Patent ID: 7969057
Filing Date: 2011-06-28
Classification: H02K

Abstract:
1. A synchronous motor comprising a stator and a rotor surrounded by the stator, the stator including a stator core and a multi-phase stator coil to create a rotating magnetic field, the rotor including: a rotating shaft about which the rotor rotates; a plurality of segments made of a soft magnetic material, the segments being located radially outward of the rotating shaft and arranged in a circumferential direction of the rotating shaft at a predetermined pitch with spaces formed therebetween, each of the segments having a recess and a pair of ends, the recess being formed in a circumferentially-central portion of the segment and recessed radially inward from a radially outer periphery of the rotor to make up a magnetic reluctance portion, the pair of ends being opposed to each other in the circumferential direction of the rotating shaft, with the recess interposed therebetween, to respectively make up a pair of salient-pole portions; a plurality of permanent magnets each of which is disposed in one of the spaces between the segments and belongs to one of first and second groups, the permanent magnets of the first group being alternately arranged with the permanent magnets of the second group in the circumferential direction of the rotating shaft, each of the permanent magnets of the first group having its N (North) pole located forward of its S (South) pole in a clockwise direction, each of the permanent magnets of the second group having its N pole located forward of its S pole in a counterclockwise direction; and a field coil that is wound around the segments to extend in the circumferential direction of the rotating shaft through the recesses of the segments, the field coil being configured to create, when energized with DC current, magnetic flux which magnetizes the pair of ends of each of the segments in opposite directions.