Passivity-Based Control for a Fuel Cell/Non-Inverting Buck-Boost Converter System

In this work, a passivity-based control for output voltage regulation of a non-inverting buck-boost converter coupled to a proton exchange membrane fuel cell is presented. The primary objective of the control is to maintain a stable voltage despite voltage variations of the fuel cell, through precise current control. There are two feedback loops designed to do this, an outer loop for current reference generation via a proportional-integral action, and an inner loop for tracking current reference, using the passive characteristics of the system. To improve the reliability of the inner current loop, an Immersion-Invariant (I&I) load estimator is developed. The overall efficacy of the controller is determined by numerical simulations that demonstrate its capacity to manage load variations and maintain a stable, regulated DC output voltage despite voltage changes from the fuel-cell stack.