Design and Implementation of Transformer-less Common-Ground Inverter With Reduced Components

Abstract

Nowadays, common-ground-type (CGT) based transformer-less inverters (TIs) are gaining more popularity in photovoltaic (PV) applications owing to their low cost, weight of the systems, losses and zero ground leakage current. For PV applications, a separate boost converter is often used to boost the low PV array voltage, resulting in increased component count, cost and lower efficiency. To resolve this issue, switched-capacitor (SC) based CGT inverter with reduced component count is proposed in this paper. The proposed amalgamation of CGT and SC technique, results in inherent boosting and zero ground leakage current. In the proposed inverter, SCs are connected in series/parallel with the dc voltage source for several instances in a fundamental cycle preserving the self-voltage balancing ability. Therefore, the proposed topology is devoid of voltage sensors to balance the voltage across SCs. Further, A simplified logic gatebased pulse-width-modulation strategy is developed. In addition, the benefits of proposed inverter are highlighted and compared with the other recent SC inverter topologies with regard to boosted voltage, elimination of leakage current and reduced component count. A laboratory prototype is developed by using DS1202/1302 dSPACE controller and experimental results are presented for both steady state and dynamic conditions and verifying the feasibility of the proposed TI.