Comprehensive control of proton exchange membrane fuel cell as backup power supply for UPS

To improve the performance of a proton exchange membrane fuel cell (PEMFC) stack, it is important to avoid the hydrogen and oxygen/air starvation of electrochemical reaction, prevent the dehydration and drying of the membrane, and track the output power. This paper conducts research in a comprehensive control strategy of the operation parameters of an uninterruptible power system (UPS) with backup PEMFC and battery power sources, such as the thermal management and control of operating temperature, pressures and mass flows of hydrogen and air for the PEMFC stack, switch of the power supply between PEMFC and battery for UPS, and the output power tracking of PEMFC. Based on the dynamic model of the anode and cathode flow system, the models of manifold and the performance curve, a detail model analysis is presented. A comprehensive control method is proposed and applied to the PEMFC system employed for the power source of UPS. The experimental results show that the comprehensive control method can effectively keep constant pressures of the inlet hydrogen and air, automatically switch the power supply between PEMFC and battery, reasonably improve the performance of the PEMFC through thermal management and control of operating temperature, and track the real-time changes of the output power and the distribution of the mass flows of hydrogen and oxygen/air.