重庆大学-过程控制-process-control-中文-翻译-第五章(1)

1ProcessControlCollegeofAutomationChongqingUniversity2AnalysisofSingleLoopSystemsOutlinePIDControllersP-controller,PIcontroller,PDcontroller,PIDcontrollerAGeneralSISOSystem一般的单输入单输出系统Transferfunctionwithprocessmodel过程模型的传递函数Signaltransmitter信号变送器ControllerActuator(controlvalves)执行器(控制阀)Closed-LoopResponse闭环响应SevenexamplesChoiceofcontrollers3AnalysisofSingleLoopSystemsPIDControllersAnexampleMonitoringtheliquidleveinavesselAdjustingtheopeningoftheaffluentvalve监测容器液体高度，调整阀门开度Keepingtheliquidlevelatsomeuserspecifiedvalue(setpoint,orreference)Theliquidlevelisboththemeasuredandcontrolledvariable液位是测量与控制的两个变量(theyarethesameinSISOsystem)4AnalysisofSingleLoopSystemsPIDControllersAnexampleObjective（目的）:Keepinghaths维持h在hsSituation:Asuddensurgeattheinletflowqiincreasesh在入口流量qi骤增增重hDeviation（偏差）:Resultingin（导致）h’=h-hs0Rectification（矫正）:Openingupthevalve(loweringtheflowresistanceR):开放的阀门(降低流动阻力R)Control:Thesignalofthecontroller,p(t)isthefunctionofthedeviationvariableh’控制型号p(t)是偏差变量h’的函数5AnalysisofSingleLoopSystemsPIDControllersAnexampleDefininganerrorsignalduetotheuseofnegativefeedback由于负反馈的使用定义一个误差信号e(t)=hs(t)-h(t)Theactualcontroloutput实际控制输出psistheactuatingsignal（预处理信号）atsteadystate(i.e.,h’=0),calledthecontrollerbiassignal被称为控制器偏差信号6AnalysisofSingleLoopSystemsPIDControllersProportionalcontrol（比例控制）(P-control):ProportionalModeThecompensation（补偿）signal(actualcontrolleroutput)isproportionalto（与..成比例）theerror（误差）,e(t)whereKcistheproportionalgainofthecontroller,determingthecontrollersensitivity（灵敏度）7AnalysisofSingleLoopSystemsPIDControllersP-controlAllcommercialdevices（商业设备）haspositivegainThecontrolleroutputmovesinthereversedirectionofthecontrolledvariable控制器的输出向控制变量的反向变化8AnalysisofSingleLoopSystemsPIDControllersP-controlIntheliquidlevelproblem液位平衡问题,ifthedisturbationintheinletmakeshriseoverh’,thuse0ppsThecontrolleroutputisdecreasedPurchasingavlavewherealoweredsignalmeansopeningthevalve降低的信号，意味着打开阀门withthenegativesteadystategain(-Kv)Thecontrolleriswrittenase(t)=hs(t)-h(t)9AnalysisofSingleLoopSystemsPIDControllersP-controlTheerrorises=0att=0Thedeviationvariableisdefinedase’(t)=e(t)-esTransferfunctionThepercentproportionalband(PB)e(t)=hs(t)-h(t)10AnalysisofSingleLoopSystemsPIDControllersP-control:S-Domain)(')('teKtpc)(')('teKtpcTime-Domain)('tp11AnalysisofSingleLoopSystemsPIDControllersP-control:12AnalysisofSingleLoopSystemsPIDControllersP-control:ModernLevelSensor现代液位传感器13AnalysisofSingleLoopSystemsPIDControllers:P-control:14AnalysisofSingleLoopSystemsPIDControllersInthesense（传感器）ofproportionalgainKcThehighergain,thefaster(lessstable)controlKc越大，响应速度快越不稳定.Thelowergain,theslower(morestable)control.Kc越小，响应速度慢越稳定.15AnalysisofSingleLoopSystemsPIDControllersFrompracticalperspective,defineanewquantity从实际应用的角度,定义一个新的量TheProportionalBand(PB)（比例范围）istheinverseoftheGain.负增益InthesenseofproportionalbandPBThehigherPB,theslower(andmorestable)control.越高的PB，越慢越稳定的控制ThelowerPB,thefaster(andlessstable)control.16AnalysisofSingleLoopSystemsPIDControllersThePercentProportionalBand百分比例带FromPracticalperspective:17AnalysisofSingleLoopSystemsPIDControllersQualitativefeaturesofp-controlP控制器的定性特点Ap-controlleraccelerates（加速）theresponseofaprocessThelargerKc,thefasteristhechangetoagivenerror误差ToolargeKcwillmaketheprocessunstableThecontrolsystemissaturatedatthephysicallimits该控制系统是饱和的物理极限Controllercanonlydeliver（传送）somuchvoltageorcurrent（电压和电流）Avalvecanonlydeliversomuchfluidwhenfullyopened阀门完全打开只能提供了这么多流体18AnalysisofSingleLoopSystemsPIDControllersProportional-integral(PI)control:PersistentModeAccumulating（累积）thehistoricalerrors（误差）(integralaction)Eliminatingtheoffset(steadystateerror)消除静差（稳态误差）whereIistheintegraltimeconstant(resettime)1/Iiscalledtheresetrate,usedincommercialdevices1/I被称为复位率，商用设备中使用19AnalysisofSingleLoopSystemsPIDControllersProportional-integral(PI)control)('tpControllerBehaviourwhene(t)isconstantSlope=E/ItIdttetp0)('1)('TimeDomainssEsPI1)()(S-DomainWhatisthedifferenceComparedwithP-control20AnalysisofSingleLoopSystemsPIDControllers:PIcontrol1.Theintegralactionmayovercompensate（过度补偿）(oscillation振荡),thusexhibitingtheunderdampedresponse因此展示了过阻尼响应2.Inpractice,integralactionisneverusedbyitself不单独应用3.Integralactionmakestheprocesssaturation（饱和）,resetwindup（积分饱和）Integraltermtakesonafinalnonzerovalue,thusPermitting（允许）estostayatzero,astimeprogresses21AnalysisofSingleLoopSystemsPIDControllers:PIcontrolResetwindup:theresetelementofthecontrollercontinuestoincrease(ordecrease)thecontrolleroutput控制器的复位元素继续增加（或减少）控制器的输出evenwhenthechangeinoutputdoesnotcauseanychangeintheprocessmeasurement(controlledvariable).即使在输出的变化不会引发任何过程中测量改变(控制变量)。withnoresulting（致使）decreaseinerror（没有导致误差减少）,theoutputwillcontinuetoincreaseuntilitreachesitslimit.22AnalysisofSingleLoopSystemsPIDControllers:PIcontrolFrompracticalperspective,avoidingresetwindup（积分饱和）Theintegraloftheerrors对误差积分23AnalysisofSingleLoopSystemsPIDControllers:PIcontrolFrompracticalperspective,avoidingresetwindupWindupvs.Anti-Windup24PIDControllersGen