Analysis of Pontryagin’s Minimum Principle-Based Energy Management Strategy for PHEV Applications

This paper presents a detailed analysis of the optimal energy management problem for a plug-in hybrid electric vehicle (PHEV) solved using the Pontryagin’s minimum principle (PMP). The aim of this analysis is to study the relationships between the control parameters and the vehicle and driving characteristics. In this study, a relationship between the state and co-state trajectories with the battery characteristics has been developed which has not been explored in a similar fashion in prior literature. Results from sensitivity analysis show a strong asymmetry in higher and lower estimation of the initial value of the co-state. A spatial domain analysis is also carried out which shows quasi linearity of the optimal state of charge (SOC) with respect to trip length for a combination of driving cycles. Knowledge gained from this exercise enables us to develop an adaptive energy management strategy.