A New Single Stage Common Ground Five-Switch Boosting Transformerless Inverter

Abstract

Transformerless inverters (TIs) are widely employed in photovoltaic (PV) applications due to their cost-effectiveness, compact size, low weight, and high efficiency. However, the absence of electrical isolation can result in ground leakage current due to the parasitic behavior of PV systems, resulting in safety concerns and compromised power quality. Conventional five-level common-ground inverters can eliminate ground leakage current through the common-ground technique and achieve double voltage boosting capability. However, this topology necessitates a considerable amount of capacitance to efficiently minimize voltage ripple due to the extended discharge time during the negative half-cycle. Moreover, the high capacitance raises concerns regarding the potential for high current stress on switches during charging modes. In this article, a new single-stage common-ground boosting transformerless inverter is introduced. The proposed topology has fewer components, a lower number of conducting devices, and reduced capacitance requirements. The proposed topology can also be extended to three-phase applications using a single power source. The article includes explanations of the proposed topology, the control method, the component design process, and the power loss calculations. In addition, a comparison with similar topologies is conducted to highlight the advantages and disadvantages of the proposed topology. Simulation results are included to confirm the functionality and practicality of the proposed topology. Finally, experimental results for a 500-W prototype operating in a closed-loop system under different loads and load changes are presented. The converter demonstrates its capability in both buck and boost modes, achieving a high efficiency of over 95%.

Keywords

• Buck-boost inverter
• common-ground inverter
• leakage current elimination
• single stage inverter