Field weakening for a doubly salient motor with stator permanent magnets

Claim 1

A permanent magnet motor comprising: a rotor, said rotor further comprising, a plurality of salient rotor poles spaced at equal angular intervals around a central axis; a stator for exciting said rotor to move, said stator further comprising, a plurality of salient stator poles spaced at equal angular intervals around said central axis, said stator poles being arranged with respect to said rotor poles to provide a constant air-gap reluctance during rotation of said rotor within said stator, and a plurality of permanent magnets shaped in parallelepipeds and arranged on diametrically opposite sides of said stator to serve as a source of flux for magnetizing the motor; and a flux by-pass collar encircling said stator and rotatable thereabout to provide a controlled bypass flux path around said permanent magnets, said flux by-pass collar further comprising a plurality of non-magnetic sections each angularly corresponding to one of said permanent magnets; whereby the flux by-pass collar may be rotated in accordance with torque requirements to cause each of said magnetic sections to bridge a corresponding permanent magnet, thereby promoting a flow of flux around said one of said permanent magnets, and thereby reducing an air gap magnetic field of said one of said permanent magnets, and the flux by-pass collar may be rotated in accordance with the torque requirements to displace each of said magnetic sections from the corresponding permanent magnet, thereby eliminating a flow of flux around said one of said permanent magnets and reducing the air gap magnetic field of said one of said permanent magnets.