METHOD FOR PERFORMING INTERNAL PURGE IN FUEL CELL SYSTEM BY USING THE DEVIATION OF STACK VOLTAGE AND CELL VOLTAGE AND DEVICE THEREFOR

摘要

PURPOSE: A purge method and a device therefor are provided to improve the purge effect, to be capable of utilizing fuel completely, to increase stability and stack efficiency of a fuel cell, and to reuse 100% of the discharged fuel and water. CONSTITUTION: The purge method for removing the flooding of a fuel cell system comprises the steps of: (a) sensing a cell voltage of a stack(130); (b) determining whether or not the flooding is generated by the cell voltage; (c) controlling a purge valve(126) and a recirculating pump(127) so that the difference of pressure between the inside of stack(130) and the purge valve(126) and the recirculating pump(127) is formed, if flooding; (d) opening the purge valve(126) so that a gas mixture containing moisture in the stack(130) is discharged out of the stack(130); (e) separating the mixture into water and gas in a water separator(125); and (f) re-supplying the stack(130) with water via a water storage tank(134) and with gas via the recirculating pump(127). The device(100) includes a stack(130) comprising a plurality of cells; a cell voltage sensing unit(132); a water separator; a purge valve(126); a recirculating pump(127); a water storage tank(134); and a system controlling unit(140).