Fault-tolerant control method for electric drive system of new energy commercial vehicle based on distributed drive

Abstract

The application provides a fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed driving, and has the characteristics that a vehicle controller receives fault information and vehicle information sent by a middle axle drive motor controller and a rear axle drive motor controller in real time; a target function is established based on the fault information and the vehicle information obtained by the vehicle controller, and total demand torque and yaw torque are solved; based on the obtained total demand torque, a drive motor driving force reconstruction strategy is formulated according to different fault information and in combination with a current driving condition, so that the vehicle can maintain a desired driving state. According to different fault conditions of the drive motor, the application adopts a corresponding control strategy, adjusts control parameters in real time to eliminate or weaken the motor fault, maximally reduces the influence of the fault on the driving state of the vehicle, and guarantees the stability and safety of the vehicle.

Description

Technical Field

[0001] This invention proposes a fault-tolerant control method for electric drive systems of new energy commercial vehicles based on distributed drive, which relates to the field of commercial vehicle drive system design and control. Background Technology

[0002] In the field of new energy commercial vehicles, the design of the drive system is crucial to the overall vehicle performance, reliability, and safety. Currently, the mainstream drive solutions for new energy commercial vehicles mainly include the electric motor + automatic manual transmission (AMT) solution and the centralized electric drive axle solution.

[0003] In the electric motor + AMT (Automated Manual Transmission) solution, the drive motor is typically located under the cab, with its output directly connected to the input shaft of the AMT transmission, forming a series connection. The AMT transmission's output then transmits power to the vehicle's rear or front axle via a drive shaft. This solution has significant technical drawbacks: when the drive motor experiences a minor malfunction, its torque output often needs to be limited, leading to a significant decrease in vehicle power performance and affecting normal driving; more seriously, if the drive motor experiences a severe malfunction and stops, the entire drive system will lose its power output capability, and the vehicle will completely lose power, posing a serious safety hazard.

[0004] Another widely used solution is the centralized electric drive axle solution. This solution highly integrates key components such as the drive motor, transmission, and differential within the axle, forming a compact electric drive unit. The power from the drive motor is reduced and amplified by the integrated transmission before being distributed to the left and right wheels by the differential. For commercial vehicles requiring dual-axle drive (such as 6x4, 8x4, etc.), two independently operating centralized electric drive axles are typically used. This solution improves redundancy: for dual-axle drive vehicles, if one electric drive axle fails, the other can usually still operate independently, providing partial drive force to the vehicle and preventing complete loss of power. However, this solution still has shortcomings: for single-axle drive (such as 4x2) commercial vehicles, a serious failure of the drive motor in its sole electric drive axle will also cause the entire drive axle to fail, and the vehicle will inevitably lose power.

[0005] Therefore, existing new energy commercial vehicle drive systems, whether electric motor + AMT or centralized electric drive axle solutions, all face the risk of complete loss of vehicle power under specific operating conditions (especially severe failure of a single drive unit), affecting vehicle driving safety and reliability. There is an urgent need for a new energy commercial vehicle drive system solution that can effectively improve power redundancy and system robustness, particularly maintaining basic driving capability even in the event of failure of critical drive components. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to provide a fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive. When one or more drive motors fail, the method redistributes the driving torque of the remaining drive motors according to the vehicle's operating conditions, ensuring the vehicle maintains driving stability and safety. The specific technical solution is as follows: A fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive, comprising: The vehicle controller receives fault information and vehicle information from the middle axle drive motor controller and the rear axle drive motor controller in real time. Based on the fault information and vehicle information obtained from the vehicle controller, an objective function is established to solve for the total required torque and yaw torque. Based on the obtained total required torque, and according to different fault information and the current driving conditions, a drive motor drive force reconfiguration strategy is formulated to keep the vehicle in the desired driving state; specifically: When only one drive motor fails, reduce the output torque of the failed motor and increase the output torque of the motor on the same side. When two drive motors on the same axle of the vehicle fail, the output torque of the failed motor is reduced, and the output torque of the normal motor on the same side is increased. When two drive motors on the same side of the vehicle fail, the output torque of the two motors on the opposite side is reduced. When two drive motors on opposite sides of the vehicle fail, the output torque of the failed motor is reduced, while the output torque of the normal motor on the same side is increased. If any three or four drive motors fail, the corresponding drive motors of the middle axle and the rear axle will each operate at the minimum driving torque.

