Patent ID: 8492037

Claim:
A fuel cell system comprising: a fuel cell stack including a plurality of single cells stacked on one another, each single cell including an anode to which fuel gas can be supplied, a cathode to which oxidizing gas can be supplied, and a solid polymer electrolyte membrane interposed between the anode and the cathode, the oxidizing gas and the fuel gas configured for counter-flow with respect to each other, the anode being divided into an anode outlet power collecting plate for measurement of local electric current at an anode-outlet side and an anode power collecting plate that collects power from regions other than the anode-outlet side; a cell voltage detector that detects a cell voltage at a cathode outlet-side of a single cell; a total voltage detector that detects a total voltage of the fuel cell stack; a cell voltage difference computing unit configured to determine an average cell voltage from the total cell voltage detector and a minimum cell voltage from the cell voltage detector and to compute a difference between the average cell voltage and the minimum cell voltage; a stack current detector that detects electric current in the fuel cell stack; an anode outlet local current detector that detects a local current at an anode outlet-side of the fuel cell stack; a current density-computing unit configured to compute a stack current density from the stack current detector and an anode outlet local current density from the anode outlet local current detector; and a wet state-judging unit configured to judge a wet state of the fuel cell stack based on the difference between the average cell voltage and the minimum cell voltage, and based on the difference between the stack current density and the anode outlet local current density, wherein the wet state judging unit is configured to judge that the anode is clogged with water if the difference between the average cell voltage and the minimum cell voltage is less than a first predetermined value and the difference between the stack current density and the anode outlet local current density is equal to or greater than a second predetermined value, and wherein the current density-computing unit is configured to store a stack effective area and an anode outlet effective area.