Reduced switch NPC-based transformerless PV inverter by developed switching pattern

The neutral point clamped (NPC) topology and its derived topologies are getting more and more widespread in the application of transformerless photovoltaic (PV) inverters as the key elements for integration of power conversion in order to improve efficiency, practicality and reliability of PV systems. The regular, active and Conergy topologies have been proven that they are very suitable due to high efficiency, low leakage current and electromagnetic interference (EMI). This paper discusses a one-switch-reduced NPC-based structure compared with Conergy NPC topology with potential for reduced cost and increased efficiency. In addition, an elegant switching function is presented and implemented here with decreased complexity, with respect to the Conergy topology, via a bidirectional switch (BDS) logic that is independent of the grid current direction. The theoretical discussion, real-time data and experimental results are provided to validate performance of the proposed converter.