Abstract: A fuel cell system is disclosed that employs a thermal sensor for measuring an amount of heat generated in the fuel cell system, wherein a sensor signal from the thermal sensor is used to adjust operation of the fuel cell system when the fuel cell system is operating outside of desired thermal operating conditions.

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 pressure sensor is in communication with the air compressor and adapted to measure a compressor outlet pressure. A power conversion module is in electrical communication with the start-up battery and the air compressor. A controller is in communication with the power conversion module and adapted to set an air compressor speed based on an available electrical energy. A closed-loop method of operating the fuel cell system at start-up is also provided, wherein an anode purge is scheduled based on an air flow rate calculated from the compressor outlet pressure and the actual speed.

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 of operating a fuel cell system comprising a fuel cell and a compressor that provides air to the fuel cell. The method comprises sensing a temperature indicative of the temperature of a fuel cell, providing a restriction in an air flow path to the fuel cell when the sensed temperature is below a threshold, and increasing the speed of the compressor to provide a desired air flow to the fuel cell. In at least some implementations, increasing the speed of the compressor increases the power drawn from the fuel cell to power the compressor and helps to increase the heat of the fuel cell. The increased speed of the compressor can also result in warmer air flow from the compressor that can further increase the temperature of the system components.

Abstract: A fuel cell system is disclosed, wherein the fuel cell system is heated by a fluid during a starting operation to mitigate against vapor condensation and ice formation in a fuel cell assembly and to decrease a warm up time of the fuel cell system.

Abstract: A fuel cell system and method for controlling relative humidity in a fuel cell system. A controller can be signally coupled to one or more sensors and configured to operate at least one flow manipulation device in response to changes in a relative humidity of a reactant passing through the cathode flowpath of the fuel cell in order to maintain the relative humidity within a prescribed range. The controller correlates one or more of a temperature setpoint, pressure setpoint, stoichiometry setpoint or actual operating condition of any of them to an operating condition of the system. In this way, a desired level of relative humidity can be achieved, maintained or both while minimizing the use of power-robbing flow manipulation devices, such as a pump, compressor, fan or related component.