Flexible method for monitoring fuel cell voltage

• US 6,455,180 B1
• Filed: 07/02/1999
• Issued: 09/24/2002
• Est. Priority Date: 07/02/1999
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Ripley, Eugene V., Mowery, Kenneth D.
• Primary Examiner(s): Brouillette, Gabrielle
• Assistant Examiner(s): ALEJANDRO, RAYMOND
• Application Number:
  US09/348,245
• Time in Patent Office: 1,180 Days
• Field of Search: 429/13, 429/12, 429/22, 429/23, 429/18, 324/433, 324/434
• US Class Current: 429/432
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• 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
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A method for equalizing the measured voltage of each cluster in a fuel cell stack wherein at least one of the clusters has a different number of cells than the identical number of cells in the remaining clusters by creating a pseudo voltage for the different cell numbered cluster. The average cell voltage of the all of the cells in the fuel cell stack is calculated and multiplied by a constant equal to the difference in the number of cells in the identical cell clusters and the number of cells in the different numbered cell cluster. The resultant product is added to the actual voltage measured across the different numbered cell cluster to create a pseudo voltage which is equivalent in cell number to the number of cells in the other identical numbered cell clusters.

Claims

1. In a method of operating a fuel cell apparatus wherein a hydrogen-rich stream is supplied to a stack of fuel cells, wherein the fuel cell stack includes a plurality of first clusters formed of identical number of fuel cells and at least one second cluster formed of a different number of fuel cells, the improvement comprising:

measuring the voltage across the entire fuel cell stack;

measuring the voltage across the second cluster of fuel cells; and

creating a pseudo cluster voltage for the second cluster based on the average cell voltage of all of the cells in the fuel cell stack, the actual voltage across the second cluster and the difference between the number of cells in the first clusters and the number of cells in the second cluster, wherein that the pseudo cluster voltage for the second cluster is compared with the voltage across each first cluster for monitoring of the performance of the fuel cell.

2. The method of claim 1 wherein the step of creating the pseudo cluster voltage for the second cluster comprises the steps of:

(a) determining the average cell voltage for the entire stack;

(b) multiplying the average cell voltage for the entire stack by the difference between the number of cells in the first clusters and the number of cells in the second cluster; and

(c) adding the product of step b to the actual measured voltage across the second cluster.

3. The method of claim 1 wherein the step of creating the pseudo cluster voltage for the second cluster further comprises the steps of:

(a) establishing a constant equal to the difference between the number of cells in each of the first clusters and the number of cells in the second cluster;

(b) multiplying the constant by the average cell voltage across the entire stack; and

(c) adding the resultant product of step (b) to the actual measured voltage across the second cluster.

4. In a method of operating a fuel cell apparatus wherein a hydrogen-rich stream is supplied to a stack of fuel cells, wherein the fuel cell stack includes a plurality of first clusters formed of identical number of fuel cells and at least one second cluster formed of a different number of fuel cells, the improvement comprising:

measuring the voltage across the entire fuel cell stack;

measuring the voltage across the second cluster of fuel cells; and

adjusting the measured voltage across the second cluster of fuel cells by a factor equivalent to the average cell voltage for each fuel cell multiplied by the difference between the number of fuel cells in the second cluster and the number fuel cells in each first cluster.

5. In a method of operating a fuel cell apparatus wherein a hydrogen-rich stream is supplied to a stack of fuel cells, wherein the fuel cell stack includes a plurality of first clusters formed of identical number of fuel cells and at least one second cluster formed of a different number of fuel cells, the improvement comprising:

measuring the voltage across the entire fuel cell stack;

measuring the voltage across the second cluster of fuel cells; and

creating a pseudo cluster voltage for the second cluster by adding a product of the average cell voltage for the entire fuel cell stack and the difference between the number of cells in the second cluster and the number of cells in each first cluster to the measured voltage across the second cluster, wherein the pseudo cluster voltage for the second cluster is compared to the voltage across each first cluster for monitoring the performance of the fuel cell.

6. A fuel cell voltage monitoring system comprising:

a fuel cell stack including a plurality of first clusters formed of a first number of fuel cells and at least one second cluster formed of a second number of fuel cells, wherein said first number is different than said second number;

a first voltage sensor that measures voltage across said fuel cell stack;

a second voltage sensor that measures voltage across said second cluster; and

a pseudo cluster voltage generator that includes an average voltage calculator for determining an average cell voltage of fuel cells in said fuel cell stack and a second cluster fill counter that stores a difference between said first and second numbers, wherein said pseudo cluster voltage generator creates a pseudo cluster voltage based on said average cell voltage, said voltage across said second cluster and said difference between said first and second numbers.

7. The fuel cell voltage monitor of claim 6 wherein said pseudo cluster voltage generator multiplies said average cell voltage by said difference.

8. The fuel cell voltage monitor of claim 7 wherein said pseudo cluster voltage generator further includes:

an adder that adds said actual measured voltage across said second cluster to said pseudo cluster voltage.

9. The fuel cell voltage monitor of claim 8 further comprising:

a third voltage sensor that senses voltage across at least one of said first clusters; and

a comparing circuit that compares said pseudo cluster voltage to said voltage across said at least one of said first clusters.