Exploiting Monotonicity to Design an Adaptive PI Passivity-Based Controller for a Fuel-Cell Systems

We present a controller for a power generation system composed of a fuel cell connected to a boost converter which feeds a resistive load. The controller aims to regulate the output voltage of the converter, regardless of sudden changes of the load and the fuel cell voltage. Leveraging monotonicity, we prove that the nonlinear system can be controlled by means of a simple passivity-based PI. We afterward extend the result to an adaptive version, allowing the controller to deal with parameter uncertainties. This adaptive design is based on an indirect control approach with parameter identification performed by a “hybrid” estimator, which combines two techniques: the gradient-descent and the immersion-andinvariance algorithms. The overall system is proven to be stable, with the output voltage regulated to its reference. Furthermore, realistic simulation results validate our proposal.