Recasting the HEV energy management problem into an infinite-time optimization problem including stability

This paper deals with the problem of finding a closed-form optimal solution for the energy management problem in charge-sustaining hybrid electric vehicles. For the first time, a generalized stability and optimality framework for this type of problem is proposed. In the proposed control design, the energy management problem, that by its very nature is a finite-time optimal control problem, is reformulated as a nonlinear-nonquadratic infinite-time optimization problem, leading to a family of state-feedback based control laws providing optimality with respect to an infinite time horizon performance functional while guarantee asymptotic stability. The analytical solution is obtained through a Lyapunov-based dissipative approach. The proposed optimal energy management control law is implemented in a pre-transmission parallel hybrid heavy duty truck and its performance is compared to the benchmark solution provided by the Pontryagin´s Minimum Principle (PMP). Reduced computational efforts and lower sensitivity of the control parameter, while maintaining performances within 2% from the optimal value, makes the novel control design a breakthrough in energy management control research.