Fuel cell system failure diagnosis method, failure diagnosis device using same, and fuel cell system

摘要

It was difficult to specify a portion which is a cause of a power generation abnormality of a fuel cell which performs the power generation by feeding an oxygen-containing oxidizer gas into a cathode and feeding a hydrogen-containing fuel gas into an anode. A failure diagnosis method of a fuel cell system, which includes a step for computing an impedance in a prescribed portion of a fuel cell of a fuel cell system from a signal obtained by superposing an alternating current on a direct current as generated from the fuel cell system under a certain operation condition, wherein when in comparison of the impedance with an impedance as computed under a previously determined standard operation condition, an abnormality is present in the prescribed portion of the fuel cell, whether a cause of the abnormality of the prescribed portion resides in any one or plural prescribed sites constituting the fuel cell system is determined by using the comparison result.