FCPM freeze start heater

• US 20050277003A1
• Filed: 06/09/2004
• Published: 12/15/2005
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Dewey, Scott
• Granted Patent: US 8,053,117 B2
• Time in Patent Office: Days
• US Class Current: 429/429
• 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 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04597 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04701 Temperature
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system that employs a start-up heater. The heater is coupled to a cold plate that warms a stack coolant during system start-up. A heater circuit measures the voltage at the output of the fuel cell stack and across the heater and the current through the fuel cell stack and through the heater. The heater circuit controls the amount heat that the heater generates by the measured voltage and current and the available power at the output of the fuel cell stack. In one embodiment, the heater includes field effect transistors (FETs) and planar resistors directly mounted to the cold plate. The FETs operate in their linear mode, allowing only the amount of current, which is required at a given voltage, to produce the power needed from the stack.

Claims

1. A fuel cell system comprising:

a fuel cell stack providing output power; and

a heater circuit including a heater for heating the fuel cell stack during system start-up, said heater being electrically coupled to the output of the fuel cell stack, said heater circuit further including a controller for controlling the amount of heat provided by the heater based on the output of the fuel cell stack.

2. The system according to claim 1 wherein the heater heats a cooling fluid flowing through the fuel cell stack.

3. The system according to claim 2 wherein the heater heats the cooling fluid by heating a heat sink coupled to the coolant flow.

4. The system according to claim 1 wherein the heater includes a plurality of FETs and power resistors.

5. The system according to claim 4 wherein the FETs operate in their linear mode, allowing only the amount of current, which is required at a given voltage, to produce the power needed from the fuel cell stack.

6. The system according to claim 1 wherein the heater circuit includes a current sensor for measuring the current flow through the heater and the fuel cell stack.

7. The system according to claim 1 wherein the heater circuit includes a voltage divider network for measuring the voltage at the output of the fuel cell stack and the voltage across the heater.

8. The system according to claim 1 wherein the controller has controller area network capabilities.

9. The system according to claim 8 wherein the heater circuit includes a controller area network transceiver for providing external signals to the controller.

10. The system according to claim 1 wherein the fuel cell system is on a vehicle.

11. A fuel cell system comprising:

a fuel cell stack providing output power;

a coolant loop including a cooling fluid flowing therethrough for cooling the fuel cell stack; and

a heater circuit including a heater for heating the fuel cell stack during system start-up, said heater being electrically coupled to the output of the fuel cell stack, wherein the heater heats the cooling fluid flowing through the fuel cell stack, said heater circuit further including a controller for controlling the amount of heat provided by the heater based on the output of the fuel cell stack, a current sensor for measuring the current flow through the heater and the fuel cell stack, a first voltage divider network for measuring the voltage at the output of the fuel cell stack and the voltage across the heater, and a controller area network (CAN) transceiver for providing external CAN signals to the controller.

12. The system according to claim 11 wherein the heater heats the coolant flow by heating a heat sink coupled to the coolant flow.

13. The system according to claim 11 wherein the heater includes a plurality of FETs and power resistors.

14. The system according to claim 13 wherein the FETs operate in their linear mode, allowing only the amount of current, which is required at a given voltage, to produce the power needed from the fuel cell stack.

15. The system according to claim 11 wherein the heater circuit further includes a second voltage divider network, said second voltage divider network measuring the voltage of one of the power resistors.

16. The system according to claim 11 wherein the fuel cell system is on a vehicle.

17. A method of heating a fuel cell stack during fuel cell system start-up, said method comprising:

electrically coupling a heater to an output of the fuel cell stack;

measuring a voltage across the output of the stack and the heater;

measuring the current through the stack and the heater;

controlling the amount of heat the heater provides based on the measured voltage and current and the available output power from the fuel cell stack; and

heating the fuel stack with the heat provided by the heater.

18. The method according to claim 17 wherein heating the fuel cell stack includes using the heater to heat a cooling fluid flowing through the fuel cell stack.

19. The method according to claim 18 wherein heating the fuel cell stack includes using the heater to heat a cold plate through which the cooling fluid flows.

20. The method according to claim 17 wherein controlling the amount of heat the heater provides includes operating the FETs in their linear mode, allowing only the amount of current, which is required at a given voltage, to produce the power needed from the fuel cell stack.