Time-Optimal Coordination Gear-Shifting Control With a Rotational Angle Difference Estimation and Alignment Algorithm in the Vehicle-Start Condition

Multigear transmission in electric vehicles (EVs) can help the drive motor operate on high-efficiency working points by shifting gears. However, big jerks and long power interruption are two crucial issues during gear-shifting process, especially in the vehicle-start condition (VSC) when the rotational angle difference between the sleeve and gear ring is unknown. We focus on a non-synchronizer electric-driven mechanical transmission (NEMT) system, which removes the complex clutch system and synchronizer. A novel gear-shifting control strategy with a rotational angle difference estimation algorithm (RADEA) and a time-optimal alignment and cooperative control strategy is proposed to reduce the time and jerks. First, the mechanical and electric structures of the NEMT are presented. Then, an experimentally validated gear-shifting dynamic model is developed. After that, a RADEA and an angle alignment algorithm are designed to reduce jerks by estimating and aligning the rotational angle difference. The time-optimal coordination control law for the shift motor is proposed to save time. Finally, a state-feedback model tracking control strategy with the time-optimal control law as the feed-forward is designed and validated on the test bench. Compared to the traditional constant-force control algorithm, the proposed strategy is more effective, taking 15 ms less time and producing only 30% of jerks.