Rotation-angle-detecting apparatus, rotating machine, and rotation-angle-detecting method

• US 8,115,479 B2
• Filed: 11/20/2007
• Issued: 02/14/2012
• Est. Priority Date: 11/21/2006
• Status: Active Grant

• Current Assignee: Hitachi Metals (Thailand) Ltd.
• Original Assignee: Hitachi Metals (Thailand) Ltd.
• Inventors: Shimoe, Osamu, Mita, Masahiro, Aimuta, Kyohei
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US12/302,232
• Publication Number:
  US 20090206827A1
• Time in Patent Office: 1,547 Days
• Field of Search: 324/207.25, 324/252, 324/260
• US Class Current: 324/207.25
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2451 Incremental encoders G01D5/2454 takes precedence

Abstract

A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles on the surface, and sensor device for detecting magnetic flux from the magnet rotor, and an electronic circuit for outputting a signal representing the rotation angle of the magnet rotor using pluralities of signals obtained from the sensor device, the sensor device having pluralities of spin-valve, giant-magnetoresistive devices for outputting two or more different phase signals from a rotating magnetic field near the rotating magnet, each spin-valve, giant-magnetoresistive device having a pinned layer and a free layer, the magnetization direction of the pinned layer being fixed, and the magnetization direction of the free layer rotating depending on a magnetic field direction, pluralities of the spin-valve, giant-magnetoresistive devices comprising a first spin-valve, giant-magnetoresistive device having a reference magnetic-field-sensing direction, and a second spin-valve, giant-magnetoresistive device having a magnetic-field-sensing direction different from that of the first spin-valve, giant-magnetoresistive device.

Claims

1. A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles on the surface, and first and second sensor devices for detecting the direction of magnetic flux from said magnet rotor;

said first sensor device containing sensor bridges X01 and Y01, in which the magnetization directions of pinned layers are perpendicular to each other;

said second sensor device containing sensor bridges X02 and Y02, in which the magnetization directions of pinned layers are perpendicular to each other;

each sensor bridge X01, Y01, X02, Y02 being a full bridge of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction;

adjacent spin-valve, giant-magnetoresistive devices in said full bridge having pinned layers whose magnetization directions are antiparallel;

said sensor bridges Y01 and Y02 being arranged such that the magnetization directions of their pinned layers are along the circumferential direction of said magnet rotor;

said sensor bridges X01 and X02 being arranged such that the magnetization directions of their pinned layers have a phase difference of 90°

or 90°

±

180n°

by electric angle, wherein n is an integer; and

voltage being applied to said full bridges to obtain differential outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said differential outputs.

2. The rotation-angle-detecting apparatus according to claim 1, which comprises a first sensor device group comprising said first and second sensor devices, and a second sensor device group comprising other sensor devices each having the same structure as that of the sensor device in said first sensor device group, the relative arrangement of the other sensor devices being the same as in said first sensor device group;

and said first sensor device group and said second sensor device group being separate from each other by 180n°

by electrical angle, wherein n is an integer.

3. The rotation-angle-detecting apparatus according to claim 1, wherein signals from said sensor bridges X01, Y01, X02 and Y02 are input to separate differential amplifiers to obtain four signals, which are calculated to output an error detection signal.

4. The rotation-angle-detecting apparatus according to claim 1, wherein signals from said sensor bridges X01, Y01, X02 and Y02 are input to separate differential amplifiers to obtain four signals, which are averaged to obtain a fifth signal, which is compared with a predetermined DC voltage to determine their difference, based on which an error detection signal is output.

5. A rotating machine comprising the rotation-angle-detecting apparatus recited in claim 1.

6. A rotation-angle-detecting apparatus comprising a magnet rotor having 2 or more magnetic poles on the surface, and first and second sensor devices for detecting the direction of magnetic flux from said magnet rotor;

the distance between the center of said first sensor device and the rotation axis of said magnet rotor being larger than the radius of said magnet rotor;

the distance between the center of said second sensor device and the rotation axis of said magnet rotor being larger than the radius of said magnet rotor;

said first sensor device containing sensor bridges X01 and Y01, in which the magnetization directions of pinned layers are perpendicular to each other;

said second sensor device containing sensor bridges X02 and Y02, in which the magnetization directions of pinned layers are perpendicular to each other;

each sensor bridge X01, Y01, X02, Y02 being a bridge circuit of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction;

the magnetization directions of pinned layers in electrically adjacent spin-valve, giant-magnetoresistive devices in said sensor bridges X01, Y01, X02 and Y02 being antiparallel;

a plane including the magnetization direction of the pinned layer in each sensor bridge X01, Y01, X02, Y02 being inclined from the rotation axis of said magnet rotor; and

voltage being applied to said sensor bridges X01, Y01, X02 and Y02 to obtain outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said outputs.

