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P a g e
Figure: 2.8 single phase full converter circuit with R load input and output waveforms
• The single
phase fully controlled
rectifier allows conversion of single phase AC into DC. Normally this
is used in various applications
such as battery charging, speed control of DC motors and front end of UPS
(Uninterruptible Power Supply) and SMPS (Switched Mode Power Supply).
•
All fou
r devices used are Thyristors. The turn-on instants of these devices are dependent on the firing
signals that are given. Turn-off happens when the current through the device reaches zero and
it is reverse
biased at least for duration equal to the turn-off time of the device specified in the data sheet.
• In positive half cycle Thyristors T1 & T2 are fired at an angle α .
• When T1 & T2 conducts
Vo=Vs
IO=is=Vo/R=Vs/R
• In negative half cycle of input voltage, SCR’s T3 &T4 are triggered at an angle of (π+α)
•
Here output current & supply current are
in opposite direction
∴
is=-io
T3 & T4 becomes off at 2π.
V
0
=
=