AEB is triggered. The torque limit is related to the hardware capability and the safety value of the reverse torque output by the drive motor 60 under the condition of ensuring the safety of the hardware and the vehicle at the vehicle speed. The torque limit can be obtained according to the vehicle performance calibration and can be preset.

[0127] In one embodiment, during the driving process of the electric vehicle 10, after the automatic emergency braking system of the electric vehicle 10 is triggered and before the automatic emergency braking system outputs the braking force, the motor controller 50 is used to receive a reverse torque signal, and the reverse torque indicated by the reverse torque signal is a preset value. The motor controller 50 is used to control the drive motor 60 to output the reverse torque indicated by the reverse torque signal in response to the reverse torque indicated by the reverse torque signal being less than or equal to the torque limit. The motor controller 50 is used to control the drive motor 60 to output the reverse torque corresponding to the torque limit in response to the reverse torque indicated by the reverse torque signal being greater than the torque limit.

[0128] When AEB is triggered, the controller integrated with the AEB system will send the AEB system enable signal and the required total braking force to the vehicle controller 20 and the brake controller 70. After receiving the AEB system enable signal and the total braking force, the vehicle controller 20 will transparently transmit them to the motor controller 50. After the motor controller 50 receives the reverse torque signal sent by the vehicle controller 20, the reverse torque signal indicates the braking force to be allocated to the drive system 30, and the motor controller 50 will determine the magnitude of the reverse torque to be output according to the reverse torque signal.

[0129] The torque limit is the maximum reverse torque capacity that the drive motor 60 can output when the AEB is triggered. The torque limit is related to the hardware capability and the safety value of the reverse torque output by the drive motor 60 under the condition of ensuring the safety of the hardware and the vehicle at the vehicle speed. The torque limit can be obtained according to the vehicle performance calibration and can be a preset value.

[0130] When the motor controller 50 receives the AEB system enable signal, it immediately controls the drive motor 60 to generate a reverse torque that does not exceed the total braking force determined by the AEB system. The reverse torque is the minimum of the maximum reverse torque capacity of the drive motor 60 and the absolute value of the total braking force. When the absolute value of the target torque indicated by the vehicle controller 20 is greater than the absolute value of the torque limit, it means that the drive motor 60 cannot achieve the target indicated by the vehicle controller 20 and can only output the reverse torque as much as possible. At this time, the motor controller 50 controls the drive motor 60 to output the reverse torque corresponding to the torque limit. When the absolute value of the target torque indicated by the vehicle controller 20 is less than or equal to the absolute value of the torque limit, it means that the drive motor 60 is capable of completing the target braking force assigned by the vehicle controller 20. At this time, it only needs to output the target torque assigned by the vehicle controller 20. At this time, the motor controller 50 controls the drive motor 60 to output the target torque indicated by the reverse torque signal.

[0131] According to the solution of the present application, reverse torque is output within the capability of the drive system 30, so that the electric vehicle 10 can quickly reach the target deceleration while ensuring the safety of the electric vehicle 10 as much as possible, shortening the emergency braking distance and improving safety.

[0132] When the motor controller 50 is used to control the drive motor 60 to output the reverse torque, the magnitude of the reverse torque output by the drive motor 60 does not change with the opening degree of the accelerator pedal of the electric vehicle 10 .

[0133] The motor controller 50 is used to control the drive motor 60 to output a torque indicated by the opening of the accelerator pedal of the electric vehicle 10 during the driving process of the electric vehicle 10. In response to the AEB system enable signal, the motor controller 50 controls the drive motor 60 to output a torque different from the torque indicated by the opening of the accelerator pedal.

[0134] When the AEB system is not triggered, the motor controller 50 controls the output torque of the drive motor 60 according to the torque indicated by the opening of the accelerator pedal, and the electric vehicle 10 runs normally. When the AEB system is triggered, the motor controller 50 performs AEB braking control in response to the AEB system enable signal, and no longer controls the drive motor 60 in response to the opening of the accelerator pedal, but directly adjusts the torque output by the drive motor 60.

[0135] According to the solution of the present application, the motor controller directly performs control during emergency braking, the communication delay is low, the response time is fast, and the safety of the electric vehicle 10 is improved.

[0136] like Figure 4As shown, in one embodiment, the vehicle controller 20 indicates a target deceleration to the motor controller 50, and the motor controller 50 is used to control the drive motor 60 to increase the output reverse torque within a preset time period in response to the actual deceleration of the drive motor 60 indicated by the resolver sensor being less than the target deceleration indicated by the vehicle controller 20.

