Patent ID: 8796898

Claim:
A permanent magnet electric motor in which a rotor is configured by a rotor core and a plurality of magnetic poles formed inside the rotor core by using two or more types of permanent magnets selected such that a product of coercivity and thickness in a magnetization direction of each magnet is different from each other, in which a stator is located outside the rotor with an air gap intervening between them and configured by an armature core and an armature winding, in which at least one permanent magnet forming the magnetic poles of the rotor is magnetized by a magnetic field generated by a current of the armature winding to change a magnetic flux content thereof irreversibly, wherein a short circuited coil is provided so as to surround a magnetic path portion of another permanent magnet excluding the permanent magnet of which magnetic flux content is changed irreversibly and a portion adjacent to the other permanent magnet where the magnetic flux leaks, wherein a short-circuit current is generated in the short circuited coil by the magnetic flux which is generated by conducting a magnetization current to the armature winding, and a magnetic field, having a magnetic force in an opposite direction to the magnetic field generated by the magnetization current, is generated by the short-circuit current, and wherein the portion adjacent to the other permanent magnet where the magnetic flux leaks is configured as a bridge part of the rotor core provided at an adjacent portion between the permanent magnet of which magnetic flux content is changed irreversibly and the other permanent magnet.