Control Strategy And Experiment For A Pure Electric Vehicle With Four-Speed AMT

At present,environmental protection and resource conservation have become two major themes in the world.Since pure electric vehicle mainly consumes electricity and can achieve"zero emission",it has become an important direction for the development of automobile industry in various countries.Since the pure electric vehicle with mechanical automatic transmission(AMT)has better dynamic and economic than the traditional vehicle with motor direct drive,it is favored by many countries.This paper takes pure electric vehicle as the research object,the economic shift rule,clutch-free shift process and experimental verification method of four-gear AMT and studied.The specific research content is as follows:Firstly,based on the real driving cycles,the economic shift schedule based on dynamic programming(DP)algorithm is studied.Taking the speed,acceleration,shift and battery state of charge(SOC)as the input and the shift instruction as the output,the economic shift rule model is built with BP neural network.Secondly,based on MATLAB/Simulink software,a vehicle simulation model,including the vehicle longitudinal dynamics model,motor model,battery model,transmission system model,and so on,is established,by employing the designed economic shift schedule.The simulation results show that the shift schedule prediction model can realize economic shift.Thirdly,aiming at the smoothness problem in the shift process of four-gear AMT,the speed control strategy of the driving motor is designed based on the fuzzy PI algorithm.To realize the motor speed control,taking the motor speed and acceleration as input,K_p andK_i as output in the fuzzy controller,and takingK_p andK_i as the input in PI controller.Finally,to verify the shift schedule and the shift process,an upper computer program is developed in LabVIEW environment based on the pure electric vehicle experimental bench of chassis domain.The shift schedule prediction model and fuzzy PI controller are employed to generate dynamic link library(DLL)in MATLAB/Simulink environment respectively,and embed in the lower computer PXI.The information of the execution part is obtained by PXI through the communication mode of CAN bus.Then,the control variables of the actuator are transmitted by PXI.The input and output parameters of the lower computer(PXI)is obtained by the upper computer and displayed in the upper computer.The results show that the shift schedule and the shift process control method designed in this paper have good real-time and reliability,and can be further applied to the real vehicle control.