Fuel cell system controller

• US 20030113601A1
• Filed: 11/25/2002
• Published: 06/19/2003
• Est. Priority Date: 07/26/2000
• Status: Active Grant

• Current Assignee: DCNS SA (Government of France)
• Original Assignee: IdaTech LLC (IdaTech Ltd.)
• Inventors: Herron, Thomas G., Edlund, David J., Holmes, Craig F.
• Granted Patent: US 6,979,507 B2
• Time in Patent Office: Days
• US Class Current: 429/23
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04298 Processes for controlling fuel cells or fuel cell systems
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04582 of the individual fuel cell
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04626 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0612 from carbon-containing material
• CPC Class Codes: H01M 8/0656 by electrochemical means H01M8/065 takes precedence
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: H01M 8/0687 Reactant purification by the use of membranes or filters
• CPC Class Codes: H01M 8/249 comprising two or more groupings of fuel cells, e.g. modular assemblies
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system that includes a control system for regulating the power produced by the fuel cell system. The fuel cell system includes a fuel cell stack adapted to produce electrical power from a feed. In some embodiments, the fuel cell system includes a fuel processing assembly adapted to produce the feed for the fuel cell stack from one or more feedstocks. The control system regulates the power produced by the fuel cell system to prevent damage to, and/or failure of, the system.

Claims

1. A fuel cell system, comprising:

a fuel processing assembly adapted to produce a feed stream containing hydrogen gas from one or more feedstocks;

a fuel cell stack including at least one fuel cell, wherein the fuel cell stack is adapted to receive at least a portion of the feed stream and to produce electrical power therefrom, and further wherein the fuel cell stack has a currently available power output;

a bypass adapted to selectively divert at least a portion of the feed stream from delivery to the fuel cell stack; and

a control system adapted to selectively actuate the bypass to control the portion of the feed stream that is diverted from delivery to the fuel cell stack and thereby regulate the rate that the feed stream is delivered to the fuel cell stack, wherein the control system is adapted to selectively actuate the bypass responsive at least in part to an applied load to the fuel cell system.

2. The fuel cell system of claim 1, wherein the bypass includes a first configuration, in which none of the feed stream is diverted from delivery to the fuel cell stack, a second configuration in which all of the feed stream is diverted from delivery to the fuel cell stack, and at least one intermediate configuration in which some, but not all, of the feed stream is diverted from delivery to the fuel cell stack.

3. The fuel cell system of claim 1, wherein the control system is adapted to actuate the bypass to selectively divert at least a portion of the feed stream when the applied load does not exceed the currently available power output of the fuel cell stack.

4. The fuel cell system of claim 1, wherein the fuel cell system further includes a battery bank adapted to store electrical power, wherein the battery bank has a current level of stored power.

5. The fuel cell system of claim 4, wherein the control system is adapted to selectively actuate the bypass responsive at least in part to the current level of stored power of the battery bank.

6. The fuel cell system of claim 4, wherein the control system is adapted to selectively actuate the bypass responsive at least in part to both the applied load to the fuel cell system and the current level of stored power of the battery bank.

7. The fuel cell system of claim 4, wherein the battery bank has a maximum level of stored power and further wherein the control system is adapted to actuate the bypass to selectively divert at least a portion of the feed stream when the current level of stored power of the battery bank is at least as great as the maximum level of stored power.

8. The fuel cell system of claim 1, wherein the fuel cell system is in communication with at least one facility adapted to apply the applied load to the fuel cell system.

9. The fuel cell system of claim 8, wherein the applied load includes at least one of an electrical load and a thermal load.

10. The fuel cell system of claim 1, wherein the control system is adapted to actuate the bypass without reducing the rate at which the fuel processing assembly produces the feed stream.

11. The fuel cell system of claim 1, wherein the fuel cell system further includes a hydrogen storage device adapted to receive at least a portion of the feed stream diverted by the bypass.

12. The fuel cell system of claim 1, wherein the fuel cell system further includes at least one hydrogen-consuming device that is adapted to receive at least a portion of the feed stream diverted by the bypass.

13. The fuel cell system of claim 12, wherein the at least one hydrogen-consuming device includes a combustion assembly that is adapted to combust a fuel stream, and further wherein the combustion assembly is adapted to receive at least a portion of the feed stream diverted by the bypass.

14. The fuel cell system of claim 13, wherein the combustion assembly includes a combustion chamber that is adapted to heat the fuel cell system.

15. The fuel cell system of claim 1, wherein the fuel processing assembly includes at least one fuel processor adapted to produce the feed stream by steam reforming a feedstock comprising water and at least one of a hydrocarbon and an alcohol.

16. The fuel cell system of claim 15, wherein the fuel processing assembly is adapted to produce a mixed gas stream containing hydrogen gas from the feedstock, and further wherein the fuel processing assembly includes a separation region in which the mixed gas stream is separated into the feed stream and at least one byproduct stream.

17. The fuel cell system of claim 16, wherein the separation region includes a membrane module including at least one hydrogen selective membrane.

18. The fuel cell system of claim 17, wherein the at least one hydrogen selective membrane is formed from at least one of palladium and a palladium alloy.

19. A method for operating a fuel cell system that is adapted to receive an applied load and which comprises a fuel processing assembly adapted to produce a feed stream containing hydrogen gas, and a fuel cell system having a currently available power output and adapted to receive at least a portion of the feed stream and to produce electrical power therefrom, the method comprising:

producing a feed stream with the fuel processing assembly operating at a rate of production of the feed stream;

delivering at least a portion of the feed stream to a fuel cell stack; and

selectively diverting a portion of the feed stream from delivery to the fuel cell stack if the applied load is less than the currently available power output.

