Experimental verification of a modular multilevel cascade inverter based on double-star bridge-cells (MMCI-DSBC)

This paper presents a modular multilevel cascade converter based on double-star bridge-cells (MMCC-DSBC), which is characterized by a cascade connection of multiple single-phase full-bridge PWM converter cells per leg. It is suitable for a wind turbine generation system with a permanent magnet synchronous generator, the frequency band of which ranges typically from 5 to 20 Hz. This paper discusses a wind turbine generation system based on the DSBC, revealing that the DSBC can achieve a grid connection with an arbitrary dc-link voltage. Moreover, the operating principles and the control method are described in this paper. The validity of the system is verified experimentally by using a 200-V 10-kW downscaled model.