Study On Magnetic Field And Vibration Noise Of Squirrel-cage Induction Motor Operating On Asymmetric Rotor

Squirrel-cage induction motors are widely used in the industry, and rotor barbreakages is a common kind of faults in motor operating, it is not only catastrophicfor motor and negative for corporate earning when motor operates under faults, butalso leads to the environmental noise pollution. Therefore, the analysis of thevariation of magnetic field and vibration noise with motor faults are practicallysignificant for maintaining the motor periodically, early diagnosing faults, andmaking production running safely.Firstly, FEM models of the Y802-2squirrel-cage induction motor with rotor barbroken of different degrees are established and the magnetic field is analyzed. Thedistributions of magnetic field, air-gap flux density and the changing law ofharmonic content in air-gap flux density at different degrees of rotor bar broken aresummed up, and a quantitative research of the changing law of stator and rotor coreflux density is taken.Secondly, the electromagnetic force on the cross section of squirrel-cageinduction motor rotor core is calculated, the distribution characteristics ofelectromagnetic force are studied, and the electromagnetic force distributions alongwith fault degrees at different cases of rotor bar broken are analyzed and summarized,all these are based on the precise analysis of magnetic field under rotor bar broken ofdifferent degrees.Lastly, we obtain intrinsic mode in each order frequency and natural frequencyof the stator of the prototype motor, then we compare the intrinsic mode in eachorder frequency with the frequency of the force wave of the radial magnetic forcewhich is generated by the interaction of every order harmonic of the air-gap forconfirming whether resonance of the motor occur or not; The radial magnetic forces are loaded on the inner faces of the stator tooth by APDL language, thedisplacements of all the nodes on the outer faces of the FEA model are calculatedthrough the harmonic response analysis, and we transferred the displacements of allthe nodes into velocities and gain the simulation of acoustical field by usingSYSNOISE, we also get both the acoustic pressure distributions and variation rule ofacoustic power in different levels of faults.In this paper, the magnetic field, vibration and noise of the squirrel-cageinduction motor by the method of FEA is analyzed, and the variation rule based onthe distributions of magnetic and acoustical field when the number of broken barschanges is approached, some results and conclusions in this paper could providepartly theoretical basis for study on induction motor with rotor bars breakages.