Patent ID: 7862941

Claim:
A fuel cell system comprising: at least one fuel cell stack; a compressor providing cathode input air to a cathode side of the fuel cell stack; a by-pass valve for allowing the cathode input air to by-pass the fuel cell stack on a by-pass line; an anode exhaust gas bleed valve for bleeding anode exhaust gas from the stack, wherein the bled anode exhaust gas is mixed with cathode exhaust gas; and a controller configured to control the anode exhaust gas bleed, said controller monitoring a closing rate of the by-pass valve and an increase of the airflow from the compressor, wherein if the closing rate of the by-pass valve and the rate of increase of the airflow exceeds predetermined thresholds, the controller prevents a bleed command from being sent to the anode exhaust gas bleed valve for a first predetermined period of time.