Research of Diagnosis Technique on PEFC Running Condition (Over Voltage Analysis and Diagnosis of PEFC by FFT)

Real time analysis on impedance spectroscopy in PEFC (Polymer Electrolyte Fuel Cell) was tried using FFT (Fast Fourier Transform) method to diagnose its running conditions. PEFC is simulated to equivalent circuit model with four resistances and three capacitances, and effects of running conditions on those were analyzed by the experiments. Results show that the voltage drops at each resistance correspond to over voltage calculated by conventional method and indicate distinctive characteristics according to deterioration of running condition. The logic is established to real time diagnosis of PEFC running conditions by classifying these voltage drops and to trace the flow chart. This method has capability of on-board diagnosis and control of fuel cell system vehicle.