AC drive apparatus, vehicle control apparatus, and power conversion method and vehicle control method

• US 20060181235A1
• Filed: 02/16/2006
• Published: 08/17/2006
• Est. Priority Date: 02/17/2005
• Status: Active Grant

• Current Assignee: Hitachi Industrial Products, Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Sugawara, Naoshi, Shimada, Keizo, Imaie, Kazuhiro, Yagyu, Takashi, Kiyofuji, Yasuhiro
• Granted Patent: US 7,315,144 B2
• Time in Patent Office: Days
• US Class Current: 318/375
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 3/0076 relating to braking
• CPC Class Codes: B60L 50/13 using AC generators and AC motors
• CPC Class Codes: B60L 7/06 for vehicles propelled by ac motors
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 3/22 by short-circuit or resistive braking
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

A motor is driven with variable frequency AC power converted from DC power, and an AC output power from the motor is converted to DC. In the conversion, an electromotive force regenerated by the motor is consumed by a plurality of resistors. When the consumption of the electromotive force is impeded in any of systems including any of the plurality of resistors, the electromotive force is consumed by the systems including the remaining resistors. Even if a system including any of the plurality of resistors fails, the electromotive force can by consumed by the other systems including the remaining resistors, thus providing a reliable rheostatic brake.

Claims

1. An AC drive apparatus comprising:

a bidirectional converter for converting DC power to variable frequency AC power for driving a motor, and converting an AC output from said motor to DC; and

a plurality of electric brakes each including a resistor connected to said bidirectional converter to consume an electromotive force regenerated by said motor, and a switch for connecting and disconnecting said resistor to and from said bidirectional converter.

2. An AC drive apparatus according to claim 1, wherein said bidirectional converter is connected to a trolley system to prevent power from flowing into said trolley system.

3. An AC drive apparatus according to claim 2, further comprising means for connecting said bidirectional converter to said trolley system and also to an output of a generator through a rectifier, and for preventing the output of said generator from flowing into said trolley system.

4. An AC drive apparatus according to claim 1, wherein said bidirectional converter is connected to an output of a generator through a rectifier.

5. An AC drive apparatus according to claim 4, wherein said switch periodically turns on and off at a period which is controlled on the basis of the regeneration state.

6. An AC drive apparatus according to claim 5, wherein said generator is driven by a prime mover, and said prime mover is controlled for rotating speed based on an operating condition of a vehicle.

7. An AC drive apparatus according to claim 1, wherein said resister is applied with a current when a voltage associated with said converter increases beyond a predetermined value.

8. An AC drive apparatus according to claim 1, wherein said resistor is cooled down by a fan, and the operation of said resistor is limited when the temperature or pressure of cooling air rises to a predetermined level or higher.

9. A vehicle control apparatus comprising:

a prime mover;

a generator mechanically connected to said prime mover;

a rectifier for rectifying an output of said generator to DC;

a bidirectional converter connected to said rectifier;

a motor connected to said bidirectional converter, and having an output transmitted to wheels;

said bidirectional converter converting the rectified output to a variable frequency AC output power for driving said motor, and converting an AC output power from said motor to DC power; and

a plurality of electric brakes each including a resistor connected to said bidirectional converter to consume an electromotive force regenerated by said motor, and a switch for connecting and disconnecting said resistors to and from said bidirectional converter.

10. A vehicle control apparatus according to claim 9, wherein said resistors are applied with a current when a voltage associated with said converter increases beyond a predetermined value.

11. A vehicle control apparatus according to claim 9, wherein said resistors are cooled down by a fan, and the operation of said resistor is limited when the temperature or pressure of cooling air rises to a predetermined level or higher.

12. A power conversion method for converting DC power to variable frequency AC power for driving an electric motor and converting an AC output power from said motor to DC, said method comprising:

consuming an electromotive force regenerated by said motor by a plurality of resistors; and

when the consumption of the electromotive force is impeded in any of systems including any of said plurality of resistors, consuming the electromotive force by the remaining systems including the other resistors.

13. A power conversion method according to claim 12, further comprising:

starting to apply said resistors with a current when a voltage associated with said converter increases beyond a predetermined value.

14. A power conversion method according to claim 13, wherein said resistor is cooled down by a fan, and the operation of said resistors are limited when the temperature or pressure of cooling air rises to a predetermined level or higher.

15. A vehicle control method for generating electric power by a rotating force of a prime mover, converting the generated output to DC power, converting the DC power to variable frequency AC power for driving a motor and converting an AC power output from said motor to DC power, and rotating wheels by a rotating force of said motor, said method comprising:

consuming an electromotive force regenerated by said motor by a plurality of resistors; and

when the consumption of the electromotive force is impeded in any of systems including any of said plurality of resistors, consuming the electromotive force by the remaining systems including the other resistors.

16. A vehicle control method according to claim 15, further comprising:

starting to apply said resistors with a current when a voltage associated with said converter increases beyond a predetermined value.

17. A vehicle control method according to claim 15, wherein said resistors are cooled down by a fan, and the operation of said resistors are limited when the temperature or pressure of cooling air rises to a predetermined level or higher.