Three-Phase Filter-Clamped Transformerless Inverter for Grid-Connected Photovoltaic Systems with Low Leakage Current

In this paper, a Filter-Clamped (FC) inverter is employed as a three-phase grid-connected Transformerless Photovoltaic (TLPV) inverter. TLPV inverters are more efficient and more cost-effective compared to the alternatives based on high and low-frequency isolation transformers. On the other hand, TLPV inverters generate high leakage current due to the removal of the isolation transformer. Prior-art TLPV topologies have been developed to overcome this issue by either adding more semiconductor switches to block potential leakage current paths or modifying the control method. In contrast, the FC inverter addresses the leakage current issue without adding any extra component or improving the control technique. Thus, it is a promising solution to TLPV systems. Having decreased the leakage current, the FC inverter improves the THD of grid injected current and the efficiency compared to the conventional three-phase Full-Bridge (FB) inverter. Simulations and experiments are provided to validate the effectiveness of the FC inverter in terms of reduced leakage current, improved grid current THD, and improved overall efficiency.