Active power factor correction For high power 3ø switched mode Rectifier

Abstract

Switched Mode rectifiers SMR often use an uncontrolled rectifier newlinewith a capacitor filter at their input to convert the mains AC into DC voltage newlineresulting in discontinuous input current causing harmonic currents and poor newlinepower factor Power factor correction for these power supplies can not be newlineachieved by the addition of power factor improvement capacitors as the newlinecurrent is discontinuous The harmonics and the power factor can be newlineimproved either by addition of passive LC harmonic filters active power newlinefactor correction circuits or by addition of active shunt filters which restore newlinethe waveform back to its undistorted state SMR s with Power Factor Correction PFC are widely used in Telecom and other High power applications These converters provide active newlinecurrent shaping to obtain lower input current harmonics and power factor newlineclose to unity One of the main concerns of the power supply industry is to newlinehave a SMR converter with a low cost and a simple PFC stage complying newlinewith the required harmonic and Electromagnetic compatibility EMC newlinestandards especially for high power three phase applications In this research newlinean attempt is made to achieve the above objective by investigating various newlinemethodologies newline newline