A 21-Level Boost Inverter with Limited Inrush-Current of Capacitors Suitable for AC Microgrids

Multilevel inverters with the integration of switched-capacitors (SC) are emerging in recent years due to their attractive features such as voltage boosting, natural voltage balancing of capacitors and single-stage power conversion using a single dc source. To alleviate the inrush current due to the charging operation of SC, this paper proposes a novel quasi-resonant switched-capacitor based multilevel inverter (QRSC-MLI). By using only 15 power switches, the proposed topology is capable of generating 21 voltage levels. Therefore, high resolution ac voltage is achieved with minimal total harmonic distortion (THD). In addition, voltage stress across power switches is lower than the maximum voltage level signifying low switching loss that reduces cooling requirement for higher compactness and lower cost. The operation of the proposed topology is verified via simulation study.