[0137] When the motor controller 50 receives the AEB trigger signal, it obtains the target deceleration indicated by the vehicle controller 20, and obtains the actual deceleration of the drive motor 60 according to the resolver signal sent by the resolver sensor, and then performs closed-loop control on the target deceleration of the drive motor 60 and the actual deceleration of the drive motor 60, adjusts the torque output by the drive motor 60, and continues to perform closed-loop control during emergency braking. When the actual deceleration of the drive motor 60 indicated by the resolver sensor is less than the target deceleration indicated by the vehicle controller 20, the motor controller 50 increases the output current to control the drive motor to increase the output reverse torque. When the actual deceleration of the drive motor 60 indicated by the resolver sensor is greater than the target deceleration indicated by the vehicle controller 20, the motor controller 50 reduces the output current to control the drive motor 60 to reduce the output reverse torque.

[0138] The target braking force causes the electric vehicle 10 to have a deceleration greater than the deceleration caused by the reverse torque.

[0139] The target deceleration generated by the electric vehicle 10 due to the reverse torque output by the drive motor 60 is smaller than the deceleration generated by the braking force output by the braking system 40. The purpose of this treatment is to give priority to the braking system and avoid the braking force generated by the drive motor 60 and the braking force output by the braking system 40 acting at the same time, which may cause the wheels of the electric vehicle 10 to lock, thereby improving the safety of the vehicle.

[0140] Exemplarily, the motor controller 50 processes the vehicle target deceleration to obtain the target deceleration of the drive motor 60. The target deceleration of the drive motor 60 is equal to the vehicle target deceleration minus the set value δ, where δ is greater than 0. For example, the vehicle target deceleration is 9m / s 2 , take δ as 2m / s 2 , then the target deceleration of the drive motor 60 is 7m / s 2 .

[0141] When AEB is triggered and the braking force of the brake system 40 has not been established, the deceleration of the electric vehicle 10 is very small, and the reverse torque is quickly output through the closed loop of the drive motor. When the braking force of the brake system 40 is established, the deceleration of the whole vehicle will reach the target deceleration, which is greater than the target deceleration of the drive motor 60. The closed loop system of the drive motor 60 will quickly withdraw the reverse torque, so that the drive system 30 and the brake system 40 are smoothly connected. The closed loop control output of the drive motor is limited to the maximum negative torque of the drive motor to 0.

[0142] After the brake system 40 outputs the target braking force, the motor controller 50 is used to control the drive motor 60 to stop outputting torque.

[0143] In one embodiment, the motor controller 50 is further configured to control the drive motor 60 to stop outputting torque after controlling the drive motor 60 to output reverse torque for a preset period of time.

[0144] The motor controller 50 is specifically used to control the drive motor 60 to output reverse torque within a preset time period before the AEB system outputs braking force to the electric vehicle 10 in response to the AEB system enable signal during the driving process of the electric vehicle 10. After the preset time period, the AEB system outputs braking force and controls the drive motor 60 to stop outputting torque.

[0145] According to the solution of the present application, when AEB is triggered, a fast-response motor controller is used to control the drive motor to output reverse torque, thereby filling the lack of hydraulic braking force for a certain period of time. Without increasing the hardware cost of the vehicle, the braking distance of the vehicle in the AEB scenario is shortened, thereby improving the safety of the vehicle.

[0146] In one embodiment, the motor controller 50 is further configured to control the drive motor 60 to stop outputting the reverse torque in response to the automatic emergency braking system being turned off during the process in which the drive motor 60 outputs the reverse torque.

[0147] When the motor controller 50 is driving the motor 60 to output the reverse torque, if the AEB process ends prematurely, the motor controller 50 will control the driving motor 60 to stop outputting the reverse torque.

[0148] When the motor controller drives the motor to output reverse torque, the controller integrated with the AEB system performs further detection. When it is detected that the AEB is falsely triggered, the AEB system stop signal is sent to terminate the AEB process. Thus, the braking system 40 does not need to output braking force. This application does not limit how to detect false triggering.

[0149] According to the solution of the present application, when AEB is triggered, the drive system first outputs reverse torque to brake the vehicle, which can reserve confirmation time for AEB, reduce the AEB false trigger rate, and improve vehicle safety.

[0150] The present application provides a method for shortening the emergency braking distance of an electric vehicle.

[0151] The method can be applied to the electric vehicle 10 described above.

