Abstract：High-frequency transformers are an essential component in series-resonant DC/DC converters，and

their stable operation has a decisive impact on the reliability，efficiency，and power density of power supply

systems. Nanocrystalline magnetic cores are widely used due to their advantages of high saturation magnetic flux，

high magnetic permeability，low coercivity，and low high-frequency losses. In order to improve the power density

of DC/DC converters，the leakage inductance of high-frequency transformers is commonly used as a resonant

inductor to achieve the soft-switching characteristics of the switching devices. However，nanocrystalline alloys

possess a high electrical conductivity，and when high-frequency leakage magnetic flux passes perpendicularly

through the surface strip，it induces strong eddy currents，which could result in potential thermal issues，thereby

compromising the stable and safe operation of the transformer and the system. An improved finite element

simulation method for high-frequency transformers was proposed for determining the distribution characteristics of

additional eddy current losses induced by high frequency leakage flux at large leakage inductance by building a

three-dimensional model of nanocrystalline strips at the edge of the independent core，and its validity was verified

by temperature rise experiments.

      Key words：nanocrystalline core；high-frequency transformer；leakage inductance；eddy current loss