The Critical Saturation Magnetization Properties of Nanocrystalline Alloy Under Rectangular Wave Excitation with...

High-frequency transformers are subject to excitation with a changing duty cycle during operation. Due to magnetic relaxation, the duty cycle of the rectangular wave affects the magnetization time of nanocrystalline alloy for the core material, which affects whether the transformer can reach the saturation operating point. Based on the micromagnetic theory, a three-dimensional model of the nanocrystalline alloy is established, and rectangular wave excitation with different duty cycle D is applied to the micro-model. The influence of D on the magnetization process is analyzed in terms of the hysteresis loss P_v and magnetic moment deflection angular velocity ω. The results indicate that when D = 0.5, P_v is the smallest, and when D increases or decreases, P_v increases. Furthermore, P_v remains the same under the rectangular wave excitation that satisfies the sum of different duty cycles of 1. Regarding ω, the smallest value occurs at the rising edge of the excitation when D = 0.1, while the largest value occurs when D = 0.9. During the falling edge stage, ω is smallest when D = 0.9 and largest when D = 0.1. These results demonstrate that the duty cycle D influences the magnetization time of the material. Due to magnetic relaxation, changing the magnetization time determines whether the material can reach saturation magnetization. Therefore, there is a critical state, which is defined as the critical duty cycle D_c. The results show that for D < 0.5, the range of D_c1 is between 0.2 and 0.21, and for D > 0.5, the range of D_c2 is between 0.8 and 0.81. Increasing the amplitude of the excitation source causes a decrease in D_c, while increasing the frequency causes an increase in D_c.