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Aproportional-actioncontroller(Pcontroller)changesthemanipulatedvariableMproportionaltothe
looperror.ThePcontrollerworksimmediately.Byitselfitcannotdrivethelooperrortozero.
:ManipulatedvariableofthePcontrolleratthetimen
:GainofthePcontroller
:Looperroratthetimen
Thefollowingpictureshowsajumpinprocessvalueandstepresponseofthecontroller:
Summary
ThePcontrollerhasthefollowingcharacteristics:
Itcannotcorrectfaultswiththecontrolprocess>lastinglooperror.
Itreactsimmediatelytoachangeintheprocessvalue.
Itisstable.
IController
Anintegral-actioncontroller(Icontroller)changesthemanipulatedvariableMproportionaltotheloop
errorandtothetime.TheIcontrollerworksbydelayedaction.Itcompletelyremediesalooperror.
Inordertocalculatethevalueofthemanipulatedvariableataperiodoftimen,thetimeupuntilthis
periodoftimemustbedividedintosmalltimeslices.Thelooperrorsattheendofeachtimeslicemust
beaddedup(integrated)andtheyarethenenteredinthecalculation.
:ManipulatedvariableoftheIcontrolleratthetimen
:ManipulatedvariableoftheIcontrolleratthetimen-1;alsocalledintegralsum
:GainoftheIcontroller
:Samplingtime,durationofatimeslice
:Integraltime:bymeansofthistime,theinfluenceoftheintegralpartiscontrolledonthe
manipulatedvariable,alsoknownasintegral-actiontime
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