Real time model-based monitoring of a PEM fuel cell flooding and drying out

The present paper deals with real time monitoring of flooding and drying out of a proton exchange membrane (PEM) fuel cell using a model-based approach coupled with voltage and current dynamic measurements. The model used in this study is inspired by the Randles equivalent electrical circuit. It was found that monitoring the evolution of the three resistances of this modified Randles model was an efficient and robust way of monitoring the state-of-health of the fuel cell stack. Fitting of the model parameters to experimental data is investigated both in the time domain, using a linear recursive least square algorithm, and in the frequency domain, using a non-linear least square Levenberg-Marquardt algorithm. A study of the voltage response of a 220cm², 6-cell, air/H₂ PEM fuel cell to a square current signal is carried out, in order to assess the performances of the different methods.