An Enhanced Fuel Cell Dynamic Model With Electrochemical Phenomena Parameterization as Test Bed for Control System Analysis

Abstract

In this work, a model of a proton exchange membrane fuel cell (PEMFC) is presented. A dynamic performance characterization is performed to assess the cell transient response to input variables. The model used in the simulation considers three different phenomena: mass transfer, thermodynamics, and electrochemistry. The main sources of voltage loss are presented: activation, electrical resistance, and concentration. The model is constructed to avoid the use of fitted parameters, reducing the experimentation required for its validation. Hence, the electrochemical model is parameterized by physical variables, including material properties and geometrical characteristics. The model is demonstrated as a test-bed for PEMFC control system design and evaluation. Results demonstrate that the steady-state and dynamic behavior of the system are represented accurately. A case study is included to show the functionality of the model. In the case study, the effect of the purge valves at the fuel cell discharges is analyzed under different scenarios. Regular purges of the cathode and the anode are shown to achieve a good performance in the system avoiding reactant starvation in the cell. A closed-loop dynamic response is included as an example of the model capabilities for the design of fuel cell control strategies. Two variables were selected to be controlled: voltage and pressure difference across the membrane. A multivariate control strategy was tested and its dynamic response was analyzed. It was found that there was a strong interaction between the control loops, making the control of the system a challenge.