Degradation-conscious control for enhanced lifetime of automotive polymer electrolyte membrane fuel cells

A linear time varying model predictive control (LTV-MPC) framework is developed for degradation-conscious control of automotive polymer electrolyte membrane (PEM) fuel cell systems. A reduced-order nonlinear model of the entire system is derived first, including the reactant and coolant supply subsystems and the fuel cell stack. This nonlinear model is then successively linearized about the current operating point to obtain a linear model. The linear model is utilized to formulate the control problem using a rate-based MPC formulation. The controller objective is to ensure offset-free tracking of the power demand, while maximizing the overall system efficiency and enhancing its durability. To this end, the fuel consumption and the power loss due to auxiliary equipment are minimized. Moreover, the internal states of the fuel cell stack are constrained to avoid harmful conditions that are known stressors of the fuel cell components. Membrane dry-out, rapid changes in the membrane hydration, and reactant starvation are among the stressors considered in this work. However, the framework can accommodate further lifetime indicators as needed. Simulation-based studies showcase the utility of the proposed control framework in meeting the outlined objectives.