Measuring cell voltages of a fuel cell stack

• US 6,313,750 B1
• Filed: 08/23/1999
• Issued: 11/06/2001
• Est. Priority Date: 08/23/1999
• Status: Expired due to Fees

• Current Assignee: Plug Power Inc.
• Original Assignee: Plug Power Inc.
• Inventors: Lacy, Robert A.
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US09/379,088
• Time in Patent Office: 806 Days
• Field of Search: 340/636, 340/635, 340/660, 340/661, 324/433, 324/434
• US Class Current: 340/636.15
• CPC Class Codes: G01R 19/0053 Noise discrimination; Analog sampling; Measuring transients measuring characteristics of individual pulses G01R29/02; digital sampling G01R19/2509; measuring noise figure G01R29/26
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• 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 includes a divider network, a memory and a circuit. The divider network is adapted to be coupled to fuel cells of a fuel cell stack and provide pairs of signals. Each pair of signals is associated with a different fuel cell and indicates a terminal voltage of the associated cell and another voltage common to the pair of signals. The memory stores indications of different common mode gains, and each common mode gain indication is associated with a different one of the pairs of signals. The circuit is coupled to the memory and adapted to generate an indication of the terminal voltage from each pair based on the associated common mode gain indication.

Claims

1. A system comprising:

a divider network adapted to be coupled to fuel cells of a fuel cell stack and provide pairs of signals, each pair of signals being associated with a different fuel cell and indicating a terminal voltage of the associated cell and another voltage common to the pair of signals;

a memory storing indications of different common mode gains, each common mode gain indication being associated with a different one of the pairs of signals; and

a circuit coupled to the memory and adapted to generate an indication of the terminal voltage from each pair based on the associated common mode gain indication.

2. The system of claim 1, wherein the circuit is adapted to substantially remove the indication of said another voltage common to the pair of signals from each pair of signals.

3. The system of claim 2, wherein the circuit removes the indication by multiplying the common mode gain indication associated with the pair of signals with said another voltage common to the pair of signals to produce a common mode component and subtracting the common mode component from the pair of signals.

4. The system of claim 1, wherein the fuel cell stack includes terminals associated with the different fuel cells and the divider network comprises resistor dividers, each resistor divider being adapted to receive a voltage from one of the different node voltages and provide a different one of the pairs of signals.

5. The system of claim 1, wherein the circuit comprises:

a multiplexer adapted to select the pairs of signals one at a time; and

a differential amplifier adapted to provide an indication of a difference between the selected pair.

6. The system of claim 5, wherein the circuit further comprises:

a microprocessor coupled to the differential amplifier and adapted to use the indication of the difference and the associated common mode gain indication to generate the indication of the terminal voltage from each pair.

7. The system of claim 1, wherein the circuit is further adapted to estimate a common mode voltage that is associated with each pair and further base the generation of the terminal voltages from each pair on the estimation.

8. The system of claim 1, wherein the circuit comprises a microprocessor.

9. The system of claim 1, wherein the circuit comprises a microcontroller and the memory is part of the microcontroller.

10. A method comprising:

coupling voltage measurement terminals of a fuel cell stack measurement apparatus to a common predetermined voltage to produce a first set of measured voltages;

using the first set of measured voltages to obtain common mode voltage gains, each common mode voltage gain being associated with a different paired grouping of the terminals;

storing indications of the common mode voltage gains in a memory;

coupling the voltage measurement terminals to nodes associated with cells of the fuel cell stack to produce a second set of measured voltages; and

generating indications of terminal voltages of the fuel cells based on the stored indications of the common mode voltage gains and the second set of measured voltages.

11. The method of claim 10, wherein the act of using the first set of measured voltages to obtain common mode voltage gains comprises:

associating each measured voltage of the first set with a different one of the paired groupings;

estimating a voltage in common with each different paired grouping; and

for each different paired grouping, dividing the associated measured voltage of the first set with the estimated voltage in common with the paired grouping.

12. The method of claim 10, further comprising:

communicating indications of the first set of measured voltages to a computer to calculate the common mode voltage gains.

13. The method of claim 12, further comprising:

storing indications of the common mode voltage gains in a memory that is external the computer.

14. The method of claim 10, wherein each voltage of the second set of measured voltages includes a different one of the terminal voltages and a common mode voltage.

15. The method of claim 14, further comprising:

for each voltage of the second set of measured voltages, substantially removing the common mode voltage.

16. The method of claim 14, further comprising:

for each voltage of the second set of measured voltages, substantially removing the common mode voltage, wherein the act of removal comprises multiplying an indication of the associated common mode gain with an indication of the common mode voltage to produce an indication of another voltage to be subtracted from the voltage of the second set.

17. An article comprising a storage medium readable by a microprocessor-based system, the storage medium storing instructions to cause a microprocessor to:

receive indications of a first set of measured voltages from a fuel cell voltage measurement apparatus produced by coupling measurement terminals of the measurement apparatus to a common predetermined voltage,

use the first set of measured voltages to obtain common mode voltage gains, each common mode voltage gain being associated with a different paired grouping of the terminals, and

communicate indications of the common mode voltage gains to a memory of the measurement apparatus.

18. The article of claim 17, wherein the storage medium stores instructions to cause the microprocessor to:

associate each measured voltage of the first set with a different one of the paired groupings

estimate a voltage in common with each different paired grouping, and for each different paired grouping and

divide the associated measured voltage of the first set with the estimated voltage in common with the paired grouping.

19. An article comprising a storage medium readable by a microprocessor-based system, the storage medium storing instructions to cause a microprocessor to:

receive indications of measured voltages produced at least in part by a divider network that is coupled to a fuel cell stack, each measured voltage being associated with a different fuel cell of the stack and including a terminal voltage of the associated cell and another common mode voltage, and

generate an indication of the terminal voltage from each indicated measured voltage based on an associated common mode gain indication.

20. The article of claim 19, wherein the storage medium stores instructions to cause the microprocessor to communicate the indications of the terminal voltages to a computer.