PMP-based Power Management Strategy for Two-State Variable FCHV Systems and its Optimality

The battery temperature affects the total fuel consumption in a hybrid vehicle, as it influences the battery efficiency and further influences the powertrain efficiency. In this research, a Pontryagin's Minimum Principle (PMP)-based optimal control problem for a fuel cell hybrid vehicle (FCHV) is formulated in which the battery temperature is designated as a second-state variable other than the battery state of charge (SOC). Moreover, optimality of the two-state variable PMP-based power management strategy is discussed based on a conclusion derived from previous research. Simulation results of the PMP-based strategy are compared to those of Dynamic Programming (DP) approach. It is concluded from this research that the two-state variable PMP-based power management strategy guarantees global optimality under certain battery assumptions. Meanwhile, the proposed strategy saves much time compared to DP approach.