A Novel 7-Level Triple-Boost Common-Ground Switched Capacitor Based Inverter

Multilevel inverters (MLIs) with a common ground (CG) feature have gained significant popularity in transformer-less grid-connected photovoltaic (PV) systems. In this paper, a novel switched capacitor (SC) based common ground type seven-level inverter topology with triple voltage boosting capability has been proposed. The common ground feature of the proposed inverter bypasses the PV stray capacitor, resulting in zero leakage current in the stray capacitor of the PV system. The proposed inverter topology requires two capacitors, rated at the source voltage and twice the source voltage, respectively, reducing overall cost and improving reliability and power density. The pulse width modulation (PWM) scheme balances the voltages across the SCs, which eliminates the need for the sensor for capacitor voltage balancing. The proposed inverter's circuit description, its operating states, PWM scheme, and control scheme for closed-loop grid-connected operation are discussed. Further, a detailed comparison with the CG-type seven-level triple-boost inverter is presented in terms of capacitor voltage rating, component count, cost factor, total standing voltage, total conducting devices per level, and maximum blocking voltage, which demonstrates the improved attribute of the proposed inverter topology. The pro-posed inverter is simulated in MATLAB Simulink environment for various steady state and dynamic conditions, which validate the feasibility and effectiveness of the proposed inverter.