Brushless permanent magnet motor with variable axial rotor/stator alignment to increase speed capability

Abstract

A brushless permanent magnet electric motor with a fixed radial air gap is operated to a much higher speed than normal maximum speed by the reduction in effective magnet pole strength. Increasing the amount of axial misalignment of the permanent magnet rotor and stator proportionally increases the speed and reduces the torque. The permanent magnet rotor is offset axially to provide axial misalignment between the rotor magnet poles and the stator, reducing the effective magnet pole strength or flux to the stator. An integral constant velocity linear bearing is used to couple the movable rotor and the fixed position motor shaft. A thrust bearing is actuated to offset the magnetic rotor against the attractive magnetic forces toward the stator. The use of a constant velocity linear bearing allows the motor shaft, radial support bearings, position encoder, cooling fan, and output coupling to remain in a constant position while rotor position is offset.

Dependencies are inferred from the claim text.