Electromagnetic Analysis Of A Triple Phase Inner-Feeding Asynchronous Motor

Inner-feeding motors are widely used as the high efficient, smooth, poleless,speed-adjusting AC asynchronous motors, and they are more economic thanvariable-frequency motors. But because of the electromagnetic coupling of the mainwinding and the inner-feeding winding that is different from the general asynchronousmotors, inner-feeding motors are easy to vibrate. Radial electromagnetic force is one of themain roots of motor vibration, so that study on radial electromagnetic force not onlypromotes the studies of motor performance, but also effects human health. This paper takesa inner-feeding motor YQT2450-6as example, studies on the main root of motor vibrationbased on field-circuit coupling method.Firstly, the effect of inner-feeding winding is neglected, the distribution for the fluxlines, air gap flux density and radial electromagnetic force are analyzed at the time ofempty load and rated load based on field-circuit coupling method, then the air gap fluxdensity and radial electromagnetic force are analyzed by means of Fourier analysis, so themain electromagnetic force which leads to vibration can be get. Further, this motor’s soundintensity level is solved. This can lay a foundation for analysis that considers the factor ofinner-feeding winding.Next, the paper explains the influence to air gap flux density and radialelectromagnetic force wave with different structure parameters such as air gap flux density,air gap length and slot width and so on. Then simulating different models whose statorslots are open or closed at the time of empty load and rated load using commercial finiteelement software, distribution of air gap flux density and radial electromagnetic force waveare obtained. This can provide reference for electromagnetic noise analysis in engineeringpractice.At last, inner-feeding winding is considered. The distribution for the flux lines, air gapflux density and radial electromagnetic force are solved at the time of empty load and ratedload based on field-circuit coupling method, then the air gap flux density and radial electromagnetic force are analyzed by means of Fourier analysis, and the sound intensitylevel is solved. At last, the important reason of motor vibration is obtained at time of ratedload through comparison with or without inner-feeding winding.