Abstract: A fuel cell system is provided that includes a fuel cell stack and an air compressor in communication with a cathode inlet, a hydrogen source in communication with an anode inlet, and a start-up battery adapted to power the air compressor. The start-up battery is at least one of a low-voltage battery and a high-voltage battery. A power conversion module is in electrical communication with the start-up battery and the air compressor. The power conversion module is adapted to boost a voltage of the start-up battery as desired and power the air compressor at start-up. A controller is in communication with the power conversion module and is adapted to set an air compressor speed based on an available electrical energy. An open-loop method of operating the fuel cell system at start-up is also provided, wherein an anode purge is scheduled based on the available electrical energy from the battery.

Abstract: A fuel cell system is provided that includes a fuel cell stack and an air compressor in communication with a cathode inlet, a hydrogen source in communication with an anode inlet, and a start-up battery adapted to power the air compressor. The start-up battery is at least one of a low-voltage battery and a high-voltage battery. A power conversion module is in electrical communication with the start-up battery and the air compressor. The power conversion module is adapted to boost a voltage of the start-up battery as desired and power the air compressor at start-up. A controller is in communication with the power conversion module and is adapted to set an air compressor speed based on an available electrical energy. An open-loop method of operating the fuel cell system at start-up is also provided, wherein an anode purge is scheduled based on the available electrical energy from the battery.

Abstract: A method for operating a fuel cell stack where electrical energy from regenerative braking is used to operate system loads instead of using fuel cell stack power to conserve hydrogen. A fuel cell stack and an ultracapacitor are electrically coupled to a high voltage electrical bus. A by-pass line is provided around a blocking diode including a by-pass contactor. A stack contactor is provided to disconnect the fuel cell stack from the electrical bus. A stand-by mode request is made if the voltage at a node proximate to the blocking diode closest to the ultracapacitor is higher than the voltage at a node proximate to the blocking diode closest to the fuel cell stack. Steps are then made to electrically prepare the high voltage electrical bus. Then, the stack contactor is opened and the by-pass contactor is closed to allow the regenerate braking energy to power the system loads.

Abstract: A fuel cell system that includes a fuel cell stack and an EESD electrically coupled to a common high voltage bus line. The EESD has a higher voltage output than the fuel cell stack, and thus the stack is unable to fully charge the EESD, for example, at system shut-down. In order to allow the fuel cell stack to fully charge the EESD, the EESD is separated into a plurality of separate electrical storage banks having lower voltage potentials. A series of contactors are provided to electrically couple the storage banks in series during normal system operation, and separately charge the storage banks using the fuel cell stack so that they are fully charged. The series of contactors can also be configured so that the storage banks can be electrically coupled in series during normal operation of the system and be electrically coupled in parallel during charging at system shut-down.

Abstract: A method for operating a fuel cell stack where electrical energy from regenerative braking is used to operate system loads instead of using fuel cell stack power to conserve hydrogen. A fuel cell stack and an ultracapacitor are electrically coupled to a high voltage electrical bus. A by-pass line is provided around a blocking diode including a by-pass contactor. A stack contactor is provided to disconnect the fuel cell stack from the electrical bus. A stand-by mode request is made if the voltage at a node proximate to the blocking diode closest to the ultracapacitor is higher than the voltage at a node proximate to the blocking diode closest to the fuel cell stack. Steps are then made to electrically prepare the high voltage electrical bus. Then, the stack contactor is opened and the by-pass contactor is closed to allow the regenerate braking energy to power the system loads.

Abstract: A fuel cell system that includes a fuel cell stack and an EESD electrically coupled to a common high voltage bus line. The EESD has a higher voltage output than the fuel cell stack, and thus the stack is unable to fully charge the EESD, for example, at system shut-down. In order to allow the fuel cell stack to fully charge the EESD, the EESD is separated into a plurality of separate electrical storage banks having lower voltage potentials. A series of contactors are provided to electrically couple the storage banks in series during normal system operation, and separately charge the storage banks using the fuel cell stack so that they are fully charged. The series of contactors can also be configured so that the storage banks can be electrically coupled in series during normal operation of the system and be electrically coupled in parallel during charging at system shut-down.

Abstract: A fuel cell system is provided that includes a fuel cell stack and an air compressor in communication with a cathode inlet, a hydrogen source in communication with an anode inlet, and a start-up battery adapted to power the air compressor. The start-up battery is at least one of a low-voltage battery and a high-voltage battery. A power conversion module is in electrical communication with the start-up battery and the air compressor. The power conversion module is adapted to boost a voltage of the start-up battery as desired and power the air compressor at start-up. A controller is in communication with the power conversion module and is adapted to set an air compressor speed based on an available electrical energy. An open-loop method of operating the fuel cell system at start-up is also provided, wherein an anode purge is scheduled based on the available electrical energy from the battery.