Research And Application Of Magnetostriction Property For Non-oriented Silicon Steel Sheets

The vibration and noise of iron core caused by its magnetostriction are one of the mainreasons that result in the motor vibration and noise. To study the effect of the iron core’smagnetostriction on the vibration, in this paper, the magnetostrictive properties of anon-oriented silicon steel sheet with ac excitation applied was deeply investigated. Basedon a one-dimensional magnetostriction measurement device, a method measuring themagnetostrictive property along arbitrary directions for a single non-oriented silicon steelsheet was proposed. A λ-(θB, Bmax) magnetostrictive mathematical model was built todescribe the relationship between magnetostriction and magnetization, and by usingFORTRAN computer language, the finite element calculation program coupled withmagnetostrictive model above was compiled, and the magnetostrictive phenomenon in thestator core of a synchronous generator was analyzed. The main research contents weregiven as follows:First of all, the magnetostrictive data of the non-oriented silicon steel sheet underdifferent magnetic flux density values were measured by using a magnetostrictivemeasurement device. In order to develop the magnetostrictive property along differentmagnetization directions for a non-oriented steel sheet sample, the magnetostrictive dataalong different angles between cutting direction and rolling direction are obtained. For theconvenience of engineering application of the measurement data, the magnetostrictivesingle value curves along different magnetized directions were abstracted in this paper, andthe magnetostrictive surface describing the relationship among the magnetostriction,magnetization value and direction was obtained by interpolation technique.Secondly, on the basis of research on the mathematical models describing material’sthe magnetostrictive property such as linear piezomagnetic equation, a λ-(θB, Bmax) modelwas proposed to modeling the anisotropic magnetostrictive characteristics of non-orientedelectrical steel sheet, and the finite element computation course of magnetic field coupledindirectly with this model was presented. Then, the finite element program taking the magnetostrictive property into accountwas compiled with FORTRAN language. Taking a simple magnetic simulation model as atest example, the comparison between the simulation computation results and experimentalones was analyzed and the effectiveness of the magnetic field analysis method wasverified.Finally, taking example of a3.025MVA three phases synchronous generator, itsmagnetostrictive distribution of motor stator iron core with no load was obtained, and themagnetostrictive deformation of iron core was analyzed when the stator’s magnetic fluxdensity changed with time periodically.