液位控制系统英文.doc

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1、InternationalRailwayJournalLevelControlSystem【Title】InternationalRailwayJournal【PublicationDate】2008【No.】periodMarchIonMatei,DumitruPopescu,CiprianLupu,llieLuicanPolitehnicaUniversityofBucharest-ControlandComputerScienceFacultySplaiulIndependenteinr.313,sector6,B

2、ucurcsti,Romaniaemail:inion@3home.ro1LevelcontrolsystemThefluidflowiscontrolledbyanelectricpomp.Theprocessinputisavoltagewithvaluesbetween0and10Vandtheoutputisthefluidlevelmeasuredbyanultrasoundstransducer.Theprocessisnonlinearbutitisapproximatedwithlinearmathema

3、ticalmodelaroundarepresentativepointoffunctioning.TheapproximatedmathematicalmodelwhichwasobtainedusingthesampleperiodTe=5s.Itisimportanttomentionthatfordesigninganumericalregulatorthreestepsmustbefollowed:-computingthediscretemodel;-performancesspecification;-co

4、mputingtheadequatecontrolalgorithmInthiscaseforthelevelcontrolwereusedthenextnumericalcontrolalgorithms:RSTandPIDwithitstwovariants,PIDlandPID2.Thesealgorithmshavedifferentperformancessothatthestudentswillhavetheopportunitytocomparethem.FirstitwillbepresentedtheR

5、STalgorithmandthanthepaperwillcontinuewithPIDalgorithmswhichwillbestructuredanalyzedandcomparedtothefirstone.2PIDalgorithmNumericalPIDalgorithmcomesfromsamplingthecontinuousPIDalgorithmwithallappropriatesamplingperiod.NumericalPIDcontrollersaresuitableonlyforproc

6、essesmodeledbyasecondordertransferfunctionwithorwithoutpuredelay.ItisworthtomentionthatsomenumericalPIDcontrollersdonothaveacontinuousequivalent.2.1PIDlnumericalalgorithmLetusconsiderthealgorithm:ThetransferfunctionsofacontinuousPIDcontroller，Thisalgorithmisspeci

7、fiedbyfourparameters:K-proportionalaction;Ti-integralaction;Td-derivativeaction;Td-filteredderivativeaction.Therearemanymethodsthatcanbeusedtosamplethisalgorithmresultinginanumericalcontrollerofthesameform.Asitmaybeseen,PIDlnumericalregulatorhasalsofourparameters

8、(rthr1r2,s1)asitscontinuousform.ThisalgorithmcanbeInternational5RailwayJournalstructuredinaRSTformifT(q-1)=R(q-1).ItiseasytonoticethatPIDlisonefreedomdegreealg