Parameters Optimization And Control Strategy Of Shifting Mechanism Of A Seamless Two-speed Transmission For Electric Vehicle

Because of its lower noise,less pollution,higher energy conversion efficiency and being the best carrier of vehicular networking technology,the pure electric vehicle has been favored by government departments,manufacturers and consumers,and is considered as one of the development trends of the automobile industry.And the ratio change of the two-speed transmission can not only improve the dynamic and economic performance of the vehicle,but also make the driving motor work in the high efficiency zone for longer time,which makes the two-speed transmission become the focus of the research on the pure electric vehicle transmission system.Based on the project of "Research on the two-speed transmission system of electric vehicle" in Chongqing,a kind of seamless two-speed transmission for pure electric vehicle is put forward in this paper,and the parameters optimization and control strategy of its shifting mechanism is studied in order to improve its shift quality.First of all,on the basis of summarizing the structure characteristics of the existing two-speed transmission,a new type of seamless two-speed transmission is put forward.Its shift process is divided into three stages,and the dynamic model of the vehicle is established in stages,and the cause of the jerk and the slipping work in the shift process of the two-speed transmission is studied by analyzing the two shifting quality evaluation indexes of the jerk and the slipping work.Secondly,the parameter optimization is carried out for the seamless two-speed transmission.The parameters of the shifting mechanical structure and the shifting motor are preliminary matched according to the design requirements.On this basis,the shifting mechanism parameters optimization model which aimed at the jerk and the slipping work is set up.The method of combining the Improved Grey Wolf algorithm with Matlab/Simulink simulation model is developed.The feasibility of the method is validated by the case,and the results show that the optimized shifting mechanism parameters can greatly improve the shift quality of the two-speed transmission.Thirdly,the control strategy of the seamless two-speed transmission is developed.The control optimization model of the shifting motor speed which aimed at the jerk and the slipping work is put forward by discretization of the optimization variable.The optimal control strategy of the two-speed transmission is obtained by using the Improved Grey Wolf algorithm combined with Matlab/simulink simulation model.And the feasibility and applicability of the optimization method are verified by three kinds of limit shifting moments.Finally,the seamless characteristics of the two-speed transmission is verified by the test.The two-speed transmission prototype is designed and assembled.The two-speed transmission performance test bench is constructed.The statistical test data is processed,and the results show that the new two-speed transmission can ensure that the power during the shifting process is not interrupted.