Research On The Magnetostrictive Property Under Rotational Magnetization

The magnetostriction of electrical steel sheet is widely considered as a source of the vibration in electric apparatus.Its property is closely relevant to such factors as the magnetization mode,magnetization frequency,stress,and so on.The accurate measurement and simulation of the magnetostrictive property of electrical steel sheet are significant for the research of the vibration and noise of electric apparatus such as motor,transformer and so on.There is a large number of rotational magnetization in the motor core and T-joint part of three phase transformer core.The research on measurement and simulation of magnetostrictive property of electrical steel sheet under rotational magnetization is still in its infancy overseas,but it has not been reported in China.In this paper,the measurement system of magnetostrictive property of electrical steel sheet under rotational magnetization in the laboratory is developed.The magnetostrictive property of a single piece of electrical steel sheet under different magnetization trajectories is measured and analyzed.The dynamic vector model is proposed,which describes the property of the rotational magnetostriction.The calculation methods of the model parameters are derived.The effectiveness of the model is confirmed by the experiment.The magnetostriction and the local deformation of the stator core of a synchronous generator are quantitatively calculated,which lays a foundation for the accurate calculation of the vibration and noise of the motor core.Main contents are summarized as follows:First of all,the independent development measurement system of magnetostrictive property under rotational magnetization is improved.The stacking position of the strain gauge in original system is moved to the center region of the sample to improve the measurement accuracy.And the magnetostriction data is measured under different rotational magnetization loci.Then,the distribution of the strain in arbitrary direction at different instants,the waveform changes of principal strain and principal angle during a magnetization period and the change rules of the peak value of the principal strain are analyzed under different magnetization conditions.The harmonic components of the principal strain waveform and the vector and hysteresis property between the principal strain and the magnetic flux density are discussed.Again,the dynamic vector model is proposed,which describes the vector relationship between the principal strain and magnetic flux density.The horizontal and vertical directions components of the principal strain are expressed as the sum of three terms,which are the constant term related to the magnetization locus,the variation term of the magnetic flux density with time and the derivative term of the magnetic flux density to the time.The mathematical expressions of the model parameters are derived in detail.The model parameters are calculated based on measured data.A database of the model parameters is built.And the effectiveness of the model is confirmed.Finally,the magnetostrictive deformation of a synchronous generator is modeled and simulated based on the magnetostrictive model.During a period,the magnetic field information of each element of the stator core at discrete instants is acquired and exported.Based on the databases of the model parameters,the model parameters of each element are calculated by the interpolation.Then,the magnetostriction data of each element is calculated.The distribution of the principal strain and the deformation of the local region are acquired.