VP12-02: Research on the simulation accuracy of static hysteresis loops of non-oriented silicon steels using a simplified LLG equation

Introduction Establishing an accurate hysteresis model is significant for predicting the loss of electrical equipment. Currently, most hysteresis models widely used are macroscopic phenomenological models, which lack research on the magnetization mechanism for the material[1]. Based on the micromagnetic Landau-Lifshitz-Gilbert (LLG) equation, a simplified mesoscale model for simulating the DC hysteresis characteristics of electrical steels is presented[2]. However, the simulation accuracy of this model is relatively poor for the hysteresis loops in the region of demagnetization and low magnetic flux densities. To solve this problem, a modification of the simplified LLG equation model is proposed by introducing a hysteresis energy density function to improve the global hysteresis simulation ability of non-oriented(NO) electrical steel. Method and Discussion To improve the calculation accuracy for all flux density levels, a hysteresis energy density function is introduced, which considers the domain wall's movement, and the domain's volume fraction followed by the Boltzmann distribution, as shown in Fig.1(a). The total magnetization can be calculated as the sum of the hysteresis magnetization and the magnetization of the simplified LLG equation. To get the parameters of the modified model, five quasi-static hysteresis loops are measured by a one-dimensional measurement system based on the Epstein Frame, as shown in Fig.1(b). The trend of parameter changes with magnetic density is shown in Figure 2(a) to(d). To verify the validity of the improved model, the calculated results were compared with the experimental data. The simulation accuracy of the proposed model is better in the demagnetization region at high magnetic densities and low magnetic densities. Conclusion In this paper, a modification of the simplified LLG equation is proposed to simulate global static hysteresis properties of NO electrical steels. The obtained results show that the proposed model can accurately simulate the static hysteresis loops of NO electrical steels in high and low magnetic flux density regions.References: [1] R. Zeinali, D. C. J. Krop, and E. A. Lomonova, IEEE Transactions on Magnetics, Vol. 56, no. 1, 6700904 (2020). [2] Y.Hane, K.Nakamura, and T.Ohinata, IEEE Transactions on Magnetics, Vol. 55, no. 7, 8401306 (2019).