An Autoboost Five-Level 3-Phase Switched-Capacitor Converter for Grid-Tied PV Interfacing

Transformerless grid-tied inverters are vital for renewable energy systems due to their efficiency, compactness, and affordability. Multilevel inverters (MLIs) are particularly favored for their ability to reduce total harmonic distortion (THD) and mitigate leakage current through a common-ground configuration. Switched-capacitor (SC) based MLIs, known for single-source multilevel output, have gained significant interest in this context. This paper presents an innovative autoboots five-level three-phase switched-capacitor converter for grid-connected photovoltaic (PV) applications. The proposed topology utilizes three SCs, three DC voltage sources, and 21 power switches, with minimal components operating at high frequencies, reducing switching losses. It features inherent voltage boosting, removing the need for additional boost stages, and offers high efficiency with a compact design. A robust control strategy ensures precise active and reactive power injection, making the topology highly suitable for modern grid requirements. Comparative analyses reveal significant improvements in efficiency, power quality, and component optimization over existing three-phase MLIs. The proposed system’s claims are validated through extensive simulations in MATLAB/Simulink and PLECS simulation environments, supported by experimental results from a laboratory-scaled prototype.