Electric system for fuel cell, fuel cell vehicle, and method of supplying electric power

• US 20060222910A1
• Filed: 03/31/2006
• Published: 10/05/2006
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Abe, Hiroyuki, Saeki, Hibiki, Aoyagi, Satoshi, Takanohashi, Hiroaki
• Granted Patent: US 7,438,984 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: B60H 1/00392 for electric vehicles having only electric drive means
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 58/31 for starting of fuel cells
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/34 by heating
• 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 8/04029 Heat exchange using liquids
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• 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 8/04626 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04686 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• 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

An electric system has a fuel cell for generating electric power by being supplied with a reactive gas, an electric storage device having a voltage lower than a voltage output from the fuel cell, a first power supply line connected to the fuel cell, a second power supply line connected to the electric storage device, and a first DC-to-DC converter for performing bidirectional voltage conversion between the first power supply line and the second power supply line. An inverter, a propulsive electric motor, and an air compressor are supplied with electric power from the first power supply line. An electrically operated air conditioner motor, windshield wiper motors, and power window motors, etc., which serve as a second electric accessory, are supplied with electric power from the second power supply line.

Claims

1. An electric system for a fuel cell, comprising:

a fuel cell for generating electric power by being supplied with a reactive gas;

a first power supply line connected to said fuel cell;

a first electric accessory serving as at least part of a fuel cell accessory for operating said fuel cell; and

an auxiliary electric system connected to said first power supply line through a first DC-to-DC converter for performing bidirectional voltage conversion, said auxiliary electric system being operable under a voltage lower than a voltage output from said fuel cell;

said auxiliary electric system comprising;

a first electric storage device;

a second power supply line connecting said first electric storage device and said first DC-to-DC converter to each other; and

a second electric accessory serving as an electric accessory other than said fuel cell accessory;

said first electric accessory being connected for being supplied with electric power from said first power supply line; and

said second electric accessory being connected for being supplied with electric power from said second power supply line.

2. An electric system according to claim 1, wherein said first electric accessory comprises at least one of an air compressor for supplying air under pressure to said fuel cell, a hydrogen pump for supplying hydrogen to said fuel cell, and a coolant circulation pump for cooling said fuel cell.

3. An electric system according to claim 1, wherein said first electric accessory has at least a portion connected to said first power supply line through a second DC-to-DC converter for lowering a voltage.

4. An electric system according to claim 3, wherein said second DC-to-DC converter lowers a voltage applied thereto and supplies the lowered voltage to said first electric accessory when a load on a main unit which is supplied with electric power from said first power supply line is smaller than a prescribed threshold value, and directly connects input and output terminals thereof and supplies electric power through the input and output terminals to said first electric accessory when the load on said main unit is equal to or greater than said prescribed threshold value.

5. An electric system according to claim 1, wherein said second electric accessory includes at least an electrically operated air conditioner motor.

6. An electric system according to claim 5, wherein said second electric accessory includes at least a portion, exclusive of said electrically operated air conditioner motor, connected to said second power supply line through a third DC-to-DC converter for lowering a voltage, and also to a second electric storage device.

7. An electric system for a fuel cell, comprising:

a fuel cell for generating electric power by being supplied with a reactive gas;

a first electric storage device having a voltage lower than a voltage output from said fuel cell;

a first power supply line connected to said fuel cell;

a second power supply line connected to said first electric storage device;

a first DC-to-DC converter for performing bidirectional voltage conversion between said first power supply line and said second power supply line;

a main unit and a first electric accessory for being supplied with electric power from said first power supply line; and

a second electric accessory for being supplied with electric power from said second power supply line.

8. A method of supplying electric power, comprising the steps of:

supplying a main unit and a first electric accessory with electric power through a first power supply line from a fuel cell which generates electric power by being supplied with a reactive gas;

supplying a second electric accessory with electric power through a second power supply line from an electric storage device having a voltage lower than a voltage output from said fuel cell;

supplying electric power having a voltage lowered from a voltage on said first power supply line by a DC-to-DC converter capable of performing bidirectional voltage conversion, through said second power supply line to said second electric accessory or to said electric storage device to charge the electric storage device; and

supplying electric power having a voltage increased from a voltage on said second power supply line by said DC-to-DC converter, through said first power supply line to said main unit or said first electric accessory.

9. A method according to claim 8, wherein said first electric accessory comprises at least one of an air compressor for supplying air under pressure to said fuel cell, a hydrogen pump for supplying hydrogen to said fuel cell, and a coolant circulation pump for cooling said fuel cell.

10. A method according to claim 8, wherein said first electric accessory has at least a portion connected to said first power supply line through a second DC-to-DC converter for lowering a voltage.

11. A method according to claim 10, further comprising the steps of:

lowering a voltage applied to said second DC-to-DC converter and supplying the lowered voltage to said first electric accessory when a load on said main unit is smaller than a prescribed threshold value; and

directly connecting input and output terminals of said second DC-to-DC converter and supplying electric power through the input and output terminals to said first electric accessory when the load on said main unit is equal to or greater than said prescribed threshold value.

12. A method according to claim 8, wherein said second electric accessory includes at least an electrically operated air conditioner motor.

13. A method according to claim 12, wherein said second electric accessory includes at least a portion, exclusive of said electrically operated air conditioner motor, connected to said second power supply line through a third DC-to-DC converter for lowering a voltage, and also to a second electric storage device.

14. A method according to claim 8, further comprising the steps of:

detecting a failure of said DC-to-DC converter; and

limiting the response of electric power output from said fuel cell if a failure of said DC-to-DC converter is detected in said step of detecting.