Two-speed transmission in electric vehicles (EVs) not only has the potential to improve the driving performance of the electric vehicle (EV), but also simplifies the powertrain control in the application, compared with single/multi-speed transmission. In order to enhance the positive impacts of two-speed transmission on EV’s economic and dynamic performance, this paper investigates the gear shifting schedule for EVs with two-speed automatic transmission using Takagi-Sugeno (T-S) fuzzy control based on the driver’s intentions. Firstly, this paper focuses on the gearshift schedule for two-speed transmissions in EVs. Secondly, to realize the coordination of the driver’s intention and targeted gear, this paper establishes a three-parameter shifting schedule with T-S fuzzy control to detect the driver’s intention, which is obtained through detecting the acceleration pedal, braking pedal, and changing rate of the acceleration pedal. The Simulink models are constructed using the functional threshold power (FTP) driving cycle to analyze the proposed T-S fuzzy gearshift schedule and compare it with the traditional dual-parameter shifting schedules. The simulation results demonstrate the improvement in EVs performance with respect to economic performance and reduction in the shifting frequency while ensuring dynamic performance.

Wollongong University: Yiyi Liang, Haiping Du; Ocean University of China: Peng Liao, Donghong Ning