Improved Modeling and Control of a PEM Fuel Cell Power System for Vehicles

This paper presents an improved nonlinear dynamic modeling and control of a proton exchange membrane (PEM) fuel cell stack power system for vehicle applications. The PEM fuel cell system considered includes a fuel tank, supply manifold, cooler and humidifier, fuel cell stack, as well as return manifold. The hydrogen and oxygen have been considered as fuels. The dynamic behavior of the flow path and stack is mainly described with three fundamental equations of mass conservation, nozzle flow, and continuity of isentropic flow. An improved empirical model is employed for the fuel cell system and have been simulated using MATLAB/Simulink. Simulation result shows that the stack pressure and flow rate affects the stack performance in terms of output voltage and currents. Thus, it is crucial to find an optimal control strategy for the pressure that facilitates a control of the output power according to power demand of a load. A new control strategy has been proposed and simulated in conjunction with the fuel cell stack and system models for vehicle applications