Configuration Design and Optimization of a Novel Two-Mode Compound Power-Split Hybrid System

Through the analysis of a CHS (Chinese hybrid system) compound power-split configuration, it is found that enhancing the system’s speed decoupling ability can reduce the electric power loss, optimize the engine operating point distribution, and enhance the vehicle dynamics. This paper proposes a novel compound power-split configuration with a two-speed AMT (Automated manual transmission), which includes an electric-vehicle mode, a low-speed power-split mode, and a high-speed power-split mode. First, the electric power characteristics and rotational speed/torque characteristics of the CHS compound power-split configuration are analyzed using the lever method, theoretically demonstrating the rationality of the two-speed AMT+ compound power-split configuration. Then, the genetic algorithm is employed to optimize the multi-parameters and multi-objectives in terms of the vehicle dynamics and economy. Finally, a comparative simulation and analysis of the vehicle’s economic and dynamic properties is performed for the new two-speed AMT+ compound power-split configuration and the original CHS compound power-split configuration. The results show that the vehicle economy is increased by 6.9 % for the new configuration, the acceleration time per 100 kilometers is decreased by 27.5 %, and the maximum speed is increased by 13.2 %.