Design of Power Electronic Transformer Based on Modular Multilevel Converter

Power electronic transformer acts as a key component of the future automation in smart grid, which is the replacement of conventional distribution transformers by a power transformer. In this paper , the optimum design of a power electronic transformer(PET) based on topology of Modular multilevel converter (M2C). M2C is an emerging and highly attractive topology intended for high- or medium-voltage power electronic devices. In the design process, the modulation scheme of M2C is analyzed. A control method for balancing the M2C DC buses has been introduced. The PET includes a dual-active-bridge DC/DC converter. The DC-DC converter realizes magnetic isolation of PET and reduces the transformer size. Meanwhile, both primary-side and secondary-side switches can achieve the zero-voltage-switching(ZVS) .The PET performs power transformer's functions, at the same time, which has advantages such as power factor correction, elimination of voltage sag and swell, and reduction of voltage flicker in load side.