Permanent magnet motor, position estimating device, and motor driving controlling device
To manufacture a permanent magnetic motor having saliency at a low cost, a permanent magnet motor includes a stator provided with an armature winding configured to form a plurality of phases, a rotor having a surface facing the stator, the rotor including a permanent magnet disposed to face the stator, the permanent magnet having a plurality of magnetic poles arranged in a circumferential direction of the rotor, and a conductive member made of a conductive material and disposed on the surface of the rotor facing the stator.
1. A permanent magnet motor comprising:
a stator including an armature winding configured to form a plurality of phases;
a rotor including a permanent magnet facing the stator, the permanent magnet being in a shape of a ring and having a plurality of magnetic poles in a circumferential direction of the rotor; and
a conductive member made of a conductive material, the conductive member being arranged on a circumferential surface of the permanent magnet facing the stator, the conductive member including a first conductive member on the circumferential surface of the permanent magnet, the first conductive member having a shape on the circumferential surface of the permanent magnet that forms a first electrically closed circuit.
2. The permanent magnet motor according to claim 1 , wherein
the armature winding forms three phases, and
a number of the magnetic poles of the permanent magnet is 3n (n is a natural number).
3. The permanent magnet motor according to claim 1 , wherein the permanent magnet motor is a permanent magnet stepping motor.
4. The permanent magnet motor according to claim 1 , wherein the conductive member has a plurality of shapes such that each of the plurality of shapes forms the first electrically closed circuit in the circumferential direction of the rotor.
5. The permanent magnet motor according to claim 1 , wherein the conductive member further comprises:
a second conductive member on the circumferential surface of the permanent magnet such that the second conductive member is surrounded by the first conductive member, the second conductive member having a shape on the circumferential surface of the permanent magnet that forms a second electrically closed circuit inside the shape that forms the first electrically closed circuit.
6. The permanent magnet motor according to claim 1 , wherein the permanent magnet is a bond magnet.
7. The permanent magnet motor according to claim 1 , wherein the armature winding is configured to receive a harmonic wave signal, and to output a coil current that includes a harmonic wave current component in response to the harmonic wave signal, wherein
a position of the rotor of the permanent magnet motor is estimable based on the harmonic wave signal and the harmonic wave current component.
8. A permanent magnet motor comprising:
a rotor attached to a shaft, the rotor including a permanent magnet having a plurality of magnetic poles in a circumferential direction of rotation;
a plurality of stators each including an armature winding surrounding the rotor and a stator core having a plurality of teeth arranged so as to align in the circumferential direction of rotation, the plurality of stators being at different positions in a length direction of the shaft; and
a plurality of conductive members made of a conductive material, the plurality of conductive members on a surface of the permanent magnet facing the plurality of stators such that each of the plurality of conductive members correspond to the stator core of a respective one of the plurality of stators arranged in a stator stack.
9. The permanent magnet motor according to claim 8 , wherein the plurality of conductive members are configured to form an opening in an annular shape on the surface of the permanent magnet facing the plurality of stators.
10. The permanent magnet motor according to claim 8 , wherein the permanent magnet motor is a permanent magnet stepping motor.
11. A permanent magnet motor comprising:
a stator including an armature winding configured to form a plurality of phases;
a rotor including a permanent magnet facing the stator, the permanent magnet having a plurality of magnetic poles in a circumferential direction of the rotor; and
a conductive member made of a conductive material, the conductive member being on a surface of the permanent magnet, wherein
the conductive member is a sheet of metallic foil to be attached to the permanent magnet.
12. The permanent magnet motor according to claim 11 , wherein the surface of the permanent magnet having the conductive member thereon faces the stator.
13. The permanent magnet motor according to claim 11 , wherein the armature winding is configured to receive a harmonic wave signal, and to output a coil current that includes a harmonic wave current component in response to the harmonic wave signal, wherein
a position of the rotor of the permanent magnet motor is estimable based on the harmonic wave signal and the harmonic wave current component.
14. A permanent magnet motor comprising:
a stator including an armature winding configured to form a plurality of phases;
a rotor including a permanent magnet facing the stator, the permanent magnet having a plurality of magnetic poles in a circumferential direction of the rotor; and
a conductive member made of a conductive material, the conductive member being on a surface of the permanent magnet, wherein
the conductive member is formed by use of conductive liquid, paste, or ink which includes non-magnetic metal.
15. The permanent magnet motor according to claim 14 , wherein the surface of the permanent magnet having the conductive member thereon faces the stator.
16. The permanent magnet motor according to claim 14 , wherein the armature winding is configured to receive a harmonic wave signal, and to output a coil current that includes a harmonic wave current component in response to the harmonic wave signal, wherein
a position of the rotor of the permanent magnet motor is estimable based on the harmonic wave signal and the harmonic wave current component.
17. A motor system comprising:
a permanent magnet motor including a stator, a rotor and a conductive member, the stator including an armature winding configured to form a plurality of phases, the rotor including a permanent magnet facing the stator, the permanent magnet having a plurality of magnetic poles in a circumferential direction of the rotor, and the conductive member being made of a conductive material, the conductive member being on a surface of the permanent magnet facing the stator,
a harmonic wave generator configured to generate a harmonic wave signal to be supplied to the armature winding of the permanent magnet motor;
a current detector configured to detect a harmonic wave current component which is a response to the harmonic wave signal; and
a position estimator configured to estimate a position of the rotor of the permanent magnet motor, based on the harmonic wave signal and the harmonic wave current component.
18. A motor driving controlling device comprising:
the motor system according to claim 17 .