US Patent 7816830 Permanent magnet alternator with segmented construction

A permanent magnet apparatus (10) for achieving electrical performance is provided. The apparatus (10) includes a cylindrical stator assembly (12) having a plurality of stator pole assemblies (92) and a cylindrical rotor assembly (14) having a plurality of rotor pole assemblies (20). Each stator pole assembly (92) includes a wire coil (102) and a laminated stack (98) of axially aligned stator segments (100). Each of the stator segments (100) has a center-post portion (106) that is detachably engaged to a back-iron portion (104). Each rotor pole assembly (20) is provided with a laminated stack (28) of axially aligned rotor segments (30) to which is secured a permanent magnet (32). Preferably, the stator pole assemblies (92) are secured to a base plate (26) by fastening rods (74) and the stator assembly (12) includes stacks (156) of back-iron portions (104) where each stack (156) is positioned to abut two stator pole assemblies (92). The rotor pole assemblies (20) are preferably secured to a rotor plate (24) by fastening rods (74) and magnet retention-stops (66,68) defined by stacked rotor segments (28,84) frictionally support the permanent magnet (32). The apparatus (10) is most desirably operated as a low-shaft-speed, permanent magnet alternator.