Improved Single Phase Transformless Voltage Source Inverter for Photovoltaic Grid-Connected System With Common-Mode Leakage Current Elimination

Abstract

This paper presents how to eliminate the common-mode leakage current in the transformerless photovoltaic grid-connected system, an improved single-phase inverter topology is present. Eliminating the leakage current is one of most important issues for transformer less inverters in grid connected photovoltaic applications. The technical challenge is how to keep the common mode voltage constant to reduce the leakage current. For this purpose an improved single phase transformer less inverter is proposed. Here in improved transformerless topology we used additional two switches.The improved trans- formerless inverter can sustain the same low input voltage as the full-bridge inverter and guarantee to completely meet the condition of eliminating common-mode leakage current. unipolar sinusoidal pulse width modulation (SPWM) control strategy can be applied to implement the three-level output in the presented inverter.