An interior permanent magnet (IPM) machine having a rotor and a stator is provided. The rotor includes a radially inner barrier devoid of magnets, and a radially outer barrier having at least one permanent magnet, each barrier having two pockets with one pocket disposed at an angle relative to the other. At least one of the pockets of the inner barrier has a shape of an irregular quadrilateral. At least one of the pockets of the outer barrier has a substantially trapezoidal shape with a first side generally parallel to a second side, wherein the first side has a portion slanted relative to the third side. In such an IPM machine, demagnetization of the outer barrier magnet is limited when operating temperatures and electrical current exceed operating conditions prescribed by design specifications.