A Five-Level Transformer-Less Grid-Tied Inverter Structure With Capacitive Voltage Divider Concept With Leakage Current Elimination

This article presents a novel single-phase inverter with six switches and five levels that shares a common ground and does not require a transformer. The proposed inverter is intended for use in photovoltaic systems that are connected to the grid. The proposed inverter is derived from the concept of a capacitive voltage divider (CVD) circuit, so that, the leakage current will be eliminated. The CVD circuit produces three levels of output voltages in the proposed inverter. The proposed novel inverter has several significant advantages, such as the elimination of leakage current without the need for additional components, the ability to transfer reactive power fully, and the use of fewer components compared to current five-level transformer-less inverters. Additionally, the voltage stress is evenly distributed across power switches, resulting in higher efficiency. Furthermore, the inverter is designed to automatically balance voltage in capacitors without requiring an additional control system. The proposed inverter achieves these advantages using a suitable switching scheme. The article also includes an explanation of the proposed circuit, the process for designing minimum capacitors, theoretical loss calculation, and a comparison of features with similar topologies to demonstrate the efficiency of the proposed inverter. In addition, a 1 kVA experimental prototype is constructed to showcase the effectiveness of the proposed inverter.