Magnetic Field Analysis for HF Transformers with Coaxial Winding Arrangements

Magnetic analysis for high frequency (HF) transformers is an important step in designing the magnetic parts of the isolated DC-DC converters. A robust and effective magnetic design help to reduce the parasitic values such as leakage inductance and consequently increase the efficiency and improve the performance of the converters. In this paper, two different HF transformers with different winding arrangements are designed and analyzed. Coaxial windings are used for the transformers in order for obtaining a better magnetic coupling and lower leakage inductance. The results are compared to the regular windings and this comparison showed the effectiveness of the coaxial windings. The design procedure and results are conducted for a power rating of 2kW and a voltage level of 400V/400V at the frequency of 5 kHz. The design method and the analysis procedure used in this paper can later be used for designing optimal isolated DC-DC converters or integrating parasitic parameters in resonant tank circuits for achieving zero voltage switching (ZVS) and zero current switching (ZCS). Especially for converters including silicon carbide (SiC) and gallium nitride (GaN) switches. For analyzing the results and magnetic fields, finite element method (FEM) is used as a numerical strategy.