Feedback control of the input DC voltage sources of the seven levels NPC voltage source inverter

In this paper, the authors examine the input DC voltage source stability of a three-phase seven-level NPC voltage source inverter. In spite of the advantages of multilevel inverters compared to two-level topologies, the unbalance voltage of the different input DC voltage sources constitute a major limitation of multilevel inverters. In this paper, the authors study the performances of a three-phase two-level PWM rectifier-three-phase seven-level NPC voltage source inverter-induction machine cascade in the case of open loop and closed loop DC output voltage of the two-level PWM rectifier.