Permanent magnet electric motor inducing short circuit current in short circuit coil

Abstract

An increase of the magnetization current can be restrained during demagnetization and magnetization, and a variable speed operation can be achieved at a high power output over a wide range of from a low speed to a high speed. A rotoris configured by a rotor core, permanent magnetshaving a small value as the product of the coercivity and the thickness in the magnetization direction thereof, and permanent magnetshaving a large value as the product. When reducing a flux linkage of the permanent magnets, a magnetic field directed to the reverse direction of the magnetization direction of the permanent magnetsdue to a current of an armature coil is caused to act on them. When increasing a flux linkage of the permanent magnets, a magnetic field directed to the same direction as the magnetization direction of the permanent magnetsdue to a current of an armature coil is caused to act on them. A short circuit coilis located in a magnetic path part of each permanent magnetother than the permanent magnets. A magnetic field due to a magnetization current induces an induced current to generate a magnetic field on the periphery of the short circuit coil. The generated magnetic field and the magnetization current generate a magnetic field to magnetize the permanent magnets