Three-phase Transformerless Grid connected PV Inverter

Abstract

Andhra Pradesh, India. Abstract: PV systems are now more affordable due to government incentives, advancement of power electronics and semiconductor technology and cost reduction in PV modules. In the past, various transformers less PV inverter topologies have been introduced, with leakage current minimized by the means of galvanic isolation and common-mode voltage (CMV) clamping. Leakage current minimization is one of the most important considerations in transformer less photovoltaic (PV) inverters. The galvanic isolation can be achieved via dc-decoupling or ac-decoupling, for isolation on the dc- or ac-side of the inverter, respectively. It has been shown that the latter provides lower losses due to the reduced switch count in conduction path. Common-mode voltage (CMV) appears in Three-phase due to working principles of the pulse width modulation (PWM) inverters. This voltage is the main source of many unwanted problems systems. In this Project, several recently proposed transformer less PV inverters with different galvanic isolation methods and CMV clamping technique are analyzed and compared. A simple modified H-bridge zero-voltage state rectifier is also proposed, to combine the benefits of the low-loss ac-decoupling method and the complete leakage current elimination of the CMV clamping method. The performances of different topologies, in terms of CMV, leakage current, total harmonic distortion, losses and efficiencies are compared. A safety issue is the main concern for the transformer less PV systems due to high leakage current. Without galvanic isolation, a direct path can be formed for the leakage currentto flow from the PV to the grid The proposed concept can be implemented to PV inverter with Three-phase by using MATLAB/SIMULATION software.