Variable-inverter-rectifier-transformer: a hybrid electronic and magnetic structure enabling adjustable high step-down conversion ratios

This paper proposes a hybrid electronic and magnetic structure that enables transformers with “fractional” and reconfigurable turns ratios (e.g. 12:0.5, 12:1, 12:2). This functionality is valuable in converters with wide operating voltage ranges and high step-up/down, as it offers a means to reduce copper loss within the transformer while also facilitating voltage doubling and quadrupling. We introduce the principle of operation of the structure and present models for its magnetic and electrical behaviour. An experimental prototype capable of accommodating a widely varying input (120-380 V_dc) and output (5, 9, 12V) validates the operating principle and modelling of the proposed structure and achieves conversion efficiencies between 93.4% and 95.7% at 25-36 W.