IMPROVINGVOLTAGEREGULATIONANDHARMONICELIMINATION USINGGENETICALGORITHMINPWM CHOPPERS
S. Srinivasarao, N. Shailajan · 2005
(ssraonitw()yahoo.co.in ),shailaja_narojugyahoo.co.uk ABSTRACT: A methodofoutputvoltage regulation and voltage harmonic elimination inapulse-width modulated AC chopper using genetic algorithms (GA)isproposed. Theoutput voltage oftheAC chopper withkpulses per half cycle isexpressed intermsofswitching angles using fourier series, andthebest switching angles areidentified forharmonic elimination andimproving output voltage regulation. Theproblem isredrafted asanoptimization task, andasolution issought through GAs.Theresults arefound tobesatisfactory. Keywords:Genetic Algorithm, AC Chopper, Pulse WidthModulation, TotalHarmonic Distortion. IIINTRODUCTION Thedevelopments achieved recently inthefield ofpower electronics madeitpossible toimprove theperformance of electrical system utility. Usually solid state powerswitching devices areemployed insource conditioning bychanging either itsmagnitude orfrequency suchasconverters, inverters, choppers, regulators orcycloconverters. The advantages offered byusing these devices arefast response, compactness, loss free control andlowpowerdemands of control circuitry. Ontheother hand, control byswitching is often accomplished by extralosses duetoharmonics presented inoutput voltage waveforms, addedtolower values ofsystem powerfactor. AnACvoltage controller is usedasoneofthepowerelectronics systems tocontrol an output acvoltage forpowerranges fromfewwatts(asin light dimmers) uptofractions ofmegawatts (asinstarting systems forlarge induction motors). ACvoltage controllers arewidely employed inmanyapplications such asindustrial heating, lightning control andstarting andspeed control of induction motors. Generally triacs oranti parallel connected thyristors areusedas powerconverters in such systems(l).Voltage