A comparative evaluation of modulation strategies for Hexverter–based Modular Multilevel Converters

In this work two different modulation strategies termed: i) nearest level control, and ii) phase disposition-sinusoidal pulse width modulation, are described, simulated and compared when applied to a Hexverter-based modular multilevel converter. In addition, two different voltage balancing algorithms are implemented and evaluated. Furthermore, total harmonic distortion regarding three-phase system voltages are assessed. In the end, synthesized branch voltage spectrum for each modulation strategy is analyzed.