Patent ID: 9373860
Filing Date: 2016-06-21
CPC Classification: H01M,Y02E

Claim Text:
1. A method of diagnosing a fault of a fuel cell stack, the method comprising: supplying, to the fuel cell stack, a plurality of alternating currents having different frequency combinations by an alternating current (AC) current generator; measuring, by a processor, a distortion rate and impedance of the fuel cell stack for each alternating current, and selecting an optimal frequency based on the measured distortion rate and impedance; supplying, to the fuel cell stack, an alternating current having the selected optimal frequency by the AC current generator; calculating, by the processor, the distortion rate of the fuel cell stack according to the alternating current having the optimal frequency, and diagnosing a drop in cell voltage based on the calculated distortion rate; and calculating, by the processor, the impedance of the fuel cell stack according to the alternating current having the optimal frequency, amount of water in the fuel cell stack based on the calculated impedance, and diagnosing a cause of the drop in cell voltage based on the calculated impedance and amount of water, wherein the selecting of the optimal frequency comprises: