Abstract: Electric machine rotor comprising: an inner rotor element and an outer rotor element positioned more outwards in the radial direction than the inner rotor element, the inner rotor element and the outer rotor element being made of a material of high permeance, and an air gap of low permeance between the inner rotor element and the outer rotor element. The outer rotor element forms a shape-mating pair with the inner rotor element, the inner rotor element and the outer rotor element being shaped in such a way that radial detachment of the outer rotor element from the inner rotor element is prevented.

Abstract: A rotor includes: a magnet having a circular cylinder shape and having a hole formed through its axial center, wherein the hole has in axial cross section a regular polygonal shape having flat portions and angle portions, and wherein a recess having a truncated cone shape is disposed at an axial end of the magnet such that the recess has its maximum diameter portion located at the axial end and has its minimum diameter portion communicating with the hole; and a shaft fitted in the hole of the magnet, wherein the outer circumference of the shaft makes contact with the flat portions of the hole of the magnet thereby forming a plurality of gaps between the outer circumference of the shaft and the angle portions of the hole of the magnet, and adhesive is filled in the gaps.

Abstract: A rotor assembly includes a superconducting winding assembly positioned within a cryogenic region of the rotor assembly. In operation, the superconducting winding assembly generates a magnetic flux linking a stator assembly. The rotor assembly also includes a torque transfer assembly that includes first and second tubes that are positioned in a radial space external to the superconducting winding assembly and that extend along a longitudinal axis of the rotor assembly.

Abstract: Embodiments of the present invention provide methods for manufacturing an even-wall rotor or stator that do not suffer from drawbacks of the prior art. Even-wall rotors or stators produced according to those methods are also provided. In one embodiment, a method for manufacturing a rotor or stator for use in a mud motor is provided. The method includes providing a vacuum chamber; providing a metal electrode at least partially disposed in the vacuum chamber; providing a mold disposed in the vacuum chamber; and melting a portion of the electrode with a direct current arc, the molten metal flowing into the mold ring.

Abstract: A motor includes a rotor core, permanent magnets and non-magnetic layers. The permanent magnets are embedded in the rotor core with each of the permanent magnets defining a pole of the rotor having a pole center and a peripheral edge section, with the peripheral edge section located in a vicinity between the poles and a vicinity of the rotor surface. The non-magnetic layers are located in a vicinity of the rotor surface at a pole center side position with respect to the peripheral edge section of each of the permanent magnets. The peripheral edge sections and the non-magnetic layers are positioned to cancel 5-th or 7-th order harmonics of an induction voltage. The poles are disposed at every approximately constant interval, varying in a constant angle. The peripheral edge sections and the non-magnetic layers are independent from one another, and the rotor core is interposed between them.