Optimal coordinating control for the overlapping shift of a seamless 2-speed transmission equipped in an electric vehicle

摘要

For a novel seamless 2-speed transmission specially equipped in the electric vehicles, the optimal coordinating control problem of the motor and the friction clutch with complex constraints on both the state and control variables during the overlapping shifts is investigated in this article. First, the shift principle and the dynamic models of the overlapping shifts between the friction clutch and the one-way clutch are analyzed. Next, the parameters for evaluating the shift quality are analyzed. The jerks in process and at the key moments (speed synchronization moments of the friction clutch or the one-way clutch) are distinguished and selected as the constraints and the objective function's terminal items, respectively. Finally, an integral optimal coordinating controller is proposed to optimize the shift trajectories and improve the overlapping shift quality. The linear feed-forward coordinating control strategy is used in the torque phase to regulate the motor torque with the engaging or disengaging process of the friction clutch to maintain the jerk within the permissible range, and the optimal control strategy based on the principle of the minimum is used to optimize the shift trajectories with complex constraints on both the control and state variables in the inertia phase. The effectiveness of the proposed optimal coordinating controller on addressing the coordinating control problem of the motor and the friction clutch during the overlapping shifts and establishing a solid foundation for the application of the seamless 2-speed transmission in electric vehicles have been verified by the simulation and experimental test-bench results.