Patent ID: 8120223

Claim:
A permanent magnet machine comprising a stator with electromagnetic windings for stator poles and a rotor located on a rotor axis that is common to an axis for the stator with an air gap between the stator and the rotor; the rotor comprising a plurality of axially-stacked sections, each section comprising a plurality of stacked laminations on a rotor shaft with a key and slot driving connection therebetween; each section having a plurality of magnets located on its periphery, the magnets creating a magnetic flux pattern that interacts with a magnetic flux pattern created by the magnetic windings of the stator poles to develop rotor torque; the laminations in one section having asymmetrically placed first magnet openings for receiving rotor magnets; the laminations of a second section having asymmetrically placed second magnet openings for receiving rotor magnets; the magnet openings for the laminations of the first section having a common geometry with respect to the magnet openings for the laminations of the second section to permit manufacture with a common machine tool; the laminations for the second section being flipped about a radial axis relative to the laminations for the first section following assembly of the rotor, the rotor openings for the laminations of the second section being angularly displaced relative to the rotor openings for the laminations of the first section, whereby rotor torque fluctuations are attenuated.