A Common Ground Nine-Level Switched Capacitor Inverter Having Quadruple Boosting Capability for Solar Photovoltaic Applications

Abstract

The nine-level switched capacitor multilevel inverter with common ground configuration presented in this work is meant specifically for grid-tied solar photovoltaic (SPV) applications. Normally the SPV panels produce low-level voltage. In order to raise its voltage, a conventionally high-boost DC-DC converter followed by an inverter is implemented. Thus, in conventional systems there are two stages, and hence more switches are needed, which increases the overall cost and reduces the efficiency of SPV systems. Keeping these drawbacks in view, this paper eliminates the conventional high-gain DC-DC converter with a novel single-source reduced-switch common-ground (CG) nine-level switched capacitor (SC) inverter, which has quadruple boosting capability. The proposed inverter has eleven switches, among which nine switches are driven at higher frequency while being clamped by low capacitor voltages, and the remaining two switches experience high stress of voltage, as these are clamped by high-voltage capacitors but are fortunately driven at fundamental frequency. This helps in reducing the switching losses. Moreover, the inverter suppresses leakage current by implementing a shared ground between its AC output and DC input. The level-shifted sine pulse width modulation method has been utilised as a control strategy for the proposed inverter. Further, the expected performance has been analysed by utilising MATLAB/Simulink simulations, and simulation results are confirmed through experimental prototype. The findings are presented by taking into account the fluctuations in load, modulation index, and output frequency. Furthermore, thermal modelling has also been done in PLECS software for analysing the efficiency and power loss of the inverter.