Selective harmonic elimination in three-phase multi-module voltage-source inverters

Modular voltage-source inverter (MVSI) structures can enhance the power quality of inverters in medium voltage pulse width-modulated applications. An MVSI uses individual three-phase modules in a shunt connection to share the total power in a symmetrical manner. The modulation of these units is normally done using optimized patterns such as selective harmonic elimination patterns, but the optimization is usually performed at the module level. This paper proposes a modulation technique that optimizes the operation of a complete MVSI taking into account all P modules. The proposed topology can remove P times the number of harmonics that the conventional approach can the same switching frequency. The proposed topology, the mathematical formulation and experimental results are presented in the paper.