Patent ID: 7476457

Claim:
A fuel cell system having fuel cells, which receive a supply of a gas and generate electric power to satisfy a load, and a secondary battery, which accumulates electric power therein and outputs the accumulated electric power to satisfy the load, said fuel cells system supplying at least one of the electric power generated by the fuel cells and the electric power output from the secondary battery to a load, said fuel cells system comprising: a gas flow rate-relating quantity measurement unit configured to measure a gas flow rate-relating quantity, which relates to a flow rate of the gas supplied to said fuel cells; and a control unit configured to specify a working point associated with an output electric current-output voltage characteristic of said fuel cells corresponding to the measured gas flow rate-relating quantity, to determine a first amount of electric power to be taken out of said fuel cells at the specified working point, to determine a second amount of electric power to be supplied to the load, to compare said first and second determined amounts of electric power, and to regulate at least one of the electric power to be output from the secondary battery and the electric power to be accumulated in said secondary battery, based on the comparison of the first and second determined amounts of electric power.