Permanent magnet electric motor

• US 8,653,710 B2
• Filed: 12/16/2009
• Issued: 02/18/2014
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sakai, Kazuto, Hashiba, Yutaka, Yuuki, Kazuaki, Tokumasu, Tadashi, Takahashi, Norio, Arata, Masanori, Matsuoka, Yusuke
• Primary Examiner(s): Nguyen, Tran
• Assistant Examiner(s): Mok, Alex W
• Application Number:
  US13/140,669
• Publication Number:
  US 20110309706A1
• Time in Patent Office: 1,525 Days
• Field of Search: 310/156.47, 310/156.53, 310/156.76, 310/156.77, 310/181, 310/182, 310/183
• US Class Current: 310/156.47
• CPC Class Codes: H02K 1/276 Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• CPC Class Codes: H02K 1/2766 having a flux concentration effect
• CPC Class Codes: H02K 2201/06 Magnetic cores, or permanent magnets characterised by their skew

Abstract

A rotor has rotor cores divided in the axial direction. A permanent magnet is mounted at the position of each of the magnetic poles of cores. The permanent magnet of each magnetic pole is configured by a single tabular member that penetrates the two divided cores in the axial direction. Convex parts are respectively provided on the outer peripheries of the respective magnetic poles of the rotor cores along the axial direction of the rotor. The convex parts are provided to positions that are displaced for each of the two divided cores. The magnetic flux density increases in the convex parts, which becomes the magnetic pole center. Since the convex parts positions are displaced to each other, a skew function can be exhibited even if the permanent magnet is mounted at the same position.

Claims

1. A permanent magnet electric motor, comprising:

a stator including an armature winding in a stator core; and

a rotor including a permanent magnet built into a rotor core,

wherein a plurality of permanent magnets penetrating the rotor core in an axial direction thereof are arranged in the respective magnetic poles in the rotor core, equally in a circumferential direction of the rotor,

the parts that cause magnetic properties to be different for each of the magnetic poles are provided in the respective magnetic poles such that the parts that cause magnetic properties to be different are unequally arranged in the circumferential direction, thereby causing the rotor core to exhibit a skew function,

two or more types of permanent magnets having different products of a coercive force and a magnetization direction thickness are used as the permanent magnet, and a variable magnetic force magnet, which is at least one of the permanent magnets configuring the magnetic poles of the rotor, is magnetized by a magnetic field that is created by the armature winding, and

the rotor includes a conductive member through which a short-circuit current flows by a magnetic flux that is generated during magnetization upon magnetizing the variable magnetic force magnet, and

the conductive member is provided in the rotor to be adjacent to the permanent magnets except the variable magnetic force magnet and extend in an axial direction of the rotor core.

2. The permanent magnet electric motor according to claim 1, wherein the parts that cause magnetic properties to be different are formed, on rotor outer peripheries of the respective magnetic poles of the rotor core, as convex parts extending in an axial direction of the rotor, and unequally arranged as the convex parts in the circumferential direction of the rotor.

3. The permanent magnet electric motor according to claim 1, wherein the part that causes magnetic properties to be different are each disposed as a magnetic barrier made from a non-magnetic material or a void such that the magnetic barrier is asymmetrical relative to the center of a permanent magnet mounting hole in the circumferential direction on the permanent magnet outer peripheral side of the rotor core.

4. The permanent magnet electric motor according to claim 1, wherein the parts that cause magnetic properties to be different are disposed as a plurality of magnets having different magnetic forces in the respective magnetic poles of the rotor core such that the alignment of the magnets is made different for each of the divided rotor cores.

5. The permanent magnet electric motor according to claim 1, wherein the parts that cause magnetic properties to be different are each disposed as a slit on the permanent magnet outer peripheral side of the rotor core such that the position of the slit is displaced with respect to the center of the permanent magnet in the circumferential direction.

6. The permanent magnet electric motor according to claim 1, wherein magnetization is performed when the center of the magnetic field that is created by the armature winding and magnetizes the variable magnetic force magnet coincides with the center of the magnetic pole of the variable magnetic force magnet of the rotor.

