Control-oriented modeling for open-cathode fuel cell systems

Due to numerous advantages of Polymer Electrolyte Fuel Cells (PEMFCs), they are becoming the mainstream fuel cell of choice for different applications. Open-cathode PEMFCs, in particular, are gaining increased popularity in low to medium power applications due to their simple structure and low parasitic losses. However, in order to achieve safe operation, increased durability and optimal performance, advanced control algorithms, which typically require control-oriented models, need to be implemented on open-cathode fuel cell systems. The open-cathode fuel cell system includes the fuel cell stack and all of the auxiliary components that are vital for its operation. In this paper, control-oriented nonlinear models are developed for individual components of air-forced open-cathode fuel cell systems. The models incorporate electrical, thermal, anode, and cathode system dynamics in addition to the interactions between different subsystems. Specifically, control-oriented purge modeling is given special attention in this paper due to lack of sufficient research in this area and in spite of its important role in the fuel cell performance. To the authors´ knowledge, this is the first work focusing on developing control-oriented models which are capable of capturing important open-cathode fuel cell dynamics and the interactions between them. All of these models are validated experimentally on a small scale open-cathode fuel cell system. Finally, control challenges that can be formulated using the proposed models are discussed.