Abstract
A squirrel-cage induction motor (abbr. IM) produces the electromagnetic vibration and the electromagnetic noise by the interaction between many harmonic fluxes in the air gap. Recently, reduction of such vibration and noise has become important subject from the standpoint of environmental improvement. The electromagnetic vibration caused by IM has been studied for many years and its basic phenomena have been analyzed. However, the electromagnetic vibration under load conditions has not been analyzed sufficiently.
In this paper, the effects of slot-combination and skewed slot on the dominant electromagnetic vibration under load conditions are theoretically and experimentally studied. First, general equations of electromagnetic force waves are derived in order to discuss easily, and the characteristics of the force waves for slot-combination and skewed slot are theoretically clarified. Next, the electromagnetic vibration for the several kinds of poles, rotor slots and skewed angles are measured, taking the effect of natural frequency of the motor into consideration. The effects of slot-combination and skewed slot on these measured vibration are characterized by the proposed theory.
