Switched-Capacitor Boost Common-Ground Six-Switch Seven-Level Inverter with Simplified Control

Recent research and developments in transformerless inverters are evidence for voltage boosting while multilevel output generation as well leakage current elimination in photovoltaic grid-tied systems. However, existing multilevel transformerless inverters (MTIs) require more number of switches and the number of voltage level is not significant. This paper introduces a novel 7-level MTI with common-ground feature employing only one input source and three complementary switches. Owing to the common-ground connection, leakage current can be nullified. The complementary switch operation reduces control complexity as only three control pulses are required to be generated. Switched-capacitor (SC) based proposed structure employs three capacitors, which are all maintains required voltage naturally. SC MTIs generally suffers from high charging current. Using a resonant cell in the input side, soft charging is attained. The operation of the proposed MTI to generate 7L output is explained and design criteria is presented. Comparative analysis with extensive simulation and experimental results are provided to validate the structural innovation.