7. A permanent magnet electric motor, comprising:

a stator including an armature winding in a stator core; and

a rotor including a permanent magnet built into a rotor core,

wherein a plurality of permanent magnets penetrating the rotor core in an axial direction thereof are arranged in respective magnetic poles in the rotor core such that the permanent magnets are displaced by a given angle that is determined by a pole pitch,

parts that cause magnetic properties to be different for each of the magnetic poles are provided in the respective magnetic poles of the rotor core such that the parts that cause magnetic properties to be different are unequally arranged in the circumferential direction, thereby causing the rotor core to exhibit a skew function,

two or more types of permanent magnets having different products of a coercive force and a magnetization direction thickness are used as the permanent magnet, and a variable magnetic force magnet, which is at least one of the permanent magnets configuring the magnetic poles of the rotor, is magnetized by a magnetic field that is created by the armature winding, and

the rotor includes a conductive member through which a short-circuit current flows by a magnetic flux that is generated during magnetization upon magnetizing the variable magnetic force magnet, and

the conductive member is provided in the rotor to be adjacent to the permanent magnets except the variable magnetic force magnet and extend in an axial direction of the rotor core.

8. The permanent magnet electric motor according to claim 7, wherein magnetization is performed when the center of the magnetic field that is created by the armature winding and magnetizes the variable magnetic force magnet coincides with the center of the magnetic pole of the variable magnetic force magnet of the rotor.

9. The permanent magnet electric motor according to claim 7, wherein the parts that cause magnetic properties to be different are formed, on rotor outer peripheries of the respective magnetic poles of the rotor core, as convex parts extending in an axial direction of the rotor, and unequally arranged as the convex parts in the circumferential direction of the rotor.

10. The permanent magnet electric motor according to claim 7, wherein the parts that cause magnetic properties to be different are each disposed as a magnetic barrier made from a non-magnetic material or a void such that the magnetic barrier is asymmetrical relative to the center of a permanent magnet mounting hole in the circumferential direction on the permanent magnet outer peripheral side of the rotor core.

11. The permanent magnet electric motor according to claim 7, wherein the parts that cause magnetic properties to be different are disposed as a plurality of magnets having different magnetic forces in the respective magnetic poles of the rotor core such that the alignment of the magnets is made different for each of the divided rotor cores.

12. The permanent magnet electric motor according to claim 7, wherein the parts that cause magnetic properties to be different are each disposed as a slit on the permanent magnet outer peripheral side of the rotor core such that the position of the slit is displaced with respect to the center of the permanent magnet in the circumferential direction.

13. A permanent magnet electric motor, comprising:

a stator including an armature winding in a stator core; and

a rotor including a permanent magnet built into a rotor core,

wherein the rotor core is divided into two or more rotor cores in an axial direction,

a plurality of permanent magnets penetrating the rotor core in an axial direction thereof are arranged in the respective magnetic poles in the rotor core,

the parts that cause magnetic properties to be different for each of magnetic poles of the divided rotor cores are provided in the respective magnetic poles such that the parts that cause magnetic properties to be different are unequally arranged in a circumferential direction, and

the parts that cause magnetic properties to be different are arranged so as to be displaced for each of the divided cores, thereby causing the rotor core to exhibit a skew function,

two or more types of permanent magnets having different products of a coercive force and a magnetization direction thickness are used as the permanent magnet, and a variable magnetic force magnet, which is at least one of the permanent magnets configuring the magnetic poles of the rotor, is magnetized by a magnetic field that is created by the armature winding, and

the rotor includes a conductive member through which a short-circuit current flows by a magnetic flux that is generated during magnetization upon magnetizing the variable magnetic force magnet, and

the conductive member is provided in the rotor to be adjacent to the permanent magnets except the variable magnetic force magnet and extend in an axial direction of the rotor core.

14. The permanent magnet electric motor according to claim 13, wherein the parts that cause magnetic properties to be different are formed, on rotor outer peripheries of the respective magnetic poles of the rotor core, as convex parts extending in an axial direction of the rotor, and unequally arranged as the convex parts in the circumferential direction of the rotor.

15. The permanent magnet electric motor according to claim 13, wherein the parts that cause magnetic properties to be different are each disposed as a magnetic barrier made from a non-magnetic material or a void such that the magnetic barrier is asymmetrical relative to the center of a permanent magnet mounting hole in the circumferential direction on the permanent magnet outer peripheral side of the rotor core.

16. The permanent magnet electric motor according to claim 13, wherein the parts that cause magnetic properties to be different are disposed as a plurality of magnets having different magnetic forces in the respective magnetic poles of the rotor core such that the alignment of the magnets is made different for each of the divided rotor cores.

17. The permanent magnet electric motor according to claim 13, wherein the parts that cause magnetic properties to be different are each disposed as a slit on the permanent magnet outer peripheral side of the rotor core such that the position of the slit is displaced with respect to the center of the permanent magnet in the circumferential direction.

18. The permanent magnet electric motor according to claim 13, wherein magnetization is performed when the center of the magnetic field that is created by the armature winding and magnetizes the variable magnetic force magnet coincides with the center of the magnetic pole of the variable magnetic force magnet of the rotor.