Multi level modulations for parallel connected NPC-PWM inverters

The neutral point clamped (NPC)-PWM inverter has been put into practical use for large capacity AC motor drives, because of its various advantages. With the increased use, still larger capacity inverters are also expected. In this paper, a parallel connected NPC-PWM inverter is presented and the conventional modulation techniques are extended to improve the inverter characteristics. Various modulation techniques are proposed and discussed, whose results are verified by experiments.