Nonlinear tracking control of output power for PEMFC systems

For controls of proton exchange membrane (PEM) fuel cell (FC) systems, it is desirable to achieve accurate tracking of desired net output power with optimal oxygen excessive ratio (OER). In this paper, a cascade control framework is proposed for the FC output power tracking problem, which is a sequential combination of a multi-input-multi-output (MIMO) robust nonlinear non-interacting (RNNI) controller and a nonlinear disturbance-decoupling (NDD) control scheme. Two major issues are addressed: one is interaction/coupling between the OER and the net output power, and the other is the parametric model uncertainty caused by fluctuations in stack temperature under various operating conditions. Simulation results show that good tracking performance is obtained with the two performance objectives well decoupled, and furthermore the impact from the parameters uncertainty can be removed via a nonlinear compensator.