Single-phase boost DC-link integrated cascaded multilevel inverter for PV applications

Abstract

This study presents a new boost DC-link integrated multilevel inverter (BDIMLI) topology for single-phase stand-alone photovoltaic applications. The BDIMLI is realised by the integration of two two-level boost DC-link converters (TBDCs) with a hybrid H-bridge inverter using symmetrical voltage sources. Conventional cascaded multilevel inverters require a large number of isolated DC source and circuit components. On the other side, switched capacitor multilevel inverter topologies require less number of sources and components, but need bulky capacitors. The proposed TBDC units charge the capacitors to the desired voltage with the high switching frequency, hence require less capacitance and component count. The proposed topology with proper selection of capacitor voltage levels can produce 9-, 11- and 13-level outputs without altering any circuit components. Besides, the proposed topology produces low-frequency common-mode voltage. The comprehensive analysis of BDIMLI in comparison with recent multilevel inverter topologies is presented. An experimental prototype of BDIMLI is built and its dynamic behaviour with different load conditions is presented for both 9- and 13-level operations.