A novel control strategy to suppress DC current injection to the grid for three-phase PV inverter

Abstract

The limitation of DC current injection to grid is critical for transformerless grid-connected PV inverter. In this paper a novel control strategy for three phase PV inverter is proposed in order to suppress DC current injection to the grid. It is based on idea of accurately sensing the DC offset voltage of three-phase PV inverter output. Since each one of the DC components in the three-phase inverter output can be eliminated, DC injection current to the grid can be effectively suppressed. The control scheme is verified on a 20kW three phase PV inverter.