Experimental study of a fuel cell stack performance operating with a power electronics converter with high-frequency current ripple

Abstract

This article presents an investigation into the effect of a high-frequency current ripple on the performance of fuel cell stacks. A current with high-frequency ripple can be drained from a fuel cell stack in applications in which a power electronics converter is the stack's electrical load, and this situation is very common in a wide variety of applications. The current ripple is a variation of its value around the average or dc component. It is caused by the switching action of the transistors in a power electronics converter, it can be calculated, and converters can be designed to have a particular current ripple amplitude and frequency. The existence of a ripple increases the Root Mean Square (RMS) value of the current (compared to their dc or average value). The study employs a boost converter to regulate the power output from the fuel cell stack, effectively generating a controlled AC ripple to observe its influence. A set of experiments are conducted to analyze the impacts of these conditions from the electrical point of view. Our results reveal that the main effect of the AC ripple is a reduction of the FC stack voltage output, like the one caused for an increase on the current, the voltage drop causes a shift on the operating condition which cause a reduced-efficiency operation. The presented findings provide information and must be considered for applications of power electronics converters feed by FC stacks. Experimental results are provided to demonstrate the discussed effects.