[0152] The control method includes that during the running process of the electric vehicle 10, after the automatic emergency braking system of the electric vehicle 10 is triggered and before the automatic emergency braking system outputs the braking force, the driving motor 60 of the electric vehicle 10 outputs the reverse torque. In response to the deceleration of the electric vehicle 10 after the automatic emergency braking system outputs the braking force being greater than or equal to the preset deceleration, the driving motor 60 stops outputting the reverse torque.

[0153] In one embodiment, after the automatic emergency braking system of the electric vehicle 10 is triggered and before the automatic emergency braking system outputs braking force, the deceleration of the electric vehicle 10 during the process in which the drive motor 60 outputs reverse torque is less than the deceleration of the electric vehicle 10 after the automatic emergency braking system outputs braking force.

[0154] According to the solution of the present application, the response time of the output torque of the drive motor 60 can usually be within 50ms. By utilizing the cooperation between the drive system 30 and the brake system 40, the braking distance of AEB can be shortened when the initial vehicle speed remains unchanged, or the intervention speed can be increased when the AEB braking distance remains unchanged, thereby further improving the safety of the entire vehicle. At the same time, confirmation time can be reserved for AEB to reduce the false trigger rate of AEB.

[0155] Taking the AEB target deceleration as -0.9g and the braking force provided by the drive motor as -0.4g as an example, the shortened braking distances of triggering AEB at different vehicle speeds of the electric vehicle 10 are shown in Table 1 below:

[0156] Table 1. Shortened emergency braking distance at different AEB triggering speeds

[0157] AEB triggering speed (km / h) The braking distance shortened value under this application method / m 90 2.266667 80 2.019753 70 1.77284 60 1.525926 50 1.279012

[0158] Combine the following Figure 5 and Figure 6 A possible AEB braking process is described.

[0159] like Figure 5 As shown, when the electric vehicle 10 is driving, the sensor continuously detects the distance to the vehicle in front or the obstacle, and then uses the data analysis module to compare the measured distance with the warning distance and the safety distance, and issues an alarm when the distance is less than the warning distance.

[0160] like Figure 5 and Figure 6 As shown, at time t1, the sensor detects that the distance between the electric vehicle 10 and the obstacle in front is less than the distance threshold, and the AEB system is triggered.

[0161] The controller integrated with the AEB system sends a total target braking force and an AEB system enable signal to the driving system 30 and the braking system 40 at the same time.

[0162] In response to the AEB system enable signal, the vehicle controller 20 controls the driving system 30 to output a reverse torque and controls the braking system 40 to output a target braking force.

[0163] The brake system 40 begins to build up hydraulic pressure at time t1 in response to the AEB system enabling signal, at which time no or very little braking force can be output.

[0164] In response to the AEB trigger, the motor controller 50 in the drive system 30 controls the drive motor 60 to output reverse torque within a preset time at time t1, and the drive motor 60 starts to adjust the torque output in response from time t1, and reaches the indicated reverse torque at time t2. The time from time t1 to t2 is the response time of the motor controller 50 and the drive motor 60, which is usually about 50 milliseconds.

[0165] After the driving motor 60 outputs the reverse torque, the speed of the electric vehicle 10 begins to decrease.

[0166] At time t3, the brake system 40 has completed the pressure build-up and starts to output the target braking force. The vehicle deceleration will reach the target deceleration, and the closed-loop control of the drive motor 60 will quickly stop the torque output, so that the drive system 30 and the brake system 40 are smoothly connected. The preset time period from t1 to t3 is the pressure build-up time of the brake system 40.

[0167] At time t4, the speed of the electric vehicle 10 drops to 0 or reaches a speed at which no collision will occur, and the entire AEB process is completed.

[0168] According to the present application, the drive motor responds quickly and outputs braking torque to reduce the vehicle speed within the time when the hydraulic braking force is not fully established when AEB is triggered. The drive system and the braking system cooperate with each other, thereby shortening the AEB braking distance or increasing the AEB intervention speed while keeping the AEB braking distance unchanged, reducing the false triggering rate of AEB and improving the safety of the vehicle.

[0169] Those of ordinary skill 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 to be beyond the scope of this application.

[0170] In the several embodiments provided in the present 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 only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, 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.

[0171] 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 can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods 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.

