불평형 자기 흡인력 작용에 따른 유도 전동기의 진동·소음 특성

Abstract

This paper presents an analytical technique for modeling the magnetic noise frequency and order in induction machines, which allows the air gap radial magnetic forces to be expressed as functions of the space harmonics due to eccentricity such as unbalanced magnetic pull (UMP), saturation, slot geometry, and the winding arrangement. The presence of harmonic-fluxes in the air gap of an induction machine produces a variety of undesirable phenomena such as parasitic torques, stray losses and magnetic noise. The radial forces, known as Maxwell’s forces, that act on the stator and the rotor are associated with the magnetic fluxes entering or leaving the iron surfaces. The harmonics in the air gap field are produced due to the distribution of the current carrying conductors in slots, slotting of the stator and rotor surfaces and magnetic saturation of the iron. Another inadvertent source of harmonic production is the eccentricity of the rotor. In actual machines the distribution and magnitudes of all the harmonic fields are also distribution and magnitudes of all the harmonic fields are also affected by the permeance variations due to the presence of slots on the stator and rotor surfaces. The use of permeance waves involves essentially a consideration of only the radial field components in the air gap. Thus, the forces acting on the stator and rotor can be easily obtained from the air gap flux density distribution.