Research On Magnetostrictive Property Under Alternating Magnetization With High Harmonics

As the capacity and volume of the motor become larger,the research on the noise of the motor body is gradually deepening and the magnetostrictive characteristics of electrical steel sheets are an important cause of the vibration of the motor body.In the past 10 years,the measurement and simulation of the magnetostrictive properties of electrical steel sheets under alternating magnetization have achieved rich research results.However,in the actual work of the stator core of the motor,there are a lot of harmonic magnetic fields.The measurement and simulation of magnetostrictive properties of electrical steel sheets under non-standard conditions such as rotating magnetization and harmonic magnetic field magnetization are still to be further studied.Based on the one-dimensional magnetostrictive characteristic measurement system,in this paper,the magnetostrictive characteristics of electrical steel sheets under different harmonic magnetic fields are measured and analyzed.The dynamic vector model describing the magnetostrictive characteristics of electrical steel sheets under harmonic magnetic field is presented.The detailed expression of the parameters in the mathematical model under harmonic magnetic field is derived.The validity of the model is verified by experimental measurements.The magnetostrictive strain calculation of an induction motor is completed according to the measurement database and the magnetostrictive model,which provides an idea and method for the magnetostrictive simulation calculation of the motor core under actual working conditions.The main research contents are as follows:Firstly,based on the existing one-dimensional magnetic characteristic measuring equipment in the laboratory,a three-axis strain gauge is used as a magnetostrictive deformation sensor,and a magnetostrictive measurement system under harmonic magnetic field is given.The magnetostrictive strains of non-oriented electrical steel sheets with different harmonic components,different magnetization directions and different magnetic flux densities are measured.The magnetostrictive strains under different high harmonics and multiple harmonics are measured.Secondly,the experimental data of magnetostrictive properties of electrical steel sheets under the different harmonic magnetic fields are analyzed.The harmonic content and magnetic field harmonic content of the main strain waveform are discussed.The magnetostrictive properties under magnetic fields with high harmonics are analyzed.Thirdly,a dynamic and vector mathematical model describing the relationship between magnetostriction and magnetic flux density is presented in time-dependent form.According to the Fourier expansion formula of magnetostriction under harmonic magnetic field,the mathematical expressions of the parameters in the dynamic vector magnetostrictive model are derived.The model parameters are calculated based on the measured data,and the validity of the model is also verified.Finally,the magnetostrictive deformation of an induction motor is modeled and simulated based on the above magnetostrictive model.In one cycle,the magnetic field data of the stator core unit is collected and output continuously.The model parameters of each unit are calculated based on the interpolation of the model parameter database.Finally,the magnetostriction data of each unit is calculated,and the distribution of the main strain of the motor core is obtained and the deformation of the local part of the core is calculated.