OPEN-LOOP SYSTEM AND METHOD FOR FUEL CELL STACK START-UP WITH LOW-VOLTAGE SOURCE

• US 20090081502A1
• Filed: 09/24/2007
• Published: 03/26/2009
• Est. Priority Date: 09/24/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Whitehouse, Kristian M., ALP, ABDULLAH B., Hortop, Matthew K., Chowdhury, Akbar, Kirklin, Matthew C.
• Granted Patent: US 9,005,785 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• 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 2250/402 Combination of fuel cell with other electric generators
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04104 Regulation of differential pressures
• CPC Class Codes: H01M 8/04111 using a compressor turbine assembly
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04231 Purging of the reactants
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04544 Voltage
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04746 Pressure; Flow
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04805 of fuel cell exhausts
• CPC Class Codes: H01M 8/04888 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04992 characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• 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

Abstract

A fuel cell system is provided that includes a fuel cell stack and an air compressor in communication with a cathode inlet, a hydrogen source in communication with an anode inlet, and a start-up battery adapted to power the air compressor. The start-up battery is at least one of a low-voltage battery and a high-voltage battery. A power conversion module is in electrical communication with the start-up battery and the air compressor. The power conversion module is adapted to boost a voltage of the start-up battery as desired and power the air compressor at start-up. A controller is in communication with the power conversion module and is adapted to set an air compressor speed based on an available electrical energy. An open-loop method of operating the fuel cell system at start-up is also provided, wherein an anode purge is scheduled based on the available electrical energy from the battery.

Claims

1. A fuel cell system comprising:

a fuel cell stack including a plurality of fuel cells and having an anode inlet and a cathode inlet;

an air compressor in fluid communication with the cathode inlet;

a hydrogen source in fluid communication with the anode inlet;

a start-up battery in electrical communication with the air compressor;

a power conversion module in electrical communication with the start-up battery and the air compressor, the power conversion module adapted to selectively boost a voltage of the start-up battery supplied to the air compressor; and

a controller in electrical communication with the power conversion module adapted to set an air compressor speed based on an electrical energy available at the compressor.

2. The fuel cell system of claim 1, wherein the start-up battery includes at least one of a low-voltage battery and a high-voltage battery.

3. The fuel cell system of claim 2, wherein the high-voltage battery is a hybrid battery.

4. The fuel cell system of claim 1, further comprising a voltage sensor adapted to measure a voltage of the start-up battery.

5. The fuel cell system of claim 1, further comprising a bypass valve disposed between the air compressor and the cathode inlet, the bypass valve adapted to selectively bypass an air flow around the fuel cell stack to an exhaust.

6. The fuel cell system of claim 1, further comprising a regulator valve disposed between the hydrogen source and the fuel cell stack, the regulator valve adapted to selectively supply an anode purge to the fuel cell stack.

7. The fuel cell system of claim 1, further comprising at least one speed sensor adapted to measure a rotational speed of the air compressor.

8. The fuel cell system of claim 1, wherein the controller is adapted to schedule an anode purge based on the available electrical energy in the start-up battery.

9. A method for starting a fuel cell stack with a low-voltage battery, comprising the steps of:

receiving a start request;

providing a power conversion module to boost the voltage of the low-voltage battery;

determining an available electrical energy from the low-voltage battery;

determining an estimated speed of the air compressor based on the available electrical energy;

starting an air compressor;

measuring an actual speed of the air compressor; and

scheduling an anode purge based on the available electrical energy when one of a) the actual speed is greater than a desired speed, and b) a compressor ramp-up time has elapsed.

10. The method of claim 9, further comprising the step of bypassing air from the air compressor around the fuel cell stack to an exhaust.

11. The method of claim 9, wherein the step of determining the available electrical energy includes calculating the available electrical energy from a measured voltage of the low-voltage battery.

12. The method of claim 9, wherein the desired speed is calculated from the estimated speed.

13. The method of claim 12, wherein the desired speed is the estimated speed minus a delta speed.

14. The method of claim 12, wherein the desired speed is a percentage of the estimated speed.

15. The method of claim 9, wherein the step of scheduling the anode purge includes at least one of:

a) setting a time for the anode purge; and

b) setting a flow rate for the anode purge.

16. The method of claim 15, wherein the anode purge flow rate is calculated from a look-up table based on the available electrical energy.

17. The method of claim 15, wherein the anode purge flow rate is optimized to maintain an exhausted hydrogen concentration of less than about four percent by volume.

18. A method for starting a fuel cell stack with one of a low-voltage battery and a high-voltage battery, comprising the steps of:

receiving a start request;

determining an available electrical energy from at least one of a) the low-voltage battery with a voltage boost, b) the high-voltage battery with a voltage boost, and c) the high-voltage battery without a voltage boost;

selecting a start-up battery from one of the low-voltage battery and the high-voltage battery;

providing a power conversion module to boost the voltage of the start-up battery, if the available electrical energy is less than a start-up energy range;

determining an estimated speed of the air compressor based on the available electrical energy;

starting an air compressor, wherein the air compressor is set to the estimated speed;

measuring an actual speed of the air compressor; and

scheduling an anode purge based on the available electrical energy when one of a) the actual speed is greater than a desired speed, and b) a compressor ramp-up time has elapsed.

19. The method of claim 18, wherein the start-up battery is selected from one of:

a) the low-voltage battery if the available electrical energy from the low-voltage battery is greater than the available electrical energy from the high-voltage battery;

b) the high-voltage battery if the available electrical energy from the low-voltage battery is less than the available electrical energy from the high-voltage battery; and

c) the high-voltage battery without the voltage boost if the available electrical energy from the high-voltage battery without the voltage boost is within a desired start-up energy range.

20. The method of claim 18, wherein the start-up energy range is a power greater than about 1.5 kW.