Signal Injection by Active Load Modulation for PEM Fuel Cell Diagnostics

Polymer Electrolyte Membrane (PEM) fuel cells have been the focus of numerous research efforts for its attractive characteristics. The fuel cell as a multi-physics system requires real-time condition monitoring and diagnostics to ensure safe operation. The Electrochemical Impedance Spectroscopy (EIS) measurement has been widely used as a characterization tool for the fuel cell system. Also, it has been deployed for diagnostics to extract impedance information, providing insight into the various electrochemical processes taking place within the fuel cell system. However, current EIS measurements are typically carried out with expensive frequency response analyser (FRA) which is also prove not portable for online use. This paper demonstrates the use of a low-cost active load that helps to implement the load modulation technique for impedance measurements. The design of the active load is presented and results for the active-load and commercial FRA are also compared for equivalent circuits models.