Study On Shift Schedule For Pure Electric Vehicle With Two-speed AMT

The multi-gear transmission technology of pure electric vehicle is a trend of the technological change of new energy vehicle in the future,and its development plays a very important role in improving the key performance of electric vehicle.In this paper,the pure electric vehicle with two-speed AMT is taken as the research object,focusing on the optimization of transmission gear ratio,the formulation of shift schedule considering road conditions,and the formulation of shift schedule combining with gear shifting process control in special working conditions.Firstly,based on the structure principle and working properties of the pure electric vehicle with two-speed AMT,the simulation platform of the vehicle was built by using AMESim.The feasible region of gear ratio was solved according to the vehicle performance index.The vehicle energy consumption in NEDC working condition was taken as the optimization objective.In order to realize the real-time tracking of shift schedule in the process of the optimization of transmission gear ratio,a dynamic gear ratio optimization scheme was adopted and the NSGA algorithm was used to solve the problem.Secondly,based on the traditional two-parameter shift schedule,the influence of road conditions on the gear shifting process is considered,and the ramp road and the lowadhesion road are selected as research objects in the road conditions.RLS algorithm with forgetting factor was used to identify the equivalent slope value,and the road adhesion coefficient was identified by using Burckhardt model.Making use of analytical method to set up uphill shift schedule.In the process of downhill the traditional shift schedule are corrected online by considering intention drivers to slow down the vehicle speed,and then formulating the corresponding shift control strategy by using fuzzy control.The combination of drive motor torque control and transmission shift schedule is adopted to improve the operation stability of driving condition in low-adhesion road.Thirdly,the shifting process of the pure electric vehicle with two-speed AMT is analyzed,and the control strategy of the shifting process is developed.Next,in order to study the shift schedule of vehicles in the process of rapid acceleration or rapid deceleration,combined with the analysis of the smoothness of the shifting process,the influence of shift schedule on gear shifting smoothness is studied.The fuzzy neural network(FNN)gear shifting control system is established to simulate the shift habit of skilled drivers in the process of rapid acceleration or rapid deceleration.Then the shift schedule based on FNN was established.Considering the influence of road conditions and special work conditions on vehicle shifting process,a multi-mode cooperative shifting control strategy is proposed,and the priority of each mode is divided and integrated.Finally,using the MATLAB/Simulink and AMESim co-simulation platform to verify the results.The results show that not only the shift schedule established Suits for Corresponding road conditions and working conditions,but also the multi-mode cooperative shifting control strategy can improve the vehicle comprehensive performance in the comprehensive road conditions.