Direct current/direct current converter for a fuel cell system

• US 20060099463A1
• Filed: 12/23/2005
• Published: 05/11/2006
• Est. Priority Date: 01/16/2002
• Status: Abandoned Application

• Current Assignee: Continental Automotive Systems US Incorporated (Continental AG)
• Original Assignee: Continental Automotive Systems US Incorporated (Continental AG)
• Inventors: Kambouris, Christos A., Bates, John T.
• Application Number:
  US11/318,166
• Publication Number:
  US 20060099463A1
• Time in Patent Office: Days
• US Class Current: 429/7
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/04888 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: H01M 8/04917 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Fuel cell systems and control methods including a fuel cell and a second energy source, such as a battery that is adapted to supplement the fuel cell. In addition, the fuel cell system utilizes a single bipolar switching module, such as an IGBT six pack module that is configured to implement a DC/DC converter, such as a DC/DC boost converter, for both the fuel cell and the battery. The fuel cell system also makes use of a controller that is configured to control either or both of input current and output voltage of the DC/DC converter.

Claims

1. A fuel cell system, comprising:

a fuel cell;

a second energy source configured to supplement the fuel cell;

a single bipolar switching module configured to implement a direct current to direct current (DC/DC) converter for both the fuel cell and the second energy source; and

a controller configured to control at least one of an input current and an output voltage of the DC/DC converter.

2. The system of claim 1 wherein the second energy source comprises a battery.

3. The system of claim 2 wherein the battery is adapted to deliver power to a load when an amount of power available from the fuel cell is less than a power demand of the load.

4. The system of claim 2 wherein the battery is adapted to supply a power demand of a load when the fuel cell is not operating.

5. The system of claim 2 wherein the battery is adapted to absorb power from the fuel cell when an amount of power available from the fuel cell is greater than a power demand of the load.

6. The system of claim 2 wherein the single bipolar switching module comprises an IGBT six pack module.

7. The system of claim 6 wherein the IGBT six pack module is further configured to be used as a component of a back end inverter.

8. The system of claim 2 wherein the controller is configured to control at least one of the input current and the output voltage of the DC/DC converter by controlling a flow of power to and from the battery to maintain an average state of charge of the battery whereby the battery can deliver a predetermined level of power in a first mode and absorb a predetermined level of power in a second mode.

9. The system of claim 1 wherein the single bipolar switching module is configured to implement a DC/DC boost converter.

10. The system of claim 9 wherein the DC/DC boost converter is adapted to boost a DC voltage from both the fuel cell and the second energy source to a DC bus capacitor bank and a load.

11. A method of controlling a fuel cell system comprising a fuel cell, a second energy source, a bipolar switching module and a controller, the method comprising:

operating the bipolar switching module as a direct current to direct current (DC/DC) converter for both the fuel cell and the second energy source; and

,

using the controller to control at least one of an input current and an output voltage of the DC/DC converter.

12. The method of claim 11 wherein the second energy source comprises a battery.

13. The method of claim 12 wherein the method further comprises delivering power from both the battery and the fuel cell to a load when an amount of power available from the fuel cell is less than a power demand of the load.

14. The method of claim 12 wherein the method further comprises delivering power from the battery to a load when the fuel cell is not operating.

15. The method of claim 12 wherein the method further comprises absorbing an excess amount of power from the fuel cell with the battery when an amount of power available from the fuel cell is greater than a power demand of the load.

16. The method of claim 12 wherein the single bipolar switching module comprises an IGBT six pack module.

17. The method of claim 16 wherein the method further comprises operating the IGBT six pack module as a component of a back end inverter.

18. The method of claim 16 wherein method further comprises operating the IGBT six pack module to boost a DC voltage from the fuel cell and the battery to a DC bus capacitor bank and a load.

21. The method of claim 11 wherein the single bipolar switching module is configured to implement a DC/DC boost converter.

22. The method of claim 21 wherein the DC/DC boost converter is adapted to boost a DC voltage from both the fuel cell and the second energy source to a DC bus capacitor bank and a load.

19. The method of claim 19 wherein the method further comprises operating the controller to control the input current and the output voltage of the DC/DC converter.

20. The method of claim 19 wherein operating the controller to control the input current and the output voltage of the DC/DC converter comprises controlling a flow of power to and from the battery so as to maintain an average state of charge of the battery whereby the battery can deliver a predetermined level of power in a first mode and absorb a predetermined level of power in a second mode.

23. A controller programmed to control a fuel cell system comprising a fuel cell, a battery, and an IGBT six pack module comprising three IGBT legs and configured to implement a DC/DC converter for both the fuel cell and the battery, by:

in a first mode, providing DC/DC conversion for the fuel cell via two of the three IGBT legs and bi-directional DC/DC conversion for the battery via the third IGBT leg;

in a second mode, providing DC/DC conversion for the battery via two of the three IGBT legs and DC/DC conversion for the fuel cell via the third IGBT leg;

in a third mode, providing DC/DC conversion for the fuel cell via all three IGBT legs; and

,

in a fourth mode, providing DC/DC conversion for the battery via all three IGBT legs.

24. A fuel cell system, comprising:

a fuel cell;

a battery;

a direct current to direct current (DC/DC) converter module coupled to the battery and the fuel cell, that converts a first DC voltage from the fuel cell to a DC output voltage and that converts a second DC voltage from the battery to the DC output voltage; and

a controller configured to control at least one of an input current and an output voltage of the DC/DC converter.

25. The system of claim 25 wherein the DC/DC converter module is a single bipolar switching module.

26. The system of claim 25, further comprising:

a switch, comprising;

a first position that couples the fuel cell and the DC/DC converter module; and

a second position that couples the battery and the DC/DC converter module.

27. The system of claim 26 wherein the switch in the first position couples the fuel cell and the DC/DC converter module so that power from the fuel cell is converted by the DC/DC converter module.

28. The system of claim 26 wherein the switch in the second position decouples the fuel cell from the DC/DC converter module and further couples the battery and the DC/DC converter module so that only power from the battery is converted by the DC/DC converter module.

29. The system of claim 28 wherein the switch in the second position couples the battery to a first leg and to a second leg of the DC/DC converter module.

30. The system of claim 29 wherein the battery is coupled to a third leg of the DC/DC converter module.

31. The system of claim 25 wherein the controller controls operation of the DC/DC converter module so that a first input current from the fuel cell is controlled to correspond to a first portion of a total power delivered from the DC/DC converter module, and wherein the controller controls operation of the DC/DC converter module so that a second input current from the battery is controlled to correspond to a second portion of the total power delivered from the DC/DC converter module.

32. The system of claim 31 wherein the controller controls operation of the DC/DC converter module so that the second input current from the battery is controlled, and so that the first input current from the fuel cell is maintained when the total power delivered from the DC/DC converter module varies.

33. The system of claim 32 wherein the maintained first input current from the fuel cell further maintains the first DC voltage from the fuel cell.