A Novel Dual-Mode Switched-Capacitor Five-Level Inverter With Common-Ground Transformerless Concept

Transformerless (TL) grid-connected photovoltaic (PV) inverters with a common-ground (CG) circuit architecture exhibit some excellent features in removing the leakage current concern and improving the overall efficiency. However, the ability to cope up with a wide range of input voltage changes whilst maintaining the output voltage in a single power conversion stage is a key technological challenge. Considering this, this work proposes a novel dual-mode switched-capacitor five-level (DMSC5L)-TL inverter with a CG feature. The proposed topology is comprised of a single dc source and power diode, three capacitors, four unidirectional and three bi-directional power switches. Based on the series-parallel switching conversion of the involved switches, the proposed DMSC5L-TL inverter can generate five distinctive output voltage levels during both the boost and buck modes of the operation with a self-voltage balancing operation for the involved capacitors. A simple dead-beat continuous current controller set (DB3CS) modulation technique is also used to handle both the active and reactive power exchange within a fixed switching frequency operation. The proposed circuit description with its DB3CS details, the design guidelines with a comparative study, and some experimental results are also given to show the feasibility of the proposed solution for the practical applications.