Design of Power Electronic Transformer based on Cascaded H-bridge Multilevel Converter

One key component of the future automation in electrical network is the replacement of conventional distribution transformers by an all-solid-state (power- electronic) alternative. In this paper, the optimum design of a power electronic transformer (PET) based on state of the art cascaded H-bridge multilevel converter is investigated. In the design process, a new and simple control method for balancing the cascaded H-bridge DC buses has been introduced. The proposed PET is extremely modular and can be extended for different voltage and power levels. It performs typical functions and has advantages such as power factor correction, elimination of voltage sag and swell, and reduction of voltage flicker in load side. Also in comparison to conventional transformers, it has lower weight, lower volume and eliminates necessity for toxic dielectric coolants.