ELECTRIC SYSTEM FOR FUEL CELL, FUEL CELL VEHICLE, AND METHOD OF SUPPLYING ELECTRIC POWER

• US 20090008166A1
• Filed: 09/03/2008
• Published: 01/08/2009
• 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, TAKANOHASHI, Hiroaki, SAEKI, Hibiki, AOYAGI, Satoshi
• Granted Patent: US 8,293,414 B2
• Time in Patent Office: Days
• US Class Current: 180/65.310
• 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, a first electric accessory serving as at least part of a fuel cell accessory for operating the fuel cell, a first DC-to-DC converter for performing bidirectional voltage conversion between the first power supply line and the second power supply line and a second DC-to-DC converter for lowering a voltage for supply electric power to the first electric accessory.

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;

an auxiliary electric system operable under a voltage lower than a voltage output from said fuel cell;

a first DC-to-DC converter for performing bidirectional voltage conversion, said first DC-to-DC converter connecting said auxiliary electric system to said first power supply line; and

a second DC-to-DC converter for lowering a voltage, said second DC-to-DC converter connecting at least a portion of said first electric accessory to said first power supply line for supplying electric power from said first power supply line to said first electric accessory;

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 second electric accessory being connected to said second power supply line 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 second electric accessory has at least a portion connected to said second power supply line through a third DC-to-DC converter.

4. An electric system according to claim 3, wherein said second DC-to-DC converter:

lowers a voltage applied thereto,

supplies a lowered voltage to said first electric accessory when a load on an electric motor is smaller than a prescribed threshold value, wherein the electric motor is supplied with electric power from said first power supply line,

directly connects input and output terminals of the electric motor, and supplies electric power through the input and output terminals to said first electric accessory when the load on said electric motor 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 the portion of said second electric accessory that is connected to said second power supply line through the third DC-to-DC converter is exclusive of said electrically operated air conditioner motor.

15. An electric system according to claim 1, wherein another portion of said second electric accessory is connected to said first power supply line through the first DC-to-DC converter.

16. An electric system according to claim 15, wherein the portion of said second electric accessory that is connected to said first power supply line through the first DC-to-DC converter includes at least an electrically operated air conditioner motor.

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

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 said fuel cell;

a first power supply line connected to said fuel cell;

a second power supply line connected to said 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;

an electric motor and a first electric accessory being supplied with electric power from said first power supply line;

a second DC-to-DC converter for lowering a voltage, said second DC-to-DC converter connecting at least a portion of said first electric accessory to said first power supply line; and

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

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

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

supplying a first electric accessory with electric power through a second DC-to-DC converter for lowering a voltage, said second DC-to-DC converter connecting at least a portion of said first electric accessory to said first power supply line;

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

supplying electric power having a voltage increased from a voltage on said second power supply line by said first DC-to-DC converter, through said first power supply line to said electric motor 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 second electric accessory has at least a portion connected to said second power supply line through a third DC-to-DC converter, and wherein said second electric accessory is supplied with electric power from said second power supply line.

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 electric motor 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 electric motor 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 the portion of said second electric accessory that is connected to said second power supply line through said third DC-to-DC converter is exclusive of said electrically operated air conditioner motor.

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

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

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

17. A method according to claim 8, wherein another portion of said second electric accessory is connected to said first power supply line through the first DC-to-DC converter.

18. A method according to claim 17, wherein the portion of said second electric accessory that is connected to said first power supply line through the first DC-to-DC converter includes at least an electrically operated air conditioner motor.