Model-Based Nonlinear Control of the Cathode Pressure of a PEM Fuel Cell System Using a VTG

Fuel cells are in risk of starvation due to a possible drop of the oxygen partial pressure during a dynamic operation. Therefore, feedback control of the cathode pressure plays an important role towards an efficient operation of a polymer electrolyte membrane (PEM) fuel cell system. In this paper, hence, a model-based nonlinear pressure control approach using a variable turbine geometry (VTG) is presented. The system model is derived from physical considerations in symbolic form, and parametrized by a least-squares parameter identification. As the derived dynamic model of the cathode subsystem is highly nonlinear, appropriate techniques using differential flatness are applied. Moreover, a sigma-point Kalman filter (SPKF) provides accurate estimates for the state variables and a lumped disturbance. Simulation results show the effectiveness and illustrate the achieved control performance.