A neutral-point potential control method for three-level inverters by injecting zero-sequence voltage

The imbalance of neutral-point potential is an internal problem with three-level inverters. To solve this problem, this paper proposes a novel neutral-point potential control method by injecting zero-sequence voltage, and gives the valid criteria for selecting which zero-sequence voltage to use. Simulations and experiments validate that the imbalance of neutral-point potential could be controlled effectively at various states of the inverter by using this method, and this control method is simple and easy and is robust.