Research On Vehicle Control Strategy Of Pure Electric Vehicle

Pure electric vehicles have the advantages of zero pollution,low noise and easy maintenance,which can effectively solve the problems caused by "oil shortage and low gas".Pure electric vehicles are one of promising products that can solve the challenge of the environment pollution in the future and ease the energy crisis.Therefore,pure electric vehicles have been focused by the countries around the world and will completely replace traditional fuel vehicles in the foreseeable future.However,the vehicle performance depends to a large extent on the vehicle control strategy,which can play a decisive role in the performance of the whole dynamics,economy,comfort and reliability of the vehicle.This paper has taken a pure electric vehicle on the market as the research object and aimed to improve the vehicle performance.Meanwhile,appropriate control strategies has been developed.The research background of pure electric vehicles has been illustrated in this study.The development status of pure electric vehicles and the current research status of the vehicle control strategy at home and abroad have been elaborated briefly.Then,the framework and working principle of pure electric vehicle power system have been demonstrated and the type selection and parameters match of motor and battery have been carried out according to the vehicle performance index of pure electric vehicle.The vehicle control strategy was designed and control strategy model was established by utilizing MATLAB/Simulink.Models contain accelerator pedal rate-of-change and dead-zone limit models,throttle amplitude calculation model,torque limit model,poweron_ctr model and poweroff_ctr model.The vehicle control strategy mainly includes the control strategies of driver signal acquisition and processing,the control strategy of torque management,the control strategy of vehicle drive,the control strategy of high-voltage power-on and the control strategy of high-voltage power-down.The driver signal acquisition and processing control strategy is composed of the acceleration torque control strategy and the accelerator pedal signal processing strategy.Torque management control strategies include torque resolution and torque limits.The vehicle drive control strategy mainly consists of 5working modes: start-up,starting,cruising,brake energy recovery and lameness.The control_logic module was clarified and the control information of the whole vehicle work mode,each relay control state and the motor target work mode can becalculated by the output of each fault flag,drive torque,brake torque and key signal.The core of the overall control logic,the Mode_Switch module,was introduced.Subsequently,the vehicle dynamics model of pure electric vehicle was briefly described,such as a driver model,a motor model,a battery model and a charger model.MATLAB/Simulink simulation software and Hardware-in-the-loop(HIL)test platform co-simulation were employed to verify the superiority of the accelerator pedal signal processing strategy in the driver signal acquisition and processing control strategy.Then the cruise mode and the energy recovery mode in the vehicle drive control strategy were simulated and analyzed.In the cruise mode,the speed of vehicle was relatively stable,guaranteeing the smoothness and stability of vehicle.In the energy recovery mode,the battery SOC rises when the vehicle is braked.Finally,the vehicle performance was also simulated and it was verified that the maximum speed,acceleration time and cruising range all met the indicator requirements.