Research On Synchronous Shift Control Of Dual-mode Two-speed Automatic Transmission For Electric Vehicles

Due to the superior dynamic response characteristics of the drive motor,the electric vehicle just adopts a few-speed transmission or even a single-stage reducer to ensure the power and economy of the vehicle.The dual-mode coupling drive system not only realizes the integration of centralized and distributed drive modes,but also meets the needs of electric vehicles for two-speed transmission.So it is considered to be the most promising form of electric vehicle transmission,but because its shifting principle is similar to the automatic mechanical transmission,power interruption and shock will inevitably occur during gear shifting.In order to solve the gear shifting problems of the above-mentioned system,and to make better use of the powerful speed and torque control characteristics of the drive motor,this paper cancels the synchronization ring structure on the basis of the dual-mode coupling drive system,and conducts control research on its shifting process.Strive to improve the shift quality of the system based on the realization of system innovation.The main research contents of this paper are as follows:(1)Through the modeling and working mechanism analysis of the dual-mode coupled drive system,analyze the mode switching process of the synchronizer system,reveal the mechanism of the synchronizer,and combine the mode switching problems of the system and the precise regulation characteristics of the electric vehicle drive motor,exploring the feasibility of an improved synchronizer-less transmission system based on the shift strategy.(2)Divide the mode switching phases of the synchronizer-less dual-mode two-speed transmission system,establish the mathematical model of each shifting phase,analyze the system engagement problems of the synchronizer-less system during the mode switching process,and analyze the influence of the speed difference and the angle difference between the coupling sleeve and the target gear on the mode switching,the control goal of the mode switching of the synchronizer-less system is clarified,and provide the model and theoretical basis for the design of the active synchronous shift control strategy.(3)Analyze the working characteristics of the permanent magnet synchronous motor and put forward performance requirements for the drive motor based on the process of switching without synchronizer mode;build a speed and current double closed-loop motor speed control model and build a sliding mode observer to better obtain drive motor parameters;in response to the control requirements of the synchronizer-less system,based on the optimal control theory,an active synchronization control strategy including odd and even matched is proposed;complete powertrain simulation model is used to simulate and test the proposed control strategy to verify The feasibility of the synchronizer-less system and the effectiveness of the active synchronous shift control strategy.The research carried out in this paper has important theoretical significance for exploring the innovative design of new electric vehicle transmission system and the optimal control of dual-mode coupled drive system.The proposed active synchronous control strategy makes better use of the dynamic response characteristics of the drive motor,and is suitable for other Electric automobile transmissions containing synchronizers have a wide range of practical application prospects.