A hybrid power system (10) for supplying power to a load (12) such as an
electric vehicle is provided. The power system (10) includes an energy
storage device (14) and a fuel cell system (16). When the state of charge
of the energy storage device (14) is greater than or equal to a
predetermined state of charge, the energy storage device (14) supplies all
of the power to the load (12). When the state of charge of the energy
storage device (14) falls below the predetermined state of charge, the
fuel cell system (16) supplies at least a portion of the power to the load
(12). In accordance with one aspect of the invention, the fuel cell system
(16) then supplies all of the power to the load (12) as long as the power
requirement of the load (12) does not exceed an optimal power output of
the fuel cell system (16).