7. A rotation-angle-detecting apparatus comprising a magnet rotor having 2 or more magnetic poles on the surface, and first and second sensor devices for detecting the direction of magnetic flux from said magnet rotor;

the distance between the center of said first sensor device and the rotation axis of said magnet rotor being larger than the radius of said magnet rotor;

the distance between the center of said second sensor device and the rotation axis of said magnet rotor being larger than the radius of said magnet rotor;

said first sensor device containing sensor bridges X01 and Y01, in which the magnetization directions of pinned layers are perpendicular to each other;

said second sensor device containing sensor bridges X02 and Y02, in which the magnetization directions of pinned layers are perpendicular to each other;

each sensor bridge X01, Y01, X02, Y02 being a bridge circuit of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction;

the magnetization directions of pinned layers in electrically adjacent spin-valve, giant-magnetoresistive devices in said sensor bridges X01, Y01, X02 and Y02 being antiparallel;

the centers of said first and second sensor devices being separate from a plane passing the thickness center position of said magnet rotor and perpendicular to the rotation axis of said magnet rotor in a rotation axis direction; and

voltage being applied to said sensor bridges X01, Y01, X02 and Y02 to obtain outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said outputs.

8. A rotation-angle-detecting apparatus comprising a magnet rotor having two magnetic poles, and a sensor device for detecting the direction of magnetic flux from said magnet rotor;

said sensor device having a magnetosensitive surface comprising pluralities of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction; and

said sensor device being arranged relative to said magnet rotor to cause the magnetic flux to cross said magnetosensitive surface, such that magnetic flux density components perpendicular to each other on said magnetosensitive surface have the same amplitude.

9. The rotation-angle-detecting apparatus according to claim 8,

said sensor device being arranged, such that φ

and χ

are in a range that;

(a) φ

is −

1.6°

to 1.5°

, and χ

is −

57.6°

to −

62.2°

,

(b) φ

is −

1.5°

to 1.6°

, and χ

is 57.6°

to 62.2°

,

(c) φ

is 33.8°

to 36.6°

, and χ

is −

2.7°

to 3.1°

,

(d) φ

is 19.2°

to 22.8°

, and χ

is 87.4°

to 92.4°

,

(e) φ

is 67.1°

to 70.8°

, and χ

is 84.2°

to 97.7°

, or

(f) φ

is 81.4°

to 98.7°

, and χ

is 158.6°

to 201.2°

,

wherein φ

is a sensor arrangement angle between a line connecting the thickness center point of said magnet rotor and the center of the magnetosensitive surface of said sensor device, and a plane passing the thickness center point of said magnet rotor and perpendicular to the rotation axis, and χ

is a sensor inclination angle between a plane passing the thickness center point of said magnet rotor and perpendicular to the rotation axis and said magnetosensitive surface;

said sensor device containing sensor bridges A01 and B01, in which the magnetization directions of pinned layers are perpendicular to each other;

each sensor bridge A01, B01 being a bridge circuit of said spin-valve, giant-magnetoresistive devices;

the magnetization directions of pinned layers in electrically adjacent spin-valve, giant-magnetoresistive devices in said bridge circuit being antiparallel; and

voltage being applied to said sensor bridges A01 and B01 to obtain outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said outputs.

10. A rotation-angle-detecting apparatus comprising a magnet rotor having two magnetic poles, and a sensor device for detecting the direction of magnetic flux from said magnet rotor;

said sensor device having a magnetosensitive surface comprising pluralities of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction; and

said sensor device being arranged relative to said magnet rotor, such that the amplitude ratio (K_eff=B⊥

_eff0/B_//eff0) of effective magnetic flux density components perpendicular to each other on said magnetosensitive surface is 1 at a position meeting the condition of a space magnetic flux density amplitude ratio K₀=B⊥

₀/B_//0≠

1.

11. A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles, and a sensor device for detecting the direction of magnetic flux from said magnet rotor;

said sensor device having a magnetosensitive surface comprising pluralities of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction; and

said sensor device being arranged relative to said magnet rotor to cause the magnetic flux to cross said magnetosensitive surface, such that magnetic flux density components perpendicular to each other on said magnetosensitive surface have the same amplitude.

12. A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles, and a sensor device for detecting the direction of magnetic flux from said magnet rotor;

said sensor device having a magnetosensitive surface comprising pluralities of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction; and

said sensor device being arranged relative to said magnet rotor, such that the amplitude ratio (K_eff=B⊥

_eff0/B_//eff0) of effective magnetic flux density components perpendicular to each other on said magnetosensitive surface is 1 at a position meeting the condition of a space magnetic flux density amplitude ratio K₀=B⊥

₀/B_//0≠

1.

13. A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles, and a sensor device for detecting the direction of magnetic flux from said magnet rotor;

said sensor device having a magnetosensitive surface comprising pluralities of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction;

said sensor device being arranged such that φ and

χ

are in a range of z≠

0, χ

=0, and χ

=4.5°

to 25°

, or in a range of z=0, φ

=0, and χ

=40°

to 60°

, wherein φ

is a sensor arrangement angle between a line connecting the thickness center point of said magnet rotor and the center of the magnetosensitive surface of said sensor device, and a plane passing the thickness center point of said magnet rotor and perpendicular to the rotation axis, and χ

is a sensor inclination angle between a plane passing the thickness center point of said magnet rotor and perpendicular to the rotation axis and said magnetosensitive surface;

said sensor device containing sensor bridges A01 and 801, in which the magnetization directions of pinned layers are perpendicular to each other;

each sensor bridge A01, B01 being a bridge circuit of said spin-valve, giant-magnetoresistive devices;

the magnetization directions of pinned layers in electrically adjacent spin-valve,giant-magnetoresistive devices in said bridge circuit being antiparallel; and

voltage being applied to said sensor bridges A01 and B01 to obtain outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said outputs.