Patent ID: 8088527

Claim:
A fuel cell system comprising: a fuel cell which receives a supply of a reactant gas to generate a power; a reactant gas supply device which supplies the reactant gas to the fuel cell; a warm-up device which warms up the fuel cell by a low-efficiency operation at a low power generation efficiency as compared to a normal operation; and a controller which reduces the supply of the reactant gas to the fuel cell while holding an output voltage of the fuel cell at a fixed value, when a power generation instruction value for the fuel cell decreases while performing the low-efficiency operation and when the supply of the reactant gas to the fuel cell is controlled so as to follow the decrease of the power generation instruction value, the controller being configured to control the supply of the reactant gas to the fuel cell and to increase the output voltage of the fuel cell, thereby charging an excessive power in excess of the power generation instruction value into a capacitance component of the fuel cell, when the supply of the reactant gas to the fuel cell is not controlled so as to follow the decrease of the power generation instruction value.