Gearshift Control in Engagement Process of Dual-Motor Coaxial Propulsion System for Electric Bus

Considering single-motor drive system cannot meet the requirements of high-performance electric buses for Beijing Winter Olympics, a dual-motor coaxial propulsion system based on single planet gear set is developed. At the same time, a shift control method based on hierarchical linear quadratic regulator (HLQR) algorithm is designed to improve the poor shift quality caused by the rapid change of output shaft speed in the shift process. In this method, the upper controller adopts robust tracking linear quadratic regulator algorithm to control the speed change rate of the output shaft in the process of gear shifting, so as to reduce the load of gear shifting actuator in the process of gear shifting; the lower controller adopts disturbance suppression linear quadratic regulator algorithm to control the shifting force and improve the adaptability of the system to disturbance conditions Through simulation analysis, the performances of hierarchical linear quadratic regulator algorithm, optimal control algorithm based on variational method and PI algorithm in the process of gear shifting were comparatively analyzed. Simulation results showed that the hierarchical linear quadratic regulator algorithm exhibited a better performance in gear control than the other two algorithms. In addition, a large number of bench test results also proved that compared with PI algorithm, hierarchical linear quadratic regulator algorithm reduced vehicle impact by 19.17% and reduced the shift force by 32.48% in the sacrifice of shift time by 5.03%.