Development Of Vehicle Control Unit Of 4 In-wheel-motor Driven EV

The distributed drive electric vehicles have been extensively studied and researched due to its advantages such as direct torque control.Battery,motor and electronic control are three key technologies for research and development of electric vehicles.This article relies on the National Natural Science Foundation of China(51375086)"Electro-Mechanical Coupling and Shimmy Control of Four-wheel Independent Electric Wheel Direct-drive Chassis System".Focusing on electric control technology,a vehicle control unit(VCU)is designed in this paper,which used for pure electric vehicle based on four-wheel independent drive to achieve safe and reliable operation of the entire vehicle.First of all,according to the vehicle controller requirements,the vehicle control system framework is determined,then referring to AUTOSAR architecture the VCU software and hardware framework definition is completed.Using the model-based V process development method,controller software development is completed by quickly controlling the prototype platform.Based on the SAE J1939 protocol,the vehicle CAN communication network was developed.An electronic vehicle chassis is built,including complete the peripheral circuit design and circuit layout.Finally,design a real vehicle experiment to verifiy the functions of the vehicle controller and the vehicle control system.The experimental results meet the design requirements.The main work of this paper is as follows:(1)Completed the overall design of the vehicle controller and control system according to the design index of the vehicle.Analyzed the technical indicators and design requirements of pure electric vehicles,then determined the functional requirements of the vehicle controller.Designed the framework of the vehicle control system and defined the technical requirements for each sub-controllers,sensors,actuators,and vehicle communication.(2)Designed the vehicle control strategy.First of all,according to the operating conditions of the electric vehicle,the working mode of the whole vehicle is divided,and the jump logic between the operating modes is designed.The torque demand analysis strategy is designed to determine the output torque based on the driver input and the vehicle state.In terms of vehicle safety,high-pressure safety is designed in software and hardware level.(3)Communication of the vehicle controller,sub-controllers,and sensors is achieved via CAN network.Based on the SAE J1939 protocol,the entire vehicle communication is designed in physical layer,data link layer and network application layer,and a complete communication protocol is set for vehicle communication to ensure the reliability,readability,and extensibility of the entire vehicle communication.(4)Based on the Woodward/MotoHawk rapid control prototype platform the vehicle controller model is completed via MATLAB/Simulink/Stateflow.According to the working conditions,completed the initial configuration of the I / O pin and data preprocessing.Stateflow is used to build the working mode state machine to realize the definition and jump logics of each working mode of the vehicle,and the control the actuator according to working mode.The torque demand module was built to calculate the vehicle torque requirement taking factors such as pedal opening,battery SOC,battery and motor temperature into account.Write.m file to complete the package of defined CAN protocol,to achieve the package and unpackage of CAN messages.(5)Completed the layout of the electrical components of the electronic vehicle chassis.Completed the layout of sensors,actuators and subsystems,peripheral circuits are designed for electrical components,and completed layout of strong and weak electrical circuits of the vehicle.The human-computer interaction interface is designed to realize the real-time display of the vehicle’s running status and the driver’s calibration and setting of the vehicle’s control parameters.(6)Designed the vehicle experiment to verify the vehicle controller and control system.The linear acceleration experiment verified that the vehicle’s design function is normal,the work safety and coordination of the VCU with the motor and battery system are verified.The design requirements for the electric vehicle experimental platform are verified through differential steering and direct torque control steering experiments,and the rationality of electronic differential steering and feasibility of differential steering is verified.Through the above work,the process from the design to the verification of the vehicle controller was completed,and the experiment verified that the vehicle controller’s work meets the design requirements.