Patent ID: 7867662

Claim:
A contactor failure detecting apparatus for use in a fuel cell system comprising: a fuel cell generates power by reaction of a fuel gas and an oxygen-containing gas, the fuel cell producing a fuel cell voltage (Vfc); a DC/DC converter increases an output voltage of said fuel cell so as to achieve a predetermined voltage; a load driven by an output voltage of said DC/DC converter, the load having a load voltage (Vld); a contactor opens and closes in order to electrically connect and disconnect said fuel cell with respect to said load through said DC/DC converter, said contactor having one end thereof connected to an output side of said fuel cell and another end thereof connected to an input side of said DC/DC converter; an energy storage device connected to said fuel cell through said DC/DC converter; and a control device programmed to: transmit a close command to said contactor; increase, following the close command, a voltage of the energy storage device so that the load voltage Vld is made higher than the fuel cell voltage Vfc (Vld>Vfc); transmit, following the increase of voltage, an ‘open’ command to said contactor; monitor the Vld and Vfc for a pre-determined time period; and identify, based on the monitoring, a contactor failure when said Vld and said Vfc are substantially equal at the end of the pre-determined time period.