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

Abstract

A brushless permanent magnet electric machine 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 constant velocity bearing 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.

Description

technical field [0001] The invention relates to a radial air gap type permanent magnet motor. In particular, the present invention relates to radial air gap permanent magnet machines in which the axial alignment of the rotor and stator can be varied to control the rotational speed and applied torque. Background technique [0002] Permanent magnet motors are known to be efficient producers / consumers of rotational energy. A brushless permanent magnet motor eliminates the commutator and brushes that are typically used in conventional motors with an electrical controller that commutates the current on the conductors. Brushless electrical controllers for permanent magnet motors allow coils of conductors to be placed in a stationary motor stator that moves in response to a rotor containing permanent magnets. [0003] Brushless permanent magnet motors are known for their durability, controllability, and lack of electrical sparks. These factors lead to problems with the commutato...

AI Technical Summary

Problems solved by technology

These factors must have an adverse effect on the ability to reduce rotor back EMF and operate above base speed

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