Evaluations and measurements of a high frequency nanocrystalline core transformer for power converters

This paper presents a method for evaluations and measurements of a high frequency nanocrystalline core transformer for power converters. An experimental platform is set up to measure the B-H characteristics of the core and the performances of the transformer with a frequency range up to 100 kHz. Using the measured B-H characteristics, a 3D FEM model of the transformer is built to simulate the performances and calculate the equivalent circuit parameters of the transformer that will be verified by the experimental data. The results show that the B-H characteristics of the nanocrystalline core are non-linear with frequency but well linear before it starts to saturation at a magnetic field of 0.6~0.8 T depending on the frequency. The linear relative permeabilities of the core are as high as around 20000 at room temperature, and the iron losses are so low that the efficiencies of the transformer are kept over 99% in the frequency range of under 100 kHz and with a magnetic field within 0.66 T.