Abstract: A technique that is usable with a fuel cell stack includes detecting an unhealthy condition of the stack, such as carbon monoxide poisoning, flooding, or fuel starvation, and implementing a recovery action to correct the detected condition. The technique further includes observing the response of the stack to the recovery action to distinguish between unhealthy conditions that have the same indications. In the event that multiple unhealthy conditions are present concurrently, the technique also includes determining an appropriate sequence of recovery actions to correct each of the unhealthy conditions.

Abstract: A fuel cell system includes a fuel cell stack, energy storage and a control subsystem. The energy storage supplements a power that is provided by the fuel cell stack, and the energy storage is coupled to the fuel cell stack and has a voltage. The control subsystem monitors the energy storage for a leakage and takes an action in response to detecting the leakage.

Abstract: A fuel cell system includes a fuel cell stack, energy storage and a control subsystem. The energy storage supplements a power that is provided by the fuel cell stack. The energy storage is coupled to the fuel cell stack and has a voltage. The control system regulates a peak of the voltage based on a temperature of the energy storage.

Abstract: A fuel cell system that includes a fuel cell stack, and energy storage that is coupled to the fuel cell stack, and a switch that is coupled between the energy storage and the fuel cell stack. The fuel cell system also includes a controller to measure at least one current to determine a likelihood of a current flowing from the energy storage to the stack at a later time and based on the determination, operate the switch to prevent the current.

Abstract: A fuel cell system includes a fuel cell stack, a DC-to-DC converter and at least one capacitor. The fuel cell stack provides a stack voltage, and the DC-to-DC converter receives the stack voltage. The capacitor(s) are coupled between the fuel cell stack and the DC-to-DC converter.

Abstract: A cogeneration fuel cell system and associated methods of operation are provided that accommodate a demand for heat as well as a demand for electric power. The system is operated among various modes to balance heat and power demand signals. In general, a fuel cell system is coupled to a power sink and a heat sink, and a controller is adapted to respond to data signals from the power sink and the heat sink. As examples, such data signals from the heat sink may include a temperature indication or a heat demand signal (such as from a thermostat), and such data signals from the power sink may include a voltage or current measurement, an electrical power demand signal, or an electrical load.

Abstract: Methods including entering a diagnostic mode of a fuel cell in response to an asynchronous event are disclosed.

Abstract: A cogeneration fuel cell system and associated methods of operation are provided that accommodate a demand for heat as well as a demand for electric power. The system is operated among various modes to balance heat and power demand signals. In general, a fuel cell system is coupled to a power sink and a heat sink, and a controller is adapted to respond to data signals from the power sink and the heat sink. As examples, such data signals from the heat sink may include a temperature indication or a heat demand signal (such as from a thermostat), and such data signals from the power sink may include a voltage or current measurement, an electrical power demand signal, or an electrical load.

Abstract: A cogeneration fuel cell system and associated methods of operation are provided that accommodate a demand for heat as well as a demand for electric power. The system is operated among various modes to balance heat and power demand signals. In general, a fuel cell system is coupled to a power sink and a heat sink, and a controller is adapted to respond to data signals from the power sink and the heat sink. As examples, such data signals from the heat sink may include a temperature indication or a heat demand signal (such as from a thermostat), and such data signals from the power sink may include a voltage or current measurement, an electrical power demand signal, or an electrical load.

Abstract: A cogeneration fuel cell system and associated methods of operation are provided that accommodate a demand for heat as well as a demand for electric power. The system is operated among various modes to balance heat and power demand signals. In general, a fuel cell system is coupled to a power sink and a heat sink, and a controller is adapted to respond to data signals from the power sink and the heat sink. As examples, such data signals from the heat sink may include a temperature indication or a heat demand signal (such as from a thermostat), and such data signals from the power sink may include a voltage or current measurement, an electrical power demand signal, or an electrical load.

