Dynamic changes in power systems affect the overall performance of fuel cells. The amplitude, frequency and duration of disturbances affect the way fuel cells response. Electrochemical Impedance Spectroscopy (EIS) is a technique that allows the study of how these disturbances affect fuel cells.

EIS studies have previously been used to study high impedance processes like corrosion and coating. The application of EIS to simulating power system processes calls for modification of EIS measuring techniques to meet the new demands. Unlike corrosion and coatings, fuel cell power system studies involve electrochemical processes, control systems and load interacting.

This paper presents impedance data intended to be used to investigate the effect of power converter loading of fuel cells during disturbances caused by operational and fault conditions. The emphasis is on identifying possible sources of error in measuring impedance data of an operating Proton Exchange Membrane (PEM) fuel cell and how these errors could be minimized. Hydrogen purging, amplitude of modulating signal and test cell(s) location within the stack were investigated to determine their effect on impedance measurement.