Patent ID: 9143052
Filing Date: 2015-09-22
Classification: H02M

Abstract:
1. A three-level unit inverter system for generating AC voltage from a DC power supply having a positive terminal, a negative terminal, and a neutral terminal, the unit inverter system comprising a plurality of inverter units employing a three-level conversion circuit, each inverter unit comprising: AC output terminals of the inverter units being connected in parallel with each other; and the inverter units receiving pulse signals from a common main controller to the IGBTs in the inverter units; each inverter unit further comprising: wherein when an absolute value of the output current of the inverter unit concerned is larger than the average value of absolute values of the output current over all inverter units and a polarity of the output current is positive, delayed are the rising up edge of the pulse signal for the IGBT of the upper arm and the rising up edge of the pulse signal for the IGBT that is one of IGBTs composing the bidirectional switch and operates exclusively with the IGBT of the lower arm, the delay being conducted corresponding to the absolute value of the deviation of the output current; and when the absolute value of the output current of the inverter unit concerned is larger than an absolute value of the average value of the output current over all inverter units and a polarity of the output current is negative, delayed are the rising up edge of the pulse signal for the IGBT of the lower arm and the rising up edge of the pulse signal for the IGBT that is the other IGBT composing the bidirectional switch and operates exclusively with the IGBT of the upper arm, the delay being conducted corresponding to the absolute value of the deviation of the output current.