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1、辍悉报蜣墒炱澡度髅工郛呦熟现SpeedControlofDCMotor氡町疔嗒堙昆懂能佃赣弯钺甲蹋RegulatorSystems囵榈倨赢鹊吁贲购烬萃笆璜舌嵩Aregulatorsystemisonewhichnormallyprovidesoutputpowerinitssteady-stateoperation.避舐有痂杖倚求皆垅澹杜撕砧睫Forexample,amotorspeedregulatormaintainsthemotorspeedataconstantvaluedespitevariationsin
2、loadtorque.Eveniftheloadtorqueisremoved,themotormustprovidesufficienttorquetoovercometheviscousfrictioneffectofthebearings.Otherformsofregulatoralsoprovideoutputpower;Atemperatureregulatormustmaintainthetemperatureof,say,anovenconstantdespitetheheatlossintheove
3、n.Avoltageregulatormustalsomaintainmustoutputvoltageconstantdespitevariationintheloadcurrent.Foranysystemtoprovideanoutput,e.g.,speed,temperature,voltage,etc,anerrorsignalmustexistundersteady-stateconditions.跹郯砀撇炯复朋掎德剥鸸疫驴拿ElectricalBraking碉纱荪艋辉菔恕髋勰睬肚洼撬孢Inmanysp
4、eedcontrolsystem,e.g.,rollingmillsminewinders,etc.,theloadhastobefrequentlybroughttoastandstillandreversed.Therateatwhichthespeedreducesfollowingareducedspeeddemandisdependentonthestoredenergyandthebrakingsystemused.Asmallspeedcontrolsystem(sometimesknownasavel
5、odyne)canemploymechanicalbraking,butthisisnotfeasiblewithlargespeedcontrollerssinceitisdifficultandcostlytoremovetheheatgenerated.骶睥饩妪帔砹掐嚷滞突迅遮樊撼Thevariousmethodsofelectricalbrakingavaiableare:亿峰艾事肆嚷材休岿眠午但箨霪(1)Regenerativebraking.造瓞祛毕铫血幛氖蒲鹰匪�酮牵(2)Eddycurrentbrak
6、ing.彝烀招剪裕吻禺瓢押累贰诬忱橐(3)Dynamicbraking.黪处彰速娈颖氯禽立诡害却憧轻(4)Reversecurrentbraking(plugging).僳谩郊凋垄奄肋猊关滁凛芒辅耒Regenerativebrakingisthebestmethod,thoughnotnecessarilythemosteconomic.Thestoredenergyintheloadisconvertedintoelectricalenergybytheworkmotor(actingtemporarilyasag
7、enerator)andisreturnedtothepowersupplysystem.Thesupplysystemthusactsasa“sink”intowhichtheunwantedenergyisdelivered.Providingthesupplysystemhasadequatecapacity,theconsequentriseinterminalvoltagewillbesmallduringtheshortperiodsofregeneration.IntheWard-Leonardmeth
8、odofspeedcontrolofDCmotors,regenerativebrakingisinherent,butthyristordriveshavetobearrangedtoinverttoregenerate.Inductionmotordrivercanregenerateiftherotorshaftisdrivenfaste
