A transformerless modular step‐up dc–dc converter for high power applications

This study presents a new step‐up dc–dc converter topology suitable for medium voltage, megawatt scale applications. The proposed converter interconnects unipolar or bipolar dc networks using a single inductor and a modular active switching network. The active switching network contains multiple series‐connected identical converter modules. Each module consists of four switches and one capacitor. The modular nature of the switching network allows scalable implementation of the converter, and utilisation of low‐voltage switches and capacitors. The proposed converter avoids the use of medium‐frequency isolation transformers. Soft switching is utilised to reduce the converter's switching losses. An analytical model of the converter is developed to facilitate converter design. Theoretical predictions are supported by a 7.6 kW scaled laboratory prototype achieving an efficiency of as high as 93.2%.