A transformer-Less DC-DC converter with large voltage transformation ratio for medium-voltage DC grid applications

This paper presents a transformer-less dc-dc converter with large voltage gain for medium voltage dc grid applications. The converter is based on a combination of boost converter and a series-parallel resonant circuit with capacitive output filter. Soft-switching of the power switches and diodes are naturally achieved due to the resonant operation. The power switches and the output diodes are subjected to a lower voltage stress compared to topologies presented in the literature. The proposed converter is modular such that multiple modules can be built (series/parallel) to achieve the desired voltage and power rating. Operating principles, analysis, and simulation results are presented to verify the effectiveness of the proposed converter.