[0007] Preferably, the fault information includes the drive motor fault type, fault level, and current allowable torque of the drive motor.

[0008] Preferably, the vehicle information includes accelerator pedal opening, vehicle speed, and vehicle yaw rate.

[0009] Preferably, the method for establishing the objective function and solving for the total required torque and yaw torque is as follows: The vehicle controller calculates the current vehicle speed based on the wheel speed of each wheel, and obtains the torque required by the driver based on the accelerator pedal opening and the preset mapping curve. Considering the vehicle's longitudinal velocity and yaw rate, a two-degree-of-freedom model of the vehicle is established; the ideal yaw rate of the vehicle is determined based on the two-degree-of-freedom model. The required yaw moment is calculated by the fuzzy PID algorithm. The input of the PID controller is the yaw rate deviation, and the output is the yaw moment required for the yaw rate deviation. Preferably, the electric drive system for the new energy commercial vehicle includes an accelerator pedal, a vehicle controller, a central distributed electric drive axle serving as the middle axle and the rear axle respectively, an ABS / EBS controller, and an ESC module; The vehicle controller is connected to the accelerator pedal, the middle axle drive motor controller, the rear axle drive motor controller, and the ABS / EBS controller via wiring harnesses. The ABS / EBS controller is connected to the front axle left wheel speed sensor, the front axle right wheel speed sensor, and the ESC module via wiring harnesses. The middle axle drive motor controller receives instructions from the vehicle controller to control the middle axle left drive motor and the middle axle right drive motor. The rear axle drive motor controller receives instructions from the vehicle controller to control the rear axle left drive motor and the rear axle right drive motor.

[0010] According to different fault conditions of the drive motor, the present invention adopts corresponding control strategies and adjusts the control parameters in real time to eliminate or reduce the motor fault, thereby minimizing the impact of the fault on the vehicle's driving status and ensuring the stability and safety of the whole vehicle. Attached Figure Description

[0011] Figure 1 This is a system architecture diagram of the electric drive system for new energy commercial vehicles of the present invention.

[0012] Figure 2 This is a flowchart of the fault-tolerant control method of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Central Distributed Electric Drive Axle: A type of electric drive axle whose structural feature is the elimination of the intermediate differential, with two drive motors driving the left and right wheels respectively after deceleration and torque amplification through a reduction mechanism.

[0015] like Figure 1 As shown, the electric drive system of the new energy commercial vehicle includes an accelerator pedal, a vehicle controller, a central distributed electric drive axle that serves as the middle axle and the rear axle respectively, an ABS / EBS controller, and an ESC module. The vehicle controller is connected to the accelerator pedal, the middle axle drive motor controller, the rear axle drive motor controller, and the ABS / EBS controller via wiring harnesses. The ABS / EBS controller is connected to the front axle left wheel speed sensor, the front axle right wheel speed sensor, and the ESC module via wiring harnesses. The middle axle drive motor controller receives instructions from the vehicle controller to control the middle axle left drive motor and the middle axle right drive motor. The rear axle drive motor controller receives instructions from the vehicle controller to control the rear axle left drive motor and the rear axle right drive motor.

[0016] like Figure 2 As shown, a fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive includes: Acquiring drive motor fault information and vehicle information: The vehicle controller receives fault information and vehicle information in real time from the middle axle drive motor controller and the rear axle drive motor controller. The fault information includes the drive motor fault type, fault level, and current allowable torque of the drive motor, which is acquired by the drive motor controller and sent to the vehicle controller in real time. The vehicle controller receives vehicle information (vehicle speed, vehicle yaw rate) and driver demand information (accelerator pedal opening). Based on the location and number of faulty motors, six types of fault modes can be identified: single motor fault, coaxial two-motor fault, same-side two-motor fault, diagonal two-motor fault, three-motor fault, and four-motor fault. The vehicle controller receives wheel speed signals from the ABS / EBS controller, accelerator pedal signals, yaw rate signals from the ESC module, steering wheel angle signals, etc.

