Immersion and Invariance Adaptive Backstepping Control of PEMFC Air Supply Systems with Unmeasurable Cathode Air Pressure

In this paper, an immersion and invariance (I&I) adaptive backstepping control strategy is proposed for proton exchange membrane fuel cell (PEMFC) air supply systems with unmeasurable cathode air pressure. To account for uncertainties such as gas leakage and stack temperature variation, an I&I adaptive full-state feedback control strategy is first proposed, which ensures asymptotic regulation of the oxygen excess ratio (OER) while maintaining satisfactory transient performance. Since the cathode air pressure is not directly accessible via sensor measurements, state reconstruction based on available output data becomes a necessity. To address this issue, an I&I adaptive observer-based partial-state feedback control strategy is then proposed, where the unknown parameters and the unmeasurable state are treated in a uniform manner. The stability of the closed-loop system is established via Lyapunov analysis, and the efficacy of the proposed control schemes is validated through numerical simulations under parametric variations.