EFFECT OF THE STATOR SLOT OPENING ON THE ELECTROMAGNETIC VIBRATION IN A SQUIRREL-CAGE INDUCTION-MOTOR

Field harmonics produce a radial electromagnetic force in a squirrel-cage induction motor with a particular number of rotor slots corresponding to the number of poles. The radial force causes vibration and acoustic noise. In this paper, a simplified equation for the radial force at no-load is introduced, and the relation between the width of the stator slot opening and the radial force is discussed quantitatively. The field harmonic component produced by the interaction between the fundamental magnetomotive force due to the stator current and the pulsation of air-gap permeance dominates for the radial force. Furthermore, the vibration of the stator core due to the radial force is calculated under a simple assumption. The calculated results are verified by experiments.