APPARATUS AND METHOD FOR CONTROLLING CONCENTRATION OF EXHAUST HYDROGEN IN FUEL CELL SYSTEM

The present disclosure relates to an apparatus and a method for controlling a concentration of exhaust hydrogen in a fuel cell system. The apparatus may include an air exhaust valve for discharging hydrogen from a cathode in a fuel cell stack to an outside environment through an air exhaust line, an air compressor for supplying ambient air to the air exhaust line, an air cut-off valve for blocking air supplied to the cathode, and a controller that opens the air exhaust valve and drives the air compressor when starting to supply hydrogen to the fuel cell stack, and opens the air cut-off valve such that a concentration of the hydrogen discharged from the cathode is reduced by air in the air exhaust line when the hydrogen supply is completed.