Abstract: A technique that is usable with a fuel cell system includes using a stored energy source to supply power to a load, placing a fuel cell stack in an inactive state during the using, returning the fuel cell stack to an active state to recharge the stored energy source and returning the fuel cell stack to the inactive state in response to the completion of the charging. Another technique may include determining a system power demand in the fuel cell system and may include determining whether a fuel cell stack is exhibiting unstable behavior during an interval of low power demand from the fuel cell stack. In response to these determinations, the fuel cell stack is isolated from the fuel cell system. Another technique includes pulsing a fuel processor of the fuel cell system with an input reactant flow to minimize at least one of a power loss and a startup time of the fuel processor.

Abstract: A system includes a first load, a second load, a fuel processor, a fuel cell stack and a circuit. The fuel processor provides a fuel flow, and the fuel cell stack is coupled to the first load and adapted to provide a power in response to the fuel flow. At least some of this power is consumed by the first load. The circuit is adapted to in response to a decrease in the power produced by the fuel cell stack and consumed by the first load, determine whether to route at least some of the power produced by the fuel cell stack and not consumed by the first load to the second load, and based on the determination, selectively route some of the power that is produced by the fuel cell stack to the second load.

Abstract: A technique that is usable with a fuel cell stack includes coupling the fuel cell stack to a load, monitoring a power that is consumed by the load and determining if the power is increasing or decreasing. If the output power is increasing, a first control technique is used to control a fuel flow to the fuel cell stack, and if the output power is decreasing, a second control technique that is different from the first control technique is used to control the fuel flow to the stack.

Abstract: A technique that is usable with a fuel cell stack includes coupling the fuel cell stack to a load and determining a power that is consumed by the load. The technique includes detecting a change in the power that is consumed by the load and controlling a fuel flow to the fuel cell stack to control a power output of the fuel cell stack to accommodate the change in the power consumed by the load. The technique also includes delaying the beginning of the controlling in response to the detection of the change in the power that is consumed by the load.

Abstract: A technique that is usable with a fuel cell stack includes providing a fuel flow and using at least some of the fuel flow to produce power with the fuel cell stack. A request is received to charge a battery. In response to the request, the technique includes determining if the remainder of the fuel flow is sufficient to produce additional power to charge the battery. Based on the determination, the remainder of the fuel flow is used to produce the additional power to charge the battery.

Abstract: A technique that is usable with a fuel cell stack includes providing a fuel flow and using at least some of the fuel flow to produce power with the fuel cell stack. A request is received to charge a battery. In response to the request, the technique includes determining if the remainder of the fuel flow is sufficient to produce additional power to charge the battery. Based on the determination, the remainder of the fuel flow is used to produce the additional power to charge the battery.

Abstract: A system includes a first load, a second load, a fuel processor, a fuel cell stack and a circuit. The fuel processor provides a fuel flow, and the fuel cell stack is coupled to the first load and adapted to provide a power in response to the fuel flow. At least some of this power is consumed by the first load. The circuit is adapted to in response to a decrease in the power produced by the fuel cell stack and consumed by the first load, determine whether to route at least some of the power produced by the fuel cell stack and not consumed by the first load to the second load, and based on the determination, selectively route some of the power that is produced by the fuel cell stack to the second load.

Abstract: A technique that is usable with a fuel cell stack includes coupling the fuel cell stack to a load and determining a power that is consumed by the load. The technique includes delaying in response to a detection of a change in the power consumed by the load, and in response to the expiration of the delaying, controlling a fuel flow to the stack to control a power output of the fuel cell stack to accommodate the change in the power that is consumed by the load.

Abstract: A technique that is usable with a fuel cell stack includes coupling the fuel cell stack to a load, monitoring a power that is consumed by the load and determining if the power is increasing or decreasing. If the output power is increasing, a first control technique is used to control a fuel flow to the fuel cell stack, and if the output power is decreasing, a second control technique that is different from the first control technique is used to control the fuel flow to the stack.