Apparatus and method for high efficiency operation of fuel cell systems

• US 9,148,085 B2
• Filed: 07/09/2013
• Issued: 09/29/2015
• Est. Priority Date: 12/02/2008
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: King, Robert Dean, Richter, Timothy Gerard
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): USYATINSKY, ALEXANDER
• Application Number:
  US13/937,643
• Publication Number:
  US 20130293175A1
• Time in Patent Office: 812 Days
• Field of Search: 429/400, 429/428, 429/432
• US Class Current: 1/1
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: H01M 16/003 of fuel cells with other electrochemical devices, e.g. capacitors, electrolysers
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/18 Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02P 90/40 Fuel cell technologies in production processes
• 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
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A drive circuit comprising a DC bus configured to supply power to a load, a first fuel cell coupled to the DC bus and configured to provide a first power output to the DC bus, and a second fuel cell coupled to the DC bus and configured to provide a second power output to the DC bus supplemental to the first fuel cell. The drive circuit further includes an energy storage device coupled to the DC bus and configured to receive energy from the DC bus when a combined output of the first and second fuel cells is greater than a power demand from a load, and provide energy to the DC bus when the combined output of the first and second fuel cells is less than the power demand from the load.

Claims

1. A drive circuit comprising:

a DC bus;

a voltage converter assembly coupled to the DC bus;

a first fuel cell coupled to the voltage converter assembly;

a second fuel cell coupled to the voltage converter assembly; and

a controller programmed to;

operate the first fuel cell to deliver a first power output to the voltage converter assembly during a first mode of operation and deliver a second power output to the voltage converter assembly during a second mode of operation, the second power output different from the first power output; and

operate the second fuel cell to deliver a third power output to the voltage converter assembly during the first and second modes of operation.

2. The drive circuit of claim 1 wherein the first and second power outputs are greater than zero.

3. The drive circuit of claim 1 wherein the controller is further programmed to:

control the first fuel cell to supply the first output power at a non-varying rate; and

simultaneously control the second fuel cell to supply the third output power at a varying rate.

4. The drive circuit of claim 3 wherein the controller is further programmed to implement an on/off sequencing of the second fuel cell to cause the second fuel cell to supply the third output power at the varying rate.

5. The drive circuit of claim 1 further comprising an energy storage device coupled to the DC bus via the voltage converter assembly;

and

wherein the controller is further programmed to control the energy storage device to deliver a supplemental output power to the voltage converter assembly.

6. The drive circuit of claim 5 wherein the energy storage device comprises one of a battery, an ultracapacitor, and a flywheel.

7. The drive circuit of claim 1 wherein the first and second fuel cells comprise regenerative fuel cells.

8. The drive circuit of claim 1 wherein the first fuel cell has a first power rating;

and

wherein the second fuel cell has a second power rating, lower than the first power rating.

9. The drive circuit of claim 1 wherein the voltage converter assembly comprises a plurality of bi-directional buck/boost converters.

10. A method of operating a fuel cell propulsion system comprising:

operating a controller programmed to cause a first fuel cell to deliver a first output to a DC-to-DC converter assembly during a first mode of operation;

operating a controller programmed to cause the second fuel cell to deliver a second output to the DC-to-DC converter assembly during the first mode of operation;

operating a controller programmed to cause the first fuel cell to deliver the second output to the DC-to-DC converter assembly during a second mode of operation;

operating a controller programmed to cause the second fuel cell to deliver the first output to the DC-to-DC converter assembly during the second mode of operation; and

operating a controller programmed to cause the DC-to-DC converter assembly to boost the first and second outputs and supply the boosted outputs to a DC link.

11. The method of claim 10 further comprising:

operating a controller programmed to cause the first fuel cell to deliver a non-varying output to the DC-to-DC converter assembly during the first mode of operation; and

operating a controller programmed to cause the second fuel cell to deliver a varying output to the DC-to-DC converter assembly during the first mode of operation.

12. The method of claim 11 further comprising operating a controller to sequence the second fuel cell between an on condition and an off condition during the first mode of operation.

13. The method of claim 10 further comprising operating a controller programmed to cause the DC-to-DC converter assembly to permit recharging of the first and second fuel cells during a third mode of operation.

14. The method of claim 10 further comprising operating a controller programmed to cause an energy storage device to deliver a third output to the DC-to-DC converter assembly during the first mode of operation.

15. The method of claim 10 further comprising:

operating a controller programmed to cause the first fuel cell to deliver a first output to the DC-to-DC converter assembly during a first mode of operation; and

operating a controller programmed to cause the second fuel cell to deliver a second output to the DC-to-DC converter assembly during the first mode of operation, the second output different than the first output.

16. A fuel cell propulsion system comprising:

a vehicle traction motor;

a DC bus coupled to the vehicle traction motor via an inverter;

a DC-to-DC converter assembly coupled to the DC bus;

a first fuel cell coupled to the DC bus via the DC-to-DC converter assembly;

a second fuel cell coupled to the DC bus via the DC-to-DC converter assembly; and

a controller programmed to;

operate the first fuel cell to deliver a first power output to the DC-to-DC converter assembly during a high-power-demand operating mode; and

operate the second fuel cell to deliver a second power output to the DC-to-DC converter assembly during a low-power-demand operating mode.

17. The fuel cell propulsion system of claim 16 wherein the controller is further programmed to:

during a first mode of operation, simultaneously operate the first fuel cell to deliver the first power output and operate the second fuel cell to deliver the second power output; and

during a second mode of operation, simultaneously operate the first fuel cell to deliver the second power output and operate the second fuel cell to deliver the first power output.

18. The fuel cell propulsion system of claim 17 wherein the first and second power outputs are greater than zero.

19. The fuel cell propulsion system of claim 16 further comprising an energy storage unit coupled to the DC-to-DC converter assembly;

and

wherein the controller is further programmed to operate the energy storage unit to supply a power output equal to a difference between a requested operating power of the vehicle traction motor and a combined power output of the first and second fuel cells.

20. The fuel cell propulsion system of claim 16 wherein the controller is further programmed to:

operate the first fuel cell to provide a variable power output; and

operate the second fuel cell to provide a non-variable power output.

21. The fuel cell propulsion system of claim 16 wherein the first and second fuel cells comprise regenerative fuel cells.