Reduction of voltage loss caused by voltage cycling by use of a rechargeable electric storage device

• US 20060147770A1
• Filed: 01/04/2005
• Published: 07/06/2006
• Est. Priority Date: 01/04/2005
• Status: Abandoned Application

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Krause, Bernd
• Application Number:
  US11/028,887
• Publication Number:
  US 20060147770A1
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A fuel cell system that employs a fuel cell stack and a supplemental power source, such as a battery or an ultra-capacitor. The power source provides supplemental power in addition to the output power of a fuel cell stack for high load demands. The fuel cell system includes a power management controller that controls the power output from the supplemental power source and the fuel cell stack as the demand on the fuel cell stack changes. During low load demands, where the voltage across the fuel cell stack may increase above a potential that could cause oxidation of platinum catalyst particles within the fuel cells in the stack, the power management controller causes the fuel cell stack to charge the power source so as to decrease the voltage output on the stack.

Claims

1. A fuel cell system comprising:

a fuel cell stack including a stack of fuel cells;

a supplemental power source electrically coupled to the fuel cell stack; and

a power controller, said controller controlling the power output of the fuel cell stack and the supplemental power source by using the power source as a load on the stack to maintain a voltage on the fuel cell stack below a predetermined oxidation threshold.

2. The fuel cell system according to claim 1 wherein the oxidation threshold is the threshold where platinum catalyst particles in the fuel cells begin to oxidize.

3. The fuel cell system according to claim 1 wherein the oxidation threshold is about 0.8 volts.

4. The fuel cell system according to claim 1 wherein the controller uses a control scheme that reduces or eliminates voltage cycling of the stack.

5. The fuel cell system according to claim 1 wherein the power source is selected from the group consisting of batteries and capacitors.

6. The fuel cell system according to claim 1 wherein the fuel cell stack and the supplemental power source provide output power to drive an electric traction system on a vehicle.

7. A fuel cell system comprising:

a fuel cell stack including a stack of fuel cells;

a supplemental power source; and

a controller for controlling the power output of the fuel cell stack and the supplemental power source, said controller electrically coupling the fuel cell stack to the power source at low load demands so as to reduce or prevent voltage cycling of the fuel cell stack.

8. The fuel cell system according to claim 7 wherein the voltage cycling is defined as the voltage where platinum catalyst particles in the fuel cells begin to oxidize.

9. The fuel cell system according to claim 8 wherein the oxidation voltage is about 0.8 volts.

10. The fuel cell system according to claim 7 wherein the power source is selected from the group consisting of batteries and capacitors.

11. The fuel cell system according to claim 7 wherein the fuel cell stack and the supplemental power source provide output power to drive an electric traction system on a vehicle.

12. A method for controlling the power output of a fuel cell system, said method comprising:

providing output power from a fuel cell stack including a stack of fuel cells;

providing output power from a supplemental power source; and

controlling the power output of the fuel cell stack and the supplemental power source so as to maintain a voltage on the fuel cell stack below a predetermined oxidation threshold.

13. The method according to claim 12 wherein the oxidation threshold is the threshold where platinum catalyst particles in the fuel cells begin to oxidize.

14. The method according to claim 12 wherein the oxidation threshold is about 0.8 volts.

15. The method according to claim 12 wherein controlling the power output of the fuel cell stack and the supplemental power source includes reducing or eliminating voltage cycling of the stack.

16. The method according to claim 12 wherein providing output power from a supplemental power source includes providing output power from a supplemental power source selected from the group consisting of batteries and capacitors.

17. The method according to claim 12 providing output power from a fuel cell stack and a supplemental power source includes providing output power to drive an electric traction system on a vehicle.