Research On Hysteresis Characteristics Of Electrical Steel Under DC Bias Condition Based On J-A Theory

The dc-biased magnetization is an unusual exciting condition for the AC power transformers,resulting in overheating,insulation degradation and heavy noise of the transformer.In addition,with the complexity of operating conditions,some electromagnetic equipment is not only affected by DC bias,but also accompanied by some high-frequency components.It is necessary to consider the effects of frequency and DC bias on the hysteresis loops.The main points of this article are:(1)The dynamic J-A model based on the classic Jiles-Atherton(J-A)model and iron loss separate theory are proposed in the way of studying the effect of eddy current loss and abnormal loss on the hysteresis loop.(2)Aiming at the problems of poor optimization ability and long calculation time existing in current single intelligent algorithm,a hybrid algorithm combining artificial fish school algorithm and linearly decreasing particle swarm optimization algorithm with optimized inertia weight is proposed.The results prove that the proposed hybrid algorithm has the advantages of being not easy to fall into local optimal solution,faster convergence speed and higher parameter identification accuracy compared with other single intelligent algorithms;In order to solve the dynamic loss coefficient,this paper uses the method of loss separation,and derives the eddy current loss and abnormal loss expressions based on Maxwell equations and loss statistics theory.Based on the field separation approach,the analytical expressions of the magnetic field strength and each loss are established to solve coefficients.(3)The magnetic properties measuring system under sinusoidal excitation was built by Epstein frame,where the hysteresis loops and core less were measured under different frequencies.Analyze the effect of frequency on the hysteresis characteristics of static simulation of magnetic materials.Based on the laws obtained from the analysis,the existing high-frequency dynamic modeling methods are reasonably improved to achieve a more accurate simulation of the hysteresis characteristics under high-frequency excitation conditions.(4)The magnetic properties measuring system under DC bias was built by Epstein frame and special DC power supply,where the hysteresis loops and core less were measured under different DC bias.A dynamic modeling method of high-frequency magnetic bias is proposed.Based on the above experimental data,the variation of model parameters(static model parameters,dynamic loss coefficients)with frequency and magnetic bias under the condition of magnetic bias is studied.The method in this paper is verified by the comparison between the calculated and experimental results.The results and conclusions obtained in this paper have important engineering significance and application prospects for the core loss calculation of transformers.