FUEL CELL STARTUP METHOD FOR FAST FREEZE STARTUP

• US 20140342258A1
• Filed: 08/04/2014
• Published: 11/20/2014
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Burch, Steven D., Clingerman, Bruce J., Wexel, Dirk, Fasse, Martin, Alp, Abdullah B., Arthur, David A.
• Granted Patent: US 9,728,799 B2
• Time in Patent Office: Days
• US Class Current: 429/429
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 1/02 to electric heating circuits
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 50/72 Constructional details of fuel cells specially adapted for electric vehicles
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60L 58/31 for starting of fuel cells
• CPC Class Codes: B60L 58/34 by heating
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04268 Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04626 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0488 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 8/04992 characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/40 : Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

Claims

1. A method of starting a fuel cell system, the method comprising the steps of:

providing a fuel cell stack, a plurality of startup components, and at least one power source;

starting the plurality of startup components using the at least one power source;

connecting the fuel cell stack to a voltage bus after the fuel cell stack achieves open circuit voltage, wherein the voltage bus provides electrical communication between the fuel cell stack and at least one of the plurality of startup components; and

controlling the fuel cell stack power using a load schedule to maintain a desired fuel cell voltage.

2. The method according to claim 1, wherein the at least one power source comprises a first power source and a second power source.

3. The method according to claim 2, wherein the first power source is a first battery and the second power source is a second battery and the first battery generates a higher voltage than the second battery.

4. The method according to claim 3, wherein the second battery is electrically linked to the voltage bus through a DC/DC boost circuit.

5. The method according to claim 3, wherein the first battery generates a voltage between 200 and 300 volts and the second battery generates a voltage between 0 and 12 volts.

6. The method according to claim 2, further comprising the steps of:

determining a state of charge of the first power source;

starting the plurality of startup components using the first power source if the state of charge of the first power source is determined to be sufficient; and

starting the plurality of startup components using the second power source if the state of charge of the first power source is determined to be insufficient.

7. The method according to claim 6, wherein the starting of the plurality of startup components using the first power source includes applying full power to at least one of the plurality of startup components and the starting of the plurality of startup components using the second power source includes applying less than full power to each of the plurality of startup components and no power to at least one of the startup components.

8. The method according to claim 1, wherein the controlling of the fuel cell stack power includes increasing the power delivered by the fuel cell stack to each of the start-up components and the at least one power source in an order determined by the load schedule until the fuel cell stack reaches a predetermined temperature.

9. The method according to claim 8, wherein the load on the fuel cell stack is reduced by decreasing the power delivered to the start-up components and the at least one power source in a reverse order according to the load schedule when the fuel cell stack goes below one of a desired average cell voltage of the fuel cell stack and a minimum cell voltage of one of the fuel cells included within the fuel cell stack.

10. The method according to claim 9, wherein the power delivered by the fuel cell stack is increased and decreased according to a ramp function.

11. The method according to claim 1, further comprising the step of decreasing power to the at least one of the startup components after the fuel cell stack achieves open circuit voltage and prior to connecting the fuel cell stack to the voltage bus.

12. The method according to claim 1, further comprising the step of opening at least one fuel injector after the fuel cell stack achieves open circuit voltage and prior to connecting to the voltage bus.

13. The method according to claim 1, further comprising the step of controlling the plurality of startup components in electrical communication with the fuel cell stack using local control loops having the ability to override the load schedule.

14. A method of starting a fuel cell system for a vehicle comprising the steps of:

starting the fuel cell system using a battery;

transferring the power providing responsibilities from the battery to the fuel cell stack after the fuel cell stack has achieved open cell voltage;

altering a load on the fuel cell stack based on a voltage of the fuel cell stack;

monitoring a temperature of the fuel cell stack; and

controlling the fuel cell stack power until a target fuel cell stack temperature is achieved.

15. The method according to claim 14, further including the step of increasing the load on a fuel cell stack by ramping up power to a set of loads in electrical communication with the fuel cell stack according to a load schedule when the fuel cell stack voltage is higher than desired.

16. The method according to claim 15, further including the step of decreasing the load on the fuel cell stack by ramping down power to the set of loads according to the reverse order specified in the load schedule when the fuel cell stack voltage is lower than desired.

17. The method according to claim 15, wherein the increasing of the load on the fuel cell stack includes, in operational order, the steps of:

supplying power to at least one load acting as a start-up component for starting the fuel cell system;

supplying power to a propulsion motor of the vehicle, if the vehicle is not idling; and

recharging the battery.

18. The method according to claim 14, wherein the desired fuel cell voltage is at least one of a fuel cell stack average cell voltage of around 0.5 volts and a fuel cell stack minimum cell voltage of around 0.2 volts.

19. The method according to claim 14, wherein the fuel cell stack ceases a start-up operation and begins normal operation when the fuel cell stack reaches a desired temperature.

20. The method according to claim 14, further including the step of determining a charge of the battery prior to the step of starting the fuel cell stack and selecting one of a fast start-up procedure and a slow start-up procedure as a function of the charge of the battery.