Electric driving device and electric power steering system including the same

Patent metadata

Field	Value
Publication number	US-9045156-B2
Application number	US-201013580284-A
Country	US
Kind code	B2
Filing date	Oct 22, 2010
Priority date	May 11, 2010
Publication date	Jun 2, 2015
Grant date	Jun 2, 2015

Abstract

A control device ( 3 ) controlling an electric motor ( 2 ) is disposed on an axial line of a rotor shaft ( 30 ) of the electric motor ( 2 ). The control device ( 3 ) includes semiconductor switching devices ( 15 ) forming a three-phase bridge circuit that controls a current of the electric motor ( 2 ) and capacitors ( 13 ) that suppresses a ripple component of a current flowing to the electric motor ( 2 ). The semiconductor switching devices ( 15 ) and the capacitors ( 13 ) are provided in pairs for respective arms of the three-phase bridge circuit and disposed concentrically. Hence, impedance across the three-phase circuit controlling a current flowing to the electric motor is reduced. Consequently, not only can ripples be absorbed efficiently but also power efficiency of a driving device can be enhanced.

First claim

The invention claimed is:

1. An electric driving device comprising: an electric motor and a control device disposed on an axial line of a rotor shaft of the electric motor and controlling driving of the electric motor, wherein the control device includes:
semiconductor switching devices forming a three-phase bridge circuit that controls a current of the electric motor;
capacitors suppressing a ripple component of a current flowing to the electric motor;
a coil reducing noises generated during a switching action of the semiconductor switching devices;
a power circuit portion including the semiconductor switching devices, the capacitors, and the coil;
a heat sink on which the power circuit portion is mounted and which releases heat generated from the power circuit portion;
a control board on which is mounted a microcomputer that generates a drive signal to drive the semiconductor switching devices; and
a plurality of electrical conducting plates insert-molded with an insulating resin, are disposed parallel to each other and concentrically with the rotor shaft in a ring shape which electrically connect the respective arms of the three-phase bridge circuit in a shortest distance and electrically connect the capacitors which are disposed along the respective arms of the three-phase bridge circuit while a positive wiring and a negative wiring of a DC power supply are aligned parallel to each other on a same plane so as to reduce electromagnetic noise in the electrical conducting plates and facilitate a connection between the arms and the capacitors of the three-phase bridge circuit, the electrical conduction plates comprising a pad connected to a power board and a welding portion exposed from the insulating resin, and a portion of the electrical conducting plates are embedded within a circuit case of the control device
wherein:
the semiconductor switching devices and the capacitors are provided in pairs for respective arms of the three-phase bridge circuit and disposed concentrically with the rotor shaft, and the welding portion electrically connected to the electrical conducting plate is exposed from the insulating resin.

2. The electric driving device according to claim 1 , wherein
the electrical conducting plates are formed in a ring shape and disposed in such a manner that the positive wiring and the negative wiring are disposed concentrically with the rotor shaft.

3. The electric driving device according to claim 1 , wherein
the heat sink is provided with a hole larger than an outside diameter of the capacitors and the capacitors are inserted into the hole.

4. The electric driving device according to claim 3 , wherein
a clearance defined by the hole of the heat sink and the capacitors is filled with a high thermal conductive member.

5. The electric driving device according to claim 1 , wherein
the heat sink is provided with a hole larger than an outside diameter of the coil and the coil is inserted into the hole.

6. The electric driving device according to claim 5 , wherein
a clearance defined by the hole of the heat sink and the coil is filled with a high thermal conductive member.

7. The electric driving device according to claim 1 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

8. The electric driving device according to claim 1 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

9. The electric driving device according to claim 2 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

10. The electric driving device according to claim 3 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

11. The electric driving device according to claim 4 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

12. The electric driving device according to claim 5 further comprising:
control terminals electrically connecting the power circuit portion and the control board,
wherein the control terminals are disposed along a peripheral edge portion of the rotor shaft about the rotor shaft of the electric motor.

13. The electric driving device according to claim 7 , wherein
the control board is provided with a hole to let the rotor shaft of the electric motor pass through, and the hole and the control terminals are disposed concentrically.

14. The electric driving device according to claim 1 , wherein
the power circuit portion includes a switching means that passes or interrupts a current flowing into the control device; and
the switching means is formed of a plurality of semiconductor switching devices.

15. The electric driving device according to claim 1 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

16. The electric driving device according to claim 1 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

17. The electric driving device according to claim 2 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

18. The electric driving device according to claim 3 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

19. The electric driving device according to claim 4 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

20. The electric driving device according to claim 5 further comprising:
a deceleration device that decelerates the electric motor,
wherein the heat sink is attached to a housing of the deceleration device.

21. The electric driving device according to claim 15 , wherein
the housing of the deceleration device and the heat sink are made of high thermal conducting metal.

22. The electric driving device according to claim 21 , wherein the high thermal conducting metal is aluminum or aluminum alloy.

23. The electric driving device according to claim 1 , wherein the plurality of electrical conducting plates are welded to the capacitors via the welding portion.

24. An electric power steering system, comprising:
an electric motor;
a steering wheel that receives torque from the electric motor; and
a control device disposed on an axial line of a rotor shaft of the electric motor and contr

Assignees

• Omae Katsuhiko
• Tominaga Tsutomu
• Ito Shinichi
• Mitsubishi Electric Corp

Inventors

• Omae Katsuhiko
• Tominaga Tsutomu
• Ito Shinichi

Classifications

• H02P27/08

  with pulse width modulation · CPC title

• H02K7/1166

  comprising worm and worm-wheel (structural association with bearings specially adapted for worm gear drives H02K7/081) · CPC title

• B62D5/0406 Primary

  including housing for electronic control unit · CPC title

• H02M7/5387

  in a bridge configuration · CPC title

• H02K11/33

  Drive circuits, e.g. power electronics (H02K11/38 takes precedence) · CPC title