Comparison of losses in multilevel converters for aerospace applications

Aerospace applications require light, efficient and reliable power conversion. Multilevel converters have some potential advantages due to their lower output harmonic distortion and also the lower device voltage rating requirements. This paper compares 2-level and 3-level solutions for an application where the desired output frequency is high and low THD is required. A conventional (2-level) inverter with sinusoidal modulation is compared with a 3-level converter in terms of power losses and harmonic distortion of the output waveforms. The modulation strategy plays an important role in the switching power loss distribution as it defines the way the switches are operated. The losses are evaluated with MOSFET and IGBT switches and the effect of the modulation strategy on the THD is also examined.