Nonlinear Adaptive Control of a Hybrid Fuel Cell Power System for Electric Vehicles - A Lyapunov Stability Based Approach

Abstract

This study deals with the problem of controlling hybrid storage systems in electric vehicles. The storage system includes a DC-to-DC switched power converter of boost type associated with a fuel-cell generator and a buck boost converter connected to a supercapacitor. Both converters operate according to the PWM principle and the whole system model is nonlinear and subject to parameter uncertainties. The control objective is threefold: ensuring a tight dc bus voltage regulation despite the uncertainties on the fuel cell (FC) voltage-current characteristic and on the load converter; (2) guaranteeing a perfect tracking of supercapacitor (SC) current to its reference despite the SC capacitance uncertainty; ensuring asymptotic stability of the closed-loop system. The control problem is dealt with using a nonlinear adaptive controller designed by the Lyapunov approach. It is formally shown that the proposed controller meets all its control objectives. This theoretical achievement is confirmed by several simulations.