Patent ID: 6900570

Claim:
A brushless electric machine, comprising: a housing comprising two halves separated by a space, the housing being fabricated from a magnetically permeable material and having an interior region; a stator mounted within the interior region and attached to the housing, the stator having a stator winding; a rotor mounted for rotation about a rotational axis within the stator, the rotor comprising a plurality of magnetic pole pieces and permanent magnets circumferentially arranged in an alternating configuration such that each permanent magnet is positioned intermediate a pair of consecutive magnetic pole pieces and the axis of magnetization lies in the plane of rotation of the rotor, the rotor being separated from the stator windings by a first air gap so as to form a first magnetic circuit, the rotor further comprising a first side, a first rotor end cap attached to the first side, a second side, and a second rotor end cap attached to the second side, each rotor end cap contacting at least some of the magnetic pole pieces, each rotor end cap being fabricated from a magnetically permeable material; and a pair of excitation windings, each excitation winding being secured to the housing on either side of the rotor such that the excitation winding extends circumferentially in the plane of rotation of the rotor and about a corresponding rotor end cap, the excitation windings being separated from the rotor end caps by a second air gap, the first and second air gaps cooperating to form a second magnetic circuit that does not pass through the permanent magnets of said first magnetic circuit.