Patent ID: 8660819
Filing Date: 2014-02-25
Classification: H01M,Y02E

Abstract:
1. A method for determining whether a water vapor transfer (WVT) unit that humidifies a cathode airflow to a fuel cell stack in a fuel cell system has failed or is failing, said method comprising: measuring relative humidity (RH) of the cathode airflow provided from the WVT unit to the fuel cell stack to provide a first RH value; calculating a high frequency resistance relative humidity of membranes in the fuel cell stack using a high frequency resistance (HFR) circuit to provide a second RH value; comparing the first RH value to the second RH value to generate an RH value difference; providing a calibration value; comparing the RH value difference to the calibration value; and determining that the WVT unit has failed or is failing if the RH difference value is greater than the calibration value.