A reluctance machine includes a stator having a stator core. The stator
core includes a central bore and a plurality of stator poles extending
inwardly from the stator core. Each of the stator poles includes a stator
pole face. The reluctance machine further includes a rotor having a
plurality of rotor poles. Each of the rotor poles includes a rotor pole
face. Each of the rotor pole faces includes a first portion, a second
portion that is radially inwardly stepped with respect to the first
portion to create a non-uniform air gap between the rotor pole face and a
corresponding stator pole face, and a protrusion located at an edge of
the second portion of the rotor pole face.