Magnetostrictive Characteristics Modeling Of Electrical Steel Sheet Considering The Effect Of Stress And Its Application

Noise has become an important index to evaluate motor performance,and the study of motor noise is inseparable from the performance analysis of motor vibration characteristics.The stator core of the motor is comprised by laminated electrical steel sheets,and the magnetostrictive phenomenon under the action of external magnetic field causes the core vibration.Aiming at the problem that the residual stress produced in the processing of electrical equipment such as transformers and AC motors will aggravate the vibration of motor core body,this thesis studied the mathematical model of magnetostriction of electrical steel sheet considering the influence of stress and its engineering application.The magnetostrictive characteristics were measured and analyzed by means of a set of measuring device for magnetic characteristics of electrical steel sheet under stress.On this basis,the magnetostrictive model employing the hyperbolic tangent function and the magnetostrictive model based on Helmholtz free energy were derived,and the parameter identifications for these two magnetostrictive models were carried out using the magnetostrictive characteristics data affected by stress.The magnetostrictive displacement distributions in a surface-mounted permanent magnet servo motor core under the action of external stress were analyzed and calculated by using a multi-physical field simulation software,which lays a foundation for accurately predicting the vibration and noise of the motor body.The main research contents are as follows:Firstly,the magnetostrictive strain characteristics of electrical steel sheet under the action of both external stress and magnetic field were measured.With the help of a set of measuring device for magnetic characteristics of electrical steel sheet under stress,the magnetostrictive characteristics of non-oriented electrical steel sheet under different magnetic flux densities were measured with the stress varying from-8MPa to 8MPa.The measurement results show that the magnetostrictive strain decreases with the increase of the tensile stress and the compressive stress increases the magnetostrictive strain.Secondly,on the basis of analyzing the above magnetostrictive characteristics of electrical steel sheet,the magnetostrictive model employing the hyperbolic tangent function and the magnetostrictive model based on Helmholtz free energy were derived,and the corresponding computer programs were compiled.Thirdly,based on the measured data,the parameter identification the above two magnetostrictive models was completed,and the relationship surface among the magnetostriction,the applied magnetic field,and stress was presented.The modeling accuracy of these two models was compared and analyzed.The results show that the modeling accuracy of the magnetostrictive model based on Helmholtz free energy is better than that based on hyperbolic tangent function.Finally,the above magnetostrictive models were applied to the multi-physical field simulation calculation of magnetostrictive strain of motor core.The simulation model for the magnetic field and structure force field of surface-mounted permanent magnet servo motor was established.Based on the multi-physical field simulation software,the effect of external stress on the core displacement of permanent magnet motor was calculated and analyzed.The calculation results show that the magnetostrictive models may effectively simulate the deformation performance of motor core under the effect of stress.