《过程控制技术》课件-控制仪表及位式控制规律

Controlinstrumentsandon-offcontrollaws控制仪表及位式控制规律控制仪表及位式控制规律Controlinstrumentsandon-offcontrollaws谢聪XieCong主讲教师Teacher理解掌握控制仪表的使用方法Understandandmastertheuseofcontrolinstruments控制仪表及位式控制规律Controlinstrumentsandon-offcontrollaws有效地运用位式控制规律Effectivelyapplyon-offcontrollawsCaseImport案例导入冬天用空调取暖时，设定好26℃，空调会先全力制热，等室温达到这个温度，它就悄悄停下来；可过一会儿温度降了点，它又立马启动继续工作。Whenusinganairconditionerforheatinginwinter,aftersettingitto26℃,theairconditionerwillfirstbeoperatedatfullcapacityforheating.Oncetheroomtemperaturereachesthissetting,itwillbequietlystopped;however,ifthetemperaturedropsabitafterawhile,itwillbeimmediatelystartedagaintocontinueworking.CaseImport案例导入冬天用空调取暖时，设定好26℃，空调会先全力制热，等室温达到这个温度，它就悄悄停下来；可过一会儿温度降了点，它又立马启动继续工作。Whenusinganairconditionerforheatinginwinter,aftersettingitto26℃,theairconditionerwillfirstbeoperatedatfullcapacityforheating.Oncetheroomtemperaturereachesthissetting,itwillbequietlystopped;however,ifthetemperaturedropsabitafterawhile,itwillbeimmediatelystartedagaintocontinueworking.控制仪表Controlinstruments位式控制规律On-offcontrollawsControlinstruments控制仪表Controlinstruments控制仪表控制规律的定义Definitionofcontrollaws控制仪表又称控制器或调节器，其作用是把被控参数的测量值PV

和给定SV

进行比较，得出偏差

e

后，按一定的控制（或调节）规律进行运算，输出控制信号MV，以推动执行器动作，实现对生产过程的自动控制。Controlinstruments,alsoknownascontrollersorregulators,functionbycomparingthemeasuredvaluePVofthecontrolledparameterwiththesetvalueSVtoobtainthedeviation

e

andthenperformingcalculationsaccordingtoacertaincontrol(orregulation)lawtooutputacontrolsignalMV.Thissignaldrivestheactuatortoachieveautomaticcontroloftheproductionprocess.Controlinstruments控制仪表控制仪表分类Classificationofcontrolinstruments按工作能源可分为Canbeclassifiedaccordingtoworkingenergy电动仪表Electricinstruments以AC220V或DC24V作为工作能源，其输入输出信号均采用DC0～10mA/DC0～10V或DC4～20mA/DC1～5V的标准信号。TheseuseAC220VorDC24Vfortheworkingenergysource,withinputandoutputstandardsignalsofDC0-10mA/DC0-10VorDC4-20mA/DC1-5V.Controlinstruments控制仪表控制仪表分类Classificationofcontrolinstruments按工作能源可分为Canbeclassifiedaccordingtoworkingenergy气动仪表Pneumaticinstruments以140kPa的气压信号作为工作能源，其输入输出信号均采用20～100kPa的标准气压信号。Theseuseapneumaticsignalof140kPafortheworkingenergysource,withinputandoutputstandardpneumaticsignalsof20-100kPa.Controlinstruments控制仪表控制仪表分类Classificationofcontrolinstruments按工作能源可分为Canbeclassifiedaccordingtoworkingenergy自力式仪表Self-poweredinstruments不需要专门提供工作能源。Thesedonotrequirethededicatedworkingenergysource.hhQ1Q1Q2液位控制/调节器Levelcontroller/regulatorQ₁：流入量Q1:inflowrateQ2：流出量Q2:outflowrateh：液位高度h:liquidlevelheightOn-offcontrollaws位式控制规律On-offcontrollaws位式控制规律基本控制规律及特点Basiccontrollawsandcharacteristics所谓控制规律是指控制器的输出值MV(ManipulationValue)与输入偏差e之间的关系。Theso-calledcontrollawreferstotherelationshipbetweenthecontroller'soutputvalueMV(ManipulationValue)andtheinputdeviatione.

