Permanent magnet rotating electric machine and electric power steering device using the same

• US 8,598,762 B2
• Filed: 02/24/2009
• Issued: 12/03/2013
• Est. Priority Date: 04/04/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Nakano, Masatsugu, Takashima, Kazuhisa, Akutsu, Satoru, Asao, Yoshihito
• Primary Examiner(s): Mullins, Burton
• Assistant Examiner(s): Johnson, Eric
• Application Number:
  US12/391,573
• Publication Number:
  US 20090251023A1
• Time in Patent Office: 1,743 Days
• Field of Search: 310/156.45, 310/156.46, 310/156.38, 310/56.28, 310/156.21, 310/156.23, 310/156.28, 310/156.19
• US Class Current: 310/156.45
• CPC Class Codes: H02K 1/2781 Magnets shaped to vary the mechanical air gap between the magnets and the stator
• CPC Class Codes: H02K 2213/03 Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems

Abstract

A permanent magnet rotating electric machine includes: a stator including: a stator core having teeth, and an armature winding wound around each of the teeth to configure the multiple phases; and a rotor including a rotor core, and permanent magnets provided in order around the rotor core. The rotor is arranged to be spaced apart from the stator with an air gap therebetween. Each of the permanent magnets has a curved surface opposed to the stator and is configured to satisfy the following relationship:

$0.65\le \frac{\mathrm{Rm}\times h1}{W\left(h1+g\right)}\le 1.37$

• • where Rm denotes a radius of curvature of the curved surface, h1 denotes a thickness of a central portion of the permanent magnet in the peripheral direction, W denotes a width of the permanent magnet in the peripheral direction, and g denotes an air gap length of the air gap.

Claims

1. A permanent magnet rotating electric machine comprising:

a stator including;

a stator core having a plurality of teeth; and

an armature winding wound around each of the plurality of teeth to configure multiple phases, wherein the armature windings are wound in same phase and in reverse directions around adjacent teeth;

a rotor having a radius Rr and including;

a rotor core; and

a plurality of permanent magnets provided in order in a peripheral direction around the rotor core; and

a roughly polygonal metal tube surrounding the rotor,

wherein the rotor is arranged to be spaced apart from the stator with an air gap therebetween, and

wherein each of the permanent magnets has a curved surface opposed to the stator and is configured to satisfy the following relationship;

2. The permanent magnet rotating electric machine according to claim 1, wherein the following relationship is satisfied

6/7≦

M/N≦

6/5

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

3. The permanent magnet rotating electric machine according to claim 1, wherein the following relationship is satisfied

3/4<

M/N<

3/2

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

4. The permanent magnet rotating electric machine according to claim 1, wherein the following relationship is satisfied

N:

M=12n±

2n;

12n (n is an integer of 1 or greater)

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

5. The permanent magnet rotating electric machine according to claim 1, wherein the following relationship is satisfied

N:

M=9n±

n;

9n (n is an integer of 1 or greater)

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

6. The permanent magnet rotating electric machine according to claim 1, wherein the stator core is configured by a plurality of split iron cores.

13. The permanent magnet rotating electric machine according to claim 1, wherein the upper limit of the demagnetization evaluation parameter (Rm·

h1)/(W(h1+g)) is 1.12.

14. The permanent magnet rotating electric machine according to claim 1, wherein the roughly polygonal metal tube is almost straight at circumferential locations between the permanent magnets.

7. A permanent magnet rotating electric machine comprising:

a stator including;

a stator core having a plurality of teeth; and

an armature winding wound around each of the plurality of teeth to configure multiple phases, wherein the armature windings are wound in same phase and in reverse directions around adjacent teeth; and

a rotor having a radius Rr and including;

a rotor core;

a plurality of permanent magnets provided in order in a peripheral direction around the rotor core; and

a roughly polygonal metal tube surrounding the rotor,

wherein the rotor is arranged to be spaced apart from the stator with an air gap therebetween,

wherein each of the permanent magnets has a curved surface opposed to the stator and is configured to satisfy the following relationship;

8. The permanent magnet rotating electric machine according to claim 7, wherein the following relationship is satisfied

6/7≦

M/N≦

6/5

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

9. The permanent magnet rotating electric machine according to claim 7, wherein the following relationship is satisfied

3/4<

M/N<

3/2

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

10. The permanent magnet rotating electric machine according to claim 7, wherein the following relationship is satisfied

N:

M=12n±

2n;

12n (n is an integer of 1 or greater)

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

11. The permanent magnet rotating electric machine according to claim 7, wherein the following relationship is satisfied

N:

M=9n±

n;

9n (n is an integer of 1 or greater)

where N denotes a number of magnetic poles formed by the plurality of permanent magnets, and M denotes a number of the teeth.

12. The permanent magnet rotating electric machine according to claim 7, wherein the stator core is configured by a plurality of split iron cores.

15. The permanent magnet rotating electric machine according to claim 7, wherein the roughly polygonal metal tube is almost straight at circumferential locations between the permanent magnets.