Permanent magnet electric motor

Patent metadata

Field	Value
Publication number	US-9496774-B2
Application number	US-201414296238-A
Country	US
Kind code	B2
Filing date	Jun 4, 2014
Priority date	Dec 15, 2008
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

According to one embodiment, a rotor is configured by a rotor core and magnetic poles. Two or more types of permanent magnets are used such that each product of coercivity and thickness in the magnetization direction becomes different. A stator is located outside the rotor with air gap therebetween and configured by an armature core winding. At least one permanent magnet is magnetized by a magnetic field by a current of the armature winding to change a magnetic flux content thereof irreversibly. A short circuited coil is provided to surround a magnetic path portion of the other permanent magnet excluding the magnet changed irreversibly and a portion adjacent to the other permanent magnet where the magnetic flux leaks. A short-circuit current is generated in the short circuited coil by the magnetic flux generated by conducting a magnetization current to the winding. A magnetic field is generated by the short-circuit current.

First claim

What invention claimed is:

1. A permanent magnet electric motor comprising:
a rotor including: a rotor core divided into two or more parts in an axial direction thereof so as to form two or more divided core parts; and a plurality of magnetic poles disposed inside the respective core parts and formed by two or more types of permanent magnets selected such that a product of coercivity and thickness in a magnetization direction of each magnet is different from each other, each position of the magnetic poles in the core parts being skewed in a circumferential direction;
a stator located outside the rotor with an air gap therebetween and including an armature core and an armature winding, the armature winding generating a magnetic field which magnetizes at least one permanent magnet forming the magnetic poles of the rotor; and
conductive short circuited coils disposed at an angle displaced according to a skewed angle of the respective core parts in the circumferential direction of the rotor and connected to each other with a stepped part at a boundary part of the respective core parts, the short circuited coils generating a short-circuit current based on a magnetic flux that is generated during magnetization upon magnetizing the permanent magnets,
the short circuited coils respectively comprising: a conductive panel disposed at the boundary part of each core part; a conductive bar protruding toward each core part in an axial direction of the rotor from each position of front and rear faces of the conductive panel displaced to each other corresponding to the skewed angle of the core parts in the circumferential direction of the rotor; and a short circuit connection part connecting tips of the conductive bars with each other at an axial end portion of the core part.

2. A permanent magnet electric motor according to claim 1 , wherein the short circuit connection part is configured by bending each tip of the conductive bars protruding from the axial end of the core part and connecting the tips with each other to form the short circuit connections.

3. A permanent magnet electric motor according to claim 1 , wherein end plates are provided on respective outer sides of the rotor core in the axial direction thereof so as to place and hold the rotor core therebetween, and the end plates are made from an insulating material or a member having greater electrical resistance than a conductive member provided in the rotor core.

4. A permanent magnet electric motor according to claim 1 , wherein end plates are provided on an outer side of the rotor core in the axial direction of the rotor core so as to place and hold the rotor core therebetween, and insulation-treatment is made to a portion of the end plate contacting a conductive member provided in the rotor core.

5. A permanent magnet electric motor comprising:
a rotor including: a rotor core divided into two or more parts in an axial direction thereof so as to form two or more core parts; and a plurality of magnetic poles disposed inside the respective core parts and formed by two or more types of permanent magnets selected such that a product of coercivity and thickness in a magnetization direction of each magnet is different from each other, each position of the magnetic poles in the core parts being skewed in a circumferential direction;
a stator located outside the rotor with an air gap therebetween and including an armature core and an armature winding, the armature winding generating a magnetic field which magnetizes at least one permanent magnet forming the magnetic poles of the rotor; and
conductive short circuited coils disposed at an angle displaced according to a skewed angle of the respective core parts in the circumferential direction of the rotor and connected to each other with a stepped part at a boundary part of the respective core parts, the short circuited coils generating a short-circuit current based on a magnetic flux that is generated during magnetization upon magnetizing the permanent magnets,
the short circuited coils respectively comprising:
a pair of conductive bars each having in a center thereof the stepped part having a length corresponding to the skewed angle; and a short circuit connection part connecting the conductive bars with each other at an axial end portion of the core part,
the permanent magnet electric motor further comprising: a space plate provided in the boundary part of each core part; and a void part formed in the space plate such that the stepped parts of the conductive bars are fitted therein.

6. A permanent magnet electric motor according to claim 5 , wherein the short circuited coil is formed by filling a melted conductive material into a pair of conductive material injection holes having in a center thereof a stepped part having a length corresponding to the skewed angle, into the short circuit connection part connecting the conductive bars with each other at the axial end portion of the core part, and into a void part formed in the space portion which is provided in the boundary part of each core part, and further solidifying the conductive material.

7. A permanent magnet electric motor according to claim 5 , wherein the short circuit connection part is configured by bending each tip of the conductive bars protruding from the axial end of the core part and connecting the tips with each other to form the short circuit connections.

8. A permanent magnet electric motor according to claim 5 , wherein end plates are provided on respective outer sides of the rotor core in the axial direction thereof so as to place and hold the rotor core therebetween, and the end plates are made from an insulating material or a member having greater electrical resistance than a conductive member provided in the rotor core.

9. A permanent magnet electric motor according to claim 5 , wherein end plates are provided on an outer side of the rotor core in the axial direction of the rotor core so as to place and hold the rotor core therebetween, and insulation-treatment is made to a portion of the end plate contacting a conductive member provided in the rotor core.

Assignees

• Toshiba Kk

Inventors

• Hashiba Yutaka
• Sakai Kazuto
• Takahashi Norio
• Yuuki Kazuaki
• Arata Masanori
• Matsuoka Yusuke
• Mochizuki Motoyasu
• Tokumasu Tadashi

Classifications

• H02K15/03 Primary

  having permanent magnets · CPC title

• H02K1/02

  characterised by the magnetic material · CPC title

• Y10T29/49012

  Rotor · CPC title

• H02K1/2766

  having a flux concentration effect · CPC title

• H02K21/028

  by modifying the magnetic circuit within the field or the armature, e.g. by using shunts, by adjusting the magnets position, by vectorial combination of field or armature sections · CPC title