Impedance spectroscopy on a single PEM fuel cell for the evaluation of current ripple effects

The use of fuel cells for powering AC loads requires to employ power converters and in particular inverters. The efficiency of these devices is usually very high, but they add a current ripple on the fuel cell side that might affect the fuel cell performance and decrease the overall system efficiency more than expected. Previous studies revealed that this performance decrease depends on the impedance spectrum of the fuel cell and in particular on the cut-off frequency of the RC equivalent circuit associated with the charge double layer, which is usually in the typical current ripple frequency range. Therefore, accurate measurements of the fuel cell impedance up to high frequencies (kHz) are necessary. In this paper the high-frequency behavior of a single PEM fuel cell is investigated via impedance spectroscopy and some critical issues concerning the effects of current ripple are discussed.