Five-Level Step-Up Switched-Capacitor Grid-Connected Inverter

Abstract

The objective of this paper is to propose a new five-level step-up switched-capacitor grid-connected inverter (FSSGI) The proposed FSSGI, which is composed of a switched-capacitor converter (SCC) and an dc-ac unfolder, is able to operate in standalone and grid-connected mode. Compared with conventional step-up inverter topologies, the advantages of the proposed FSSGI include high conversion efficiency, self-balancing of capacitor, and voltage stress reduction on the switches for low power applications. In addition, the leakage current cause by the high common mode voltage (CMV) can be reduced since the unfolder is only switched at the low frequency. Also, the electrolytic capacitor can be replaced with the long lifetime film capacitor by reducing the required capacitance. The principle of operation, voltage gain analysis, and design methodology are described in this paper. Finally, the computer simulations and hardware experimental results are shown to verify the performance of the proposed FSSGI. A 400-W prototype is built and tested, and the peak and rated power conversion efficiency are 97.89% and 97.45%, respectively.