Research On Electronic Differential Control Strategy Of Distributed Drive Electric Vehicle

With the deterioration of the environment and the scarcity of energy,the global automotive industry began to attach importance to the development of new energy vehicles.With the rise of new energy vehicles,distributed drive electric vehicles have also received widespread attention.Especially the electronic differential of distributed drive electric vehicle is still a subject which needs to be studied urgently.In order to improve the steering stability and active safety of the vehicle,the electronic differential control strategy of the distributed drive electric vehicle is studied in this paper,which combines the yaw stability and wheel sliding rate of the vehicle when steering with the distributed drive electric vehicle driven directly by hub motor.The main research contents of this paper include:(1)Determine the drive system of distributed drive electric vehicle.By comparing the performance advantages of various motors,permanent magnet brushless DC motor(BLDCM)is selected as the drive motor.According to the parameters and dynamic performance indexes of electric vehicle studied in this paper,the characteristic parameters of permanent magnet BLDCM are calculated.Finally,after analysis,the closed-loop control of torque is used as the control strategy of motor system.(2)Establishing a joint simulation architecture.Based on Car Sim and Simulink software,this paper establishes the joint simulation model needed in this paper.Firstly,the whole vehicle model is built in Car Sim,then the mathematical model needed is analyzed in Simulink,and the two kinds of models are combined and integrated to get the joint simulation architecture needed in this paper.(3)Based on the fuzzy control algorithm,a yaw moment distribution control strategy is proposed for the electronic differential control system.In this paper,two methods are used to distribute yaw moment: one is direct torque distribution,the other is to establish a torque distribution model under the constraints of motor faults,road adhesion coefficient and vehicle dynamic performance,to distribute the yaw moment required for steering directly;the other is direct slip rate distribution,which determines the wheel slip rate and operation based on magic tire formula.For the relationship between yaw moments at the center of mass,the yaw moments are allocated to the wheels.Finally,the sliding rate tracking strategy is used to control the torque of each wheel.Based on the above work,two electronic differential control strategies are compared and analyzed under three working conditions: double line shifting,steering wheel angle step input and steering wheel angle sinusoidal input,and their feasibility is verified.The simulation results show that the performance of the direct sliding rate allocation control strategy is better than that of the direct torque allocation control strategy.