Digital Knowledge Collection:
http://hdl.handle.net/11189/1765
Mon, 24 Sep 2018 11:46:09 GMT2018-09-24T11:46:09ZNatural balance of multicell converters: The general case
http://hdl.handle.net/11189/1769
Title: Natural balance of multicell converters: The general case
Authors: Wilkinson, Richardt H; Meynard, Thierry A; Mouton, Hendrik du Toit
Abstract: This paper focuses on the development of the natural
balancing theory for the -cell case. It describes the relationship
between the models for different numbers of cells in a generic
model for a -cell multicell converter. The model discussed is
based on the same principles that were used to develop the two-cell
model in [16], except that the mathematics is much more involved.
The same conclusions that were found to be true for the two-cell
case was also found to be true for the general case of cells. These
conclusions include that the natural balancing mechanism of
multicell converters depends on the overlap of the groups of harmonics
of the switching function as well as on the load impedance.
It will also be shown that the self-balancing mechanism ensures
safe operation under most operating conditions where a high
enough switching frequency is chosen and the load is not purely
reactive. Two new aspects of the balancing theory were identified
in the -cell case: 1) for fixed duty-cycle modulation there exists
certain values of the duty-cycle that causes the natural balancing
mechanism to fail and 2) for -cell converters the balance booster
concept can be extended to a number of balance boosters tuned
to multiples of the switching frequency. A “DesignTool” based on
the balancing theory was developed to aid practicing engineers in
designing multicell converters.Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/11189/17692006-01-01T00:00:00ZNatural balance of multicell converters: The two-cell case
http://hdl.handle.net/11189/1768
Title: Natural balance of multicell converters: The two-cell case
Authors: Wilkinson, Richardt H; Meynard, Thierry A; Mouton, Hendrik du Toit
Abstract: The multicell converter topology is said to possess a
natural voltage balancing property. This paper is the first of a twopart
series in which multicell converters are modelled for the general
case of -cells. This paper focuses on the development of the
natural balancing theory for the two-cell case. An understanding
of the two-cell case is fundamental to understanding the general
balancing theory. The switching functions used in switching these
converters are mathematically analyzed. Equivalent circuits are
derived and presented. The switching and balancing properties
of these converters are mathematically analyzed. The main conclusion
of the analysis is that the natural balancing of these converters
are influenced by three factors namely, the harmonic content
of the reference waveform, the switching frequency and the
load impedance. Mathematical tools are presented that can help
designers to predict if balancing problems would occur for a particular
set of operating conditions. As a result of the detailed understanding
of the balancing mechanism that is gained through
this theory it is shown that by adding a balance booster, the load
impedance can be manipulated to improve the natural balancing
of the converter. Simulation results are included to verify the presented
balance theory and properties.Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/11189/17682006-01-01T00:00:00Z