Dynamo electric machine with permanent magnet rotor structure

Abstract

A permanent magnet generator includes an annular stator with windings on the inner face. A round rotor is rotatably mounted in the stator, and includes a plurality of circumferentially spaced rectangular openings inwardly of the outer peripheral portion of the core. Radial U-shaped grooves are formed between the openings. A magnetic unit, including a rectangular permanent magnet and an abutting magnetic conductive shim, is close-fitted within each opening. The core includes core lamination and separate end laminations of a structure corresponding to the core laminations. The end laminations are rotated about an axis through the core to offset the magnetic unit openings with respect to the magnetic unit opening of the core laminations. The laminations are riveted together, with the offset end lamination retaining the magnetic units within the core. The shims respond to the magnetic flux resulting from rotation of the rotor to generate eddy currents and a resulting magnetic flux which cancels harmonic components from the total magnetic flux through the stator and thereby minimizes zero crossings and distortion of the output voltage and current.