MV=f(e)

控制器的输入信号e

由变送器送来的测量值PV（ProcessValue）和设定值SV（SettingValue）比较得出Thecontroller'sinputsignaleisobtainedbycomparingthemeasuredvaluePV(ProcessValue)sentbythetransmitterwiththesetvalueSV(SetValue).e=PV–SVe=SV–PV或orOn-offcontrollaws位式控制规律控制规律Controllaws断续控制Discontinuouscontrol控制器输出接点信号Thecontrolleroutputscontactsignals

双位控制Two-positioncontrol

三位控制Three-positioncontrol连续控制ContinuouscontrolOn-offcontrollaws位式控制规律控制规律Controllaws断续控制Discontinuouscontrol控制器输出接点信号Thecontrolleroutputscontactsignals

双位控制Two-positioncontrol

三位控制Three-positioncontrol双位控制器只有两个输出值，对应的执行机构只有开和关两个极限位置，所以也被称为开关控制。Atwo-positioncontrollerhasonlytwooutputvalues,andthecorrespondingactuatorhasonlytwoextremepositions:onandoff.Therefore,two-positioncontrolisalsoknownason-offcontrol.连续控制Continuouscontrol控制器输出连续信号Thecontrolleroutputscontinuoussignals

比例（P）控制Proportional(P)control

比例积分控制（PI）Proportional-integralcontrol(PI)

比例微分控制（PD）Proportional-derivativecontrol(PD)

比例积分微分控制（PID）Proportional-integral-derivativecontrol(PID)On-offcontrollaws位式控制规律理想的双位控制器输出值MV

与输入偏差e

之间的关系：TherelationshipbetweentheoutputvalueMVofanidealtwo-positioncontrollerandtheinputdeviatione:e

≥0（或

e

<0）时Whene≥0(ore<0)MVmaxMV=MVmine

≤0（或

e

>

0）时Whene≤0(ore>0)MV有中间区的双位控制特性Characteristicsoftwo-positioncontrolwithanintermediatezoneMVmaxMVmine理想双位控制特性Characteristicsofidealtwo-positioncontrolMVmaxMVmineMVOn-offcontrollaws位式控制规律例：双位温度控制系统Example:Two-positiontemperaturecontrolsystem～进水Waterinlet出水Wateroutlet220VOn-offcontrollaws位式控制规律例：双位温度控制系统Example:Two-positiontemperaturecontrolsystem温度低于给定值时，温控器输出高电平，继电器闭合，加热器通电加热；Whenthetemperatureislowerthanthesetvalue,thetemperaturecontrolleroutputsahighlevel,therelayisclosed,andtheheaterispoweredonforheating;温度高于给定值时，温控器输出低电平，继电器断开，加热器断电。whenthetemperatureishigherthanthesetvalue,thetemperaturecontrolleroutputsalowlevel,therelayisopened,andtheheaterispoweredoff.～进水Waterinlet出水Wateroutlet220V温度给定值SettemperatureOn-offcontrollaws位式控制规律二位式控制器电路原理图Schematicdiagramoftwo-positioncontrollercircuit测量信号Measuredsignal给定信号Setsignal－＋＋∞U0二位式控制是一种最简单的控制/调节器，根据被调量偏差e符号的正、负，输出MV只有两个位置，高电平或低电平，可以作为一个电气开关使用。Thetwo-positioncontrolleristhesimplestcontroller/regulator.Basedonthepositiveornegativesignofthedeviationeofthecontrolledvariable,theoutputMVhasonlytwopositions,highlevelorlowlevel.Therefore,itcanbeusedasanelectricalswitch.On-offcontrollaws位式控制规律双位控制效果Two-positioncontroleffecttMVTT0ttMVTT0t有中间区的双位控制效果Two-positioncontroleffectwithanintermediatezoneOn-offcontrollaws位式控制规律tMVTT0ttMVTT0t被控温度在T0

