Optimization of compound power split configurations in PHEV bus for fuel consumption and battery degradation decreasing

Highlights: • One-dimensional ECMS based on DTPs shows advantage in fuel consumption and battery degradation reducing. • The reason for fuel consumption decreasing is system efficiency points closer to maximum efficiency line. • Fuel consumption and battery degradation decrease with lever length β close to −0.5 and α close to 1.5 • Only 17 of 18 compound power-split configurations with two planetary gear sets are applicable. -- Abstract: Compound power-split configurations exhibit better fuel consumption than input and output power-split configurations. However, there is a need to understand how to design the best compound power-split configuration. In this paper, potential compound power-split configurations with two planetary gear sets are explored. Based on the planetary connection, there are 18 possible compound power-split configurations, but only 17 of those are applicable because of the lever length limitation. According to one-dimensional Equivalent Consumption Minimization Strategy and battery degradation model, the impact of compound power-split configuration design and control on fuel consumption and battery degradation are investigated. The results show the one-dimensional Equivalent Consumption Minimization Strategy based on Direct Transmit Points can further decrease the fuel consumption and battery degradation in compound power-split configurations. Similarly, the design parameters with lever length β close to −0.5 and lever length α close to 1.5 also lead to fuel consumption and battery degradation decreasing. The advantage of fuel consumption is observed because the system efficiency operation points are closer to the maximum efficiency line in optimized compound power-split design and control. Moreover, the compound power-split configuration can further decrease battery degradation in optimized design and control is because the current through the battery is less.