Abstract:
High frequency switching power supplies have become part of electronic
equipments to provide regulated DC of desired voltages at a low cost and high
efficiency. These power supplies have several advantages over their counterpart the
linear power supplies. Main advantages are smaller compact size due to elimination
of step down transformer and small filters due to high frequency operation. These
power supplies have high efficiency because the regulating devices in them works
as switches ensuring low device loss. Their output voltage can be controlled for a
wide range of input voltage fluctuation by changing the duty cycle of the switching
signals.
Four common types of switch mode converters are used in DC to DC conversion.
They are BUCK, BOOST, BUCK-BOOST and CI\UK converters. Researchers are
trying to modifY these DC regulator to regulate AC voltages.
Utility AC voltage fluctuation both momentary and prolonged, affect adversely the
domestic, industrial and commercial customers. In this thesis an AC Cl\uk regulator
made of. ideal switches and practical IGBT switches have investigated. For
generation of switching voltage a commercially available IC chip SG l524B is used,
thus circuit is compact and more viable. The same chip is utilized to regulate the
output voltage by varying the gate signal voltage of the IGBTs if any changes occur
in output voltage. As a result the regulator is maintaining constant voltage across
the load during any change in supply voltage as well as for variation of load.
Freewheeling path and surge voltage across switches create problem in the proposed
regulator. Snubbers are used for suppressing surge voltage across switches. Input
current of this regulator is greatly reduced to a acceptable limit but still efficiency of
this regulator is very poor and needs further research to increase the efficiency to
make the regulator commercially viable. In this thesis input filter capacitor of
proper size is used for improving the power factor and which decreases the input
current.
