Permanent-magnet electric motor

Patent metadata

Field	Value
Publication number	US-10673291-B2
Application number	US-201515561561-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Jun 17, 2015
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A permanent-magnet electric motor includes an annular stator core, a rotor core, and a rotating-position detection sensor. In each of a plurality of magnet insertion holes formed in the rotor core, a rare-earth magnet and a ferrite magnet are disposed adjacent to each other in an axial direction of the rotor core. The rotor core has an axial length longer than an axial length of the stator core. The rare-earth magnet is disposed in each of the magnet insertion holes to be opposed to the stator core in a radial direction of the stator core. The ferrite magnet disposed in each of the magnet insertion holes is disposed between the rare-earth magnet disposed in the corresponding magnet insertion hole and the rotating-position detection sensor.

First claim

The invention claimed is:

1. A permanent-magnet electric motor comprising:
an annular stator core;
a rotor core that is disposed in the stator core and has a plurality of magnet insertion holes; and
a rotating-position detection sensor that is disposed to be opposed to the rotor core and detects a rotating position of the rotor core, wherein
in each of the plurality of magnet insertion holes, a rare-earth magnet and a ferrite magnet are disposed adjacent to each other in an axial direction of the rotor core,
the rare-earth magnet and the ferrite magnet are disposed in a single, identical magnet insertion hole,
a length of the rotor core in the axial direction is longer than a length of the stator core in the axial direction,
the rare-earth magnet is disposed in each of the plurality of magnet insertion holes to be opposed to the stator core in a radial direction of the stator core,
the ferrite magnet disposed in each of the plurality of magnet insertion holes is disposed between the rare-earth magnet disposed in a corresponding one of the plurality of magnet insertion holes and the rotating-position detection sensor, and
when a distance in the axial direction from the ferrite magnet to the rotating-position detection sensor is L 1 and a distance in the axial direction from the rare-earth magnet to the rotating-position detection sensor is L 2 , the distance L 1 is shorter than the distance L 2 .

2. The permanent-magnet electric motor according to claim 1 , wherein
an end of the rotor core on the side of the rotating-position detection sensor overhangs from an end surface of the stator core on the side of the rotating-position detection sensor to the side of the rotating-position detection sensor and extends to a vicinity of the rotating-position detection sensor, and
the ferrite magnet is disposed in an overhanging part of the rotor core and extends to the vicinity of the rotating-position detection sensor together with the rotor core.

3. The permanent-magnet electric motor according to claim 1 , wherein
the rare-earth magnet and the ferrite magnet disposed in each of the plurality of magnet insertion holes have been concurrently magnetized by a single magnetizing yoke.

4. A permanent-magnet electric motor comprising:
an annular stator core;
a rotor core that is disposed in the stator core and has a plurality of magnet insertion holes; and
a rotating-position detection sensor that is disposed to be opposed to the rotor core and detects a rotating position of the rotor core, wherein
a rare-earth magnet is disposed in each of the plurality of magnet insertion holes,
a ferrite magnet is disposed in every other magnet insertion hole of the plurality of magnet insertion holes in a rotation direction of the rotor core,
the ferrite magnet disposed in every other magnet insertion hole of the plurality of magnet insertion holes in the rotation direction of the rotor core is disposed axially adjacent to the rare-earth magnet disposed in a corresponding one of the plurality of magnet insertion holes,
a length of the rotor core in the axial direction is longer than a length of the stator core in the axial direction,
the rare-earth magnet is disposed in each of the plurality of magnet insertion holes to be opposed to the stator core in a radial direction of the stator core,
the ferrite magnet disposed in every other magnet insertion hole of the plurality of magnet insertion holes in the rotation direction of the rotor core is disposed between the rare-earth magnet disposed in a corresponding magnet insertion hole of the plurality of magnet insertion holes and the rotating-position detection sensor, and
when a distance in the axial direction from the ferrite magnet to the rotating-position detection sensor is L 1 and a distance in the axial direction from the rare-earth magnet to the rotating-position detection sensor is L 2 , the distance L 1 is shorter than the distance L 2 .

5. The permanent-magnet electric motor according to claim 4 , wherein
an end of the rotor core on the side of the rotating-position detection sensor overhangs from an end surface of the stator core on the side of the rotating-position detection sensor to the side of the rotating-position detection sensor and extends to a vicinity of the rotating-position detection sensor, and
the ferrite magnet disposed in every other magnet insertion hole of the plurality of magnet insertion holes in a circumferential direction is disposed in an overhanging part of the rotor core and extends to the vicinity of the rotating-position detection sensor together with the rotor core.

6. The permanent-magnet electric motor according to claim 4 , wherein
the rare-earth magnet disposed in each of the plurality of magnet insertion holes and the ferrite magnet disposed in every other magnet insertion hole in the circumferential direction have been concurrently magnetized by a single magnetizing yoke.

Assignees

• Mitsubishi Electric Corp

Inventors

• Oikawa Tomoaki
• Yamamoto Mineo
• Ishii Hiroyuki
• Aso Hiroki
• Oya Junichiro
• Urabe Yuto
• Shimokawa Takaya

Classifications

• H02K11/215

  Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements · CPC title

• H02K1/276 Primary

  Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] · CPC title

• H02K1/02

  characterised by the magnetic material · CPC title

• H02K1/146

  consisting of a generally annular yoke with salient poles · CPC title

• H02K21/16

  having annular armature cores with salient poles (with homopolar co-operation H02K21/20) · CPC title