Sliding mode control of electric power system comprised of fuel cells, DC-DC boost converters and ultracapacitors

The paper deals with controlling an autonomous electric power system that comprises Proton Exchange Membrane fuel cell (PEMFC) that is considered as a primary source of electrical energy, the DC-DC boost power converter, and the ultracapacitor. System´s PEMFC/ultracapacitor/DC-DC boost power converter zero dynamics are analyzed and appeared to be stable. 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 adaptive gain super-twisting sliding mode controller controls the current in PEMFC. The decoupled SMCs are designed for controlling the output voltage and the fast component of the load current that is commanded to the ultracapacitor. The efficacy and robustness of the proposed three-fold SMC and 2-SM adaptive-gain controllers are confirmed via computer simulations.