Abstract
Keywords - sliding optimal control, Pontryagins minimum principle, hybrid electric vehicle, energy management, supervisory control strategy
Abstract - The hybrid electric vehicle is one of the promising alternatives of the engine-powered vehicle for better fuel economy and lower emissions. Energy management in the hybrid electric vehicle is regarded as an optimal control problem and has been solved by many researchers with dynamic programming, Equivalent Consumption Minimization Strategy, etc. In this paper, Pontryagins minimum principle is used to solve for a practical optimal solution. Since the Hamiltonian is piece-wise continuous and is not always convex, a better solution, sliding optimal control, is found for constant torque and speed requirements. The sliding optimal control cannot be implemented precisely because the switching frequency cannot be infinitely high in practice. Switching at 1 Hz is recommended according to the weak relationship between the switching frequency and the Hamiltonian. Finding the optimal solution for time-varying power requests will be accomplished next.