Patent ID: 7526346

Claim:
A method for controlling the temperature of a fuel cell stack in a fuel cell system, said method comprising: developing a thermal model of the fuel cell stack that employs non-linear equations; generating an error signal that is the difference between a desired stack temperature and a temperature of a cooling fluid out of the fuel cell stack; applying feedback control to the error signal to generate a control signal; modifying a disturbance signal to generate a modified disturbance signal; adding the control signal to the modified disturbance signal to generate a linearization variable; generating a mass flow rate signal using the linearization variable; and linearizing the thermal model using the mass flow rate signal to reject the disturbance in the modified disturbance signal, wherein linearizing the thermal model includes using the mass flow rate signal, the disturbance and a temperature of the cooling fluid into the stack; said fuel cell system including a controller that controls the temperature of the fuel cell stack using the linear thermal model.