Study On Experiment Platform Of Four-wheel-independent-drive Ev And Its Driving Force Control System

Four-Wheel-Independent-Drive (4WID) Electric Vehicle (EV) will be the important developing direction of future vehicle's technology due to its advantages in vehicle dynamics control and optimized driving torque distribution, compared with traditional combustion vehicle. A 4WID EV experiment platform and driving force control system was established in this thesis, theoretical method and key technologies related to the platform and control system are studied.The architecture of the Four Wheel Independent Drive vehicle, which will be set up based on the existing off-road vehicle chassis, was proposed at first. Based on the overall design of the 4WID EV, a novel layout of four wheels independent drive system, which realized the function of individual wheel driven by individual electric motor by means of a novel driving axle with double main reducers, was proposed and the key sub-systems were designed. The experiment platform of Four-Wheel ndependent-Drive electric vehicle based on existing BJ2023 off road vehicle was estabilished according to the overall design.The hierarchical control system of 4WID EV driving force distribution is studied in the thesis. In the longitudinal driving force and yaw moment determineing layer that is designed to realize the real-time and continuous control target determineing function, the fuzzy logic yaw moment control method which will ensure the vehicle stability during the driving process is proposed.. In the multi-objective-optimization driving force distribution layer, the driving motor failure control method based on the fault information of driving motor is designed to solve the motor failure problem during driving condition. According to the current vehicle states, the economical and safe driving force allocation modes are presented respectively. The safety mode is focused on improving tire lateral force margin, which will enhance the stability margin of vehicle lateral movement. The economical mode is focused on improving the economical performance during driving condition. In the tire slip ratio control layer, the PI control method is utilized, with which the optimized tire slip ratio is guaranteed by controlling the motor driving torque.To validate the effectiveness of and the experiment platform of the 4WID EV , the groud experiments are carried out. To validate the effectiveness of the proposed driving force control method, the key technologies and the overall performance of the control system for the 4WID EV are tested by simulation and road tests. The experimental results show that the 4WID prototype test vehicle can provide a stable and reliable platform for vehicle dynamics control research, the proposed driving force distribution control system can effectively control and improve the dynamics of 4WID EV.