A permanent magnet machine includes a rotor and an irregular polyhedron shaped magnet assembly. The rotor may define at least one magnet opening and may be configured to rotate within a circular opening defined by a stator. The irregular polyhedron shaped magnet assembly may be disposed in the magnet opening and may define a magnetization direction, wherein a height along the magnetization direction and perpendicular with a lamination plane of the rotor is greater at both ends than at a central portion disposed therebetween.