Adaptive Passivity-Based Control for a Fuel Cell-Quadratic Boost Converter System

Passivity-based control of a quadratic step-up converter coupled to a proton exchange membrane fuel-cell (PEM) is presented in this study. The main purpose of the control scheme is to keep the load voltage constant through precise current regulation. As a result, two feedback loops are used for this purpose: a non-linear inner (current) loop that uses the passive features of the system for current tracking and an outer (voltage) loop that generates the current reference through a proportional integral action over the output voltage. Additionally, an adaptation law is designed employing the immersion-invariance (I&I) scheme to enhance the robustness of the inner current loop with respect to load uncertainty. Hence, an adaptive energy-based controller with asymptotic stability is achieved. Simulations are performed with the aim to assess the controller performance. Is is observed that the output voltage regulation is robust in terms of load variation and unregulated DC voltage from the fuel-cell stack.