Patent ID: 6989619
Filing Date: 2006-01-24
Classification: H02K

Abstract:
1. A brushless electric machine comprising: a stator and a rotor spaced from the stator to define a primary air gap relative to an axis of rotation for the rotor; a rotor having an axis of rotation and having pairs of rotor pole portions of opposite polarity disposed at least partly around a circumference of the rotor; first and second stationary excitation coil assemblies for receiving direct current from an external source and being positioned across secondary air gaps so as to induce a component of flux in the rotor which increases a resultant flux in the primary air gap when said direct current is of a first polarity and which reduces resultant flux in the primary air gap when said direct current is of a second polarity opposite said first polarity; wherein permanent magnet (PM) material is disposed between the rotor pole portions for conveying a second component of flux to or from the primary air gap and for inhibiting the component of flux from leaking from said pole portions prior to reaching the primary air gap when said direct current is of the first polarity; and further comprising ring-shaped flux collector members disposed between the first stationary excitation coil assembly and the second stationary excitation coil assembly and respective ends of the rotor to conduct flux in an axial direction relative to the rotor while inhibiting eddy currents.