Analysis of a voltage balancing technique with reduced switching transitions in a flying capacitor multilevel converter

Abstract

This paper reports the analysis of a voltage balancing technique based on optimal switching transitions for a flying capacitor (FC) multilevel converter using phase disposition pulse-width modulation. Since multiple switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. For the selection of the transitions, two techniques are studied and compared in terms of capacitor voltage ripples and switching frequencies. In the first technique, called optimum transition voltage balancing technique, the transitions between two consecutive voltage levels that produce high switching frequencies are avoided. On the other hand, all the transitions between consecutive levels are considered in the second technique. It is therefore called unrestricted voltage balancing technique. Study analyses are conducted by simulation considering all the possible modulation indices and load power factors.