On-line energy distribution for hybrid electric vehicles using optimal power-split-ratio

This paper presents a near-optimal on-line energy control strategy based on power-split-ratio for hybrid electric vehicles. Firstly, a typical series-parallel hybrid electric vehicle model, Prius II, is developed and validated by ADVISOR. Secondly, the optimal energy distribution problem is initially solved by dynamic programming. Considering the frequent engine start-stop phases in existing energy management strategies, the objective of dynamic programming is to optimally balance the fuel consumption and the engine start-stop phases. Lastly, through analysis of the engine operating points obtained from dynamic programming results, the improved control rules are proposed by obtaining the engine optimal operating line and finding the optimal power-split-ratio in different driving situations. Moreover, A Matlab/Simulink model is built to evaluate the validity of the proposed control rules. Four different driving cycles are tested, and the results show 10%-30% performance improvement in comparison with the results in ADVISOR.