Numerical comparison of ECMS and PMP-based optimal control strategy in hybrid vehicles

During the last decade, the equivalent consumption minimization strategy (ECMS) and the Pontryagin’s Minimum Principle (PMP)-based optimal control strategy have been developed for power management of hybrid vehicles, and it has been noticed that there are some similarities between the two strategies. Establishing their exact relationship and distinguishing their fundamental differences have become necessary for further development in the field of power management strategy. The two strategies are numerically compared and their relationship is established in this research. The two strategies are applied to a fuel cell hybrid vehicle (FCHV) in a computer simulation environment and the simulation results of the two strategies are also compared. It is concluded that the numerical comparison result depends on the open-circuit-voltage (OCV) of the battery model. As a result, the ECMS and the PMP-based optimal control strategy can numerically have the same solutions for non-plug-in hybrid vehicles by adjusting two parameters. Differences between the two strategies are also discussed and the superiority of the PMP-based optimal control strategy is emphasized.