FUEL CELL SYSTEMS WITH MAINTENANCE HYDRATION BY DISPLACEMENT OF PRIMARY POWER

• US 20080299420A1
• Filed: 05/30/2007
• Published: 12/04/2008
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: DCNS SA (Government of France)
• Original Assignee: IdaTech LLC (IdaTech Ltd.)
• Inventors: Snider, Tod L., Kelley, Mason P., Laven, Arne
• Granted Patent: US 7,754,361 B2
• Time in Patent Office: Days
• US Class Current: 429/411
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/04126 Humidifying
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04492 Humidity; Ambient humidity; Water content
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/0485 of the electrolyte
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 90/40 Fuel cell technologies in production processes

Abstract

Fuel cell systems that perform maintenance hydration by supplying power to satisfy at least part of an applied load from an energy-consuming assembly while a primary power source is in electrical communication with and available to supply power to the energy-consuming assembly to satisfy the portion of the applied load being satisfied by the fuel cell system. In some embodiments, a fuel cell system may determine a start time, or start condition, for maintenance of the fuel cell system. The fuel cell system then may be activated from an inactive condition according to the start time, or start condition, by initiating delivery of at least fuel, and optionally oxidant, to a fuel cell stack of the system. Power then may be supplied from the activated fuel cell system at an output voltage that is higher than a voltage at which power from the primary power source is being supplied, such that the applied load is satisfied, at least in part, by the power from the fuel cell system instead of the power from the primary power source. Upon operation of the fuel cell system for a period sufficient to rehydrate the fuel cell stack, operation of the fuel cell system may be discontinued, with the primary power source resuming supplying power to satisfy the applied load from the energy-consuming assembly.

Claims

1. A method of performing maintenance hydration of a fuel cell system serving as an auxiliary power source for an energy-consuming assembly that is disposed in electrical communication with a primary power source, the method comprising:

determining a start time for maintenance of the fuel cell system;

activating the fuel cell system from an inactive condition according to the start time by initiating delivery of at least fuel to a fuel cell stack of the system; and

supplying power from the activated fuel cell system to satisfy at least a portion of an applied load from the energy-consuming assembly, wherein the power from the fuel cell system is supplied at an output voltage that is higher than a voltage at which power from the primary power source is being supplied to the energy-consuming assembly, such that the energy-consuming assembly uses, at least in part, the power from the fuel cell system instead of the power from the primary power source, thereby operating the fuel cell system for power generation and associated hydration while the primary power source is available.

2. The method of claim 1, wherein the step of supplying power is continued for a hydration interval and then is stopped after completion of a predetermined maintenance hydration treatment.

3. The method of claim 2, wherein the hydration interval corresponds to a predetermined time interval, and wherein the step of supplying power is stopped after the power from the fuel cell system has been supplied to the energy-consuming assembly for the predetermined time interval.

4. The method of claim 2, wherein the predetermined maintenance hydration treatment corresponds to a predetermined amount of power supplied from the fuel cell system, and wherein the step of supplying power is stopped after the predetermined amount of power has been supplied to the energy-consuming assembly from the fuel cell system by the step of supplying power.

5. The method of claim 2, wherein the step of supplying power is stopped after a predetermined amount of water has been generated in the fuel cell stack by the step of supplying power.

6. The method of claim 2, further comprising a step of monitoring a characteristic of the power supplied from the fuel cell system during the step of supplying power, wherein the step of supplying power is stopped before the predetermined maintenance hydration treatment has been completed if the step of monitoring indicates that the power supplied from the fuel cell system does not meet one or more predetermined criteria.

7. The method of claim 6, further comprising a step of repeating the steps of determining a start time, activating the fuel cell system, and supplying power if the step of supplying power is stopped before the predetermined maintenance hydration treatment has been completed.

8. The method of claim 1, wherein the step of determining a start time includes a step of determining a start time corresponding to a predetermined period of inactivity of the fuel cell system.

9. The method of claim 1, wherein the step of determining a start time includes a step of determining a start time at least in part according to a measured parameter of the fuel cell system, a measured parameter outside the fuel cell system, or both.

10. The method of claim 9, further comprising a step of measuring at least one parameter selected from the group consisting of temperature, humidity, and hydration, wherein the step of measuring at least one parameter provides the measured parameter according to which the start time is at least partially determined.

11. The method of claim 1, wherein the steps of determining a start time, activating the fuel cell system, and supplying power are performed automatically.

12. The method of claim 1, further comprising a step of adjusting the output voltage of the fuel cell system.

13. The method of claim 12, wherein the step of adjusting the output voltage includes a step of increasing the output voltage, if needed, to supply power from the fuel cell system at an output voltage that is higher than the voltage of power from the primary power source.

14. The method of claim 13, wherein the step of increasing the output voltage includes a step of increasing the output voltage (a) until the fuel cell system is generating power above a threshold level or (b) until the output voltage reaches and/or exceeds a threshold value, whichever comes first, and wherein, if the output voltage reaches and/or exceeds the threshold value first, the steps of activating the fuel cell system and increasing the output voltage are repeated one or more times until the fuel cell system is generating power above the threshold level such that the step of supplying power can be performed.

15. The method of claim 14, wherein, if the output voltage reaches and/or exceeds the threshold value, the steps of activating the fuel cell system and increasing the output voltage are repeated after waiting a predetermined time interval.

