Preventing reactant starvation of a 5 kW PEM fuel cell stack during sudden load change

Reactant (hydrogen and air) starvation during PEMFCs operation can produce serious irreversible damages. To preventing reactant starvation and, at the same time, to allow a dynamic operation of the fuel cell system, both stoichiometric ratio γ_H2 and stoichiometric ratio γ_Air of the input gases need to be adjusted rapidly during sudden load change. In order to study the detailed local characteristics of starvations, simultaneous measurements of the dynamic variation of pressure, flow rate, temperature, current density, and relative humidity in an experimental PEMFC stack have been performed during both air and hydrogen starvations. This study is based on the real-time control of Nedstack P5.0-40 bench PEM fuel cell test system and presents a suitable control strategy for hydrogen/air supply, based on PID feedback and feedforward control of the reactant feeds for preventing the starvation and/or obtaining the maximum net power of PEMFC stack to sudden changes in load.