A Three-Level Converter with Reduced Filter Size using Two Transformers and Flying Capacitors

Abstract

This paper proposes a pulse-width modulation (PWM) three-level converter with reduced filter size using two transformers. The proposed converter has many advantages. All switches sustain only the half of the input voltage and since the secondary rectified voltage is a three level waveform, the output filter inductor can be reduced. Also, because of the power sharing of transformer and reduced output inductor, high efficiency can be obtained. The operational principle, analysis, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 600W, 500-600V input, and 60V output.