Transformerless Common Ground Quasi-Z-Source Three Phase Inverter for PV Applications

The leakage current is one of the major issues in transformerless PV inverters. It is essential to minimize the leakage current as low as possible. To achieve this, many topologies have been proposed based on different novel modulation techniques, novel circuit configurations. These topologies are predominantly voltage source inverters (VSIs) with discontinuous input current and have buck type characteristics. This paper presents a common ground based quasi-Z-source converter for PV applications. The leakage current is eliminated as the common mode voltage is zero due to the common ground. The proposed converter has continuous input current profile and gives buck-boost type AC output. MPPT operation can also be integrated with ease. The topology uses optimal number of switches as that of the conventional inverters proposed in the literature. The detailed operating principle and steady state analysis are discussed to show the advantages of the proposed inverter. Simulation results are provided to verify the operation of the proposed inverter.