Fuel cell power systems and methods of operating fuel cell power systems

• US 6,858,335 B2
• Filed: 11/14/2001
• Issued: 02/22/2005
• Est. Priority Date: 11/14/2001
• Status: Active Grant

• Current Assignee: Emergent Power Inc. (Plug Power Inc.)
• Original Assignee: Relion Incorporated (Plug Power Inc.)
• Inventors: Schmidt, Timothy J., DeVries, Peter D., Dodge, Jonathan
• Primary Examiner(s): Crepeau, Jonathan
• Application Number:
  US09/987,225
• Publication Number:
  US 20030091882A1
• Time in Patent Office: 1,196 Days
• Field of Search: 429/13, 429/23
• US Class Current: 429/430
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04544 Voltage
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04574 Current
• CPC Class Codes: H01M 8/04597 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04873 of the individual fuel cell
• 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 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/249 comprising two or more groupings of fuel cells, e.g. modular assemblies
• 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: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 90/40 Fuel cell technologies in production processes

Abstract

Fuel cell power systems and methods of operating fuel cell power systems are described. According to one aspect, a fuel cell power system includes a fuel cell configured to generate electrical energy; switch mode power conditioning circuitry configured to electrically condition the electrical energy generated by the fuel cell, wherein the switch mode power conditioning circuitry comprises a controller configured to monitor an electrical status of the fuel cell and to adjust the conditioning of the electrical energy using the switch mode power conditioning circuitry responsive to the monitoring, wherein the controller is configured to provide a pulse width modulated control signal to control the switching of the switch mode power conditioning circuitry and to vary a duty cycle of the control signal to adjust the conditioning of the electrical energy using the switch mode power conditioning circuitry.

Claims

1. A fuel cell power system comprising:

a plurality of fuel cells configured to generate electrical energy;

a plurality of switch mode power conditioning circuits configured to electrically condition the electrical energy generated by the fuel cells, and wherein the plurality of switch mode power conditioning circuits are associated with the individual fuel cells; and

a controller which generates a control signal, and which monitors an electrical status of the respective fuel cells, and further which adjusts the conditioning of the electrical energy generated by the respective fuel cell using the individual switch mode power conditioning circuits responsive to such monitoring, and wherein the controller includes sequencing circuits which applies the control signal from the controller to the respective switch mode power conditioning circuits at different moments in time.

2. A fuel cell power system comprising:

a plurality of fuel cells configured to generate electrical energy;

a plurality of switch mode power conditioning circuits each comprising a switch, and an electrical energy storage device and which are configured to electrically condition the electrical energy generated by the respective fuel cells, and wherein the plurality of switch mode power conditioning circuits are associated with the respective fuel cells;

a battery having a voltage and which is electrically coupled with each of the switch mode power conditioning circuits, and which further stores the electrical energy generated by the respective fuel cells; and

a controller which monitors the voltage of the battery, and which further provides a pulse width modulated control signal having a duty cycle and which controls the switching of the respective switch mode power conditioning circuits, and wherein the controller varies the duty cycle of the pulse width modulated control signal to adjust the conditioning of the electrical energy generated by the respective fuel cells using the respective switch mode power conditioning circuits in response to the monitoring to substantially maintain the voltage of the battery within a defined range; and

sequencing circuitry which applies the pulse width modulated control signal to the respective switch mode power conditioning circuits at different moments in time.

3. A fuel cell power system comprising:

a plurality of fuel cells;

a plurality of switch mode power conditioning circuits which each include an energy storage device and a switch, and wherein each of the switch mode power conditioning circuits are configured to electrically condition electrical energy which is generated by the respective fuel cells; and

a controller which provides a plurality of pulse width modulated control signals having a duty cycle to the respective switch mode power conditioning circuits to control the respective switches;

monitors an electrical status of the respective fuel cells; and

which varies the duty cycles of the pulse width modulated control signals, and wherein the controller adjusts the conditioning of the electrical energy generated by the respective fuel cells by utilizing the respective switch mode power conditioning circuits in response to the monitoring, and wherein the controller further includes a sequencing circuit electrically coupled with the respective switch mode power conditioning circuits and which receives at least one of the pulse width modulated control signals, and which applies a first of the pulse width modulated control signals to a first of the switch mode power conditioning circuits at a first moment in time, and applies a second of the pulse width modulated control signals to a second one of the switch mode power conditioning circuits at a second moment in time, which is after the first moment in time.

