Method and apparatus for controlling a fuel cell system

• US 20030235730A1
• Filed: 06/24/2002
• Published: 12/25/2003
• Est. Priority Date: 06/24/2002
• Status: Active Grant

• Current Assignee: United States Department of Energy
• Original Assignee: United States Department of Energy
• Inventors: Rajashekara, Kaushik, Noetzel, John G., Haltiner, Karl J. Jr.
• Granted Patent: US 6,989,211 B2
• Time in Patent Office: Days
• US Class Current: 429/431
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/34 by heating
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells
• CPC Class Codes: Y10S 429/90 Fuel cell including means for power conditioning, e.g. Conversion to ac

Abstract

A method of operating a fuel cell includes the step of selectively connecting and disconnecting the fuel cell to at least one electrical load dependent at least in part upon at least one of a fuel cell voltage, a fuel cell current and a fuel cell temperature.

Claims

1. A fuel cell system, comprising:

a fuel cell unit having a fuel cell stack, said fuel cell unit producing a fuel cell voltage and a fuel cell current;

a power conditioner electrically connected to said fuel cell unit, said power conditioner including a power switching device, said power switching device selectively connecting and disconnecting said fuel cell voltage to at least one load dependent at least in part upon at least one of an operating temperature of said fuel cell stack, said fuel cell voltage, and said fuel cell current to thereby produce an output voltage.

2. The fuel cell system of claim 1, wherein said power conditioner further comprises a mode controller, said mode controller electrically connected to and receiving said fuel cell current, said fuel cell voltage and said output voltage, said mode controller issuing a mode signal dependent at least in part upon said fuel cell current, said fuel cell voltage and said output voltage.

3. The fuel cell system of claim 2, wherein said power conditioner further comprises control logic, said control logic electrically connected to said mode controller and receiving said mode signal, said control logic decoding and issuing a control signal dependent at least in part upon said mode signal.

4. The fuel cell system of claim 3, wherein said power conditioner further comprises drive circuitry, said drive circuitry electrically connected to said control logic and receiving said control signal, said drive circuitry electrically connected to said power conditioner and issuing thereto a drive signal dependent at least in part upon said control signal.

5. The fuel cell system of claim 4, wherein said power switching device comprises one of an integrated gate bipolar transistor and a power metal oxide semiconductor field effect transistor, said power switching device having at least one control terminal electrically connected to and receiving said drive signal.

6. The fuel cell system of claim 1, wherein said power switching device comprises one of an integrated gate bipolar transistor and a power metal oxide semiconductor field effect transistor.

7. A power conditioner for use with a fuel cell, said fuel cell generating a fuel cell voltage and a fuel cell current, said power conditioner comprising:

at least one power switching device, said power switching device configured for selectively connecting and disconnecting said fuel cell voltage to at least one load dependent at least in part upon at least one of an operating temperature of said fuel cell stack, said fuel cell voltage, and said fuel cell current to thereby produce an output voltage.

8. The power conditioner of claim 7, wherein said power conditioner further comprises a mode controller, said mode controller electrically connected to and receiving said fuel cell current, said fuel cell voltage and said output voltage, said mode controller issuing a mode signal dependent at least in part upon said fuel cell current, said fuel cell voltage and said output voltage.

9. The fuel cell system of claim 8, wherein said power conditioner further comprises control logic, said control logic electrically connected to said mode controller and receiving said mode signal, said control logic decoding and issuing a control signal dependent at least in part upon said mode signal.

10. The fuel cell system of claim 9, wherein said power conditioner further comprises drive circuitry, said drive circuitry electrically connected to said control logic and receiving said control signal, said drive circuitry electrically connected to said power switching device and issuing thereto a drive signal dependent at least in part upon said control signal.

11. The fuel cell system of claim 10, wherein said power switching device comprises one of an integrated gate bipolar transistor and a power metal oxide semiconductor field effect transistor, said power switching device having at least one control terminal electrically connected to and receiving said drive signal.

12. The fuel cell system of claim 7, wherein said power switching device comprises one of an integrated gate bipolar transistor and a power metal oxide semiconductor field effect transistor.

13. A method of operating a fuel cell, said fuel cell generating a fuel cell voltage and a fuel cell current and having a fuel cell temperature, said method comprising the steps of:

selectively connecting and disconnecting the fuel cell to at least one electrical load dependent at least in part upon at least one of said fuel cell voltage, said fuel cell current and said fuel cell temperature.

14. The method of claim 13, wherein said selectively connecting and disconnecting step comprises the steps of:

determining that the fuel cell temperature is equal to or greater than an operating temperature;

comparing the fuel cell voltage to a reference voltage;

biasing a power switching device into a linear mode of operation when the fuel cell temperature has reached the operating temperature and when the difference between the reference voltage and the fuel cell voltage is relatively small; and

biasing the power switching device with a pulse-width modulated signal when the fuel cell temperature has reached the operating temperature and when the difference between the reference voltage and the fuel cell voltage is relatively large.

15. The method of claim 14, comprising the further step of biasing the power switching device into a current-limiting mode when the fuel cell temperature has reached a start-up temperature.

16. The method of claim 15, comprising the further step of biasing the power switching device into a current-blocking mode when the fuel cell temperature is less than the start-up temperature.