Research On The Hysteretic Modeling Of Silicon Steel Sheet Under Non-sinusoidal Magnetization

As an indispensable part of power equipment and electronic devices,soft magnetic materials represented by silicon steel sheet have been widely concerned and studied by researchers and transformer manufacturers.The cores of large-scale motors,transformers,reactors and other equipment are usually magnetized by the sinusoidal excitation of power frequency.However,with the popularization of high voltage DC transmission（HVDC）technology,the large number of power electronic components generate DC bias and high order harmonics in power system,which leads to the distortion of magnetic flux and the increase of iron loss,aggravating local overheating and endangering the safe operation of power system.Therefore,the research on non-sinusoidal excitation is studied.The magnetic properties simulation method of silicon steel sheet is of great significance to the optimizing design and safe operation of electrical equipment.The research in the paper is sponsored by the National Natural Science Foundation of China（Grand No.51777073,51577066）and National Key Research and Development Program of China（Grand No.2017YFB0902703）.In this paper,the static and dynamic hysteresis loops of grain oriented（GO）silicon steel（27ZH95）under non-sinusoidal excitation are measured by Epstein frame in BROCKHAUS magnetic property measurement platform,and the loss curves of hybrid excitation are analyzed.Afterwards,the dynamic hysteresis model under harmonic excitation is constructed by combining the classical Preisach model and the theory of loss separation.In terms of the excess loss component,the function between the statistical parameter V₀ and the peak value of flux density B_m and frequency f is constructed according to the mathematical relationship.The dynamic model of harmonic excitation can be extended to the hybrid excitation of DC bias,fundamental and single harmonic.For the static part,the Preisach model is improved to generate asymmetric Everett functions based on the ascending and descending branches respectively,which is suitable for the simulation of asymmetric hysteresis loops caused by DC bias.As for the dynamic part,the functional relationship of statistical parameter V₀with respect to harmonic order k,peaked flux density B_acm and DC magnetic field strength H_dc is constructed.In order to extend the model,the hybrid excitation with various phase difference is analyzed.By comparing the simulated results from the proposed dynamic hysteresis model with the experimental ones under different non-sinusoidal conditions,it is found that the hysteresis loops are in good agreement,and the error s of corresponding total loss are mostly less than 10%,which verifies the effectiveness and accuracy of this paper.