Patent ID: 8004140

Claim:
An internal permanent magnet machine comprising: a stator assembly comprising a stator core, the stator core comprising a plurality of stator teeth, the stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity; and a rotor assembly comprising a rotor core, the rotor assembly disposed inside said cavity and configured to rotate about the longitudinal axis, wherein the rotor assembly comprises: a shaft comprising a plurality of protrusions alternately arranged relative to a plurality of bottom structures; a plurality of stacks of laminations, the stacks disposed on the protrusions and dovetailed circumferentially around the shaft; a plurality of a pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque; each pair of permanent magnets disposed between the stacks of laminations; and a plurality of middle wedges mounted between each pair of permanent magnets; wherein the plurality of stacks of laminations, the pair of permanent magnets, and the plurality of middle wedges extend along an entire axial length of the shaft.