Static and Dynamic Current-Voltage Modeling of a Proton Exchange Membrane Fuel Cell Using an Input-Output Diffusive Approach

This paper deepens in the study of the recently described diffusive proton exchange membrane fuel cell (FC) model. This model has demonstrated a close agreement to the experimental data provided by a real FC. The diffusivemodel is approximated by a finite-dimensional model that allows formulating an optimization problem of least square error type to estimate the model distribution. The diffusive model is identified by means of experimental measurements of current (input) and voltage (output) in the FC. It is well known that the FC static current-voltage characteristic has three operation regions, with only the ohmic region being strictly linear, so that it is very difficult to approximate the whole operation range with a linear model. Therefore, a new method is presented in this paper extending the diffusive approach by means of a linear parameter-varyingmodel with the aim to overcome the limitations of linear time-invariant models. In addition, discrete-time expressions for the new diffusive model approach are derived. The obtained model is simple and can be used in systems that require real-time emulators or complex long-time simulations. Experimental results using the Ballard Nexa 1.2-kW FC illustrate the advantages of the new diffusive model approach with respect to previous reports.