控制工程6(英文).ppt
Ch10TheDesignofFeedbackControlSystemsBasicconceptApproachtosystemdesignCascadecompensationnetworksPhase-leaddesignusingBodediagramPhase-lagdesignusingBodediagram
10.1IntroductionThedesignofacontrolsystemisconcernedwiththearrangementortheplan,ofthesystemstructureandtheselectionofsuitablecomponentsandparameters.Thealterationoradjustmentofacontrolsysteminordertoprovideasuitableperformanceiscalledcompensation.Acompensatorisanadditionalcomponentorcircuitthatisinsertedintoacontrolsystemtocompensateforadeficientperformance.
TypesofcompensationCascadecompensationFeedbackcompensationOutput,orloadcompensationInputcompensationCompositecompensationFeedforward+feedback
10.2ApproachtosystemdesignApproachtosystemdesignRootlocusmethodFrequencyresponsemethod(Bodediagram)
10.3CascadecompensationnetworksPassivenetworksOperationalamplifiercircuitsPhase-leadnetworkPhase-lagnetworkPhase-lag-leadnetwork
TransferfunctionofcompensatorThecompensatorcanbechosentoaltertheshapeoftherootlocusorthefrequencyresponseofthecontrolsystem.Ingeneral,thecompensationnetworkcanbechosentohaveaTF:
TheTFofphase-leadcompensation
TheTFofphase-lagcompensation
10.4Phase-leaddesignusingBodediagramDesignprincipleIfthephasemarginisnotsufficient,phaseleadcanbeaddedtothephase-anglecurveofthesystembyplacingtheinasuitablelocation.Toobtainmaximumadditionalphaselead,wedesiretoplacethenetworksothatthefrequencyislocatedatthefrequencywherethemagnitudeofcompensatedcurvecrossesthe0-dBaxis.
Designprocedure1Evaluatetheuncompensatedsystemphasemarginwhentheerrorconstantsaresatisfied.2Allowingforasmallamountofsafety,determinethenecessaryadditionalphaselead,3Evaluateafrom
4Evaluate10logaanddeterminethefrequencywheretheuncompensatedmagnit