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

• US 20060222909A1
• 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: Ojima, Kuniaki, Saeki, Hibiki, Aoyagi, Satoshi
• Granted Patent: US 7,527,112 B2
• Time in Patent Office: Days
• US Class Current: 429/9
• CPC Class Codes: B60H 1/00392 for electric vehicles having only electric drive means
• 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 8/04365 of other components of a fuel cell or fuel cell stacks
• 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 8/04686 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04694 characterised by variables to be controlled
• 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: 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 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells
• CPC Class Codes: Y10S 903/944 Characterized by control of fuel cell

Abstract

An electric system has a fuel cell and an electric storage device which are connected in parallel to each other with respect to a propulsive motor, and a DC-to-DC converter connected closer to the electric storage device than a junction where the fuel cell and the electric storage device are connected in parallel to each other. An electric power control system includes a power supply controller having a failure detector for detecting a failure of the DC-to-DC converter. When the failure detector detects a failure of the DC-to-DC converter, the response of electric power output from the fuel cell is limited.

Claims

1. An electric system for a fuel cell in which the fuel cell and an electric storage device are connected in parallel to each other with respect to a load, comprising:

a DC-to-DC converter connected closer to the electric storage device than a junction where the fuel cell and the electric storage device are connected in parallel to each other;

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

response limiting means for limiting the response of electric power output from said fuel cell when said failure detecting means detects a failure of said DC-to-DC converter.

2. An electric system according to claim 1, wherein said response limiting means sets an allowable output change upon the failure of said DC-to-DC converter to a value smaller than an allowable output change when said DC-to-DC converter is normal.

3. A fuel cell vehicle for being propelled by a propulsive motor, said fuel cell vehicle having an electric system in which a fuel cell and an electric storage device are connected in parallel to each other with respect to the propulsive motor and connected to the propulsive motor through a power converter, comprising:

a DC-to-DC converter connected closer to the electric storage device than a junction where the fuel cell and the electric storage device are connected in parallel to each other;

reactive gas supply means for supplying a reactive gas to said fuel cell;

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

response limiting means for limiting the response of electric power output from said fuel cell when said failure detecting means detects a failure of said DC-to-DC converter.

4. A fuel cell vehicle according to claim 3, wherein said response limiting means sets an allowable output change upon the failure of said DC-to-DC converter to a value smaller than an allowable output change when said DC-to-DC converter is normal.

5. A fuel cell vehicle according to claim 3, wherein said reactive gas supply means comprises:

a pump for delivering said reactive gas; and

an electric motor for actuating said pump;

said electric motor being supplied with electric power from a power supply line having said junction.

6. A fuel cell vehicle according to claim 4, wherein said allowable output change comprises an allowable torque change of said propulsive motor.

7. A fuel cell vehicle according to claim 3, further comprising regenerative electric power limiting means for limiting regenerative electric power of said propulsive motor to a value equal to or smaller than a prescribed failure regenerative electric power limit value upon the failure of said DC-to-DC converter.

8. A fuel cell vehicle according to claim 7, wherein said regenerative electric power limiting means comprises:

means for calculating an allowable motor regenerative electric power upper limit value of said propulsive motor based on a voltage in said electric system; and

means for limiting the regenerative electric power of said propulsive motor to a value equal to or smaller than a smaller one of said failure regenerative electric power limit value and said allowable motor regenerative electric power upper limit value.

9. A fuel cell vehicle according to claim 3, further comprising:

vehicle accessory electric power limiting means for limiting at least part of electric power consumed by a vehicle accessory upon the failure of said DC-to-DC converter.

10. A fuel cell vehicle according to claim 9, wherein said vehicle accessory comprises an electrically operated air conditioner motor.

11. A fuel cell vehicle for being propelled by a propulsive motor, said fuel cell vehicle having an electric system in which a fuel cell and an electric storage device are connected in parallel to each other with respect to the propulsive motor and connected to the propulsive motor through a power converter, comprising:

a DC-to-DC converter connected closer to the electric storage device than a junction where the fuel cell and the electric storage device are connected in parallel to each other;

reactive gas supply means for supplying a reactive gas to said fuel cell;

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

protection control means for protecting said fuel cell when said failure detecting means detects a failure of said DC-to-DC converter.

12. A method of supplying electric power in an electric system in which a fuel cell and an electric storage device are connected in parallel to each other with respect to the propulsive motor and connected to the propulsive motor through a power converter, and a DC-to-DC converter is connected closer to the electric storage device than a junction where the fuel cell and the electric storage device are connected in parallel to each other, comprising the steps of:

(a) supplying a reactive gas to said fuel cell;

(b) detecting a failure of said DC-to-DC converter; and

(c) limiting the response of electric power output from said fuel cell when a failure of said DC-to-DC converter is detected in said detecting step (b).

13. A method according to claim 12, wherein in said limiting step (c), an allowable output change upon the failure of said DC-to-DC converter is set to a value smaller than an allowable output change when said DC-to-DC converter is normal.

14. A method according to claim 13, wherein in said supplying step (a), said reactive gas is delivered by a pump, and said pump is actuated by an electric motor, said electric motor being supplied with electric power from a power supply line having said junction.

15. A method according to claim 13, wherein said allowable output change comprises an allowable torque change of said propulsive motor.

16. A method according to claim 12, further comprising the step of:

(d) limiting regenerative electric power of said propulsive motor to a value equal to or smaller than a prescribed failure regenerative electric power limit value upon the failure of said DC-to-DC converter.

17. A method according to claim 16, wherein said limiting step (d) comprises the steps of:

(e) calculating an allowable motor regenerative electric power upper limit value of said propulsive motor based on a voltage in said electric system; and

(f) limiting the regenerative electric power of said propulsive motor to a value equal to or smaller than a smaller one of said failure regenerative electric power limit value and said allowable motor regenerative electric power upper limit value.

18. A method according to claim 12, further comprising the step of:

(g) limiting at least part of electric power consumed by a vehicle accessory upon the failure of said DC-to-DC converter.

19. A method according to claim 18, wherein said vehicle accessory comprises an electrically operated air conditioner motor.