Current-Fed Switched-Capacitor 5-Level Single-Phase Inverter

Abstract

This paper presents a current-fed switched- capacitor 5-Level single-phase inverter and the respective modulation strategy. The power circuit is a full bridge topology composed of two 3-level switched-capacitor cells as legs, where each leg creates an instantaneous average voltage positive or negative, according to the output sinusoidal waveform requirement. The operating principle and the mathematical analysis are presented for continuous conduction mode. The mathematical analysis shows that the proposed topology and modulation promote a natural equalization of voltages on capacitors. Thus, a balance voltage control is not necessary. The resulting frequency on the output filter is four times the switching frequency which allows the size reduction of the output filter. Experimental results were obtained from a prototype with an input voltage of 48 V, switching frequency of 10 kHz, and an output voltage of $110 V_{rms}/50$ Hz for a load of 115 W. The experimental results confirm the mathematical analysis regarding natural voltage balance and output filter frequency.