Design of a high efficiency controlled rectifier by two stage cuk conversion

Abstract

In this thesis, a new topology of input current shaping of single phase rectifier with high efficiency, high power factor and controlled output voltage has been studied. The topology used is Cuk ac-dc conversion at the front end of the rectifier to have sinusoid input current by the use of small sized LC filter to reduce THD and also to make input power factor unity. A second stage of Cuk conversion has been used to keep the rectifier efficiency high as a controlled rectifier. The study is carried out by analysis and the .results are verified by simulation software. The proposed rectifier allows a controlled rectifier operation with duty cycle control of any of the converter at high conversion efficiency. The results of Single Phase dual Cuk Rectifier with Resistive Load Having Input/Output Filter is compared with those of single phase uncontrolled rectifier with resistive load, .boost regulated bridge rectifier with resistive load having input/output filters and single stage Cuk rectifier with resistive load having input/output filters. The result shows that by varying the duty cycle of both bidirectional switches of the dual Cuk Rectifier simultaneously the desired objectives of the thesis has been obtained. The drawback of the boost regulator and the single stage Cuk regulator has been eliminated. The efficiency of the proposed rectifier remains most of the time above 90%, power factor is always above 0.9 and the THD is always below 3% with variable output voltage.