Energy management strategy of dual planetary hybrid electric vehicle based on optimal transmission efficiency

Abstract

A power split hybrid electric vehicle with dual planetary gear sets is studied in this paper. Firstly, power split and circulation phenomenon are further described by analyzing the mechanical relations of power coupling mechanism based on the lever analogy. Transmission efficiency and electric power ratio are further obtained. The working modes of the hybrid electric vehicle (HEV) are divided according to the system operation mechanism. On this basis, the engine optimal operating line (OOL) control strategy and mechanical point (MP) control strategy are designed. Furthermore, a fuzzy controller is designed to realize the optimal torque distribution of the engine and the motors in the MP control strategy. Test results demonstrate that the MP control strategy can guarantee the higher efficiency of the transmission system, which also shows a good performance in improving the HEV fuel economy by adjusting the engine operating point.