Christoph Haederli - Les thèses en ligne de l'INP - Institut National ...

Introduction 7
2.3 Glossary
Note that this glossary only contains expressions that are either introduced by the author or
expressions considered ambiguous.
TABLE 3, DEFINITION OF EXPRESSIONS
Expression
3-L DC link ML
converter
ANPC (type) 1
ANPC (type) 2
ANPC (type) 3
Apparent output
switching frequency
Average switching
function s (t)
CM Average switching
function
Duty cycle
Explanation
A family of converters with any number of levels starting from three.
The “3-L” in the expression is referring to the number of levels in the
DC link only: U DC-, U NP, U DC+
ANPC converter with flying capacitors in the output converter stage
only (common for upper and lower DC link)
ANPC converter with flying capacitors in DC link converter stages
only (separate for upper and lower DC link)
ANPC converter with flying capacitors in all three converter stages
(two adjacent to the DC link, one at the output)
Frequency of switching actions observed at the output of the
converter per phase (excluding glitches). This is not equal to the sum
of the average cell frequencies, as multiple cells may switch at a time.
Average value of the switching function over one modulation period
(continuous function from -1 to 1). This value is equal to the output
reference value if such a reference is used and is therefore a direct
indicator of the output voltage (without correction according to actual
DC link and flying capacitor voltages). For the 2-L converter, the duty
cycle of the output half bridge could be used instead (0 to 1). For ML
converters, there is no equivalent duty cycle with direct physical
meaning (linked to a switching cell). However an equivalent phase leg
duty cycle from 0 to 1 can be defined. The use of the average
switching function is preferred in this thesis, due to its intuitive
physical meaning and its good usability in equations.
Common mode average switching function. This equals to the average
of the average switching function of all phases in a multiphase system.
Consequently, it can range from -1 to 1 for m=0 and is physically
constrained to smaller values for m>0.
Ratio of on time versus total time of a switching cell (variable α used
in this thesis) or a switching device (variable d used in this thesis) over
one modulation period. It can also refer to the relative output voltage
of a phase leg referred to the DC- potential (α L used). However, such a
duty cycle is not necessarily linked to a physical duty cycle of an
individual device and its use in this thesis is very limited (see also
above).