Simplified Mathematical Model for Calculating the Oxygen Excess Ratio of a PEM Fuel Cell System in Real-Time Applications

The oxygen starvation phenomenon is a dangerous operating condition that reduces the lifetime of PEM fuel cells. The detection and prevention of this undesired phenomenon require estimation of the oxygen excess ratio λ_O2. The mathematical complexities of the reported methods for obtaining λ_O2 complicate its real-time calculation and require high-performance computational devices, which significantly increase the costs of the system. In this paper, a mutual information approach is used in obtaining a simplified mathematical model for the calculation of λ_O2. The usage of such a simplified model requires much less computational power for real-time monitoring of the variable λ_O2, while it provides comparable results to those obtained by using the complex model. Therefore, it represents a cost-effective solution, suitable for usage within applications that require high sampling frequencies, like emulators, converter and air compressor control loops, simulations, etc. In order to validate the accuracy of this simplified λ_O2 calculation model, a real-time monitoring system was built and experimentally tested using both the simplified and complex models. The matching experimental results validate the proposed simplification and justify the use of this simplified model within real-time monitoring applications.