High frequency analysis of switch-mode power transformer with coaxial winding structures for DC-DC converters

A multielement transformer with coaxial winding structure is found to have an excellent voltage ratio and low leakage inductance at high frequency applications. From a small signal test, the voltage ratio is very close to the turn ratio up to 17 MHz. The high frequency equivalent circuit with measured parameters matches the signal test closely from 100 kHz to 1 MHz. The ratio between the leakage inductance and the magnetizing inductance is 0.3265% at 1 MHz. It is an idea power transformer for DC-DC converters, comparing with pot core transformers and planar structure transformers.