Patent ID: 6891302

Claim:
A brushless electrical machine, comprising: a rotor for rotation about an axis, said rotor being constructed of a rim portion and a substantially hollow a center portion; said rim portion being constructed from ferromagnetic material and having a partially hollow core at an inner end of a slot into said hollow core, said slot being defined by opposing surfaces, one of which has multiple, circumferentially spaced protrusions around said rotor; a stationary field coil mounted coaxial with said rotor and located in said partially hollow core of said rim portion, said field coil having windings that can be electrically energized to produce homopolar magnetic flux in said protrusions, and said flux circulates in a poloidal flux path in said rim, said poloidal flux path having a single magnetic air gap across said slot; a plurality of stationary armature windings located within said magnetic air gap such that said homopolar flux from said protrusions induces an alternating voltage in said armature windings when said rotor rotates.