Stability Analysis for the Grid-Connected Three-Phase Asymmetrical Cascaded Multilevel Inverter with Switched Capacitor Technique

Multilevel inverters (MLIs) have become increasingly popular for grid integration. This study introduces an innovative twenty-five-level switched-capacitor multilevel inverter (SCMLI) configuration specifically developed for applications in grid integration. The asymmetrical SCMLI generates a 25-level output voltage utilizing twelve power semiconductor switches, two diodes, two capacitors, and two asymmetric DC voltage sources with a quinary ratio. Unlike current designs, this topology features self-balancing capacitors without the need for additional circuitry, making it well suited for grid-connected applications that require higher voltage levels with fewer devices and a reduced total standing voltage (TSV). The inverter uses a level-shifted in-phase disposition (LS-IPD) multicarrier modulation technique to generate switching signals during the grid-connected operations. A comparative study with recent topologies highlighted the benefits of the proposed structure. Various operational modes are analyzed through simulations in MATLAB/Simulink.