Research On The Characteristics Of Shifting Of 2-Speed Uninterrupted Shift Transmission For Pure Electric Vehicles

It can be effectively balanced the dynamics and economy performance of the vehicle if a two-speed transmission is applied for a Pure Electric Vehicle(PEV). At present, more and more experts and scholars have carried out researches in this area. Considering PEV’s driving characteristics, a 2-Speed Uninterrupted Shift Transmission(2-Speed UST),which is a novel seamless transmission concept, is put forward in this dissertation. In 2-Speed UST, the power is transmitted by a friction clutch and a overrunning clutch alternately so that to realize gear shift, and this replaces the synchronizer actuator of the ordinary mechanical transmission.In this dissertation, the operating principle, dynamic shift characteristics, shift quality optimization and the vehicle performance of 2-Speed UST are deeply investigated through theoretical, simulation and experimental methods. The main research work is as follows:2-Speed UST transmission scheme is proposed, a mathematical model of this transmission system was set up through Newton mechanics methods, and upshift/downshift principle and method of operation of 2-Speed UST were analyzed.Matching calculation of vehicle parameters and Modeling and Simulation for 2-Speed UST. Key parameters of driveline system are calculated in accordance with the standards, including motor, battery and transmission gear ratio. Based on this results, a vehicle driveline simulation models is established on the MATLAB/Simulink simulation platform. The simulation and verification of uninterrupted shift characteristics of 2-Speed UST were carried out.2-Speed UST test bench is built, and measurement and control software on host computer is written,which is based on MATLAB / Real-time Windows Target toolbox. The experiment results show that 2-Speed UST has realized the designed function of torque uninterrupted shift. Considering the shift shocks appeared in results of UST shift functional experiment and vehicle performance simulation during inertia phase, 2-Speed UST upshift control strategy and downshift control strategy have been designed and applied in the simulation model and the experiment system respectively. By the Comparison and analysis of the different simulation and experiment results, the designed UST upshift/downshift control strategies have been validated effective to solve the shift shock problem.Research on vehicle performance. Vehicles equipped with this 2-Speed mechanical transmission is also studied on power and economy performance. the ratio of the transmission system is optimized by using MATLAB genetic algorithm toolbox to find the optimal solution, which further enhances the vehicle performance. the results shows that, compared to other transmissions, not only the vehicle performance but also cost issues are given consideration to through 2-Speed UST.