Cell maintenance device for fuel cell stacks

• US 7,474,078 B2
• Filed: 12/19/2003
• Issued: 01/06/2009
• Est. Priority Date: 12/19/2003
• Status: Expired due to Fees

• Current Assignee: Texaco Development Corporation (Chevron Corp.), Texaco Incorporated (Chevron Corp.)
• Original Assignee: Texaco Incorporated (Chevron Corp.)
• Inventors: Baker, Howard S.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US10/740,740
• Publication Number:
  US 20050136293A1
• Time in Patent Office: 1,845 Days
• Field of Search: 320/129, 320134-136, 320/139, 320/101, 320/141, 429/17, 429/13, 324430-433
• US Class Current: 320/134
• CPC Class Codes: H01M 8/04238 Depolarisation
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A method and apparatus for maintaining the cells of a fuel cell stack are disclosed. The apparatus includes a fuel cell maintenance device including means for imposing a low impedance across at least one cell of a fuel cell stack, e.g., a switch, and a pulse generator. The pulse generator is capable of pulsing a cathode of the at least one cell of through the low impedance imposing means, e.g., when the switch is closed. The method transparently maintains the cells of a fuel cell stack, and includes sequentially pulsing the cathodes of a plurality of cells in a fuel cell stack, and maintaining a consistent number of the cells providing power to a load of the fuel cell stack while sequentially pulsing the cathodes of the cell.

Claims

1. A fuel cell maintenance device, comprising:

a switch;

a pulse generator capable of pulsing a cathode of at least one cell of a fuel cell stack through the switch when the switch is closed wherein the pulse generator generates a digital pulse;

a relay capable of shorting the cell of a fuel cell stack; and

a dielectrically isolated driver capable of driving the relay.

2. The fuel cell maintenance device of claim 1, wherein the relay comprises a solid-state relay.

3. The fuel cell maintenance device of claim 1, wherein the relay is further capable of shorting a second cell of the fuel cell stack.

4. The fuel cell maintenance device of claim 1, further comprising:

a second switch through which the pulse generator is capable of pulsing a cathode of a second cell when the second switch is closed; and

a control circuit capable of controlling to which of the first and second relays the pulse generator output is transmitted.

5. The fuel cell maintenance device of claim 4, wherein the second switch includes:

a second relay capable of shorting at least a second cell of a fuel cell stack; and

a second dielectrically isolated driver capable of driving a second relay responsive to the pulse generator output.

6. The fuel cell maintenance device of claim 5, wherein at least one of the first relay and the second relay is further capable of shorting one of a third cell and a fourth cell of the fuel cell stack.

7. The fuel cell maintenance device of claim 1, wherein at least one of the switch and the pulse generator is capable of receiving power returned from the fuel cell stack.

8. The fuel cell maintenance device of claim 7, further comprising a voltage regulator coupled to at least one of the switch and the pulse generator and configured to receive the power returned from the fuel cell stack.

9. The fuel cell maintenance device of claim 1, wherein the pulse generator is capable of pulsing a cathode of a second cell when the switch is closed.

10. A fuel cell maintenance device, comprising:

at least one relay capable of shorting at least one cell of a fuel cell stack;

a dielectrically isolated driver capable of driving the relay;

a pulse generator capable of pulsing a cathode of the cell through the relay when the dielectrically isolated driver closes the relay to short the cell wherein the pulse generator generates a digital pulse wherein at least one of the relay, the dielectrically isolated driver and the pulse generator is capable of receiving power returned from the fuel cell stack; and

a voltage regulator through which at least one of the relay, the dielectrically isolated driver and the pulse generator is capable of received power returned from the fuel cell stack.

11. The fuel cell maintenance device of claim 10, wherein the relay comprises a solid-state relay.

12. The fuel cell maintenance device of claim 10, wherein the relay is further capable of shorting a second cell of the fuel cell stack.

13. The fuel cell maintenance device of claim 10, further comprising:

a second relay capable of shorting at least a second cell of a fuel cell stack;

a second dielectrically isolated driver capable of driving second relay responsive to the pulse generator output; and

a control circuit capable of controlling to which of the first and second relays the pulse generator output is transmitted.

14. The fuel cell maintenance device of claim 13, wherein at least one of the first relay and the second relay is further capable of shorting one of a third cell and a fourth cell of the fuel cell stack.

15. The fuel cell maintenance device of claim 10, wherein the pulse generator is capable of pulsing a cathode of a second cell through the relay when the dielectrically isolated driver closes the relay to short the cell.

16. A fuel cell maintenance device for a fuel stack including at least one fuel cell, the fuel cell maintenance device comprising:

at least one relay electrically connected in parallel across the cell;

a dielectrically isolated driver operably associated with the relay to drive the relay;

a pulse generator electrically connected to the dielectrically isolated driver to pulse a cathode of the cell through the relay when the dielectrically isolated driver closes the relay wherein the pulse generator generates a digital pulse; and

a power return from the fuel cell stack to at least one of the pulse generator, the relay and dielectrically isolated driver, wherein the power return includes a voltage regulator.

17. The fuel cell maintenance device of claim 16, wherein the relay comprises a solid-state relay.

18. The fuel cell maintenance device of claim 16, wherein the relay is further electrically connected in parallel across a second cell of the fuel cell stack.