20. The method of claim 19, wherein the selectively diverting step does not include reducing the rate of production of the feed stream by the fuel processing assembly.

21. The method of claim 19, wherein the portion includes all of the feed stream.

22. The method of claim 19, wherein the portion includes some, but not all, of the feed stream.

23. The method of claim 19, wherein the fuel cell system further includes a battery bank that is adapted to store at least a portion of the electrical power produced by the fuel cell stack and which includes a current level of stored power and a maximum amount of stored power, and further wherein the selectively diverting step includes selectively diverting a portion of the feed stream from delivery to the fuel cell stack if the applied load is less than the currently available power output and the current level of stored power of the battery bank is within a predetermined range of the maximum amount of stored power.

24. The method of claim 23, wherein the selectively diverting step does not include reducing the rate of production of the feed stream by the fuel processing assembly.

25. The method of claim 23, wherein the portion includes all of the feed stream.

26. The method of claim 23, wherein the portion includes some, but not all, of the feed stream.

27. The method of claim 23, wherein the selectively diverting step includes selectively diverting a portion of the feed stream from delivery to the fuel cell stack if the applied load is less than the currently available power output and the current level of stored power of the battery bank is equal to the maximum amount of stored power.

28. The method of claim 27, wherein the selectively diverting step does not include reducing the rate of production of the feed stream by the fuel processing assembly.

29. The method of claim 19, wherein the selectively diverting step includes delivering a subportion of the portion of the feed stream to at least one hydrogen storage device.

30. The method of claim 19, wherein the selectively diverting step includes delivering a subportion of the portion of the feed stream to at least one hydrogen-consuming device.

31. The method of claim 30, wherein the at least one hydrogen-consuming device includes a combustion assembly that is adapted to combust the subportion of the portion of the feed stream.

32. The method of claim 31, wherein the combustion assembly includes a combustion chamber that is adapted to heat the fuel cell system.

33. The method of claim 19, wherein the fuel processing assembly includes at least one fuel processor adapted to produce the feed stream by steam reforming a feedstock comprising water and at least one of a hydrocarbon and an alcohol.

34. The method of claim 33, wherein the fuel processing assembly is adapted to produce a mixed gas stream containing hydrogen gas from the feedstock, and further wherein the fuel processing assembly includes a separation region in which the mixed gas stream is separated into the feed stream and at least one byproduct stream.

35. The method of claim 34, wherein the separation region includes a membrane module including at least one hydrogen selective membrane.

36. The method of claim 35, wherein the at least one hydrogen selective membrane is formed from at least one of palladium and a palladium alloy.

37. A fuel cell system, comprising:

a fuel processing assembly adapted to produce a feed stream containing hydrogen gas from one or more feedstocks;

a fuel cell stack including at least one fuel cell, wherein the fuel cell stack is adapted to receive at least a portion of the feed stream and to produce electrical power therefrom, and further wherein the fuel cell stack has a currently available power output;

a battery bank adapted to store electrical power, wherein the battery bank has a current level of stored power;

a bypass adapted to selectively divert at least a portion of the feed stream from delivery to the fuel cell stack; and

a control system adapted to selectively actuate the bypass to control the portion of the feed stream that is diverted from delivery to the fuel cell stack and thereby regulate the rate that the feed stream is delivered to the fuel cell stack, wherein the control system is adapted to selectively actuate the bypass responsive at least in part to the current level of stored power of the battery bank.

38. The fuel cell system of claim 37, wherein the bypass includes a first configuration, in which none of the feed stream is diverted from delivery to the fuel cell stack, a second configuration in which all of the feed stream is diverted from delivery to the fuel cell stack, and at least one intermediate configuration in which some, but not all, of the feed stream is diverted from delivery to the fuel cell stack.

39. The fuel cell system of claim 37, wherein the battery bank has a maximum level of stored power and further wherein the control system is adapted to actuate the bypass to selectively divert at least a portion of the feed stream when the current level of stored power of the battery bank is within a selected range of the maximum level of stored power.

40. The fuel cell system of claim 37, wherein the battery bank has a maximum level of stored power and further wherein the control system is adapted to actuate the bypass to selectively divert at least a portion of the feed stream when the current level of stored power of the battery bank is at least as great as the maximum level of stored power.

41. The fuel cell system of claim 37, wherein the control system is adapted to actuate the bypass without reducing the rate at which the fuel processing assembly produces the feed stream.

42. The fuel cell system of claim 37, wherein the fuel cell system further includes a hydrogen storage device adapted to receive at least a portion of the feed stream diverted by the bypass.

43. The fuel cell system of claim 37, wherein the fuel cell system further includes a hydrogen-consuming device that is adapted to receive at least a portion of the feed stream diverted by the bypass.

44. A fuel cell system, comprising:

means for producing electrical power from a feed; and

means for controlling the fuel cell system for preventing the electrical power produced by the system from exceeding both a maximum rated power output of the system and a currently available power output of the system.

45. The system of claim 44, further including means for producing the feed.

46. The system of claim 45, further including means for producing heat responsive to a demand for thermal energy.

47. The system of claim 45, wherein the means for controlling include at least one controller adapted to measure at least one selected variable and to regulate the fuel cell system if the at least one selected variable exceeds one or more corresponding threshold values.