Symmetrical Voltage Balancing Control for Four-level Flying Capacitor Converter Based on Phase-Shifted PWM

Abstract

A symmetrical voltage balancing control (SVBC) method for the four-level flying capacitor (FC) converter is addressed in this paper, which is built on phase-shifted pulse width modulation (PS-PWM). However, the PS-PWM technique is hard to maintain balanced FC voltages in practice. The proposed method balances FC voltages by using a proportional (P) controller without any complicated algorithm, also achieves the output voltage regulation. Thus, the PS-PWM technique could be significantly improved by the proposed method. In addition, the averaged state-space model and small-signal model for the four-level FC converter are analyzed in details. Some experimental results are given to illustrate the proposed method.