A new approach to optimally tune the control strategy for hybrid vehicles applications*

The paper presents an innovative method for the optimal tuning of energy management control strategies for hybrid electrical vehicles. The method is based on the analysis of an existing optimal control law, which can be obtained using Dynamic Programming, by means of the local partial derivatives. This permits to obtain a set of upper and lower bounds for instantaneous value of the time-varying Lagrange multiplier of the constrained optimization problem, which can be represented in so-called Λ-plots. From that plots, it is possible to provide an estimate of the optimal parameters for tuning energy management control strategies as the Equivalent Consumption Minimization Strategy and Pontryagin Minimum Principle. Λ-plots also provide a good framework for analysing the equivalence of different control strategies. The Λ-plot method is demonstrated for both series and parallel configurations of a hybrid electrical vehicle.