A New Two-Stage Single-Phase Transformerless Inverter Topology with a Novel DC/DC High Gain Boost Converter and a Three-Level Neutral-Point-Clamped Inverter for Photovoltaic Systems

A new two-stage grid-connected inverter is presented in this paper. The proposed single-phase transformerless inverter topology consists of a novel front-end interleaved switched-capacitor boost converter and a half-bridge neutral-point-clamped inverter (HB NPC). The proposed topology is designed to be applied in photovoltaic (PV) conversion systems. The new two-stage compact inverter structure with a high gain interleaved boost converter in the first stage boosts the DC input voltage and provides the maximum power point tracking of the PV panels. In the second stage, a new arrangement of the HB NPC inverter is employed to implement the common ground technique, eliminate the leakage current and provide the DC/AC integration of the system to the grid. In comparison with conventional topologies, the presented inverter has two-stage operation with a compact single-stage design. As a result, the presented topology has several advantages, such as a reduction in the number of power semiconductors, higher efficiency, eliminated leakage current, and higher boosting gain. The design procedure, operating principles, comparison assessment, and simulation results for a 4600 W prototype are presented to verify the effectiveness of the proposed inverter. MATLAB/Simulink and PLECS Blockset are the simulation programs used to validate the performance of the presented topology.