共模骚扰的成因与对策

,(,100044)::,,,,,,:;;;:TN97:A:100324897(2002)11200412071,:,,,,,,,22.11,()(),,,UDMIDM,+UDMvZSvZtvZLvZtv-UDM1Fig.1ConversionofCMcurrentintoDMcurrent,,PQUCM,,P,,,PQUCM,UCM,,,22Fig.2PathofCMcurrent,,ZL,2,,[1]14301120021115RELAYVol.30No.11Nov.15,2002©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.:(1)12,4(a)12,,,,,,,,,,,,4(b),,,,4(c)A,C2,B(2)12,5,,4Fig.4Isolationtransformercuttingground-loop6Fig.6Opticalisolatorcuttingground-loop,,5Fig.5CMRFchoke(3)12,6,,,,,,,,,24©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(PCB),ABLP,UCM,UCM,,A,B7(b),ICMIDM,,[1]2.37Fig.7IllustrationofcurrentdrivingCMradiation1PCB,,8,AB,IDMAB,,8Fig.8CMradiationcausedbydividingground2PCBAB,9PCB,,IDMIDMABPCBABLP,IDMLPUCM,,,,,,PCB9Fig.9ExampleforcurrentdrivingCMradiation3.1.210,UDM,,ICMICM=jCAUDM:CA34,©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.=nP20(n=1,2,3,),,[1]3.3,,,12Fig.12Staticshieldingbetweenswitchtransistorandheat-sink3.3.1,,,(1)3.2,,,,PCB,PCB,(2)Cd,2,Cd,IDM,IDMABLp,UCM,Cd,,3,Cd,ICM,Cd,,,12,,,,,0V,,44©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(3)13(),,,,,360,,,(14),,,,,,13Fig.13TypicalCMradiation14Fig.14Pig-taileffectatconnectorofshieldedcable(4)PCBPCB,,,,,,PCB3.3.2(1),,,,,89AB,(2)PCBEMC,PCB,EMC,15EMC,EMC,(),,EMCEMCIPOEMC,,IPOPCBIPO,,15EMCFig.15EMCgroundandCMdecouplingcapacitor(3),54,©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.[2]:,,,,,,17,,(),(18),16Fig.16Typicalstructureofpowersupplyfilter17Fig.17Correctmountingofpowersupplyfilter,,,,,,,;,;,64©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(18),,23,L-C,,4,,,,,,:[1].[M].:,1999.[2]KeithArmstrong.DesignTechniquesforEMCPart3:FiltersandSurgeProtectionDevices[M/OL].1999.http:PP[3]FrancoFioro.ElectromagneticEmissionsofIntegratedCircuits[M/OL].http:PP:2002206211;:2002206227:(1979-),,,;(1946-),,,,Generationandsuppressionofcommon-modedisturbanceLIUPing,SHAFei(EMCResearchSectionofNorthernJiaotongUniversity,Beijing100044,China)Abstract:Common2modedisturbanceisalwaysthechiefcriminaloftheworkingfailureofelectronicandelectricappliances.Itcanalsomaketheradiated2emissiontestoftheappliancesoverlimit.Therearetwocategoriesofit:oneisthecommon2modedisturbanceintrudingintotheequipment;theotheristhatradiatingfromtheequipment.Applyingthebalancecircuitandcuttingthegroundloopcanchoketheformeronethatmainlycausedbygroundloop.Thelatterisemittedthroughtheconnectingcablesthatareequivalenttotheasymmetricelementantennas.Socommon2modefiltersandshieldingcablescanbeusedontheantennastoreducetheradiation.ButmostattentionshouldbeputonthePCBdesign,elementspositionandlineconnection,whichcansuppressthesourceofthecommon2modedisturbance.Thispaperdealswithacomprehensiveanddetailedintroductionabouttheclassification,cause,behaviorandsuppressionmethodsofthecommon2modedisturbancecombiningtheorywithexamples.Keywords:common2modedisturbance;groundloop;common2moderadiation;common2modechoke74,©1994-2009ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.