Nonlinear Voltage Regulation Strategy for a Fuel Cell/Supercapacitor Power Source System

The main purpose of this work is to model and control a fuel cell/supercapacitor power source system to feed a DC-bus with a constant output voltage despite load changes. The fuel cell is modeled as a nonlinear current-dependent voltage source meanwhile, the supercapacitor is represented as an ideal capacitor. The power converters are modeled using a average model techniques. Furthermore, the proposed nonlinear state feedback control method is based on backstepping techniques and Lyapunov stability analysis to ensure that error signals converge to zero. A load estimator is designed using Immersion-Invariance (I&I) theory to track load changes through available measurements. Finally, simulation results show that the proposed control scheme stabilizes the system when step changes are applied to the load.