Assessment of Overmodulation Strategies for AC Drives Considering Harmonics Content and Switching Losses

This paper performs a comparative analysis of overmodulation methods for AC electric drives. Criteria for the analysis considers three aspects: output vs. commanded modulation index (i.e., linearity); harmonic content; and the number of commutations (i.e., switching losses). The analysis focuses on existing methods reported in the literature. Improvements for the existing methods will be proposed as a result of the analysis. The analysis is experimentally validated on a three-phase three-level Neutral-Point-Clamped (NPC) inverter.