Design of 2 DOF Fuzzy Control System for Fuel Cell Systems

Fuel Cell Systems (FCSs) are a promising energy source for various applications due to their high efficiency and low environmental impact. However, the commercialization of FCSs has been hindered by their limited lifespan, which is largely affected by cell degradation. To address this issue, we propose a 2 DOF fuzzy control system that is capable to maximize the net stack output power while considering cell degradation. The proposed control system is composed of a data-driven Reference Generator (RG), a data-driven Feedforward Controller (FFC), and a feedback PI controller which are designed to regulate the Oxygen Excess Ratio (OER) to achieve maximum net power output. To handle the dominant nonlinearity, we learn and deploy Fuzzy Models (FMs) as the RG and FFC. In this context, we analyzed the stack current-OER relationship at optimal stack temperature and learned the nonlinear characteristic with FMs. Then, the PI controller is tuned to track the generated reference to maximize the net stack power for different stack currents. To analyze the impact of improvements on cell lifetime, we developed a degradation model based on electrochemical impedance spectroscopy. The results show that the fuzzy control system can maximize the net stack output power while simultaneously prolonging fuel cell life as a result of the high-performing OER control loop. We believe that the proposed 2 DOF fuzzy control system is a step towards the commercialization of fuel cells and enables their widespread adoption as a sustainable energy source for various applications.