Hybrid nine-level single-phase inverter based on modular multilevel cascade converter

This paper presents a hybrid single-phase inverter based on a modular multilevel cascade converter (MMCC) with double-star chopper cells (DSCC). The proposed inverter is constituted by one five-level (5L) DSCC leg and one two-level (2L) leg, providing a nine-level voltage at its output. For this, a hybrid modulation technique is employed, allowing the DSCC leg to operate at the switching frequency and the 2L leg to operate at the fundamental frequency, which reduces switching losses. Compared to other nine-level cascaded H-bridge inverters, the proposed topology requires only one isolated voltage source and generates less losses in the semiconductors. At last, to investigate the proposed system and control strategy, simulation and experimental results are presented.