DUAL CONVERTER USING THYRISTORS
Dual converter is a power electronics control system
to get either polarity DC from AC rectification by forward converter and
reverse converter . It can run a DC motors in either direction with speed
control too .This single phase converter is achieved by using a pair
of thyristor controlled bridge (4 SCRs X 2 ) that enables the DC motor to get
reversed polarity for either direction rotation and speed control also lowered in steps by
Microcontroller triggering each bridge SCR bank of duly interfaced through opto-isolators. A pair of
switches is used to input logical signal for the desired output. If input of
230 volt ac is given to the dual SCR bridge we can have a 100 watt lamp load
and the DC polarity across the lamp is checked. Or a low power DC motor of 220 volt can be used. As demo our project
uses 12 volt ac at the input and a 12 volt DC motor to verify either direction
rotation as the polarity gets reversed.
The
power supply consists of a step down transformer 230/12V, which steps down the
voltage to 12V AC. This is converted to DC using a Bridge rectifier. The
ripples are removed using a capacitive filter and it is then regulated to +5V
using a voltage regulator 7805 which is required for the operation of the microcontroller
and other components.
BLOCK DIAGRAM
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