A Design Method of Transformer Turns Ratio with the Loss Components Analysis of an Isolated Bidirectional DC-DC Converter

This paper deals with transformer turns ratio design with the consideration of loss minimization in isolated bidirectional DC-DC converter. Generally, the rms value of current, magnitude of current at switching instance, and duty ratio of a converter vary according to the turns ratio of an isolation transformer in the converter under the same voltages and output power level. Therefore, the transformer turns ratio has an effect on the total loss in a converter. The switching and conduction losses of IGBTs and MOSFETs consisting of dual-active bridge converter are analyzed, and iron and copper losses in an isolation transformer and inductor are calculated. Total losses are calculated and measured in cases of four different transformer turns ratios through simulation and experiment with 3-kW converter, and an optimum turns ratio that provides minimum losses is found. The usefulness of the proposed transformer turns ratio design approach is verified through simulation and experimental results.

절연형 양방향 DC-DC 컨버터의 손실 성분 분석을 통한 변압기 권선비 설계 방법