Nonlinear Observer-Based Air Supply Subsystem Control via a High-Order Fully Actuated Approach for Fuel Cell

In the air supply subsystem of proton exchange membrane fuel cells (PEMFCs), airflow rate and cathode pressure are key state variables and require precise coordinated control to improve the service life of the proton exchange membrane and enhance the air supply subsystem efficiency. However, the airflow rate and cathode pressure have strong nonlinearity and highly coupled characteristics, making it particularly difficult to precisely coordinate control. To tackle these challenges, this study presents a high-order fully actuated (HOFA) system approach for PEMFCs to achieve accurate cooperative control of the airflow and cathode pressure. First, a HOFA system model for the air supply subsystem is developed based on the fully actuated system approach. The accuracy of this HOFA system model is then validated by the detailed comparison with the high-fidelity model. A nonlinear observer is constructed to estimate unknown disturbances, with its global stability rigorously proven. Second, a low-gain controller is designed utilizing the unique structure and advantages of the HOFA system approaches, with its stability rigorously verified using the Lyapunov method. Finally, the verification is performed on a hardware-in-the-loop (HIL) platform, demonstrating the effect of the proposed controller. The HIL verification result indicates that the proposed control strategy outperforms other existing control strategies.