Energy management for fuel cell hybrid vehicles based on a stiffness coefficient model

In this paper, a novel stiffness coefficient model (SCM) is proposed for power flow distribution between two power sources, fuel cell system and battery. Then the energy management strategy is developed based on the SCM for a prototype FCHV. The power flow distribution in different power sources could be dynamically adjusted by the proposed strategy according to the logic relationship between the power demand and the fuel cell output power at peak efficiency point, and the fuel economy of the FCHV could be improved as much as possible by making the fuel cell system work in high-efficiency area. The designed control strategy is verified by the simulation and the practical test. In the test, for a combined cycle which includes three typical driving cycles, the fuel economy of the FCHV with the proposed control strategy is increased averagely by 5.18% with maintaining power balance and stable control.