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Modeling,Simulation,andReductionofConductedElectromagneticInterferenceDuetoaPWMBuckTypeSwitchingPowerSupplyIA.FarhadiAbstract:UndesiredgenerationofradiatedorconductedenergyinelectricalsystemsiscalledElectromagneticInterference(EMI).HighspeedswitchingfrequencyinpowerelectronicsconvertersespeciallyinswitchingpowersuppliesimprovesefficiencybutleadstoEMI.Differentkindofconductedinterference,EMIregulationsandconductedEMImeasurementareintroducedinthispaper.CompliancywithnationalorinternationalregulationiscalledElectromagneticCompatibility(EMC).PowerelectronicsystemsproducersmustregardEMC.ModelingandsimulationisthefirststepofEMCevaluation.EMIsimulationresultsduetoaPWMBucktypeswitchingpowersupplyarepresentedinthispaper.ToimproveEMC,sometechniquesareintroducedandtheireffectivenessprovedbysimulation.IndexTerms:Conducted,EMC,EMI,LISN,SwitchingSupplyI.INTRODUCTIONFASTsemiconductorsmakeitpossibletohavehighspeedandhighfrequencyswitchinginpowerelectronics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,PATHANDVICTIMOFEMIUndesiredvoltageorcurrentiscalledinterferenceandtheircauseiscalledinterferencesource.Inthispaperahigh-speedswitchingpowersupplyisthesourceofinterference.Interferencepropagatedbyradiationinareaaroundofaninterferencesourceorbyconductionthroughcommoncablingorwiringconnections.Inthisstudyconductedemissionisconsideredonly.Equipmentsuchascomputers,receivers,amplifiers,industrialcontrollers,etcthatareexposedtointerferencecorruptionarecalledvictims.Thecommonconnectionsofelements,sourcelinesandcablingprovidepathsforconductednoiseorinterference.Electromagneticconductedinterferencehastwocomponentsasdifferentialmodeandcommonmode9.A.DifferentialmodeconductedinterferenceThismodeisrelatedtothenoisethatisimposedbetweendifferentlinesofatestcircuitbyanoisesource.RelatedcurrentpathisshowninFig.19.Theinterferencesource,pathimpedances,differentialmodecurrentandloadimpedancearealsoshowninFig.1.B.CommonmodeconductedinterferenceCommonmodenoiseorinterferencecouldappearandimposebetweenthelines,cablesorconnectionsandcommonground.Anyleakagecurrentbetweenloadandcommongroundcouldbemodeledbyinterferencevoltagesource.Fig.2demonstratesthecommonmodeinterferencesource,commonmodecurrentsIcm1andIcm2andtherelatedcurrentpaths9.Thepowerelectronicsconvertersperformasnoisesourcebetweenlinesofthesupplynetwork.Inthisstudydifferentialmodeofconductedinterferenceisparticularlyimportantanddiscussionwillbecontinuedconsideringthismodeonly.III.ELECTROMAGNETICCOMPATIBILITYREGULATIONSApplicationofelectricalequipmentespeciallystaticpowerelectronicconvertersindifferentequipmentisincreasingmoreandmore.Asmentionedbefore,powerelectronicsconvertersareconsideredasanimportantsourceofelectromagneticinterferenceandhavecorruptingeffectsontheelectricnetworks2.Highlevelofpollutionresultingfromvariousdisturbancesreducesthequalityofpowerinelectricnetworks.Ontheothersidesomeresidential,commercialandespeciallymedicalconsumersaresosensitivetopowersystemdisturbancesincludingvoltageandfrequencyvariations.ThebestsolutiontoreducecorruptionandimprovepowerqualityiscomplyingnationalorinternationalEMCregulations.CISPR,IEC,FCCandVDEareamongthemostfamousorganizationsfromEurope,USAandGermanywhoareresponsiblefordeterminingandpublishingthemostimportantEMCregulations.IECandVDErequirementandlimitationsonconductedemissionareshowninFig.3andFig.479.Fordifferentgroupsofconsumersdifferentclassesofregulationscouldbecomplied.ClassAforcommonconsumersandclassBwithmorehardlimitationsforspecialconsumersareseparatedinFig.3andFig.4.FrequencyrangeoflimitationisdifferentforIECandVDEthatare150kHzupto30MHzand10kHzupto30MHzrespectively.Complianceofregulationsisevaluatedbycomparisonofmeasuredorcalculatedconductedinterferencelevelinthementionedfrequencyrangewiththestatedrequirementsinregulations.InunitedEuropeancommunitycomplianceofregulationismandatoryandproductsmusthavecertifiedlabeltoshowcoveringofrequirements8.IV.ELECTROMAGNETICCONDUCTEDINTERFERENCEMEASUREMENTA.LineImpedanceStabilizationNetwork(LISN)1-Providingalowimpedancepathtotransferpowerfromsourcetopowerelectronicsconverterandload.2-Providingalowimpedancepathfrominterferencesou