Development of high frequency step-up transformer for DC-DC converter

High frequency step-up transformers for non-resonant DC-DC converter have been developed. The rated parameters of the transformers are 5kVA of capacity, from 650V, 7.7A of primary to 16.7kV, 0.3A of secondary with squared wave at 5kHz of frequency and the withstand voltage of the transformer is 100kV. Avoiding parasitic oscillation, distributed windings are applied to get low capacitance of the windings and reduce the capacity into about one hundredth. This paper also reports the test result of frequency characteristics of the step-up ratio and phase.