Regulating a fuel cell powered heating system

• US 6,379,826 B1
• Filed: 11/18/1999
• Issued: 04/30/2002
• Est. Priority Date: 11/18/1999
• Status: Expired due to Fees

• Current Assignee: Plug Power Inc.
• Original Assignee: Plug Power Inc.
• Inventors: Lacy, Robert A.
• Primary Examiner(s): Chaney, Carol
• Assistant Examiner(s): Martin, Angela J.
• Application Number:
  US09/442,526
• Time in Patent Office: 894 Days
• Field of Search: 429/12, 429/13, 429/24, 429/20, 429/21, 429/22, 429/26, 429/92, 429/61, 429/62
• US Class Current: 429/432
• CPC Class Codes: H01M 8/04 Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04731 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04873 of the individual fuel cell
• CPC Class Codes: H01M 8/04888 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system includes a fuel cell stack, an inverter, a reformer and a circuit. The fuel cell stack is adapted to produce heat in response to a fuel flow, and the inverter is coupled to the fuel cell stack and is adapted to use electrical energy produced by the fuel cell stack to furnish electrical power that is received by a power grid. The reformer is adapted to produce the fuel flow, and the circuit is adapted to interact with the reformer to produce an approximate predetermined amount of heat. The circuit also determines cell voltages of the fuel cell stack, selects the minimum cell voltage, and interacts with the inverter to regulate the amount of the electrical power that is furnished by the inverter based on the selected voltage.

Claims

1. A method comprising:

regulating a fuel cell system to produce an amount of heat, the fuel cell system producing electrical energy;

scanning at least one cell voltage of the fuel cell system;

transferring the electrical energy from the fuel cell system to a power grid; and

regulating a rate of the transfer based on the at least one cell voltage.

2. The method of claim 1, wherein the scanning comprises:

continually monitoring the cell voltages during the regulation to determine the lowest voltage of the cell voltage.

3. The method of claim 1, wherein said at least one cell voltage may be associated with different fuel cells of the fuel system during the regulation.

4. The method of claim 1, wherein the regulating comprises:

controlling an output voltage based on said at least one voltage.

5. The method of claim 1, wherein the regulating comprises:

preventing the cell voltages from decreasing below a threshold voltage.

6. The method of claim 1, wherein the regulating comprises preventing said at least one voltage from decreasing below a threshold voltage.

7. A fuel cell system comprising:

a fuel cell stack adapted to produce heat in response to a fuel flow;

a power conditioning unit coupled to the fuel cell stack and adapted to use electrical energy produced by the fuel cell stack to furnish electrical power that is received by a power grid; and

a circuit adapted to;

interact with the fuel cell system to produce an amount of heat,

determine at least one cell voltage of a fuel cell of the fuel cell stack,

interact with the power conditioning unit to regulate the amount of the electrical power being furnished by the power conditioning unit based on the voltage of the at least one cell.

8. The fuel cell system of claim 7, wherein the circuit comprises:

a voltage monitoring circuit to scan the cell voltages.

9. The fuel cell system of claim 7, wherein the voltage monitoring circuit continually scans the cell voltages.

10. The fuel cell system of claim 7, wherein the circuit comprises:

a controller adapted to receive a signal indicative of the heat.

11. The fuel cell system of claim 7, wherein the said at least one voltage may be associated with different fuel cells of the fuel cell stack during the regulation by the circuit.

12. The fuel cell system of claim 7, wherein the circuit interacts with the power conditioning unit to regulate the transfer of power by regulating an output voltage of the power conditioning unit.

13. The fuel cell system of claim 7, wherein the circuit is adapted to prevent cell voltages of the stack from decreasing below a threshold voltage.

14. The fuel cell system of claim 7, wherein the circuit is adapted to prevent said at least one voltage from decreasing below a threshold voltage.

15. A fuel cell system comprising:

a fuel cell stack adapted to produce power and heat in response to a fuel flow; and

an apparatus adapted to regulate the fuel flow to control the amount of heat produced by the fuel cell stack based on the lowest cell voltage of the fuel cell stack.

16. The fuel cell system of claim 15, wherein the apparatus is adapted to scan cells of the fuel cell stack to locate the cell having said lowest cell voltage.

17. The fuel cell system of claim 15, wherein the apparatus comprises:

a voltage monitoring circuit to scan voltages of cells of the fuel cell stack.

18. The fuel cell system of claim 17, wherein the voltage monitoring circuit is adapted to continually scan the voltages of the cells.

19. The fuel cell system of claim 15, wherein the apparatus comprises:

a controller adapted to receive a signal indicative of a heat.

20. The fuel cell system of claim 15, wherein the apparatus is adapted to prevent the voltages of cells of the stack from decreasing below a threshold voltage.

21. A method comprising:

regulating a fuel cell system to produce an amount of heat, the fuel cell system producing electrical energy;

scanning at least one cell voltage of the fuel cell system;

comparing the at least one cell voltage to a threshold voltage; and

transferring the electrical energy from the fuel cell system to a power grid when the at least one cell voltage is greater than the threshold voltage.