This work develops an 8th order, non-linear thermal model of an automotive Proton Exchange Membrane (PEM) fuel cell system. Subsystem models were developed from first principals where ever possible and validated against data from a physical system. The entire model was then validated against system data from a General Motor\u27s 120kW fuel cell system. The system model was analyzed in both the time and frequency domain. Next, a reduced, 3rd order model was constructed from the full model and then linearized. The performances of all three models were compared and it was found that the 3rd order linear model provided an acceptable representation of the full non-linear model. Using the models developed in the first section, different control strategies were examined. A proportional-integral (PI) controller was developed as a baseline and compared to a full state feedback Linear Quadratic controller. This controller was augmented to include output variable feedback to improve the steady state performance of the controller. The state feedback controller was found to have faster response and less interaction between the controlled variables than the baseline controller. Because some of the states are unmeasured, an estimator was developed to determine the state values for the full state feedback controller
