Kj. Binns et al., MAJOR DESIGN PARAMETERS OF A SOLID CANNED PERMANENT-MAGNET MOTOR WITHSKEWED MAGNETS, IEE proceedings. Part B. Electric power applications, 140(3), 1993, pp. 161-165
Permanent magnets buried in the rotors of synchronous machines are now
accepted as a means of producing a high performance machine which can
take advantage of rare earth magnets. The magnets can with advantage
be nonradial, but an alternative strategy is to use radial magnets wit
h a significant skew. It will be seen that this arrangement leads to a
drastic reduction in harmonics and cogging torques. The use of a supp
orting tube on the rotor whether magnetic or not, is also investigated
with a view to overcoming problems of high-speed operation.