MULTI-POINT FUEL CELL VOLTAGE MONITOR

• US 20110129749A1
• Filed: 12/24/2007
• Published: 06/02/2011
• Est. Priority Date: 12/24/2007
• Status: Active Grant

• Current Assignee: Audi AG (Volkswagen AG)
• Original Assignee: Audi AG (Volkswagen AG)
• Inventors: Reiser, Carl A.
• Granted Patent: US 9,231,262 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• 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 8/04671 of the individual fuel cell
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: H01M 8/04701 Temperature
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04768 of the coolant
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell voltage monitor (12a, 12b, 40, 140, 440) detects and may respond to, a problematic operating condition at or near a fuel cell (10) or within a subset (n) of fuel cells, as in a fuel cell stack assembly (110). Two or more co-planar, spaced voltage leads or contacts in a fuel cell plane, as at a separator plate, detect the presence of a voltage difference within the plate/plane as an indication of an operating problem at or near the fuel cell. Placement of such arrangements of at least two spaced voltage leads at various subset intervals (n), of fuel cells in a stack assembly allow monitoring for such problems throughout the stack assembly, either by analysis of voltage difference between co-planar leads at respective individual fuel cells or by comparison of voltage differences between aligned pairs of voltage leads at opposite ends of a subset.

Claims

1. A fuel cell voltage monitor (12a, 12b, 40, 140) for detecting a problematic operating condition at a fuel cell (10), comprising:

a fuel cell (10) having a plurality of nominally planar elements stacked in layered arrangement, said elements including an anode (14, 14a), a cathode (16, 16a), an electrolyte (18), and anode and cathode plates (22, 20), the anode (14, 14a) and cathode (16, 16a) being on opposite sides of the electrolyte (18) and between the respective plates (22, 20);

at least two voltage leads (12a, 12b) in operative electrical contact with a same one (eg, 22, 14) of said nominally planar elements and positioned in spaced apart (S) relation on the plane of the element to sense the respective voltages thereat; and

voltage comparing circuitry (40, 140) operatively connected (Va, Vb) to the two voltage leads (12a, 12b) for comparing the respective voltages and providing a signal (42) indicative of a difference in said respective voltages, a said voltage difference being occasioned by in-plane current flow commensurate with the existence of an operating problem at said fuel cell (10).

2. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 1 wherein said anode and cathode plates (22, 20) are separator plates, and the at least two voltage leads (12a, 12b) are in operative electrical and physical contact with one of said anode and cathode separator plates (22, 20).

3. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 2 wherein said at least two voltage leads (12a, 12b) are in operative electrical and physical contact with the anode separator plate (22).

4. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 1 wherein the nominally planar elements of the fuel cell (10) are rectilinear and have a plurality of corners, and said at least two voltage leads (12a, 12b) are located substantially at different ones of said corners.

5. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 4 wherein said at least two voltage leads (12a, 12b) are two in number and are located at opposite ones of said corners.

6. A fuel cell voltage monitor (12a, 12b, 40, 140, 440) for detecting a problematic operating condition at a fuel cell stack assembly (110), comprising:

a fuel cell stack assembly (110) comprising a number of fuel cells (10) stacked in serial physical and electrical relation, each fuel cell (10) having a plurality of nominally planar elements stacked in layered arrangement, said elements including an anode (14, 14a), a cathode (16, 16a), an electrolyte (18), and anode and cathode separator plates (22, 20), the anode (14, 14a) and cathode (16, 16a) being on opposite sides of the electrolyte (18) and between the respective separator plates (22, 20);

at least two voltage leads (12a, 12b) in operative electrical contact with a same one (eg, 22, 14) of said nominally planar elements and positioned in spaced apart (S) relation on the plane of the element for each of a plurality (FC₁, FC_n1+1, . . . FC_{n1+n2+n3 . . . +nx+1}) of said fuel cells (10) at spaced intervals “

n”

in the stack assembly (110) to sense the respective voltages thereat; and

voltage comparing circuitry (40, 140, 440) operatively connected (Va, Vb;

Va₁, Vb₁;

Va_n1, Vbn1;

Va_n1+n2, Vb_n1+n2;

Va_{n1+n2+n3 . . . +nx}, Vb_{n1+n2+n3 . . . +nx},) to the at least two voltage leads (12a, 12b) in said plurality of said fuel cells (10) in the stack (110) for comparing the respective voltages and providing a signal (42, 52;

342n, 352) indicative of a difference in selected ones of said respective compared voltages, a said voltage difference in said selected ones of said compared voltages being occasioned by in-plane current flow commensurate with the existence of an operating problem substantially at or between the respective ones of said plurality of said fuel cells (10) in the stack assembly (110) responsible for said voltage difference in said selected ones of compared voltages.

7. The fuel cell voltage monitor (12a, 12b, 40, 140, 440) of claim 6 wherein each of said fuel cell intervals “

n”

in the stack assembly (110) is the same.

8. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 6 wherein the voltage comparing circuitry (40, 140) provides signals (42) indicative of a difference in voltage for each of said at least two voltage leads (12a, 12b) for each of said fuel cells (10) at which said at least two voltage leads are located.

9. The fuel cell voltage monitor (12a, 12b, 40, 140) of claim 8 wherein the voltage comparing circuitry (40, 140) further includes threshold circuitry (50) operatively connected to the signals (42) indicative of voltage differences, if any, for each of said fuel cells (10) at which said at least two voltage leads are located for indicating (52) that a said voltage difference exceeds a predetermined threshold level.

10. The fuel cell voltage monitor (12a, 12b, 40, 440) of claim 6 wherein the at least two voltage leads (12a, 12b) are located at respective first (a) and second (b) spaced positions on the respective fuel cell elements having the at least two voltage leads (12a, 12b) positioned thereon, said first (a) and said second (b) spaced positions being substantially the same for each of the plurality of fuel cell elements having the at least two voltage leads (12a, 12b) positioned thereon, the leads (12a) at a plurality of said first spaced positions (a) being operatively connected as pairs to voltage comparing circuitry (Δ

Va) to determine and provide a voltage difference signal (242a) between the respective pairs of said leads (12a) at said first positions defining there between a respective subset (n) of the stack assembly, the leads (12b) at a plurality of said second spaced positions (b) being operatively connected to voltage comparing circuitry (Δ

Vb) to determine and provide a voltage difference signal (242b) between the respective pairs of said leads (12b) at said second positions and defining there between the same said subset (n) of the stack assembly as for said pairs of leads at said first position, said first position and said second position voltage difference signals (242a, 242b) being connected to a voltage comparator (340) for comparing the respective voltage differences and providing a further difference signal 342n indicative of in-plane current flow commensurate with the existence of an operating problem substantially at or between the respective pair of said fuel cells (10) defining a respective said subset (n) in the stack assembly (110).

11. The fuel cell voltage monitor (12a, 12b, 40, 440) of claim 6 further including a controller (60) to regulate operation of the fuel cell stack assembly 110, the controller being connected and responsive to a difference signal (42, 52;

342n, 352) to provide a fuel cell stack assembly operating control signal 62.

12. A method for monitoring and operating a fuel cell stack assembly (110), the fuel cell stack assembly comprising a number of fuel cells (10) stacked in serial physical and electrical relation, each fuel cell (10) having a plurality of nominally planar elements stacked in layered arrangement, said elements including an anode (14, 14a), a cathode (16, 16a), an electrolyte (18), and anode and cathode separator plates (22, 20), the anode (14, 14a) and cathode (16, 16a) being on opposite sides of the electrolyte (18) and between the respective separator plates (22, 20), comprising the steps of:

detecting the voltage at two or more spaced locations (12a, 12b) at the same one (eg, 22, 14) of the nominally planar elements in each of a plurality (FC₁, FC_n1+1, . . . FC_{n1+n2+n3 . . . +nx+1}) of the fuel cells (10) at intervals “

n”

in the stack assembly (110) to provide respective voltage signals;

comparing (40, 140, 440) two or more of said voltage signals (Va, Vb;

Va₁, Vb₁;

Va_n1, Vbn1;

Va_n1+n2, Vb_n1+n2;

Va_{n1+n2+n3 . . . +nx}, Vb_{n1+n2+n3 . . . +nx},) for each of two fuel cells at respective opposite ends of a said interval “

n”

to provide respective voltage differential signals (42, 52;

342n, 352); and

providing from the respective voltage differential signals (42, 52;

342n, 352), a control signal (62) to regulate operating performance of the fuel cell stack assembly.

13. The method of claim 12 wherein the step of comparing detected voltages comprises comparing with one another the voltages (Va, Vb;

Va_n1, Vb_n1;

Va_n1+n2, Vb_n1+n2) for the at least two spaced locations (12a, 12b) associated with the same fuel cell (10).

14. The method of claim 12 wherein the step of detecting voltages comprises:

detecting the voltages (Va, Vb, Va_n1, Vb_n1, etc) at first and second spaced positions that have the same locations (12b, 12a) on each of the fuel cells (10) at said intervals “

n”

;

comparing the detected voltages (Va, Va_n1;

Va_n1, Va_n1+n2;

etc) for the same first position at each of the two fuel cells (FC₁, FC_n1+1;

etc) at opposite ends of a said interval “

n”

to provide a first position voltage differential signal (242a);

comparing the detected voltages (Vb, Vb_n1;

Vb_n1, Vb_n1+n2;

etc) for the same second position at each of the two fuel cells (FC₁, FC_n1+1;

etc) at opposite ends of a said interval “

n”

to provide a second position voltage differential signal (242b);

comparing the first position voltage differential signal (242a) and the second position voltage differential signal (242b) to provide a resultant voltage differential signal (342n); and

providing (350, 60) from the resultant voltage differential signal (342n), the control signal (62) to regulate operating performance of the fuel cell stack assembly (110).