A novel buck converter for power factor correction using PWM technique

A buck converter is a step-down AC to DC converter. By eliminating input bridge diodes, the rectifier´s efficiency is further improved. More over the rectifier doubles its output voltage which extends usable energy of the buck capacitor after a drop out of the line voltage. In conventional method a bridgeless buck rectifier also works as a voltage doubler, it can be designed to meet harmonic limit specifications with an output voltage that is twice that of a buck PFC rectifier. The drawback of this method is universal line boost PFC front end is related to its relatively high output voltage. Here the output is constant and cannot be varied. In the paper method the diode is eliminated and thyristor is used. Here thyristor works as a varied one. It´s advantageous that the output can be varied with the variation in the input. It utilizes two switches along with an output inductor and output capacitor. Whether you look at a large computer server, a personal desktop or a laptop computer, a cell phone or a GPS unit all will contain a buck converter in one form or another.