Control of fuel cell-based electric power system using adaptive sliding mode control and observation techniques

The paper deals with controlling an autonomous electric power system that comprises of a primary source of power supply, Proton Exchange Membrane fuel cell (PEMFC), DC-DC boost power converter as a power conditioner, and the ultracapacitor for an auxiliary power supply. Relative degree approach is applied for direct control of the output load voltage as well as the fuel cell and ultracapacitor current in the presence of the model uncertainties. The zero dynamics of the studied electric power system is analyzed and appeared to be stable. The non-minimum phase property of the DC-DC boost converter is eliminated by controlling the fuel cell current based on the power balance. The adaptive super-twisting sliding mode observer is employed for identification of the load resistance, which estimated value is used for generating the fuel cell current command profile. The adaptive gain second order (2-SM) super-twisting sliding mode controller is proposed for controlling the current in PEMFC. The conventional Sliding Mode Controllers (SMC) is designed for controlling the output voltage of the converter and the load current of the ultracapacitor. The efficacy and robustness of the proposed decentralized three-fold electric power system controller that consists of two SMCs and one 2-SM adaptive-gain controller are confirmed via computer simulations.