Magnetic levitation motor
A magnetic levitation motor which rotates a rotor in a levitated state with respect to a stator by a direct-current magnetic field and stator windings. The magnetic levitation motor comprises: a direct-current magnetic field generating device ( 4 ) which forms a magnetic flux having a radial pattern with an axis at the center in a stator ( 2 ) and a rotor ( 3 ); a first stator winding ( 6 ) for generating a levitation control magnetic flux ( 5 ) to control levitation of the rotor ( 3 ) in a radial direction; and a second stator winding ( 7 ) for generating a rotating magnetic field to rotate the rotor ( 3 ). The rotor ( 3 ) is provided with a yoke portion ( 9 ) and a motor magnet ( 10 ) which are opposed to a stator core ( 8 ) of the stator ( 2 ). A part of a bias magnetic flux ( 11 ) and a part of a levitation control magnetic flux ( 5 ) form a magnetic circuit directly reaching the stator core from the yoke, thereby increasing a levitation force of the rotor.
1. A magnetic levitation motor which rotates a rotor in a levitated state with respect to a fixed stator, the magnetic levitation motor comprising:
a direct-current magnetic field generating means for forming a magnetic flux having a radial pattern with an axis at a center in the stator and the rotor;
a stator core having salient-pole portions formed so as to outwardly protrude in a radial pattern;
a first stator winding for generating a levitation control magnetic flux to control levitation of the rotor in a radial direction; and
a second stator winding for generating a rotating magnetic field to rotate the rotor, the rotor having a yoke portion and a motor magnet which are opposed to said stator core of the stator;
wherein said yoke portion has a motor magnet attachment step portion and said motor magnet attachment step portion has a thickness in an axial direction, smaller than a thickness of the stator in the axial direction, and a thickness in a radial direction, substantially equal to a thickness of the motor magnet.
2. The magnetic levitation motor according to claim 1 , wherein the direct-current magnetic field generating means is a permanent magnet.
3. The magnetic levitation motor according to claim 1 , wherein the motor magnet and a permanent magnet as the direct-current magnetic field generating means are attached on both sides with a stator core opposed portion of the yoke portion, which is opposed to the stator core and excludes the motor magnet attachment step portion, being sandwiched therebetween.
4. The magnetic levitation motor according to claim 1 , wherein a number of magnetic poles of the rotor is not less than six.
5. The magnetic levitation motor according to claim 1 , wherein the motor magnet is a permanent magnet attached on a peripheral surface of the rotor.
6. The magnetic levitation motor according to claim 1 , wherein the motor magnet is a permanent magnet embedded in a peripheral surface of the rotor.
7. A magnetic levitation motor which rotates a rotor in a levitated state with respect to a fixed stator, the magnetic levitation motor comprising:
a direct-current magnetic field generating means for forming a magnetic flux having a radial pattern with an axis at a center in the stator and the rotor;
a stator core having salient-pole portions formed so as to outwardly protrude in a radial pattern;
a first stator winding for generating a levitation control magnetic flux to control levitation of the rotor in a radial direction; and
a second stator winding for generating a rotating magnetic field to rotate the rotor, the rotor having an inner surface which is opposed to said salient-pole portions of said stator core of the stator and comprises a yoke portion and a motor magnet;
wherein said yoke portion has a motor magnet attachment step portion and said motor magnet attachment step portion has a thickness in an axial direction, smaller than a thickness of the stator in the axial direction, and a thickness in a radial direction, substantially equal to a thickness of the motor magnet.
8. The magnetic levitation motor according to claim 7 , wherein the direct-current magnetic field generating means is a permanent magnet.
9. The magnetic levitation motor according to claim 7 , wherein the motor magnet and a permanent magnet as the direct-current magnetic field generating means are attached on both sides with a stator core opposed portion of the yoke portion, which is opposed to the stator core and excludes the motor magnet attachment step portion, being sandwiched therebetween.
10. The magnetic levitation motor according to claim 7 , wherein a number of magnetic poles of the rotor is not less than six.
11. The magnetic levitation motor according to claim 7 , wherein the motor magnet is a permanent magnet attached on a peripheral surface of the rotor.
12. The magnetic levitation motor according to claim 7 , wherein the motor magnet is a permanent magnet embedded in a peripheral surface of the rotor.