The Effect of Inverter Ripple on Solid Oxide Fuel Cell Performance

The effect of inverter ripple (feedback on a fuel cell from the DC to AC inverter) current on solid oxide fuel cell performance is not well understood. At NETL, both models and experimental work are being pursued to try and understand the effect of inverter ripple on cell performance. The modeling work has led us to speculate that large oscillations in voltage due to the inverter may have deleterious effects on cell performance and lifetimes. Results showed the behavior of the reactant concentrations within the stack electrodes under inverter loads with frequencies between 60 Hz and 1250 Hz. The conclusion was that due to the fluctuating reactant concentrations, temporary conditions (on the order of the frequency of ripple) would occur where the concentration of H 2 at the anode/electrolyte interface varied significantly from the average value. Since much work in the development of fuel cells relies on steady state test data, concern is raised that final operation on an inverter would have significantly different performance results. Here we report the results of experimental tests of the effect of ripple on solid oxide fuel cells. Data was acquired over several weeks on the performance of an individual cell while being exposed to 30% ripple current at a frequency of 60Hz. No degradation that could be attributed to inverter ripple was detected over the period of testing.