[0017] The vehicle controller calculates the current vehicle speed based on the wheel speed of each wheel, and obtains the torque T required by the driver based on the accelerator pedal opening and the preset mapping curve. Considering the vehicle's longitudinal velocity and yaw rate, a two-degree-of-freedom model of the vehicle is established; the ideal yaw rate of the vehicle is determined based on the two-degree-of-freedom model; the required yaw torque is calculated using a fuzzy PID algorithm, with the PID controller input being the deviation between the ideal yaw rate and the actual yaw rate, and the output being the yaw torque Yaw_T required for the deviation of the yaw rate. Then, based on the total required torque and yaw moment, the required drive torque for each wheel drive motor is calculated: T= ; = ; ; ; T represents the total required torque; This is the required drive torque for the right drive motor of the middle bridge; ; ; This is the required drive torque for the left drive motor of the rear axle; This refers to the yaw moment of the entire vehicle.

[0018] Torque distribution: Based on the obtained total required torque, and according to different fault information and current driving conditions, a drive motor drive force reconfiguration strategy is formulated to keep the vehicle in the desired driving state; specifically: Single motor failure: Only one drive motor fails, while the remaining three drive motors operate normally. When a single wheel fails, the unbalanced drive torque causes lateral disturbances that affect the vehicle's normal operation. The desired driving state is maintained by reducing the output torque of the failed drive motor and increasing the output torque of the motor on the same side. Taking the right drive motor of the middle axle as an example, assuming its currently available torque is... The torque required by the right drive motor on the right axle's right wheel is... The lost torque is This is adjusted by increasing the drive torque of the right drive motor on the rear axle. To compensate for the loss of longitudinal force and prevent the generation of unexpected yaw moments; ; This refers to the drive torque output by the right drive motor of the rear axle; This is the required drive torque for the right drive motor of the rear axle; This represents the driving torque loss of the right drive motor of the middle bridge.

[0019] Coaxial dual-motor failure: When two coaxial drive motors of a vehicle fail, and the remaining two drive motors operate normally, the vehicle can maintain the desired driving state by reducing the output torque of the failed drive motor and increasing the output torque of the normal motor on the same side. Taking the failure of the left and right drive motors on the middle axle as an example, assuming their torque losses are respectively... and The loss of driving torque and the prevention of unexpected yaw torque are compensated by adding two drive motors to the rear axle. ; ; This refers to the drive torque output by the left drive motor of the rear axle; This is the required drive torque for the left drive motor of the rear axle; ; This refers to the drive torque output by the right drive motor of the rear axle; This is the required drive torque for the right drive motor of the rear axle;

[0020] Failure of two motors on the same side: If two drive motors on the same side of the vehicle fail, while the remaining two drive motors operate normally, the output torque of the two motors on the opposite side is reduced to maintain torque balance and ensure vehicle stability. Taking the failure of the middle axle and the left drive motor of the rear axle as an example, let's assume the lost torque is as follows: Unintended yaw moment is prevented by reducing the torque of the two drive motors on the right side, i.e.: ; ; ; ; This represents the drive torque loss of the left drive motor on the middle bridge. ; ; This represents the drive torque loss of the left drive motor on the rear axle.

[0021] Two diagonally opposite motors fail: If two motors on the vehicle's diagonal fail, the remaining two drive motors will continue to operate normally. The output torque of the failed motor will be reduced, and the output torque of the normal motor on the same side will be increased to maintain the vehicle's desired driving state. Taking a failure of the left drive motor on the middle axle and the right drive motor on the rear axle as an example, assuming their torque losses are respectively... and The loss of driving torque and the prevention of unexpected yaw torque are compensated by adding the remaining two drive motors. ; ; This refers to the drive torque lost by the right drive motor of the rear axle; This represents the drive torque loss of the left drive motor of the middle bridge.

