Multioutput Switched-Capacitor Multilevel Inverter With Intrinsic Elimination of the Photovoltaics Induced Leakage Current and High Boost Factor
Xiaofeng Zheng, Jia Yao, Zhiyuan Xu, Adrian Ioinovici
Abstract
In this article, a new multioutput switched-capacitor multilevel inverter (SCMLI) and a few trade-off solutions are proposed. It concomitantly features a common input source-load ground, eliminating thus the photovoltaic cell leakage current, a permanent nonzero input current, a high boost factor, equal to that in a similar no common ground inverter, and the smallest number of capacitors and switches per output and per boost factor compared with their count in the available common ground switched-capacitor (SC) inverters. Its basic structure is constituted by two SC subcircuits. The originality of the proposed inverter comes from a novel operation scheme in which one of the two SC subcircuits supplies the positive half-sinusoid of both outputs, whereas the other SC subcircuit supplies the negative half-sinusoid of both outputs. The alternative solutions require a few more switches. Their new switching strategies provide an equal capacitor voltages ripple, thus leading to smaller capacitance values and less capacitor-induced losses. An original design of an input choke allows drastically reducing the input current ripple, as required in alternative energy-powered applications. The new SCMLI was conceived as an inverter powered by a solar cell that supplies standalone residential ac loads of small powers. A laboratory 400 W nine-level prototype is built to verify the theoretical analyses and feasibility of the proposed topology.