Three-Parts Modulation And Hybrid Voltage Balancing For Three-Phase Five-Level NPC Inverter

This paper proposes three parts modulation and hybrid voltage balancing for a three-phase five-level NPC inverter. Three parts modulation is composed of carrier-based sub-modulations and offers access to soft balancing. Whereas hybrid balancing combines soft balancing and active balancing to address voltage unbalance caused due to three-parts modulation and inverter loading. The modulation and balancing scheme combination discussed here offers a reduction in auxiliary circuit and inverter switching. Workability of the combination is shown with voltage unbalance analysis of the modulation and demonstration of hybrid balancing over a critical range of modulation index. This is supported by Matlab-Simulink simulation and experimental demonstration on a three-phase five-level NPC inverter setup.