上下振荡，不能稳定在T0

。ThecontrolledtemperatureoscillatesaboveandbelowT0andcannotbestabilizedatT0.双位控制效果Two-positioncontroleffect有中间区的双位控制效果Two-positioncontroleffectwithanintermediatezoneOn-offcontrollaws位式控制规律三位控制Three-positioncontrol控制器有三个输出状态值，可以控制两个继电器。Thecontrollerhasthreeoutputstatevaluesandcancontroltworelays.测量信号Measuredsignal给定1Setsignal1－＋＋∞U01－＋＋∞U02给定2Setsignal2三位控制器电路原理图Schematicdiagramofthree-positioncontrollercircuitMVmaxMVmineMVe2e1关系曲线RelationshipcurveOn-offcontrollaws位式控制规律三位控制Three-positioncontrol控制器有三个输出状态值，可以控制两个继电器。Thecontrollerhasthreeoutputstatevaluesandcancontroltworelays.测量信号Measuredsignal给定1Setsignal1－＋＋∞U01－＋＋∞U02给定2Setsignal2三位控制器电路原理图Schematicdiagramofthree-positioncontrollercircuitMVmaxMVmineMVe2e1关系曲线RelationshipcurveOn-offcontrollaws位式控制规律三位控制Three-positioncontrol控制器有三个输出状态值，可以控制两个继电器。Thecontrollerhasthreeoutputstatevaluesandcancontroltworelays.测量信号Measuredsignal给定1Setsignal1－＋＋∞U01－＋＋∞U02给定2Setsignal2三位控制器电路原理图Schematicdiagramofthree-positioncontrollercircuitMVmaxMVmineMVe2e1关系曲线RelationshipcurveOn-offcontrollaws位式控制规律例：温度三位控制系统Example:Temperaturethree-positioncontrolsystem温度低于T1时，温控器使继电器1、2都吸合，加热器1、2都通电加热；WhenthetemperatureislowerthanT1,thetemperaturecontrollermakesbothrelay1andrelay2beclosed,andbothheater1andheater2arepoweredonforheating;温度高于T1低于T2时，温控器使继电器1吸合、继电器2断开，只有加热器1通电；whenthetemperatureishigherthanT1andlowerthanT2,thetemperaturecontrollermakesrelay1beclosedandmakesrelay2beopened,andonlyheater1ispoweredon;J1J2T2T112220V进水Waterinlet出水Wateroutlet温度高于T2时，继电器1、2都断开。whenthetemperatureishigherthanT2,bothrelay1andrelay2areopened.On-offcontrollaws位式控制规律温度三位控制效果Temperaturethree-positioncontroleffect温度偏差大时，升温速度快；温度偏差小时，小幅调整。Whenthetemperaturedeviationislarge,theheatingrateisfast;whenthetemperaturedeviationissmall,thereisaminoradjustment.tMVTT2T1tOn-offcontrollaws位式控制规律温度三位控制效果Temperaturethree-positioncontroleffect温度偏差大时，升温速度快；温度偏差小时，小幅调整。Whenthetemperaturedeviationislarge,theheatingrateisfast;whenthetemperaturedeviationissmall,thereisaminoradjustment.tMVTT2T1t要使调节过程平稳准确，必须使用控制输出值能连续变化的控制器。Acontrollerwithacontinuouslyvariablecontroloutputvaluemustbeusedtomaketheregulationprocessstableandaccurate.CourseSummary课程小结CourseSummary课程小结输出为有限离散状态（如全开/全关、高/低电平），根据偏差阈值切换状态。Theoutputisinalimiteddiscretestate(suchasfullyopened/fullyclosed,high/lowlevel),andthestateisswitchedaccordingtothedeviationthreshold.核心原理Coreprinciple结构简单、成本低、易实现。Si