Three-level LLC SRC for high and wide input voltage applications

Abstract

A new three-level LLC series-resonant-converter (TL LLC SRC) for high and wide input voltage applications is proposed. It consists of two half bridge LLC SRCs in series, sharing a resonant inductor and a transformer. The main advantages of the proposed converter are that the voltages across all switches clamp to half of the input voltage and keep the balance. Thus, it is suitable for high input voltage applications. Moreover, due to its simple driving signals, the additional circulating current of the conventional TL LLC SRCs does not appear in the converter, and driving circuitry can be designed to be simpler. The validity of this study is confirmed by the experimental results of a prototype converter with 400-600V input, 48V/20A output.