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1、ChapterthreeThesingle-loopcontrolsystem3.1Theconfigurationofasingle-loopcontrolsystem3.2Thechannelpropertyofaprocess3.3Thecharacteristicsofthreebasiccontrolmodes,theP,I,D,andtheelectionofcontrolmode3.4ThePI,PDandPIDcontrolmodes3.5Themanipulatingelement3.1.1.CONSTRUCTIO
2、N:Asingle-loopcontrolsystemconsistsofsomeparts:aprocessoraplant,amanipulatingElement,acontrollerthatincludesanerrordetectorandcontrolmodel,andameasuringtransmitter.evmcSPDInthisfigure:e---theerrorsignal,theinputsignalofcontroller;v---thecontrolcommand,theoutputsignalof
3、controller;m---themanipulatingvariable,theoutputsignalofmanipulating-element;c---thecontrolledvariable,theoutputsignalofthecontrolsystem;SP---thereferencevalueofthecontrolsystem,theinputsignalofsystem;D---disturbancevariable,inputsignalofthesystemyet;---themeasuring-va
4、lueofthecontrolledvariable.3.1.2.Thecontrolledvariableandthemanipulatingvariable.ThecontrolledvariableThecontrolledvariable(C)istheprocessoutputvariablethatistobecontrolled.Inaprocesscontrolsystem,thecontrolledvariableshouldbeagoodmeasureofthequalityoftheproduct.Usuall
5、y,thecontrolledvariableisthemostimportantoneofparametersinaprocesswhosecharacteristicsarealwaysreflectedthroughtheseparameters.Usually,therearealwayssomeparametersinaprocess,whichcanreflectthecharacteristicsoftheprocess.Thusitisveryimportanthowtoselectaparameterastheco
6、ntrolledvariable,whichmostcanreflectthecharacteristicofaprocess,amongtheseparametersintheprocess.Forselectingthecontrolledvariable,weshallconsiderthreefacts:1.Thecontrolledvariablemostcanreflectthecharacteristicofaprocess,amongtheseparametersintheprocess.2.Itispreferab
7、letoselectaimmediate-variableasthecontrolledvariableamongsomevariablesinaprocess.3.Thevariable,selectedasthecontrolledvariable,canbemeasuredandcontrolledwithresent-technique.(2).Themanipulating-variableAmanipulating-variableisthevariablethataffectsthecontrolledvariable
8、ofaprocessbyforpeopleadjustingitfortocontroltheprocess.Inotherword,amanipulating-variableistheprocessinputvariabletha
