Patent ID: 8142947

Claim:
A start-up method for a fuel cell system that includes a fuel cell that carries out power generation by the electrochemical reaction between a fuel gas and the oxygen gas in the air; a fuel gas discharge path and a fuel gas supply path that are connected to the fuel cell; a fuel gas circulation path that connects the fuel gas discharge path to the fuel gas supply path; and a purge valve provided on the fuel gas circulation path in order to discharge the circulating fuel gas from the fuel gas circulation path, the method comprising the steps of: starting the supply of the fuel gas to the fuel cell; opening the purge valve after the start of the supplying of the fuel gas; calculating a valve open time depending on a voltage of the fuel cell or a temperature of the fuel cell; comparing the valve open time to a time that passed from the opening of the purge valve; if the calculated valve open time is less than the time that passed from the opening of the purge valve, closing the purge valve; and if the calculated valve open time is greater than the time that passed from the opening of the purge valve, closing the purge valve depending on concentration of the fuel gas included in the discharge gas from the fuel gas circulation path.