FUEL CELL STARTUP METHOD FOR FAST FREEZE STARTUP

• US 20080081224A1
• Filed: 09/29/2006
• Published: 04/03/2008
• 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 Incorporated (General Motors Company)
• Inventors: Clingerman, Bruce J., Arthur, David A., Burch, Steven D., Alp, Abdullah B., Wexel, Dirk, Fasse, Martin
• Granted Patent: US 8,835,065 B2
• Time in Patent Office: Days
• US Class Current: 429/13
• 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:

(a). providing a fuel cell stack, a first power source, at least one startup component;

(b). determining a state of charge of the first power source;

(c). selecting one of at least two startup procedures for starting the at least one startup component as a function of the state of charge of the first power source;

(d). controlling power flow between the fuel cell system and the first power source; and

(e). maintaining a desired fuel cell stack voltage using a load schedule to manage a load on the fuel cell stack.

2. The method according to claim 1, including performing said step (c) by selecting the first power source for starting the startup components if the state of charge of the first power source is sufficient, and selecting a second power source for starting the startup components if the state of charge of the first power source is insufficient.

3. The method according to claim 2, further comprising the step of providing power to a plurality of loads via the first power source.

4. The method according to claim 1, wherein the at least one startup component is an air compressor, a valve heater, or a high temperature coolant pump.

5. The method according to claim 3, wherein the loads include at least one of a fuel cell stack end plate heater, a supplemental startup coolant heater, and a vehicle cabin heater.

6. The method according to claim 1, including performing said step (e) by controlling the fuel cell stack power using the load schedule to attain a fuel cell stack average cell voltage.

7. The method according to claim 1 including performing said step (e) by controlling the fuel cell stack power using the load schedule to attain a fuel cell stack minimum cell voltage.

8. The method according to claim 1, further comprising the step of employing a ramp function as loads are added and removed according to the load schedule.

9. The method according to claim 1, further comprising the step of operating local control loops in parallel with the load schedule.

10. The method according to claim 9, wherein the local control loops have the ability to override the local schedule.

11. The method according to claim 1, further comprising the step of monitoring a temperature of the fuel cell stack and maintaining a desired fuel cell stack voltage using the load schedule until a target fuel cell stack temperature is achieved.

12. The method according to claim 1, wherein an electric supplemental coolant heater is disposed in a coolant loop radiator bypass.

13. A method of starting a fuel cell system having a fuel cell stack, a first power source, a second power source, a plurality of startup components, the method comprising the steps of:

a. determining a state of charge of the first power source;

b. starting the startup components using the first power source if the state of charge of the first power source is sufficient;

c. starting the startup components using the second power source if the state of charge of the first power source is sufficient;

d. connecting the fuel cell stack to a voltage bus after the fuel cell stack achieves open circuit voltage;

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

f. controlling the startup components connected to the fuel cell using local control loops having the ability to override the load schedule; and

g. monitoring a temperature of the fuel cell stack and controlling the fuel cell stack power using the load schedule until a target fuel cell stack temperature is achieved.

14. The method according to claim 13, further comprising the step of decreasing power to the startup components after the fuel cell stack achieves open circuit voltage and prior to connecting the fuel cell stack to the voltage bus.

15. The method according to claim 13, 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.

16. The method according to claim 13, 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.

17. The method according to claim 13, including performing said step (e) by employing a load schedule supplying power to the startup components for operation, at least on fuel cell stack end plate heater, an electric supplemental coolant heater, an electric cabin heater, recharging of the high voltage power source, and employing inefficient cathode controls in that order.

18. The method according to claim 13, wherein an electric supplemental coolant heater is disposed in a coolant loop radiator bypass.

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

(a). starting the fuel cell system using a battery;

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

(c). increasing the load on a fuel cell stack by ramping up power to a set of loads according to a schedule when a fuel cell stack voltage is higher than desired;

(d). 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 schedule when the fuel cell stack voltages are lower than desired;

(e). monitoring a temperature of the fuel cell stack; and

(f). controlling the fuel cell stack power using the schedule until a target fuel cell stack temperature is achieved.

20. The method according to claim 19, 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.