A Nonlinear Controller Based on a High Gain Observer for a Cascade Boost Converter in a Fuel Cell Distributed Power Supply System
Résumé
This study aims to design a controller for a cascade boost converter connected to a fuel cell in a distributed generator system. Knowing that the fuel cell voltage is too low to satisfy load requirement, and it varies with a nonlinear manner depending on the load current with uncertainties lying on fuel cell operating conditions, we use a DC converter to step up the low voltage and find out a control law to regulate the converter output voltage. Here, a lyapunov stability technique is used to design the nonlinear controller. An average current mode control method is adopted to satisfy the above objective. Moreover, a high gain observer is developed to estimate the converter output current instead of to be captured. Besides, the cascade boost converter is proved to be more suitable for high DC link voltage compared to a single boost converter. Theoretical studies and simulation using Matlab Simpower System tools show that the adaptive controller meets the objectives for what it is designed.