PERMANENT MAGNET ROTATING ELECTRIC MACHINE AND ELECTRIC POWER STEERING DEVICE USING THE SAME

• US 20090251023A1
• Filed: 02/24/2009
• Published: 10/08/2009
• Est. Priority Date: 04/04/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: ASAO, Yoshihito, TAKASHIMA, Kazuhisa, NAKANO, Masatsugu, AKUTSU, Satoru
• Granted Patent: US 8,598,762 B2
• Time in Patent Office: Days
• US Class Current: 310/156.380
• 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:

$0.65\le \frac{\mathrm{Rm}\times h1}{W\left(h1+g\right)}\le 1.37$

• • 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 the multiple phases; and

a rotor including;

a rotor core; and

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

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;

$0.65\le <br><br>\frac{\mathrm{Rm}\times <br><br>h<br><br><br><br>1}{W<br><br>\left(h<br><br><br><br>1+g\right)}\le <br><br>1.37$

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.

2. The permanent magnet rotating electric machine according to claim 1, wherein the armature windings are wound in same phase and in reverse directions around adjacent teeth.

3. The permanent magnet rotating electric machine according to claim 2, 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.

4. The permanent magnet rotating electric machine according to claim 2, 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.

5. 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.

6. 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.

7. The permanent magnet rotating electric machine according to claim 1, further comprising a projection portion provided between adjacent permanent magnets, the projection portion being made of magnetic substance and projecting from the rotor core.

8. The permanent magnet rotating electric machine according to claim 7, wherein the projection portion and each of the permanent magnets are configured to satisfy the following relationships,

h3/h2≧

0.38 and h1≧

h3

where h1 denotes a thickness of the central portion of the permanent magnet in the peripheral direction, h2 denotes a thickness of an end portion of the permanent magnet in the peripheral direction, and h3 denotes a height of the projection portion.

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

10. The permanent magnet rotating electric machine according to claim 1, wherein a metallic tube is provided around the plurality of permanent magnets.

11. An electric power steering device comprising the permanent magnet rotating electric machine according to claim 1.

12. 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 the multiple phases; and

a rotor including;

a rotor core; and

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

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;

$0.40\le <br><br>\frac{h<br><br><br><br>2}{h<br><br><br><br>1}\le <br><br>0.73$

where h1 denotes a thickness of a central portion of the permanent magnet in the peripheral direction, and h2 denotes a thickness of an end portion of the permanent magnet in the peripheral direction.

13. The permanent magnet rotating electric machine according to claim 12, wherein the armature windings are wound in same phase and in reverse directions around adjacent teeth.

14. The permanent magnet rotating electric machine according to claim 13, 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.

15. The permanent magnet rotating electric machine according to claim 13, 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.

16. The permanent magnet rotating electric machine according to claim 12, 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.

17. The permanent magnet rotating electric machine according to claim 12, 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.

18. The permanent magnet rotating electric machine according to claim 12, further comprising a projection portion provided between adjacent permanent magnets, the projection portion being made of magnetic substance and projecting from the rotor core.

19. The permanent magnet rotating electric machine according to claim 18, wherein the projection portion and each of the permanent magnets are configured to satisfy the following relationships,

h3/h2≧

0.38 and h1≧

h3

where h1 denotes a thickness of the central portion of the permanent magnet in the peripheral direction, h2 denotes a thickness of an end portion of the permanent magnet in the peripheral direction, and h3 denotes a height of the projection portion.

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

21. The permanent magnet rotating electric machine according to claim 12, wherein a metallic tube is provided around the plurality of permanent magnets.

22. An electric power steering device comprising the permanent magnet rotating electric machine according to claim 12.