16. The method of claim 12, further comprising a step of measuring an electrical characteristic of the power from the primary power source, wherein the step of adjusting the voltage is based at least in part on the step of measuring an electrical characteristic of the power from the primary power source.

17. The method of claim 1, further comprising a step of measuring the applied load from the energy-consuming assembly before the step of activating the fuel cell system, wherein the step of activating the fuel cell system is postponed if the applied load does not meet one or more predetermined criteria.

18. A fuel cell system with maintenance hydration while serving as an auxiliary power source for an energy-consuming assembly that is disposed in electrical communication with a primary power source, the fuel cell system comprising:

a fuel cell stack;

a reactant delivery system for delivering at least a fuel to the fuel cell stack for generation of electrical output;

an output circuit for conducting the electrical output to the energy-consuming assembly; and

a controller operatively coupled to at least the reactant delivery system and the output circuit and configured to (1) determine a start time for maintenance of the fuel cell system, (2) activate the fuel cell system from an inactive condition according to the start time by initiating delivery of at least fuel to the fuel cell stack from the reactant delivery system, and (3) regulate an output voltage at which the electrical output is conducted to the energy-consuming assembly from the activated fuel cell stack such that power is supplied from the activated fuel cell system to satisfy at least a portion of an applied load from the energy-consuming assembly, wherein the power from the fuel cell system is supplied at an output voltage that is higher than a voltage at which power from the primary power source is being supplied to the energy-consuming assembly, such that the energy-consuming assembly uses, at least in part, the power from the fuel cell system instead of the power from the primary power source, thereby operating the fuel cell system for power generation and associated hydration while the primary power source is available.

19. The fuel cell system of claim 18, wherein the controller is configured to permit supplying of the power from the fuel cell system to the energy-consuming assembly for a hydration interval and then to stop the supplying of the power after completion of a predetermined maintenance hydration treatment.

20. The fuel cell system of claim 19, wherein the hydration interval corresponds to a predetermined time interval, and wherein the controller is configured to stop the supplying of power after the power from the fuel cell system has been supplied to the energy-consuming assembly for the predetermined time interval.

21. The fuel cell system of claim 19, wherein the predetermined maintenance hydration treatment corresponds to a predetermined amount of power supplied from the fuel cell system, and wherein the controller is configured to stop the supplying of the power after the predetermined amount of power has been supplied to the energy-consuming assembly from the fuel cell system.

22. The fuel cell system of claim 19, wherein the output circuit includes a sensor for monitoring a characteristic of the power supplied to the energy-consuming assembly from the fuel cell system, and wherein the controller is configured to stop the supplying of the power from the fuel cell system to the energy-consuming assembly before the predetermined maintenance hydration treatment has been completed if one or more signals from the sensor indicate that the power supplied from the fuel cell system does not meet one or more predetermined criteria.

23. The fuel cell system of claim 22, wherein the controller is configured to repeat determination of a start time, activation of the fuel cell system, and regulation of an output voltage if the controller stops the supplying of the power before the predetermined maintenance hydration treatment has been completed.

24. The fuel cell system of claim 18, wherein the output circuit includes a sensor for measuring a characteristic of the electrical output, and wherein the controller is operatively coupled to the sensor and configured to regulate the output voltage according to one or more signals received from the sensor.

25. The fuel cell system of claim 18, wherein the controller is configured to determine a start time corresponding to a predetermined period of inactivity of the fuel cell system.

26. The fuel cell system of claim 18, further comprising a sensor operatively coupled to the controller and configured to measure at least one parameter selected from the group consisting of temperature, humidity, and hydration, wherein the controller is configured to determine the start time at least in part based on one or more signals received from the sensor.

27. The fuel cell system of claim 24, wherein the controller is configured to increase the output voltage (a) until the fuel cell system is generating power above a threshold level or (b) until the output voltage reaches and/or exceeds a threshold value, whichever comes first, and wherein, if the output voltage reaches and/or exceeds the threshold value first, the controller is configured to repeat determination of a start time, activation of the fuel cell system, and adjustment of the output voltage one or more times until the fuel cell system is generating power above the threshold level.

28. The fuel cell system of claim 27, wherein the controller is configured to repeat determination of a start time, activation of the fuel cell system, and adjustment of the output voltage after waiting a predetermined time interval, if the output voltage reaches and/or exceeds the threshold value.

29. The fuel cell system of claim 19, further comprising a sensor for measuring an electrical characteristic of the power from the primary power source, wherein the controller is configured to regulate the output voltage based at least in part on one or more signals received from the sensor.

30. A fuel cell system with maintenance hydration while serving as an auxiliary power source for an energy-consuming assembly that is disposed in electrical communication with a primary power source, the fuel cell system comprising:

a fuel cell stack;

means for periodically supplying power from the fuel cell stack to satisfy at least a portion of an applied load from the energy-consuming assembly, wherein the power from the fuel cell system is supplied at an output voltage that is higher than a voltage at which power from the primary power source is being supplied to the energy-consuming assembly, such that the energy-consuming assembly uses, at least in part, the power from the fuel cell system instead of the power from the primary power source, thereby operating the fuel cell system for power generation and associated hydration while the primary power source is available