Harnessing monotonicity to design an adaptive PI passivity-based controller for a fuel-cell system

In this paper, a controller is designed to regulate the output voltage of a fuel-cell (FC) system comprising a proton-exchange membrane FC feeding a purely resistive load through a boost converter. The controller aims to maintain voltage regulation regardless of uncertainties in the resistive load. Leveraging the monotonicity of the FC polarization curve, it is demonstrated that the non-linear system can be controlled with a simple proportional–integral (PI) action through the PI-passivity-based control (PI-PBC) methodology. The result is subsequently extended to an adaptive version, enabling it to address parametric uncertainties, including inductor parasitic resistance, load variations, and fuel cell polarization curve parameters. The overall system is proved to be stable by regulating the output voltage under parametric uncertainty. Experimental results validate the proposed controller.