Measuring cell voltages of a fuel cell stack

• US 6,140,820 A
• Filed: 12/27/1999
• Issued: 10/31/2000
• Est. Priority Date: 12/27/1999
• Status: Expired due to Term

• Current Assignee: Plug Power Inc.
• Original Assignee: Plug Power Inc.
• Inventors: James, David E.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/472,649
• Time in Patent Office: 309 Days
• Field of Search: 320/116, 320/117, 320/119, 320/120, 320/122, 320/FOR 116, 320/FOR 114, 324/425, 324/426, 324/430, 324/433, 324/434
• US Class Current: 324/434
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

Abstract

A system that is usable with a stack of fuel cells that have cell terminals includes scanning units and a circuit. The scanning units are coupled to the stack and establish different groups of the fuel cells. Each scanning unit has a ground that is referenced to a different one of the cell terminals, and each scanning unit is adapted to measure the voltages of the fuel cells in an associated one of the groups and indicate the measured voltages. The circuit is adapted to communicate with the scanning units to receive the indicated voltages.

Claims

1. A system usable with a stack of fuel cells that have cell terminals, comprising:

scanning units coupled to the stack and establishing different groups of the fuel cells, each scanning unit having a ground referenced to a different one of the cell terminals and being adapted to measure the voltages of the fuel cells in an associated one of the groups and indicate the measured voltages; and

a circuit adapted to receive the indicated voltages from the scanning units.

2. The system of claim 1, wherein the circuit and the stack have a common ground connection.

3. The system of claim 1, wherein the ground of at least one of the scanning units is connected to the cell terminal of one of the cells in the associated group.

4. The system of claim 1, wherein at least one of the scanning units has an associated maximum input voltage that is less than the voltage of at least one of the terminals of the associated group with respect to a ground of the fuel cell stack.

5. The system of claim 4, wherein the maximum input voltage is between approximately 16 to 30 volts.

6. The system of claim 4, wherein the stack provides a voltage between approximately 90 and 150 volts.

7. The system of claim 1, wherein the stack provides a voltage between approximately 90 and 150 volts.

8. The system of claim 1, wherein the stack provides a voltage greater than 150 volts.

9. The system of claim 1, further comprising:

voltage regulators, each regulator providing power to at least one of the scanning units and having a ground in common with the ground associated with one of said at least one of the scanning units.

10. The system of claim 1, wherein at least one of the scanning units comprises:

a differential amplifier adapted to measure the voltages of the fuel cells in the associated group; and

multiplexing circuitry to selectively couple the terminals of the fuel cells in the associated group to the differential amplifier.

11. The system of claim 10, wherein said at least one of the scanning units further comprises:

a processing unit adapted to operate the multiplexing circuitry to selectively couple the terminals of the fuel cells in the associated group to the differential amplifier and receive a signal from the differential amplifier indicative of the measured voltages.

12. The system of claim 1, wherein at least one of the scanning units comprises:

optical isolation circuitry to communicate the indication to the circuit.

13. The system of claim 1, further comprising:

a bus coupled between the scanning units and the circuit, the bus being used by the circuit to communicate with the scanning units.

14. A system usable with a serially coupled array of voltage sources that have terminals, comprising:

scanning units coupled to the array and establishing different groups of the voltage sources, each scanning unit having a ground referenced to a different one of the terminals and being adapted to measure the voltages of the voltage sources in an associated one of the groups and indicate the measured voltages; and

a circuit adapted to communicate with the scanning units to receive the indicated voltages.

15. The system of claim 14, wherein the circuit and the array have a common ground connection.

16. The system of claim 14, wherein the ground of at least one of the scanning units circuit is connected to the terminal of one of the voltage sources in the associated group.

17. The system of claim 14, wherein at least one of the scanning units has an associated maximum input voltage that is less than the voltage of at least one of terminals of the associated group with respect to a ground of the array.

18. The system of claim 14, wherein the array comprises a fuel cell stack.

19. The system of claim 14, wherein the array comprises a battery bank.

20. The system of claim 14, further comprising:

voltage regulators, each regulator providing power to at least one of the scanning units and having a ground in common with the ground associated with one of said at least one of the scanning units.

21. The system of claim 14, wherein at least one of the scanning units comprises:

a differential amplifier adapted to measure the voltages of the voltage sources in the associated group; and

multiplexing circuitry to selectively couple the terminals of the voltage sources in the associated group to the differential amplifier.

22. The system of claim 21, wherein said at least one of the scanning units further comprises:

a processing unit adapted to operate the multiplexing circuitry to selectively couple the terminals of the voltage sources in the associated group to the differential amplifier and receive a signal from the differential amplifier indicative of the measured voltages.

23. The system of claim 14, wherein at least one of the scanning units comprises:

optical isolation circuitry to communicate the indication to the circuit.

24. The system of claim 14, further comprising:

a bus coupled between the scanning units and the circuit, the bus being used by the circuit to communicate with the scanning units.

25. A method usable with a stack of fuel cells, comprising:

dividing the fuel cells into groups;

establishing ground references at the different terminals of the cells, each ground reference being associated with one of the groups; and

measuring the voltages of the fuel cells in each group using the associated ground reference.

26. The method of claim 25, wherein the ground reference that is associated with at least one of the scanning units is connected to the terminal of one of the cells in the associated group.

27. The method of claim 25, wherein the measuring comprises:

for each group, sequentially measuring the cell voltages one at a time.