Modeling Study of a Combined Fuel Cell Stack/Switch Mode DC DC Converter

Abstract

A fuelcell stack produces a low and unregulated dc voltage; therefore, a dcdc converter is required to step up and regulate the output voltage. A major drawback is that the output voltage of the fuelcell stack exhibits a nonlinear behavior since the output voltage drops when more current is drawn. This output voltage will be later connected to a switchmode dcdc converter to step up its value; therefore, it is very important to consider the dynamic behavior of fuelcell stack as input to a switching converter. In this work, a model is proposed for a combined fuelcell stack/boost converter system. The interest of this model is clearly motivated by the need to have a model compatible with the standard techniques for controller design as currentmode control. The model is tested using a power module and a boost converter delivering an output power of 740 W. The power module uses polymer electrolyte membrane fuel cells (PEMFCs) and delivers a variable output dc voltage between 24 V to 42 V. Experimental results verify the theoretical results given within.