Fuel Cell Condition Monitoring Using Optimized Broadband Impedance Spectroscopy

Determining the state of health of fuel cell systems is essential to improving its performance and life expectancy. This paper presents the development of a new rapid online condition monitoring system using optimized broadband impedance spectroscopy (OBIS). The hardware was specifically designed to be low cost and scalable to meet the needs of single cell and stack level testing. It is shown how classic electrochemical impedance spectroscopy (EIS) is limited when testing under extreme nonlinear conditions. The design process of the broadband signal is tailored for polymer electrolyte membrane fuel cell diagnostics in order to minimize measurement time and system disturbance while maximizing accuracy. The long measurement time of standard EIS makes it impractical to use for rapid fault diagnosis, and it is shown how the OBIS system is able to deliver impedance measurements under conditions where EIS cannot be applied. The proposed system is tested for an array of possible operational phenomena and faults and the results compared with that obtained from a commercial frequency response analyzer to demonstrate performance.