Permanent magnet motor

Patent metadata

Field	Value
Publication number	US-9601950-B2
Application number	US-201114005992-A
Country	US
Kind code	B2
Filing date	May 26, 2011
Priority date	May 26, 2011
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A permanent magnet motor ( 1 ) is configured such that mN≠K is satisfied to an integer m, where the pole number of a rotor ( 3 ) is K and the number of divided iron cores ( 10 - 12 ) of a stator ( 2 ) is N, and N values of r(θ), r(θ+360°/N), . . . , r(θ+(i−1)×360°/N), . . . , r(θ+(N−1)×360°/N) are equal so that the absolute value of the difference between any two of the N values becomes up to a predetermined value, where r(θ) is an inner radius defined as, on a plane perpendicular to a rotary shaft ( 7 ) of the rotor ( 3 ), a distance from the rotary shaft ( 7 ) center to a surface of the stator iron core ( 4 ) facing the rotor ( 3 ) where an angle from a fitting portion ( 15 ) of the partial iron core ( 10 ) is θ on the perpendicular plane, θ taking 0 to 360°/N.

First claim

The invention claimed is:

1. A permanent magnet motor, wherein
a relationship of mN≠K is satisfied with respect to an integer m, where the pole number of a rotor is K and the number of partial iron cores of a stator iron core of a stator is N, and
N values of r(θ+(i−1)×360°/N), . . . , r(θ+(N−1)×360°/N), with respect to i=1 to N, are set to be equal so that the absolute value of the difference between any two values of the N values, due to a clearance for fitting the partial iron cores and manufacturing deviations, becomes equal to or smaller than a predetermined value, where r(θ) is an inner radius defined as, on a plane perpendicular to a rotary shaft of the rotor, a distance from the center of the rotary shaft to a point on a surface of the stator iron core facing to the rotor at which an angle from a fitting portion of the partial iron core is θ on the perpendicular plane, θ taking a value of 0 to 360°/N,
wherein
a parameter calculated by the following expression (1) is set to be equal to or smaller than a predetermined value,

Δ
⁢

⁢

M
⁡

(

Lm

μ
⁢

⁢
r

)

2

⁢

Br
2

(

Lm

μ
⁢

⁢
r

+
g

)

2

[

Expression
⁢

⁢
1

]

wherein ΔM is the average value of Δmax with respect to the axial direction height of the stator iron core, Δmax being the maximum value, with respect to θ, of the absolute value of the difference between any two values among the N values of r(θ+(i−1)×360°/N), . . . , r(θ+(N−1)×360°/N), with respect to i=1 to N,
wherein Lm is the thickness (m) of the permanent magnet, μr is a recoil permeability, g is an air gap length (m), and Br is the residual magnetic flux density (T) of the permanent magnet, and
wherein the predetermined value for the parameter is 2.2×10 −5 (mT 2 ).

2. A permanent magnet motor, wherein
a relationship of mN≠K is satisfied with respect to an integer m, where the pole number of a rotor is K and the number of partial iron cores of a stator iron core of a stator is N, and
N values of r(θ+(i−1)×360°/N), . . . , r(θ+N−1)×360°/N), with respect to i=1 to N, are set to be equal so that the absolute value of the difference between any two values of the N values, due to a clearance for fitting the partial iron cores and manufacturing deviations, becomes equal to or smaller than a predetermined value, where r(θ) is an inner radius defined as, on a plane perpendicular to a rotary shaft of the rotor, a distance from the center of the rotary shaft to a point on a surface of the stator iron core facing to the rotor at which an angle from a fitting portion of the partial iron core is θ on the perpendicular plane, θ taking a value of 0 to 360°/N,
a parameter calculated by the following expression (2) is set to be equal to or smaller than a predetermined value,

⁢

(
θ
)

⁢

(

Lm

μ
⁢

⁢
r

)

2

⁢

Br
2

(

Lm

μ
⁢

⁢
r

+
g

)

2

[

Expression
⁢

⁢
2

]

where Δ(θ) is a periodic shape difference Δ(θ)=r(θ)max−r(θ)min per 360°/N, r(θ)max and r(θ)min being the maximum value and the minimum value among the N values of r(θ+(i−1)×360°/N), . . . , r(θ+(N−1)×360°/N), with respect to i=1 to N,
and
wherein the predetermined value for the parameter is 2.2×10 −5 (mT 2 ).

3. The permanent magnet motor according to claim 1 , wherein a relationship of L/N=n is satisfied with respect to an integer n, where L is the slot number of the stator.

4. The permanent magnet motor according to claim 3 , wherein the value of N is set at the smallest value among integers satisfying the relationship of mN≠K with respect to the integer m and satisfying the relationship of L/N=n with respect to the integer n.

5. The permanent magnet

Assignees

• Yamamura Akihiro
• Takashima Kazuhisa
• Nakano Masatsugu
• Mitsubishi Electric Corp

Inventors

• Yamamura Akihiro
• Takashima Kazuhisa
• Nakano Masatsugu

Classifications

• H02K29/03 Primary

  with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems · CPC title

• H02K2213/03

  Machines characterised by numerical values, ranges, mathematical expressions or similar information · CPC title

• H02K1/2706 Primary

  Inner rotors · CPC title

• H02K21/16

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