A switched capacitor multilevel inverter with high power density for photovoltaic applications

This paper proposes a novel step-up switched-capacitor multilevel inverter (SCMLI) achieving high power density and low total voltage stress. Compared to conventional designs, the proposed inverter eliminates the need for an output bridge, and all switches experience voltage stress equal to the input voltage. Leveraging level- and phase-shifted pulse width modulation (LPSPWM), the capacitance requirements of all capacitors are significantly reduced to just a few microfarads (μF). This allows for the deployment of compact and cost-effective ceramic capacitors. Furthermore, GaN MOSFETs are employed to push power density even higher due to their superior switching characteristics. The driving circuits have also been optimized, resulting in a design that necessitates fewer driver chips and isolated DC/DC converters compared to previous iterations. To validate the theoretical analyses and feasibility of this novel topology, a 120W, seven-level prototype has been successfully built in a laboratory setting.