[0022] Three-motor failure: If any three drive motors fail, and the remaining drive motor operates normally, the middle and rear axles will each operate at the minimum driving torque of the left and right drive motors, prioritizing vehicle stability. Taking the failure of the left and right drive motors of the middle axle and the right drive motor of the rear axle as an example, assuming the lost torque is respectively... and The middle and rear axles operate according to their respective minimum drive torque, that is: ; ; ; ; .

[0023] In a four-motor failure scenario: the middle and rear axles each operate at the minimum driving torque of their respective left and right drive motors, prioritizing vehicle stability. Taking a failure of the left and right drive motors on the middle axle and the left and right drive motors on the rear axle as an example, assuming the lost torque is respectively... and , The middle and rear axles operate according to their respective minimum drive torque, that is: , .

[0024] ; ; ; ; ; ; ; .

[0025] This invention dynamically adjusts and redistributes the driving torque of the remaining normal drive motors based on the vehicle's real-time driving conditions, ensuring the vehicle maintains driving stability and safety. The fault-tolerant control method adopts adaptive control strategies for different drive failure conditions, eliminating or actively mitigating the impact of the failure by adjusting motor control parameters in real time, thereby minimizing the negative impact of the failure on the vehicle's dynamics.

[0026] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive, characterized in that, include: The vehicle controller receives fault information and vehicle information from the middle axle drive motor controller and the rear axle drive motor controller in real time. Based on the fault information and vehicle information obtained from the vehicle controller, an objective function is established to solve for the total required torque and yaw torque. Based on the obtained total required torque, and according to different fault information and combined with the current driving conditions, a drive motor drive force reconfiguration strategy is formulated to keep the vehicle in the desired driving state. Specifically: When only one drive motor fails, reduce the output torque of the failed motor and increase the output torque of the motor on the same side. When two drive motors on the same axle of the vehicle fail, the output torque of the failed motor is reduced, and the output torque of the normal motor on the same side is increased. When two drive motors on the same side of the vehicle fail, the output torque of the two motors on the opposite side is reduced. When two drive motors on opposite sides of the vehicle fail, the output torque of the failed motor is reduced, while the output torque of the normal motor on the same side is increased. If any three or four drive motors fail, the corresponding drive motors of the middle axle and the rear axle will each operate at the minimum driving torque.

2. The fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive according to claim 1, characterized in that, The fault information includes the drive motor fault type, fault level, and current allowable torque of the drive motor.

3. The fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive according to claim 1, characterized in that, The vehicle information includes accelerator pedal opening, vehicle speed, and vehicle yaw rate.

4. The fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive according to claim 1, characterized in that, The method for establishing the objective function and solving for the total required torque and yaw torque is as follows: The vehicle controller calculates the current vehicle speed based on the wheel speed of each wheel, and obtains the torque required by the driver based on the accelerator pedal opening and the preset mapping curve. Considering the vehicle's longitudinal velocity and yaw rate, a two-degree-of-freedom model of the vehicle is established; the ideal yaw rate of the vehicle is determined based on the two-degree-of-freedom model. The required yaw moment is calculated using a fuzzy PID algorithm. The PID controller input is the yaw rate deviation, and the output is the yaw moment required by the yaw rate deviation. The fuzzy controller input is the slip rate deviation of the drive wheel, and the output is the rate of change of the slip rate deviation.

5. The fault-tolerant control method for a new energy commercial vehicle electric drive system based on distributed drive according to claim 1, characterized in that, The electric drive system for the new energy commercial vehicle includes an accelerator pedal, a vehicle controller, a central distributed electric drive axle serving as the middle axle and the rear axle respectively, an ABS / EBS controller, and an ESC module. The vehicle controller is connected to the accelerator pedal, the middle axle drive motor controller, the rear axle drive motor controller, and the ABS / EBS controller via wiring harnesses. The ABS / EBS controller is connected to the front axle left wheel speed sensor, the front axle right wheel speed sensor, and the ESC module via wiring harnesses. The middle axle drive motor controller receives instructions from the vehicle controller to control the middle axle left drive motor and the middle axle right drive motor. The rear axle drive motor controller receives instructions from the vehicle controller to control the rear axle left drive motor and the rear axle right drive motor.

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