Research On Multi-objective Optimal Torque Distribution Strategy Of Distributed Drive Electric Vehicle

The continuous consumption of energy and environmental pollution and other issues make the driving energy of traditional vehicles have to be transformed and upgraded.Electric drive has become the key to solve the problem of vehicle energy,so electric vehicles came into being.Compared with traditional engine driven vehicles and centralized electric drive vehicles,distributed drive has the advantages of short drive chain,high efficiency,independent and controllable torque,fast response speed,increased space in the car and so on,which are favored by the market.Many researchers have launched research on it.How to distribute the torque of the distributed drive electric vehicle under different working conditions can make the optimal solution of the safety and economy of the vehicle,which has become a research hotspot.In this paper,the distributed hub motor drive electric vehicle is taken as the research object,and the distributed drive torque distribution strategy is studied to improve the economy and safety of the whole vehicle.The torque control of the whole vehicle adopts the hierarchical control idea.The upper layer is the decision-making layer of driving torque and yaw torque,and the lower layer is the motor torque distribution layer.In the lower layer,the multi-objective optimization function is used to improve the economy and safety of vehicles.The multi-objective optimization function torque allocation strategy includes economy,stability optimization function and motor failure control strategy.When the vehicle is in the direct driving condition and the motor fails,the vehicle takes improving economy as the main torque distribution strategy and improving vehicle stability as the auxiliary optimization strategy;when the vehicle is in emergency turning and obstacle avoidance,the vehicle takes improving stability as the main torque distribution strategy and improving vehicle economy as the auxiliary optimization strategy;The control rules of single motor failure,double motor failure and multi motor failure are formulated in the motor failure torque distribution strategy.The control rules and fuzzy PID control are combined to form the motor failure torque distribution strategy.In order to verify the effectiveness and superiority of multi-objective optimization function torque distribution strategy in vehicle economy?stability and safety,based on Car Sim and MATLAB/Simulink software,the joint simulation platform of torque distribution control strategy is built,and the distributed dynamic model and torque control model of electric vehicle are established.First of all,the multi-objective optimization function torque distribution strategy and dynamic load torque distribution strategy in NEDC(New European Driving Cycle)and FTP75(Federal Test Process-75,fuel consumption test in the United States)is used to simulate the whole vehicle economy.Secondly,vehicle stability simulation is carried out under step,single shift and double shift line conditions.Finally,the multi-objective optimization function torque distribution strategy and general PID control strategy are used to simulate the driving safety and stability of vehicles under different initial speed,acceleration and braking conditions at the battery failure level.The simulation results show that under the NEDC and FTP75 conditions,the multi-objective joint function torque distribution strategy can reduce battery power consumption and the SOC value of the battery has a significant promote.Under the step condition,the single shift line condition and the double shift line condition,the multi-objective optimization function torque distribution strategy is closer to the target reference value in the sideslip angle,the yaw rate and the track tracking of the vehicle;Under the condition of motor failure setting,fuzzy PID rules control the yaw angle,yaw rate and lateral acceleration of the vehicle in different conditions,which greatly improves the stability and safety of the vehicle in running condition.