Multilevel inverter employing cascaded transformers

This paper presents a novel multilevel inverter employing series-connected transformers to reduce the harmonics of output voltage. The proposed inverter consists of three full-bridge modules and their corresponding transformers. Continuous output voltage levels can be generated from a suitable selection of turn-ratio of transformer. And it appears as an integral ratio to the input DC source. Because of the series operation of transformers, an output filter inductor is not required. The validity of the proposed multilevel inverter is verified through the experimental results using a 500 [W] prototype, which can generate 110 [V_ac] output voltage from 12 [V_dc] input.