Patent ID: 8053120

Claim:
A method of controlling a fuel cell system which comprises a power generation unit including an anode, a cathode, and an electrolytic film provided between the anode and the cathode, a fuel tank which stores a raw fuel or a highly concentrated fuel, a collection path coupled to the power generation unit, which collects an emission supplied from the anode, a mixing tank communicated with the power generation unit via the anode collection path and communicated with the fuel tank, which mixes the emission with the raw fuel or the highly concentrated fuel to produce a mixture fuel, a fuel circulation unit provided between the mixing tank and the power generation unit, which supplies the mixture fuel from the mixing tank to the anode of the power generation unit so that the mixture fuel is circulated between the mixing tank and the power generation unit, a fuel supply unit which supplies the raw fuel or the highly concentrated fuel from the fuel tank to the mixing tank, an air supply unit which supplies air to the cathode of the power generation unit, a power adjustment unit which adjusts a current applied to a load of the fuel cell system, and temperature adjustment means for adjusting a temperature of the power generation unit, the method comprising: detecting a concentration and a volume of the mixture fuel in the fuel tank to be supplied to the anode of the power generation unit during power generation to generate a detection signal; and controlling at least one of the fuel circulation unit, the fuel supply unit, and the air supply unit based on the detection signal to control at least one of the concentration and the volume of the mixture fuel, wherein the controlling includes increasing an amount of the mixture fuel supplied by the fuel circulation unit when the detection signal indicates that the concentration or the volume of the mixture fuel in the mixing tank is increased above a predetermined level, and decreasing the amount of the mixture fuel supplied by the fuel circulation unit when the detection signal indicates that the concentration or the volume of the mixture fuel in the mixing tank is decreased below the predetermined level.