Online Shift Schedule Optimization of 2-Speed Electric Vehicle Using Moving Horizon Strategy

Energy consumption of a vehicle is greatly influenced by its driving behavior, which is reflected by gear shift strategy in powertrain systems. Because of the discrete gear ratio and nonlinear dynamics of vehicles, devising an optimal gear shift strategy is quite challenging. This paper presents an online shift schedule optimization strategy for improving energy efficiency of an electric vehicle (EV) with 2-speed automated manual transmission (AMT). The optimal gear shift strategy is obtained by solving a nonlinear time-varying optimal problem, wherein, the equivalent energy consumption, including motor power and travelling distance is chosen as the objective function. By exploiting the particular structure of the problem and combining Pontryagin's minimum principle and numerical methods, a compuationally efficient solution approach is proposed, in the frame of moving horizon control. Simulation results on an AMESim model of an EV with 2-speed AMT over multiple driving cycles using different controllers are presented, and Hardware in the Loop simulation for experimental validation is also given in this paper. The results indicate that both energy efficiency and computational speed are improved.