Patent ID: 7993786
Filing Date: 2011-08-09
Classification: H01M,Y02E

Abstract:
1. A fuel cell system comprising: a fuel cell stack that generates electricity; an exhaust conduit for exhausting a portion of the fuel cell stack; an exhaust valve that externally vents a fuel gas from a fuel chamber of the fuel cell stack and through the exhaust conduit; a supply conduit for supplying a newly supplied fuel gas to the fuel cell stack; and a controller configured to determine a point in time at which a voltage produced by the fuel cell stack starts to rise configured to compute an estimated time, to replace an oxidant gas in the supply conduit, the fuel chamber and the exhaust conduit with the newly supplied fuel gas based on the point in time, and configured to replace the oxidant gas, at a time of starting-up the fuel cell system by maintaining the exhaust valve in an open position and by closing the exhaust valve upon expiration of the estimated time.