Natural balancing mechanisms in converters
Date
2011-03
Authors
Van der Merwe, Johannes Wilhelm (Wim)
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
AFRIKAANSE OPSOMMING: Hierdie proefskrif handel oor die natuurlike balanserings meganismes van veelvlakkige
en modulêre omsetters wat fase-skuif dragolf puls wydte modulasie gebruik.
Die meganismes kan in twee hoof groepe verdeel word: ‘n swak balanserings
meganisme wat afhanklik is van die oorvleuling van die skakelfunksies en ‘n
sterk meganisme wat voorkom ongeag of die skakelfunksies oorvleul al dan nie.
Die sterk meganisme verdeel verder in twee subgroepe, ‘n direkte oordrag van onbalans
energie en ‘n meganisme wat afhang van die verliese in die stelsel. Elkeen
van die meganismes word aan die hand van ‘n omsetter topologie waarin die spesifieke
meganisme oorheers beskryf en ontleed. In die ondersoek word klem geplaas
op die daarstelling van uitdrukkings om die tydskonstantes van herbalansering na
’n afwyking vir elk van die omsetter toplologieë te beskryf.
ENGLISH ABSTRACT: This thesis investigates the natural balancing mechanisms in multilevel and modular converters using phase shifted carrier pulse width modulation. Two groups of mechanisms are identified; a weak balancing mechanism that is only present when the switching functions are interleaved and a strong mechanism that occurs irrespective of the interleaving of the switching functions. It is further shown that the strong balancing mechanism can be divided into a balancing mechanism that depends on the direct exchange of unbalance energy and a loss based balancing mechanism. Each of the mechanisms is discussed and analysed using a converter where the specific mechanism dominates as example. Emphasis is placed on the calculation of the rebalancing time constant following a perturbation. Closed form expressions for the rebalancing time constants for each of the analysed converters are presented.
ENGLISH ABSTRACT: This thesis investigates the natural balancing mechanisms in multilevel and modular converters using phase shifted carrier pulse width modulation. Two groups of mechanisms are identified; a weak balancing mechanism that is only present when the switching functions are interleaved and a strong mechanism that occurs irrespective of the interleaving of the switching functions. It is further shown that the strong balancing mechanism can be divided into a balancing mechanism that depends on the direct exchange of unbalance energy and a loss based balancing mechanism. Each of the mechanisms is discussed and analysed using a converter where the specific mechanism dominates as example. Emphasis is placed on the calculation of the rebalancing time constant following a perturbation. Closed form expressions for the rebalancing time constants for each of the analysed converters are presented.
Description
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011.
Keywords
Natural balancing, Fourier series analysis, Modular converters, Flying capacitor converter, Stability analysis, Dissertations -- Electrical engineering, Theses -- Electrical engineering