Gear-shifting Control of Clutchless Automated Mechanical Transmission Without Synchronizer in Short-distance Pure Electric Vehicle

To shorten shift time and reduce shift impact of the clutchless automated mechanical transmission (CLAMT) without synchronizer, dynamical models of each shift stage were established, a time-optimal control method for the shift actuator, a speed closed-loop control method which combined electric brake and proportional integral (PI) control for the brushless direct current (BLDC) traction motor (with trapezoidal-shaped back-electromotive force) and a multi-stage control method in neutral position of the automated mechanical transmission (AMT) were proposed. By directly providing the highest voltage and implementing electric brake, rapid start and stop of the direct current (DC) shift motor were realized and position precision can reach 0.08 mm under the proposed time-optimal control method for shift actuator. Since rotate speed of BLDC traction motor was difficult to rapidly decrease by vector control, PI control and electric brake were combined by the speed closed-loop control method of traction motor to decrease rotate speed of BLDC traction motor in a short time. Neutral distances of AMT were divided into two parts by the proposed multi-stage control method in neutral position, and coordination strategies with different traction motors and shift motors were implemented in two parts to reduce shift time as much as possible. At last, experiments under typical working conditions were conducted on a short-distance pure electric vehicle with CLAMT without synchronizer, as well as motor and transmission integrated controller. The results show that the shift time in running conditions and in static conditions is nearly equal, shift impact decreases simultaneously by the proposed control method of shift process.