dc.contributor.author	Song, Byeong-Mun	en
dc.contributor.committeechair	Lai, Jih-Sheng	en
dc.contributor.department	Electrical and Computer Engineering	en
dc.date.accessioned	2014-03-14T20:20:06Z	en
dc.date.adate	2001-12-11	en
dc.date.available	2014-03-14T20:20:06Z	en
dc.date.issued	2001-07-24	en
dc.date.rdate	2002-12-11	en
dc.date.sdate	2001-12-10	en
dc.description.abstract	This dissertation presents voltage stabilization techniques for flying capacitors used in soft-switching multilevel active power filters. The proposed active filter has proved to be a solution for power system harmonics produced by static high power converters. However, voltage unbalance of the clamping capacitors in the active filter in practical applications was observed due to its unequal parameters. Thus, the fundamentals of flying capacitors were characterized dealing with voltage balancing between flying capacitors and dc capacitors under practical operation, rather than ideal conditions. The study of voltage balancing provides the fundamental high-level solutions to flying capacitor based multilevel converter and inverter applications without additional passive balancing circuits. The use of proposed voltage balancing techniques made it possible to have a simple structure for solving the problems associated with the conventional bulky passive resistors and capacitor banks. Furthermore, the proposed control algorithms can be implemented with a real time digital signal processor. It can achieve the high performance of the active filter by compensating an adaptive gain to the controller. The effectiveness of the proposed controller was confirmed through various simulations and experiments. The focus of this study is to identify and develop voltage stabilization techniques for flying capacitors used in a proposed active filter. The voltage unbalance is investigated and characterized to provide safe operations. After having defined the problems associated with the voltage unbalance, the most important voltage stabilization techniques are proposed to solve this problem, in conjunction with an instantaneous reactive power (IRP) control of an active filter. In order to reduce the switching losses and improve the efficiency of the active filter, the proposed soft-switching techniques were evaluated through simulation and experimentation. Experimental results indicate that the proposed active filter achieved zero-voltage conditions in all of the main switches and zero-current turn-off conditions to the auxiliary switches during commutation processes. Also, various studies on soft-switching techniques, multilevel inverters, control issues and dynamics of the proposed active filter are discussed and analyzed in depth.	en
dc.description.degree	Ph. D.	en
dc.identifier.other	etd-12102001-152502	en
dc.identifier.sourceurl	http://scholar.lib.vt.edu/theses/available/etd-12102001-152502/	en
dc.identifier.uri	http://hdl.handle.net/10919/30026	en
dc.publisher	Virginia Tech	en
dc.relation.haspart	CH-4.pdf	en
dc.relation.haspart	Appendix-1.pdf	en
dc.relation.haspart	CH-6.pdf	en
dc.relation.haspart	CH-3.pdf	en
dc.relation.haspart	CH-0.pdf	en
dc.relation.haspart	Reference.pdf	en
dc.relation.haspart	CH-1.pdf	en
dc.relation.haspart	CH-2.pdf	en
dc.relation.haspart	Vita.pdf	en
dc.relation.haspart	CH-5.pdf	en
dc.relation.haspart	Appendix-2.pdf	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	Soft-Switching Topologies	en
dc.subject	Multilevel Converters	en
dc.subject	Active Power Filter	en
dc.subject	Voltage Balancing	en
dc.subject	Flying Capacitor	en
dc.title	Voltage Balancing Techniques for Flying Capacitors Used in Soft-Switching Multilevel Active Power Filters	en
dc.type	Dissertation	en
thesis.degree.discipline	Electrical and Computer Engineering	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	doctoral	en
thesis.degree.name	Ph. D.	en

Voltage Balancing Techniques for Flying Capacitors Used in Soft-Switching Multilevel Active Power Filters

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