Power Factor Correction in Ac-Dc System

Abstract

With the increase in demand of modern advance power electronics devises,there has been a tremendous stress on the utility power quality. The steady growth of use of electronics equipment in various industries and household application has become a significant problem as per the line current harmonic is concerned. Their adverse effects on the power system are instability problem,the increase in reactive power demand , the neutral current magnitude increase and becomes the cause of overheating of transformers and induction motors, as well as the dreadful conditions of system voltage waveforms. Different nonlinear loads that are responsible for higher input current THD(%) are the bridge rectifiers, florescent lamps ,SMPS devise, Arc furnace electric welding machines etc..In this thesis we deal with power factor correction in AC-DC system (Rectifiers).There is Active and Passive method for PFC which involves use of active and passive elements respectively. Different conventional and nonlinear control schemes are analyzed for the switching for Rectifiers. Our objective is to get a sinusoidal input voltage i.e in phase with the applied source. For this we are dealing with different DC-DC topologies such as forward flyback, boost and interleaved and their adverse effect when they are cascaded with Vienna rectifier, synchronous bridgeless rectifier and a modified Novel AC-DC converter. For this work MATLAB/SIMULINK power system toolbox is used to simulate and RUN the proposed topologies Simulation results are presented and the improvement in the supply current can be seen in the obtained waveform of the different topologies. The power factor nearly equal to unity is obtained almost in all the topologies and Harmonic distortion within the IEC 555-2 norms.