A temperature control scheme for a fuel cell stack thermal sub-system in a
fuel cell system that uses a non-linear thermal model and disturbance
rejection to provide an optimum stack temperature. The thermal sub-system
includes a coolant loop directing a cooling fluid through the stack, a
pump for pumping the cooling fluid through the coolant loop, and a
radiator for cooling the cooling fluid outside of the fuel cell stack.
The system includes a controller for controlling the speed of the pump so
as to maintain the temperature of the stack at a desired temperature. The
controller uses the thermal model to anticipate a temperature of the
cooling fluid out of the fuel cell stack to control the speed of the
pump.