Method for controlling fuel cell system

A method of controlling a fuel cell system including:

• a fuel cell which generates power by supplying a fuel gas to an anode and supplying an oxidant gas to a cathode;
• a fuel gas supply path through which the fuel gas supplied to the anode flows;
• a fuel off-gas exhaust path through which a fuel off-gas exhausted from the anode flows;
• an oxidant gas supply path through which the oxidant gas supplied to the cathode flows;
• an oxidant off-gas exhaust path through which an oxidant off-gas exhausted from the cathode flows;
• an oxidant off-gas circulation path which connects the oxidant gas supply path and the oxidant off-gas exhaust path;
• an oxidant gas supply unit which supplies the oxidant gas to the cathode, and
• an oxidant off-gas circulation unit which is arranged on the oxidant off-gas circulation path and circulates the oxidant off-gas,
• the method comprising:
• a stop command sensing process of sensing a stop command output when the fuel cell system stops;
• an anode pressure increasing process of increasing pressure so that pressure of the anode reaches a first predetermined pressure value after the stop command has been sensed in the stop command sensing process;
• and
• a stop-time discharge process of performing discharge by consuming oxygen remaining within the oxidant off-gas while driving the oxidant off-gas circulation unit after the anode pressure increasing process.