Ripple Current Effects on PEMFC Ageing Test by Experimental and Modeling

PEMFCs’ systems usually require power conditioning by a DC/DC boost converter to increase the output fuel cell voltage, especially for automotive applications and stationary applications. The output fuel cell current is then submitted to the high frequency switching leading to a current ripple. The ripple current effects on fuel cell are studied by experimental ripple current ageing test on a 5 cell stack (MEA surface of 220 cm2 ) and compare to a reference ageing test. The stack is run in nominal conditions but an AC component is added to the DC current load. The AC component is a 5 kHz triangle which amplitude is ±20% of the DC component in order to simulate a boost waveform. Fuel cell characterizations (polarization curves, impedance spectra and voltammetry) provide information on the PEMFC ageing and the performance evolution. Local conditions are computed through a dynamic stack model. The model takes into account transport phenomena, heat transfer, and semi-empirical electrochemical reactions and includes a meshing to calculate local conditions on the MEA surface (gas reactant pressures, local temperature, gas molar fractions, water activity, and local electronic current density). The consequences about performance and ageing during high frequency ripple current are explained.Copyright © 2010 by ASME