Patent ID: 8647783
Filing Date: 2014-02-11
Classification: G01R,H01M,Y02E

Abstract:
1. A method for determining a normalized high frequency resistance value of a fuel cell stack, said method comprising: measuring a high frequency resistance of the fuel cell stack; increasing the relative humidity of cathode air entering the fuel cell stack; increasing a base stoichiometry set-point of the fuel cell stack to be higher than a nominal stoichiometry; intermittently bleeding the fuel cell stack to improve water management in the fuel cell stack; utilizing a water buffer model to estimate a membrane hydration state of the fuel cell stack; performing an auto-learning process to determine a base fuel cell stack high frequency resistance at humidified conditions once the water buffer model estimates that the membrane hydration state of the fuel cell stack is at saturation; storing data gathered during the auto-learning process for the base fuel cell stack high frequency resistance at humidified conditions; and subtracting the base fuel cell stack high frequency resistance at humidified conditions from the measured high frequency resistance, and adding a base fuel cell stack high frequency resistance of a reference fuel cell stack to determine the normalized high frequency resistance value of the fuel cell stack.