[0172] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A motor controller for shortening emergency braking distance, characterized in that: The motor controller is used for an electric vehicle, and is used to control the drive motor of the electric vehicle to output a positive torque to drive the wheels of the electric vehicle. The electric vehicle also includes an automatic emergency braking system, and the automatic emergency braking system is used to output a braking force to brake the electric vehicle after being triggered; The motor controller is also used to: control the drive motor to output reverse torque after the automatic emergency braking system is triggered and before the automatic emergency braking system outputs braking force during the driving process of the electric vehicle, and the direction of the reverse torque is opposite to the direction of the rotation speed of the drive motor.

2. The motor controller according to claim 1, wherein: The motor controller is used to control the drive motor to output the reverse torque until the speed of the electric vehicle is reduced to zero.

3. The motor controller according to claim 2, characterized in that: During the process in which the motor controller controls the drive motor to output the reverse torque, the deceleration of the electric vehicle before the emergency brake system outputs the braking force is smaller than the deceleration of the electric vehicle after the emergency brake system outputs the braking force.

4. The motor controller according to claim 1, wherein: The motor controller is used to: During the process of controlling the drive motor to output the reverse torque, in response to the automatic emergency braking system outputting a braking force and the deceleration of the electric vehicle being greater than or equal to a preset deceleration, the drive motor is controlled to stop outputting the reverse torque.

5. The motor controller according to claim 4, characterized in that: In the process in which the motor controller is used to control the drive motor to output the reverse torque before the automatic emergency braking system outputs the braking force, the deceleration of the electric vehicle is less than the preset deceleration or the deceleration of the drive motor is less than the preset deceleration.

6. The motor controller according to claim 4, characterized in that: The motor controller is used to: During the process in which the braking force output by the automatic emergency braking system increases from zero, the motor controller controls the reverse torque output by the drive motor to decrease to zero.

7. The motor controller according to claim 1, characterized in that: The motor controller is used to: After the drive motor outputs the reverse torque for a preset period of time, controlling the drive motor to stop outputting the torque; The deceleration of the electric vehicle within the preset time period is smaller than the deceleration of the electric vehicle during the process in which the automatic emergency braking system outputs the braking force after the preset time period.

8. The motor controller according to any one of claims 1 to 7, characterized in that: The motor controller is used to control the magnitude of the reverse torque output by the drive motor to be less than or equal to a torque limit.

9. The motor controller according to claim 8, characterized in that: During the driving process of the electric vehicle, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs a braking force, the motor controller is used to receive a reverse torque signal, and the reverse torque indicated by the reverse torque signal is a preset value; The motor controller is used to: In response to the reverse torque indicated by the reverse torque signal being less than or equal to the torque limit, controlling the drive motor to output the reverse torque indicated by the reverse torque signal; In response to the reverse torque indicated by the reverse torque signal being greater than the torque limit, the drive motor is controlled to output a reverse torque corresponding to the torque limit.

10. The motor controller according to claim 1, wherein: When the motor controller is used to control the drive motor to output the reverse torque, the magnitude of the reverse torque output by the drive motor does not change with the opening of the accelerator pedal of the electric vehicle.

11. The motor controller according to claim 1, wherein: The motor controller is used to: In response to the actual deceleration of the drive motor indicated by the resolver sensor being less than the target deceleration, the drive motor is controlled to increase the output of the reverse torque.

12. The motor controller according to claim 1, wherein: The motor controller is also used to: During the process in which the drive motor outputs the reverse torque, in response to the automatic emergency braking system being turned off, the drive motor is controlled to stop outputting the reverse torque.

13. A method for shortening the emergency braking distance of an electric vehicle, characterized in that: The method comprises: During the driving process of the electric vehicle, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs a braking force, the driving motor of the electric vehicle outputs a reverse torque; In response to a deceleration of the electric vehicle being greater than or equal to a preset deceleration after the automatic emergency braking system outputs a braking force, the drive motor stops outputting a reverse torque.

14. The method according to claim 13, characterized in that After the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs braking force, the deceleration of the electric vehicle during the process of the drive motor outputting reverse torque is less than the deceleration of the electric vehicle after the automatic emergency braking system outputs braking force.

15. An electric vehicle, characterized in that: The electric vehicle comprises a motor controller, a drive motor, and an automatic emergency braking system according to any one of claims 1 to 12; wherein: During the driving process of the electric vehicle, after the automatic emergency braking system of the electric vehicle is triggered and before the automatic emergency braking system outputs a braking force, the driving motor of the electric vehicle outputs a reverse torque; In response to a deceleration of the electric vehicle being greater than or equal to a preset deceleration after the automatic emergency braking system outputs a braking force, the drive motor stops outputting a reverse torque.

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