Apparatus for diagnosing fault of fuel cell stack

An apparatus for diagnosing a failure in a fuel cell stack, the apparatus comprising:

• an alternating current (AC) absorption unit connected between both terminals of the fuel cell stack and switched based on an applied AC signal to enable a current from the fuel cell stack to be absorbed and flow;
• a load unit connected between both terminals of the fuel cell stack and in which the current from the fuel cell stack flows;
• an AC signal generator configured to generate the AC signal and supply the generated AC signal to the AC absorption unit;
• and
• a processor configured to:
• measure a stack current including an absorption current that flows through the AC absorption unit and a load current that flows through the load unit;
• measure stack voltage of the fuel cell stack;
• and
• diagnose the failure in the fuel cell stack based on the measured stack voltage or stack current.

A method of operating a fuel cell stack failure diagnosis apparatus, the method comprising:

• generating, by an alternating current (AC) signal generator, a driving current of a predetermined frequency;
• measuring, by a processor, a stack voltage and a stack current based on the generated driving current;
• calculating, by the processor, a distortion rate based on the measured stack voltage;
• adjusting, by the processor, a frequency of the stack current based on a control signal;
• diagnosing, by the processor, a failure in the fuel cell stack based on the calculated distortion rate.