浙大电力电子系统建模及控制ch3_DC-DC变换器的电流峰值控制

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1、Chapter3CurrentProgrammedControlConceptofCurrentProgrammedControlCurrentprogrammedcontrolvs.dutycyclecontrolAdvantagesofcurrentprogrammedcontrol:•Simplerdynamics—inductorpoleismovedtohighfrequency•Simplerobustoutputvoltagecontrol,withlargephasemargin•cu

2、rrentlimitingability•Transformersaturationproblemsinbridgeorpush-pullconverterscanbemitigatedAdisadvantage:susceptibilitytonoiseBuckconverter:inductorcurrentslopesInductorcurrentslopes,CCMInductorcurrentslopesm1and–m2buckconverterboostconverterbuck–boos

3、tconverterSteady-stateinductorcurrentwaveform,CPMSolveford:Insteadystate:iL(TS)iL(0)m1M1m2M2dDThenPerturbedinductorcurrentwaveformdˆIsnegativeChangeininductorcurrentperturbationoveroneswitchingperiodABSteady-statewaveformCDPerturbedwaveformFromrecta

4、ngletriangleABCFromrectangletriangleABDChangeininductorcurrentperturbationovermanyswitchingperiodsSimilarlyDDForstability:11'D1DExample:unstableoperationforD=0.6Example:stableoperationforD=1/3Stabilizationviaadditionofanartificialramptothemeasuredswi

5、tchcurrentwaveformNow,transistorswitchesoffwhenSteadystatewaveformswithartificialrampStabilityanalysis:perturbedwaveformdˆTSmaiˆ(0)Lmiˆ(T)2mLS1dˆTSSimilarlyStabilityanalysis:changeinperturbationovercompleteswitchingperiodsFirstsubinterval:Secondsubinte

6、rval:Netchangeoveroneswitchingperiod:Afternswitchingperiods:Characteristicvalue:Thecharacteristicvalueα•Forstability,require

7、α

8、<1•Buckandbuck-boostconverters:m2=–v/LSoifviswell-regulated,thenm2isalsowell-regulated•Acommonchoice:ma=0.5m2Thisleadstoα=–1at

9、D=1,and

10、α

11、<1for0=

12、rcurrentequali(t)LInductorcurrentfollowsthecommanddynamicallyiL(t)Tsic(t)Thefirst-orderapproximation(simpleCPMmodel)Ifneglectswitchingrippleandartificialramp•AccuratewhenconverteroperateswellintoCCM(sothatswitchingrippleissmall)