Abstract: Switched Mode Power Supply (SMPS) is an integral part of the computer that converts ac to multiple numbers of suitable dc voltages to impart power to different parts of the PC. It contains a diode bridge rectifier (DBR) with a capacitor filter followed by an isolated dc-dc converter to achieve multiple dc output voltages of different ratings. The uncontrolled charging and discharging of the capacitor result in a highly distorted, high crest factor, periodically dense input current at the single phase ac mains; this violates the limits of international power quality (PQ) standards such as IEC 61000- 3-2. Further, the neutral current in the distribution system increases if these PCs are used in large numbers which creates serious problems like overloading the neutral conductor, noise, de-rating of the transformer, voltage distortion etc. In this paper, a non isolated power factor corrected (PFC) converter is being proposed to be used at the front end to improve the power quality of an SMPS for a PC. The front-end converter is able to reduce the 100-Hz ripple in its output that is being fed to the second stage isolated converter.
Keywords: Switched Mode Power Supply, diode bridge rectifier, power quality, and power factor corrected.