Online Implementation of an Integrated Explicit and Nonlinear Model Predictive Control (exNMPC) Framework for a PEM Fuel Cell System

This work presents the use of advanced control methodologies for a Polymer Electrolyte Membrane (PEM) fuel cell system. Two Model Predictive Control (MPC) strategies, a multi-parametric and a nonlinear MPC, are combined into a framework (explicit Nonlinear MPC - exNMPC) in order to systematically exploit their synergistic benefits and enhance the behaviour of the system. The new controller solves online a dynamic simultaneous optimization problem using a warm-start procedure that considers a piecewise affine (PWA) approximation defined offline over the partition of the system's feasible space. The proposed control scheme is deployed on an industrial Supervisory Control and Data Acquisition (SCADA) system and its response is explored. Experimental studies demonstrate that the multivariable exNMPC controller exhibits a very good performance in terms of computational requirements while achieving an excellent convergence rate even at varying operating conditions.