Impacts of blended mode and charge-sustaining mode on the battery efficiency for a serial FC-PHEV

This paper investigates the impact of two different real-time power energy management systems on the battery used in a serial topology of a Fuel Cell Plugin Hybrid Electric Vehicle (FC-PHEV): the blended mode and the charge-sustaining mode. With the blended mode, the FC contributes to the propulsion power when the power demand is high or when the battery is depleted. The charge-sustaining mode considered for this study allows the battery to be depleted in a first step. In a second step, the FC is used to maintain the battery energy within a narrow interval. Earlier designs of the two methods for FC-PHEV put emphasis on the vehicle dynamics control and the hydrogen energy saving, neglecting to consider their impacts on the battery pack efficiency. For the same rolling conditions, the simulation results with a lead-acid battery pack suggest that the charge-sustaining mode has the potential to improve the battery pack average efficiency compared to the blended mode. However, the charge-sustaining mode may require more hydrogen to achieve this improvement than what is needed when the blended mode is used.