Investigations on Three Phase Front end Ac Dc Converters for Power Quality Improvement

Abstract

The revolution in power electronics has opened an era for widespread use of power newlineconverters of different power rating from few Watts to Mega-Watts. Three-phase AC-DC newlineconverters are most widely used power converters as the distributed electric power is AC newlinesupply, while the applications based on DC supply as well as variable frequency AC newlinesupply, need conversion of AC supply into DC supply. newlineLarge current harmonics and poor power factor in the utility interface are common newlineproblems in three-phase AC-DC converters. These AC-DC converters are used invariably newlineat the front-end in numerous applications which may or may not be electrically isolated newlinefrom the AC supply system depending on the rating and nature of the load and also the newlineprevalent Standards requirement. The applications such as electrochemical, newlineelectrometallurgical and electrical heating process, high voltage direct current systems, newlineadjustable speed drives, battery charging, aerospace and naval equipment s, uninterrupted newlinepower supplies etc., use AC-DC conversion at the front-end. These processing industries newlineand adjustable speed drives are the main applications wherein large amount of power is newlineinvolved in AC-DC converters. These AC-DC converters are generally diode-based, newlinethyristor-based or self-commutating device-based converters depending on applications, newlinesize and cost. newlineThe wide spread use of AC-DC converters for various applications have resulted in newlinepower pollution leading to failure of sensitive equipment s, reduced efficiency, etc. This newlinehas led to the development of power quality standards and hence attracted attention of newlinemany researchers for improving the power quality at AC mains. This research work aims newlineat classifying and investigating different three-phase AC-DC converters that employ newlinediodes. The AC-DC converters are mainly classified on the basis of the circuit newlineconfiguration used for power quality improvement. They are passive, active and hybrid AC-DC converters.