A Multiphase Series Connected Converter for High Voltage High Power Dc-dc Applications

Modular multilevel series topologies such as parallel hybrid converter (PHC) are gaining popularity in high power applications owing to fewer sub-modules (SMs), low energy storage and switch requirements. However, the existing PHC requires bulky dc link inductor due to the presence of large voltage ripples at the dc link. Moreover, the voltage handling capability of the PHC is limited because of the use of series-connected switches in its H-bridges. This paper presents a series-stacked multi-phase topology suitable for high voltage high power dc-dc conversion applications. The multiphase structure employed in the proposed converter helps in increasing power level, improving modularity and reliability, and minimizing the dc filtering requirement. A multi-phase front-to-front simulation model developed in PSCAD/EMTDC affirms the performance of the proposed converter. The working principle of the proposed topology is also verified by a developed single-stage hardware prototype.