Method and apparatus for starting a fuel cell engine in a vehicle equipped with an ultracapacitor

• US 7,862,943 B2
• Filed: 08/01/2008
• Issued: 01/04/2011
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Ikeya, Kengo, Izawa, Kazuyuki, Keyes, David John, Hortop, Matthew K., Greifenstein, Ellen
• Primary Examiner(s): Crepeau; Jonathan
• Assistant Examiner(s): DOUYETTE, KENNETH J
• Application Number:
  US12/184,766
• Publication Number:
  US 20100028727A1
• Time in Patent Office: 886 Days
• Field of Search: 429/12, 429/13, 429/22, 429/9, 429/429, 429/432, 180/65.2
• US Class Current: 429/429
• CPC Class Codes: B60K 6/32 characterised by the fuel cells
• CPC Class Codes: B60W 10/28 including control of fuel cells
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60Y 2400/112 Batteries
• CPC Class Codes: B60Y 2400/114 Super-capacities
• CPC Class Codes: H01M 16/003 of fuel cells with other electrochemical devices, e.g. capacitors, electrolysers
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A hybrid fuel cell system that employs a fuel cell stack and an ultracapacitor. A diode is provided on a high voltage electrical bus between the fuel cell stack and the ultracapacitor so that high voltage from the ultracapacitor does not affect the operation of the fuel cell stack. During system start-up, a by-pass switch is closed to by-pass the ultracapacitor so that power from the ultracapacitor can be used to start various system loads, such as a cathode side air compressor that provides air to the fuel cell stack. A 12 volt-to-high voltage converter is employed to provide a low power, high voltage supply from a low voltage battery to the system loads at start-up when the by-pass switch is opened, but before a fuel cell stack switch is closed.

Claims

1. A method for starting a hybrid fuel cell system, said method comprising:

providing a high voltage electrical bus;

providing a fuel cell stack electrically coupled to the high voltage electrical bus;

providing a high voltage DC power storage device electrically coupled to the high voltage electrical bus;

providing a diode in the high voltage electrical bus that prevents voltage from the high voltage storage device from accessing the fuel cell stack;

providing a by-pass line around the diode;

providing a fuel cell stack switch between the fuel cell stack and the high voltage electrical bus;

electrically coupling system loads to the high voltage electrical bus;

electrically coupling a low voltage to high voltage boost converter to the high voltage electrical bus;

closing a by-pass switch in the by-pass line so that electrical power from the high voltage DC storage device goes around the diode and is able to operate the system loads;

starting the fuel cell stack using the system loads;

determining if an output voltage of the fuel cell stack is stable;

opening the by-pass switch if the fuel cell stack voltage is stable; and

closing the fuel cell stack switch after the by-pass switch is opened.

2. The method according to claim 1 wherein providing a high voltage DC storage device includes providing an ultracapacitor.

3. The method according to claim 1 wherein operating the system loads includes operating an air compressor motor that provides power to an air compressor that drives air to the fuel cell stack.

4. The method according to claim 1 further comprising turning on the boost converter before opening the by-pass switch so as to allow the boost converter to be ready to provide power to the system loads when the by-pass switch is opened and the stack switch is closed.

5. The method according to claim 1 wherein electrically coupling system loads to the high voltage electrical bus includes electrically coupling an electric traction motor to the high voltage electrical bus.

6. The method according to claim 5 wherein the electric traction motor propels a vehicle.

7. The method according to claim 1 further comprising turning off the boost converter after the stack switch is opened.

8. The method according to claim 1 further comprising electrically coupling a 12 volt battery to the low voltage to high voltage boost converter to provide the low voltage.

9. A method for starting a hybrid fuel cell system, said method comprising;

electrically disconnecting a fuel cell stack from a high voltage electrical bus;

providing electrical power from a high voltage DC power storage device to a compressor motor on the high voltage electrical bus through a by-pass switch that by passes a diode in the electrical bus, said compressor motor driving a compressor that provides air to a cathode side of the fuel cell stack;

opening the by-pass switch after the stack voltage becomes stable;

closing a fuel cell stack switch to connect the fuel cell stack to the high voltage electrical bus after the by-pass switch is opened; and

providing electric power to the compressor motor from a low voltage to high voltage boost converter during the time that the by-pass switch is opened, but before the fuel cell stack switch is closed.

10. The method according to claim 9 wherein the high voltage DC storage device is an ultracapacitor.

11. The method according to claim 9 further comprising turning on the boost converter before opening the by-pass switch so as to allow the boost converter to be ready to provide power to system loads when the by-pass switch is opened and the stack switch is closed.

12. The method according to claim 9 further comprising electrically coupling a 12 volt battery to the low voltage to high voltage boost converter to provide the low voltage.

13. A fuel cell system comprising:

a high voltage electrical bus;

a compressor motor electrically coupled to the high voltage electrical bus;

a fuel cell stack electrically coupled to the high voltage electrical bus;

a fuel cell stack switch for selectively connecting and disconnecting the fuel cell stack to the high voltage electrical bus;

a high voltage DC power storage device electrically coupled to the high voltage electrical bus;

a diode in the high voltage electrical bus that prevents voltage from the high voltage storage device from accessing the fuel cell stack;

a by-pass line around the diode;

a by-switch in the by-pass line; and

a low voltage to high voltage boost converter electrically coupled to the high voltage electrical bus, said boost converter providing power to the compressor motor during system start-up after the by-pass switch is opened, but before the fuel cell stack switch is closed.

14. The system according to claim 13 wherein the high voltage DC storage device is an ultracapacitor.

15. The system according to claim 13 wherein the boost converter is turned on before opening the by-pass switch so as to allow the boost converter to be ready to provide power to system loads when the by-pass switch is opened and the stack switch is closed.

16. The system according to claim 13 further comprising a 12 volt battery electrically coupled to the low voltage to high voltage boost converter.

17. The system according to claim 13 further comprising an electric traction motor electrically coupled to the high voltage electrical bus.