Shifting Process Control for Two-Speed Automated Mechanical Transmission of Pure Electric Vehicles

Abstract

Shifting processes are analyzed for a pure electric vehicle equipped with a two-speed automated mechanical transmission without a clutch in order to study the relationship between shifting jerk, shifting time, and synchronizer tooth grinding. Results show that shifting time has a negative correlation with shifting jerk, which is related to the torque variation rates of the driving and shifting motors. Tooth grinding of the synchronizer is related to the relative speed between the synchronizer sleeve and lock ring during shifting processes. Based on the analysis, a shifting control strategy for pure electric vehicles is proposed in order to decrease shifting jerk, avoid tooth grinding of the synchronizer, and shorten shifting time. Experimental results obtained show that the proposed control strategy can achieve smooth, reliable, and quick shifts for an electric vehicle.