Single-phase AC-AC double-star chopper-cells (DSCC) converter without common DC-link capacitor

This paper presents a single-phase AC-AC converter based on Modular Multilevel Cascade Converter (MMCC) with Double-Star Chopper-Cells (DSCC). This structure is composed by three DSCC-legs, the middle leg is shared, and also it does not present a common DC-link capacitor. It is suitable for regenerative low-power AC-AC conversion. The voltage-balancing control is presented to regulate the floating DC capacitor voltages. Furthermore, a grid current and terminal load voltage control is presented to correct the Power Factor (PF) and to ensure sinusoidal waveforms. Details about a designed 16-SM prototype are also presented. The experimental results allow validating the control strategies and the effectiveness of the proposed structure.