Active Capacitor Voltage Balancing in Single-Phase Flying-Capacitor Multilevel Power Converters


Two active capacitor voltage balancing schemes are proposed for single-phase (H-bridge) flying-capacitor multilevel converters. They are based on the circuit equations of flying-capacitor converters. Consequently, they can be implemented using straightforward control rules. In particular, the first technique is based on an algorithm which follows the standard multilevel modulation. Then, it utilizes a redundant state selection table for capacitor voltage balancing. In the second method, multiple duty cycles are defined and modulated in direct response to the capacitor voltages. The most important advantage of these two proposed methods is that they can be utilized to converters with any desired number of levels in their output voltage. Moreover, the analysis and implementation of both methods are straightforward. Through simulation and experimental implementation, these methods are shown to be effective on capacitor voltage regulation in flying-capacitor multilevel converters.


Electrical and Computer Engineering


National Science Foundation (U.S.)


This work was supported in part by the National Science Foundation under Grant 0812121.

Keywords and Phrases

Capacitor Voltage Balancing; Capacitor Voltages; Circuit Equation; Control Rules; Direct Response; Duty Cycles; H-Bridges; Multilevel Converter; Multilevel Modulation; Natural Capacitor Voltage Balancing; Output Voltages; State Selection; Voltage Regulators; Capacitors; Active Capacitor Voltage Balancing; Flying-Capacitor Multilevel Converters; Redundant State Selection (RSS)

International Standard Serial Number (ISSN)

0278-0046; 1557-9948

Document Type

Article - Journal

Document Version


File Type





© 2012 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Feb 2012