Development Of The Control System Of A Two-speed Seamless Shift Transmission

Equipping a multi-speed transmission,which can improve dynamic performance and energy efficiency of electric vehicles(EVs),is becoming a new direction of EVs' drivetrain system.Thus,it is of great significance to study on the two-speed seamless shift transmission.Based on the mechanical structure of the two-speed seamless shift transmission proposed by our research group,this paper mainly focuses on the shift schedule,the speed ratio optimization,the normal gearshift control,the shift control algorithm and shift schedule during regenerative braking of the transmission.A simulation environment for an EV equipped with the two-speed seamless shift transmission is built.The simulation environment includes motor,battery,the transmission,longitudinal dynamics of the vehicle,friction clutch,bandbrake and so on.The theoretical researches and some experiments are made to solve the relationship between the applied force and the friction torque of friction clutch or the relationship between pushing force and the brake torque of bandbrake.The simulation environment can reflect the dynamic characteristics of the transmission to some extent,which provides the basis for the further study of the high-level and middle-level control strategies of the transmission.The shift schedule and speed ratio optimization of the two-speed seamless shift transmission are studied.With the help of dynamic programming algorithm,the EV including the battery is taken as a whole model to obtain the global optimized shift schedule,and thus the optimal speed ratios of the transmission are obtained.On the basis of the dynamic performance shift schedule and the energy efficiency shift schedule,the personified dynamic shift schedule is modified by utilizing the driver's attention obtained by the fuzzy inference method.A control algorithm of normal gearshift based on the optimal trajectories and control sequence is designed.In order to optimize the objective function including vehicle shock and friction loss,the discrete time Riccati equation is used to obtain the optimal trajectories and control sequence.Following the trajectories and incorporating feedforward control,the control algorithm controls the friction elements and the motor cooperatively.Thus,the vehicle shock and friction loss are both reduced.A seamless shift control algorithm of the transmission equipped on EVs during the regenerative braking process is proposed.The input-state stability design is used to guide the selection of the parameters of the control algorithm.An integrated two-parameter downshift schedule during the braking process is proposed to reduce the dependence on the hydraulic brake system,lower the level of difficulty of cooperative control and improve the efficiency of regenerative braking.The results of the Hardware-in-the-loop show that the algorithm has high control accuracy,can realize the seamless shift during brake,and has good robustness.The prototype of the two-speed seamless shift transmission is developed and the bench test of dynamic performance is conducted.The selection and development of the friction clutch,band brake,actuators,and the transmission's prototype are carried out.Moreover,the transmission control system that meets the requirements of the transmission is designed and made.A dynamic performance test bench for the transmission including drive motor,load motor,host computer,slave computer and so on is set up,and the bench test of the transmission's dynamic performance is performed.At last,a real vehicle test is conducted.Both the bench test and the real vehicle test verify that the transmission is able to achieve seamless shift.