An Improved Energy Management Strategy for Fuel Cell Hybrid Vehicles Based on Pontryagin's Minimum Principle

For finding a balance between fuel economy and durability of fuel cell hybrid power systems, this article proposes an improved real-time energy management strategy (EMS) based on Pontryagin's minimum principle (IM-PMP). We introduce the fuel cell output change rate with weighted coefficient into the Hamiltonian function to limit frequent power fluctuations so as to improve the durability of the fuel cell. In addition, a real-time costate updating method is proposed for unknown driving conditions. This method determines the optimal value of costate according to the real-time state of charge (SOC), which can ensure the online implementation of the EMS and control the SOC of the lithium battery within a certain range. By constructing the hardware-in-the-loop experimental platform, the proposed strategy is compared with the finite state machine (FSM) strategy. Compared with FSM, the hydrogen consumption of the IM-PMP strategy is reduced by 10.1%, and the fuel cell operating stress is reduced by 38.3%. The SOC of the lithium battery is maintained at around 0.6. The experimental results verify the superiority of the proposed EMS.