19. The fuel cell maintenance device of claim 16, further comprising;

a second relay electrically connected in parallel across a second cell of a fuel cell stack;

a second dielectrically isolated driver capable of driving second relay responsive to the pulse generator output; and

a control circuit capable of controlling to which of the first and second relays the pulse generator output is transmitted.

20. The fuel cell maintenance device of claim 19, wherein at least one of the first relay and the second relay is further electrically connected in parallel across one of a third cell and a fourth cell of the fuel cell stack.

21. The fuel cell maintenance device of claim 16, wherein:

the relay is electrically connected in parallel across a second cell; and

the pulse generator is electrically connected to the dielectrically isolated driver to pulse a cathode of the second cell through the relay when the dielectrically isolated driver closes the relay.

22. An apparatus, comprising:

a fuel stack, including a plurality of cells;

a switch bank, including a plurality of switches, each switch electrically connected in parallel across at least one of the cells;

a pulse generator capable of pulsing the cathodes of the cells when the respective switch is closed wherein the pulse generator generates a digital pulse;

a control circuit electrically connected in series between the pulse generator and the switch bank to sequentially open and close the switches;

a relay capable of shorting at least one cell of a fuel cell stack; and

a dielectrically isolated driver capable of driving the relay.

23. The apparatus of claim 22, wherein the relay comprises a solid-state relay.

24. The apparatus of claim 22, wherein the relay is further capable of shorting a second cell of the fuel cell stack.

25. The apparatus of claim 22, wherein each switch is capable of shorting a plurality of cells.

26. The apparatus of claim 22, wherein at least one of the switch bank and the pulse generator is capable of receiving power returned from the fuel cell stack.

27. The apparatus of claim 26, further comprising a voltage regulator through which at least one of the switch bank and the pulse generator is capable of receiving power returned from the fuel cell stack.

28. The apparatus of claim 22, wherein control circuit includes:

a counter driven by a clock; and

a multiplexer multiplexing the output of the pulse generator to the switches responsive to the count of the counter.

29. A method for transparently maintaining the cells of a fuel cell stack, the method comprising:

sequentially pulsing the cathodes of a plurality of cells in a fuel cell stack, wherein sequentially pulsing the cathodes includes generating a pulse train and sequentially supplying the pulse train to the cells, wherein sequentially supplying the pulse train to the cells includes supplying the pulse train to a first cell of the fuel cell stack to pulse a cathode thereof; and

switching the supply of the pulse train from the first cell to a second cell of the fuel stack to pulse a cathode thereof wherein a pulse generator generates a digital pulse; and

maintaining a consistent number of the cells providing power to a load of the fuel cell stack while sequentially pulsing the cathodes of the cells.

30. A method for transparently maintaining the cells of a fuel cell stack, the method comprising:

sequentially pulsing the cathodes of a plurality of cells in a fuel cell stack;

maintaining a consistent number of the cells providing power to a load of the fuel cell stack while sequentially pulsing the cathodes of the cells;

supplying the pulse train to a first cell of the fuel cell stack to pulse a cathode thereof wherein a pulse generator generates a digital pulse; and

switching the supply of the pulse train from the first cell to a second cell of the fuel stack to pulse a cathode thereof.

31. A fuel cell maintenance device, comprising:

means for imposing a low impedance across at least one cell of a fuel cell stack;

wherein the low impedance imposing means includes a switch that imposes the low impedance when closed and receiving a pulse from the pulse generator;

wherein the switch comprises a relay capable of shorting the cells of a fuel cell stack and a dielectrically isolated driver capable of driving the relay; and

a pulse generator capable of pulsing a cathode of the at least one cell of a fuel cell stack through the low impedance imposing means wherein the pulse generator generates a digital pulse.

32. The fuel cell maintenance device of claim 31, wherein the relay comprises a solid-state relay.

33. The fuel cell maintenance device of claim 31, wherein the relay is further capable of shorting a second cell of the fuel cell stack.

34. The fuel cell maintenance device of claim 31, further comprising:

second means for imposing a low impedance across at least a second cell of a fuel cell stack; and

a control circuit capable of controlling to which of the first and second low impedance imposing means the pulse generator output is transmitted.

35. The fuel cell maintenance device of claim 34, wherein the second low impedance imposing means includes a second switch that imposes the low impedance when closed and receiving a pulse from the pulse generator.

36. The fuel cell maintenance device of claim 35, wherein the second switch includes:

a second relay capable of shorting at least a second cell of a fuel cell stack; and

a second dielectrically isolated driver capable of driving a second relay responsive to the pulse generator output.

37. The fuel cell maintenance device of claim 36, wherein at least one of the first relay and the second relay is further capable of shorting one of a third cell and a fourth cell of the fuel cell stack.

38. The fuel cell maintenance device of claim 31, wherein at least one of the low impedance imposing means and the pulse generator is capable of receiving power returned from the fuel cell stack.

39. The fuel cell maintenance device of claim 38, further comprising a voltage regulator coupled to at least one of the switch and the pulse generator and configured to receive the power returned from the fuel cell stack.

40. The fuel cell maintenance device of claim 31, wherein the pulse generator is capable of pulsing a cathode of a second cell through the low impedance imposing means.