Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power transfer in applications such as static var compensation. Simulation and laboratory measurements verify the proposed joint-phase redundancy control.
J. Huang and K. Corzine, "Extended Operation of Flying Capacitor Multilevel Inverters," IEEE Transactions on Power Electronics, Institute of Electrical and Electronics Engineers (IEEE), Jan 2006.
The definitive version is available at http://dx.doi.org/10.1109/TPEL.2005.861108
Electrical and Computer Engineering
Keywords and Phrases
Converter; Capacitor Voltage Balancing; Flying Capacitor; Flying Capacitor Multilevel Inverters; Inverter; Invertors; Joint-Phase Redundancy Control; Modulation Indices; Motor Drive Operation; Motor Drives; Multilevel; Power Capacitors; Power Factors; Reactive Power; Reactive Power Transfer; Rectifier; Static VAr Compensators; Static Var Compensation; Switching Convertors; Transistor Switching States; Voltage Balancing
International Standard Serial Number (ISSN)
Article - Journal
© 2006 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.