4. A fuel cell power system comprising:

a plurality of fuel cells;

a plurality of switch mode power conditioning circuits each including an energy storage device, and a switch, and wherein the respective switch mode power conditioning circuits electrically condition electrical energy which is generated by the respective fuel cells; and

a controller which provides a plurality of pulse width modulated control signals which have a duty cycle to the respective switch mode power conditioning circuits to control the respective switches, and wherein the controller further monitors an electrical status of the respective fuel cells, and varies the duty cycle of the pulse width modulated control signals to adjust the conditioning of the electrical energy in response to the monitoring, and wherein the controller applies the pulse width modulated control signals to the respective switch mode power conditioning circuits at different moments in time during a switching period.

5. A method of operating a fuel cell power system comprising:

generating electrical energy using a plurality of fuel cells;

conditioning the electrical energy using a plurality of switch mode power conditioning circuits individually associated with respective ones of the fuel cells, and wherein the switch mode power conditioning circuits each comprise a switch, and an electrical energy storace device;

providing a pulse width modulated control signal to control the respective switches;

monitoring an electrical status of the respective fuel cells; and

adjusting the condition of the electrical energy generated by the respective fuel cells in response to the monitoring, and wherein the adjusting comprises varying a duty cycle of the pulse width modulated control signal, and applying the pulse width modulated control signal to the respective switch mode power conditioning circuits at different moments in time.

6. A method of operating a fuel cell power system comprising:

generating electrical energy using a plurality of fuel cells;

conditioning the electrical energy by using a switch mode power conditioning circuitry comprising a plurality of switch mode power conditioning circuits associated with the respective fuel cells, and wherein each of the switch mode power conditioning circuits comprises a switch and an electrical energy storage device configured to electrically condition the generated electrical energy;

controlling the respective switches by using a pulse width modulated control signal;

storing the electrical energy generated within a battery;

monitoring a voltage of the battery;

adjusting the conditioning of the electrical energy by using the plurality of switch mode power conditioning circuits in response to the monitoring of the voltage of the battery, and wherein the adjusting further comprises increasing a duty cycle of the pulse width modulated control signal in response to the voltage of the battery being below a first threshold, and decreasing the duty cycle of the pulse width modulated control signal in response to the voltage of the battery being above a second threshold;

providing electrical energy from the respective switch mode power conditioning circuits to a load; and

applying the pulse width modulated control signal to the switch mode power conditioning circuits at different moments in time to control the respective switches of each of the switch mode power conditioning circuits.

7. A method of operating a fuel cell power system comprising:

generating electrical energy using a plurality of fuel cells;

conditioning the electrical energy of the fuel cells using a plurality of switch mode power conditioning circuits individually including an electrical energy storage device and a switch; and

providing a plurality of control signals to the switch mode power conditioning circuits during a switching period to control the respective switches, wherein the providing the control signals comprises applying the control signals to the switch mode power conditioning circuits at different moments in time during the switching period.

8. The method of claim 7 wherein the providing comprises providing a common signal and sequencing the common signal to provide the plurality of control signals.

9. The method of claim 7 wherein the providing comprises providing the control signals comprising a plurality of different control signals, and sequencing the different control signals.

10. The method of claim 7 wherein the conditioning electrical energy comprises conditioning electrical energy of the fuel cells using the switch mode power conditioning circuits associated with respective ones of the fuel cells.

11. The method of claim 7 further comprising:

monitoring an electrical status of the fuel cells; and

adjusting the control signals responsive to the monitoring.

12. The method of claim 11 wherein the providing comprises providing the control signals comprising pulse width modulated control signals and the adjusting comprises adjusting duty cycles of the control signals.

13. The method of claim 11 wherein the monitoring comprises monitoring the electrical status comprising individual voltages of the fuel cells, and the adjusting comprises reducing a duty cycle of one of the control signals responsive to the voltage of the respective fuel cell being outside a predetermined range.

14. The method of claim 11 wherein the monitoring comprises monitoring the electrical status comprising individual voltages of the fuel cells, and the adjusting comprises reducing duty cycles of the control signals responsive to the voltages of the respective fuel cells being below a threshold.

15. The method of claim 7 further comprising:

providing electrical energy to a battery coupled with the switch mode power conditioning circuits;

monitoring an electrical status of the battery; and

adjusting the control signals responsive to the monitoring to maintain the electrical status of the battery within a range.