Power factor correction of a diode rectifier using dual slope delta modulation technique

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.