Resolver having decreased permanence error due to harmonic components

Patent metadata

Field	Value
Publication number	US-10753772-B2
Application number	US-201815995160-A
Country	US
Kind code	B2
Filing date	Jun 1, 2018
Priority date	Jul 31, 2017
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A resolver includes a resolver rotor fixed to a rotating shaft, and a resolver stator disposed around the resolver rotor. The resolver stator includes an annular stator core having a plurality of salient poles which protrudes radially inward and which is disposed at regular intervals in a circumferential direction. The resolver rotor has an outer peripheral surface defined by an outer radius Rm(φ) which is obtained by blending, with respect to a first function Gp(φ) where an air gap between the resolver rotor and the salient poles is proportional to a sine wave (sin φ) related to an angle φ of the resolver rotor, a second function Gip(φ) where the inverse of the air gap is proportional to the sine wave (sin φ), at a predetermined ratio α.

First claim

What is claimed is:

1. A resolver comprising:
a resolver rotor fixed to a rotating shaft; and
a resolver stator disposed around the resolver rotor,
wherein:
the resolver stator includes an annular stator core which has a plurality of salient poles protruding radially inward and which is disposed at regular intervals in a circumferential direction;
the resolver rotor has an outer peripheral surface defined by an outer radius obtained by blending, with respect to a first function where an air gap between the resolver rotor and the salient poles is proportional to a sine wave related to an angle of the resolver rotor, a second function where an inverse of the air gap is proportional to the sine wave, at a predetermined ratio;
the ratio is set greater than zero; and
the outer radius is calculated according to an expression (A), based on the angle, a stator inner radius indicating a length from a center of rotation of the shaft to a radially inner end face of the salient poles, the ratio, and a maximum value and a minimum value of the air gap set in advance:

Rm
⁡

(
ϕ
)

=

Rs
-

{

α
×

Gip
⁡

(
ϕ
)

+

(

1
-
α

)

×

Gp
⁡

(
ϕ
)

}

⁢

⁢

Gp
⁡

(
ϕ
)

=

{

(

G
⁢

⁢
max

-

G
⁢

⁢
min

)

⁢
sin
⁢

⁢
ϕ

}

/
2

+

(

G
⁢

⁢
min

+

G
⁢

⁢
max

)

/
2

⁢

⁢

Gip
⁡

(
ϕ
)

=

1

[

{

1

G
⁢

⁢
min

-

1

G
⁢

⁢
max

2

}

⁢
sin

Assignees

• Mabuchi Motor Co

Inventors

• Yamamoto Shigeru

Classifications

• H02K11/225 Primary

  Detecting coils · CPC title

• G01D2205/77

  Specific profiles · CPC title

• G01D5/24433

  by mechanical means · CPC title

• G01D5/2046

  by a movable ferromagnetic element, e.g. a core · CPC title

• G01D5/204

  by influencing the mutual induction between two or more coils (G01D5/22 takes precedence) · CPC title