Single DC source three-phase multilevel inverter using reduced number of switches

A novel pulse-width modulation-less three-phase multilevel DC-AC inverter using only one DC source is presented in this study. The proposed approach enables multilevel output to be realised by a few cascaded H-bridges and a three-leg inverter using minimum number of power switches. As an illustration, a 19-level three-phase inverter has been implemented based on cascading four H-bridges and a three-leg inverter. Switching strategy has been derived for the proposed inverter such that a three-phase power system with 19 output levels can be realised with proper capacitor voltage regulation and a single energy source. Only 22 power switches instead of 108 are required to achieve the objective. Experimental results are included to demonstrate the outstanding performance of the proposed inverter. Although only 50 Hz results are presented, the proposed inverter could be applied in aircraft systems by only changing the switching frequency.