Patent ID: 8404392
Filing Date: 2013-03-26
Classification: H01M,Y02E,Y02T

Abstract:
1. A method for operating a fuel cell system in a stand-by mode, said method comprising: providing a high voltage electrical bus; providing a fuel cell stack electrically coupled to the high voltage electrical bus; providing a high voltage DC-power energy storage device electrically coupled to the high voltage electrical bus; providing an electric traction system electrically coupled to the high voltage electrical bus; providing a blocking diode in the high voltage electrical bus that prevents voltage from the high voltage energy storage device and the electric traction system from being applied to the fuel cell stack; providing a by-pass line including a by-pass contactor around the blocking diode; providing a fuel cell stack contactor between the fuel cell stack and the high voltage electrical bus; determining that the voltage at a first node in the electrical bus coupled to the blocking diode opposite to the fuel cell stack is higher than the voltage at a second node in the electrical bus coupled to the blocking diode closer to the fuel cell stack; and putting the system in the stand-by mode by opening the fuel cell stack contactor and closing the by-pass contactor so that electrical energy from the electric traction system goes around the blocking diode when the voltage at the first node is higher than the voltage at the second node.