An Efficient Approximation Method for an Individual Fuel Cell Impedance Characterization

In this study, an efficient method of approximating individual fuel cell impedances in a stack is proposed and experimentally verified. Two different proton exchange membrane (PEM) fuel cell stacks (600 W with 24 cells and 1.2 kW with 47 cells) were used to develop and verify the method. Both PEM fuel cell stacks were operated using room air and pure hydrogen (99.999%). Impedance and current - voltage (I-V) data were collected for stack and individual cell levels under various operating conditions. The experimental result shows that the individual cell impedance is directly proportional to the corresponding cell voltage. Therefore individual cell impedance can be accurately estimated by performing only stack impedance and individual cell voltage measurements.