A stepper motor includes a rotor, a stator, a plurality of stator windings, and a plurality of permanent magnets. The permanent magnets are coupled to the outer surface of the rotor and are spaced apart from the plurality of stator poles, and each permanent magnet is shaped like an arc having an arc length and is circumferentially spaced apart from two adjacent permanent magnets by a spacing angle. In some instance, the arc length of each permanent magnet is equal, and the spacing angles are not all equal. In other instances, the arc length of two or more of the permanent magnets is unequal to the arc lengths of the other permanent magnets, and the spacing angles are not all equal.