基于壓降型PWM開關(guān)電源的建模、仿真和減少傳導(dǎo)性電磁干擾-外文翻

基于壓降型PWM開關(guān)電源的建模、仿真和減少傳導(dǎo)性電磁干擾-外文翻Modeling,Simulation,andReductionofConductedElectromagneticInterferenceDuetoaPWMBuckTypeSwitchingPowerSupplyI

A.Farhadi

Abstract:UndesiredgenerationofradiatedorconductedenergyinelectricalsystemsiscalledElectromagneticInterference(EMI).HighspeedswitchingfrequencyinpowerelectronicsconvertersespeciallyinswitchingpowersuppliesimprovesefficiencybutleadstoEMI.Differentkindofconductedinterference,EMIregulationsandconductedEMImeasurementareintroducedinthispaper.CompliancywithnationalorinternationalregulationiscalledElectromagneticCompatibility(EMC).PowerelectronicsystemsproducersmustregardEMC.ModelingandsimulationisthefirststepofEMCevaluation.EMIsimulationresultsduetoaPWMBucktypeswitchingpowersupplyarepresentedinthispaper.ToimproveEMC,sometechniquesareintroducedandtheireffectivenessprovedbysimulation.

IndexTerms:Conducted,EMC,EMI,LISN,SwitchingSupply

I.INTRODUCTION

FASTsemiconductorsmakeitpossibletohavehighspeedandhighfrequencyswitchinginpowerelectronics[]1.Highspeedswitchingcausesweightandvolumereductionofequipment,butsomeunwantedeffectssuchasradiofrequencyinterferenceappeared[]2.Compliancewithelectromagneticcompatibility(EMC)regulationsisnecessaryforproducerstopresenttheirproductstothemarkets.ItisimportanttotakeEMCaspectsalreadyindesignphase[]3.ModelingandsimulationisthemosteffectivetooltoanalyzeEMCconsiderationbeforedevelopingtheproducts.Alotofthepreviousstudiesconcernedthelowfrequencyanalysisofpowerelectronicscomponents[]4[]5.DifferenttypesofpowerelectronicsconvertersarecapabletobeconsideredassourceofEMI.TheycouldpropagatetheEMIinbothradiatedandconductedforms.LineImpedanceStabilizationNetwork(LISN)isrequiredformeasurementandcalculationofconductedinterferencelevel[]6.InterferencespectrumattheoutputofLISNisintroducedastheEMCevaluationcriterion[]7[]8.NationalorinternationalregulationsarethereferencesfortheevaluationofequipmentinpointofviewofEMC[]7[]8.

II.SOURCE,PATHANDVICTIMOFEMI

Undesiredvoltageorcurrentiscalledinterferenceandtheircauseiscalledinterference

source.Inthispaperahigh-speedswitchingpowersupplyisthesourceofinterference.

Interferencepropagatedbyradiationinareaaroundofaninterferencesourceorbyconductionthroughcommoncablingorwiringconnections.Inthisstudyconductedemissionisconsideredonly.Equipmentsuchascomputers,receivers,amplifiers,industrialcontrollers,etcthatareexposedtointerferencecorruptionarecalledvictims.Thecommonconnectionsofelements,sourcelinesandcablingprovidepathsforconductednoiseorinterference.Electromagneticconductedinterferencehastwocomponentsasdifferentialmodeandcommonmode[]9.

A.Differentialmodeconductedinterference

Thismodeisrelatedtothenoisethatisimposedbetweendifferentlinesofatestcircuitbyanoisesource.RelatedcurrentpathisshowninFig.1[]9.Theinterferencesource,pathimpedances,differentialmodecurrentandloadimpedancearealsoshowninFig.1.

B.Commonmodeconductedinterference

Commonmodenoiseorinterferencecouldappearandimposebetweenthelines,cablesorconnectionsandcommonground.Anyleakagecurrentbetweenloadandcommongroundcouldbemodeledbyinterferencevoltagesource.

andFig.2demonstratesthecommonmodeinterferencesource,commonmodecurrentsI

cm1andtherelatedcurrentpaths[]9.ThepowerelectronicsconvertersperformasnoisesourceI

cm2

betweenlinesofthesupplynetwork.Inthisstudydifferentialmodeofconductedinterferenceisparticularlyimportantanddiscussionwillbecontinuedconsideringthismodeonly.

III.ELECTROMAGNETICCOMPATIBILITYREGULATIONSApplicationofelectricalequipmentespeciallystaticpowerelectronicconvertersindifferentequipmentisincreasingmoreandmore.Asmentionedbefore,powerelectronicsconvertersareconsideredasanimportantsourceofelectromagneticinterferenceandhavecorruptingeffectsontheelectricnetworks[]2.Highlevelofpollutionresultingfromvariousdisturbancesreducesthequalityofpowerinelectricnetworks.Ontheothersidesomeresidential,commercialandespeciallymedicalconsumersaresosensitivetopowersystemdisturbancesincludingvoltageandfrequencyvariations.ThebestsolutiontoreducecorruptionandimprovepowerqualityiscomplyingnationalorinternationalEMCregulations.CISPR,IEC,FCCandVDEareamongthemostfamousorganizationsfromEurope,USAandGermanywhoareresponsiblefordeterminingandpublishingthemostimportantEMCregulations.IECandVDErequirementandlimitationsonconductedemissionareshowninFig.3andFig.4[]7[]9.

Fordifferentgroupsofconsumersdifferentclassesofregulationscouldbecomplied.ClassAforcommonconsumersandclassBwithmorehardlimitationsforspecialconsumersareseparatedinFig.3andFig.4.FrequencyrangeoflimitationisdifferentforIECandVDEthatare150kHzupto30MHzand10kHzupto30MHzrespectively.Complianceofregulationsis

evaluatedbycomparisonofmeasuredorcalculatedconductedinterferencelevelinthementionedfrequencyrangewiththestatedrequirementsinregulations.InunitedEuropeancommunitycomplianceofregulationismandatoryandproductsmusthavecertifiedlabeltoshowcoveringofrequirements[]8.

IV.ELECTROMAGNETICCONDUCTEDINTERFERENCEMEASUREMENT

A.LineImpedanceStabilizationNetwork(LISN)

1-Providingalowimpedancepathtotransferpowerfromsourcetopowerelectronicsconverterandload.

2-Providingalowimpedancepathfrominterferencesource,herepowerelectronicsconverter,tomeasurementport.

VariationofLISNimpedanceversusfrequencywiththementionedtopologyispresentedin

Fig.7.LISNhasstabilizedimpedanceintherangeofc