Study On The Control Strategy Of Driving Force Distribution Of Distributed Drive Electric Vehicle

Electric vehicles avoid the consumption of non-renewable energy sources like fossil fuels of traditional car,achieving zero emissions to reduce the degree of atmospheric pollution.It is the focus of the future automotive technology research.Distributed driving electric vehicle which has the driving motor directly arranged on the driving wheel or near the driving wheel has the advantages of short drive chain,high efficiency,compact structure as the new research hotspot.The drive motor's torque response quickly and has higher control accuracy,because of the four motor it has more controllable degree of freedom.This thesis mainly studies about the stability control and driving force distribution control strategy.A dynamic simulation model is built according to the characteristics of distributed drive vehicle.A tire model is established accord to magic formula.The driver model of target vehicle speed tracking and any path tracking is established.I also build up seven degrees of freedom vehicle dynamics model,motor model,transmission system model and wheel model.Considering the parameter transfer relationship each sub module will be connected to another to form a distributed drive electric vehicle dynamics simulation platform.The analysis strategy of the pedal is established,and the longitudinal force is solved according to the input of the driver.Taking the two degree of freedom model as the reference model,the yaw rate is chosen as the control variable.Using the fuzzy control theory and the traditional PID controller,the variable parameter fuzzy PID control is used to control the yaw stability of the vehicle.The effectiveness of the upper motion tracking control is verified by means of the average distribution method using typical vehicle running condition.Based on optimal control theory,the driving force distribution control strategy is established,which is based on the minimum road adhesion rate consumption and the highest vehicle driving efficiency.According to the problem,I choose SQP and ACTIVESET to solve the optimization problem.The means can improve the calculation speed.In order to avoid the local optimal solution I choose genetic algorithm to determine the initial value.The validation of the driving force distribution control is tested.Multi-condition control strategy based on the logic threshold transition of yaw rate is established.A weighted objective function with the highest adhesion rate and the system drive efficiency is established to work at the multi-conditions.In thesis I set up straight and steering strategy wheel single motor broke.The driving force distribution of fault tolerant control strategy can work under the condition of different side wheels broke down.The effectiveness of the control algorithm is verified under the corresponding working conditions.