The effect of tooth shape on radial forces in step motors

The effect of tooth shape on radial forces inside the air-gap acting on the stator for a typical step motor tooth profile is investigated by a 3D finite element method. It is found that the radial force acting on the stator varies from high to low values due to rotor movement. The magnitude of the vibration depends on the tooth shape and the stator and rotor tooth to valley ratio and level of saturation. The results show that a rectangular tooth shape with a stator tooth to valley ratio of 1:1 and a rotor tooth to valley ratio of 1:3 is the best for reducing radial force variation for the cases studied.<>