20150008786 | THREE-PHASE PERMANENT MAGNET-TYPE SYNCHRONOUS MOTOR - A cogging torque can be significantly reduced in a three-phase permanent magnet-type synchronous motor. In a three-phase permanent magnet-type synchronous motor where a fraction of 2N/3P is not an integer assuming the number of magnetic poles of a rotator is P and the number of slots of a stator is N, the stator includes a tooth facing a surface of a magnetic pole of the rotator via a void and a tooth width of the tooth in the circumferential direction is approximately ½ of a slot pitch of the stator. In a three-phase permanent magnet-type synchronous motor of an outer rotor type, the tooth of the stator has a radial cross section with an approximately uniform shape from a tooth tip portion to a tooth root portion or a radial cross section with a larger tooth root portion than a tooth tip portion to allow mounting a winding unit from the tooth tip portion. The winding unit is preliminarily wound by a coil. | 01-08-2015 |