An interior permanent magnet motor comprising: a rotor assembly disposed within a stator assembly ; the rotor assembly being configured for rotating about a central axis relatively to the stator assembly ; the rotor assembly defining a plurality of magnet pockets within the rotor assembly along a radially outboard surface of the rotor assembly , each magnet pocket being substantially rectangular in cross-sectional shape, and each magnet pocket being configured to facilitate insertion of a group of permanent magnet segments into and retention of the group of permanent magnet segments within, the magnet pocket ; the rotor assembly further comprising a group of permanent magnet segments disposed in each magnet pocket , the stator assembly comprising a plurality of winding posts , each having a stator tooth at a radially inward end of each of the plurality of winding posts , and each stator tooth defining an inner surface , characterized in that each inner surface consists of a leading planar stator tooth surface , an intermediate planar stator tooth surface , and a trailing planar stator tooth surface , wherein the leading planar stator tooth surface and the trailing planar stator tooth surface are angled toward the central axis with respect to the intermediate planar stator tooth surface , and wherein a leading chord length of the leading planar stator tooth surface is substantially equal to a trailing chord length of the trailing planar stator tooth surface , and an intermediate chord length of the intermediate planar stator tooth surface is equal to a sum of the leading chord length and the trailing chord length . a rotor assembly disposed within a stator assembly ; the rotor assembly being configured for rotating about a central axis relatively to the stator assembly ; the rotor assembly defining a plurality of magnet pockets within the rotor assembly along a radially outboard surface of the rotor assembly , each magnet pocket being substantially rectangular in cross-sectional shape, and each magnet pocket being configured to facilitate insertion of a group of permanent magnet segments into and retention of the group of permanent magnet segments within, the magnet pocket ; the rotor assembly further comprising a group of permanent magnet segments disposed in each magnet pocket , the stator assembly comprising a plurality of winding posts , each having a stator tooth at a radially inward end of each of the plurality of winding posts , and each stator tooth defining an inner surface , characterized in that each inner surface consists of a leading planar stator tooth surface , an intermediate planar stator tooth surface , and a trailing planar stator tooth surface , wherein the leading planar stator tooth surface and the trailing planar stator tooth surface are angled toward the central axis with respect to the intermediate planar stator tooth surface , and wherein a leading chord length of the leading planar stator tooth surface is substantially equal to a trailing chord length of the trailing planar stator tooth surface , and an intermediate chord length of the intermediate planar stator tooth surface is equal to a sum of the leading chord length and the trailing chord length . <EOS>