Humidifier leak diagnosis system and method for a fuel cell system

A humidifier leak diagnosis system for a fuel cell system, the humidifier leak diagnosis system comprising:

• a fuel cell stack;
• an air supply system comprising at least one of an air compressor, a humidifier, an air cutoff valve, or an air pressure control valve;
• and
• a controller configured to
• set a reference pressure for humidifier leak diagnosis based on at least one of a speed of the air compressor, an opening degree of the air cutoff valve, or an opening degree of the air pressure control valve,
• enter a humidifier leak diagnosis mode based on an inlet air pressure of the fuel cell stack, wherein the controller is configured to enter the humidifier leak diagnosis mode when the inlet air pressure of the fuel cell stack is measured to be lower than the reference pressure for humidifier leak diagnosis, and
• determine whether or not a humidifier leak has been generated based on an output or an output voltage of the fuel cell stack generated through adjustment of at least one of an opening degree of the air cutoff valve or an opening degree of the air pressure control valve in humidifier leak diagnosis,
• wherein the controller is configured to perform additional humidifier leak diagnosis when an output voltage of the fuel cell stack is maintained to be lower than a reference output voltage for a reference time or more under a condition that i) the air cutoff valve is opened to a first opening degree and ii) the air pressure control valve is opened to a second opening degree or to be closed.