Engine Start-up H∞ Robust Optimal Control of the Compound Power-Split System

To improve the vehicle ride comfort during switching from pure electric mode to e-CVT mode of the compound power-split hybrid system, while ensuring the robustness of switching control under the conditions of model uncertainty and external disturbance, an engine start-up H∞ robust control strategy is proposed. Firstly, a dynamic model of the compound power-split hybrid system is established, and the switching process from pure electric mode to e-CVT mode is analyzed. Secondly, an optimal crank curve of engine speed is designed based on dynamic programming taking vehicle ride comfort and engine start-up time as optimization indexes. Then, considering the damping perturbation of input shaft, the uncertainty of driver input, road load and output speed, as well as the disturbance of measurement noise, an engine start-up H∞ robust controller is developed. Finally, offline simulation and bench test are conducted to verify the proposed strategy. The results show that the strategy can effectively reduce the vehicle jerk to below 11.52 m/s3, and has strong ability to restrain the model uncertainty and external disturbance. © 2020, Society of Automotive Engineers of China. All right reserved.