Abstract:
Nowadays power converters with high power factor are becoming part of the electronic
equipment. These power converters generally use high frequency switching and have
three distinct advantages over their counterpart, the linear power supplies. The advantages
are smaller compact size due to elimination of step down transformer and small filters due
to high frequency operation. They are more efficient because the regulating switches
. work in switching (ON/ OF) mode ensuring minimum device loss. The other advantages
are their output voltages are isolated and can be controlled for a wide range of input
voltage fluctuation by ON/OFF ratio (duty cycle) contro!.
At present power converters with high power factor commonly .use high frequency
multiple pulse or sine triangular modulation to generate controlling signals of switching
devices. Delta modulation technique has been adopted in many power converters for easy
implementation and versatile contro!. In this Thesis possible use of dual slope delta
modulation (one form of delta modulation) technique for an efficient power factor
correction of a diode rectifier has been investigated. The implementation of this method
requires the use of a single switch boost chopper. The switch is activated by dual slope
delta modulation technique. The effect of the switch at the output and input side of the
diode rectifier is analysed. The converter draws sinusoidal ac currents from the ac source
with nearly unity power factor while operating at a fixed switching frequency. The
theoretical analysis has been verified by the practical hardware implementation. From
theoretical and practical analysis it is clear that power factor correction of a diode rectifier
using dual slope delta modulation is possible, advantageous and easy to implement.
