
100 Electrotechnical Systems
waveform frequency that is specied but its relation to the modulating signal fre-
quency as a whole number K
n
. Such a mode demands use of PLL. The three-phase
modulating signal comes to the input U
st
, and the synchronizing signal U
t
comes to
the inputwt. The input w disappears in the un-synchronized mode, and during the
internal generation of the modulating signal all the inputs disappear. At the output
P1, 6 or 12pulses are formed for the rst bridge, and so many are formed at the out-
put P2 for the second bridge. The pulse arrangement for the two-level inverter is the
same for the previous blocks, and for the ...