Energy management strategy for hybrid fuel cell vehicle

Fuel cell vehicles (FCV) are characterized by the utilization on the same electric bus of an hydrogen fuel cell (FC) stack as a primary energy source and a storage element like batteries as energy storage system. In our project, the fuel cell is a Polymer Electrolyte Membrane (PEM), which is well adapted for transport field applications. A lithium rechargeable battery, more specifically a LiFePO4, is used to supplement the FC over the driving cycle. According to the requirements of the drive cycle of the vehicle, a 20 kW PEM FC system and a 5 kWh LiFePO4 battery are considered here. To define the power supplied by the source and the energy storage system, an energy management system (EMS) is used. A power split strategy is implemented in the EMS in order to obtain an optimal behaviour for the vehicle in terms of hydrogen consumption and considering the constraints of the system (FC and battery dynamics). Due to the non linear FC dynamics, a non linear control is applied which results in a simplification of the optimization problem.