A Modified Switched-Coupled-Inductor quasi-Z-source Inverter

This paper proposes a modified switched-coupled-inductor quasi-Z-source inverter, which is characterized by a continuous input current, low DC-link voltage overshoot and high efficiency. The bootstrap capacitor in this improved module enhances the boost capability of the inverter at a low shoot-through duty cycle D. Thanks to the distinct positions of the third and fourth windings N23 and N24 of the multi-winding coupled-inductor in the proposed inverter, these windings have low current stress during shoot-through state and no current flow at non-shoot-through state. The work environment of the coupled-inductor is optimized and the inverter efficiency is substantially improved due to its low copper loss. This paper studies the operating modes, analyzes the voltage and current stresses of different components, and studies their energy consumption in detail. Finally, the feasibility of the proposed inverter is validated via a 1 kW prototype developed in the lab and the test results are consistent with the theoretical analysis.