A Single-Source Three-Phase Six-Level Flying Capacitor-Based Converter

This paper presents s a six-level flying capacitor-based converter (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$6 \mathrm{L}-\text{FCB}$</tex>) topology designed for three-phase applications using a single DC source. The proposed topology addresses the limitations of conventional multilevel converters, such as the need for multiple isolated sources, auxiliary balancing circuits, and excessive component count. By employing four flying capacitors per phase and a proper switching-state selection algorithm, the system achieves effective voltage balancing without additional hardware. The topology leverages level-shifted carrier PWM and introduces a priority index-based control strategy that uses phase current direction to regulate capacitor voltages. This enables simplified implementation while maintaining high-quality output voltage with reduced harmonic distortion. A comparison with other sixlevel converters demonstrates the superiority of the proposed design. Simulation results validate the effectiveness of the modulation and balancing techniques under various operating conditions, including changes in load and modulation index.