| In order to prevent the damage of electric equipment such as transformer or motor caused by partial overheating of iron core during operation,accurate prediction of magnetic field distribution and iron loss distribution is of great significance to the design and manufacture of electrical equipment.There are still many challenges for engineers to calculate the core loss of electrical equipment accurately in the process of electrical equipment development.By actual measurement,it is found that there exists the harmonic,dc bias and rotational magnetization,etc.in the operation of the electrical equipment,and it is complicated to predict the complex characteristics of electrical equipment under these conditions.At present,the commercial software of electromagnetic field simulation is commonly used in the calculation of engineering to compute the magnetic fields and loss.Because the commercial software can’t accurately estimate rotational loss,there is certain error between the simulated results and measured ones.In this context,in order to improve the calculation accuracy of the rotational loss of the core of electrical products,this thesis carried out in-depth research on the simulation of the rotational magnetization characteristics and the rotational loss of the electrical steel sheet.The main research contents include:Firstly,based on the study on traditional scalar Play hysteresis model,a Play model was established to characterize the vector hysteresis characteristics of electrical steel sheet under rotational magnetization.The mathematical form of vector Play model under rotational magnetization was deduced.Based on the hysteresis loop of electrical steel sheet under rotational magnetization measured by two-dimensional magnetic measurement system,the parameters of the model such as Everett function,shape function and anisotropy matrix were identified.The identified parameters were substituted into the vector Play hysteresis model under rotational magnetization,and the properties of magnetic field intensity were predicted by using the known magnetic flux density trajectory,and compared with the measured data.Secondly,in order to further improve the simulation accuracy of the model,the vector Play hysteresis model under rotational magnetization was further improved.To solve the problem of low simulation accuracy when magnetization was near saturation,the variables were introduced into hysteresis operator to improve the simulation accuracy of the model in saturation region.In order to improve the simulation accuracy in the unsaturated region,an asymmetric Everett function value calculation method was proposed to improve the accuracy of model parameter identification.The form of shape function was improved to make it suitable for simulation under rotational magnetization.The anisotropic coefficient matrix considering axial ratio was modified.The simulation results of the improved vector Play hysteresis model under rotational magnetization were compared with the measured values to verify the validity and accuracy of the model.Finally,based on the hysteresis loop predicted by the improved vector Play hysteresis model under rotational magnetization,the rotational loss of electrical steel sheet was calculated by combining Poynting’s law,and the method was applied to the calculation of rotational loss of ring and frame cores.The study results show that the vector Play hysteresis model under rotational magnetization proposed in this thesis can effectively calculate the rotational core loss of electrical products,improve the calculation accuracy of the core loss of the core,and realize the engineering application of the vector Play hysteresis model under rotational magnetization. |
