SOCIETY OFAUTOMOTIVE ENGINEERS, INC. TwoPennsylvania Plaza,NewYork,N.Y.10001 ControloftheAutomotive Electrical Environment GilmanB.Andrews TheBendixCorp. International Automotive Engineering Congress Detroit,Mich. January8-12,1973730045 Downloaded from SAE International by University of New South Wales, Sunday, September 16, 2018©SOCIETY OFAUTOMOTIVE ENGINEERS, INC.,1973 Downloaded from SAE International by University of New South Wales, Sunday, September 16, 2018730045 ControloftheAutomotive Electrical Environment Gilman B.Andrews TheBendixCorp. THEAPPLICATION ofelectronics tothemotorvehicle,as predictedbymanyobserversoftheindustry,hasbegunto showsubstantial increasesinrecentyears.Besidestheenter tainment andcommunications functions thathavebeentradi tionalstrongholds oftheelectronic art,control,measurement anddisplayfunctionsarenowbeingperformed electronically. Fuelinjection,antiskid,speedcontrol, displays—the listin creaseswitheachmodelyear. Someofthefunctionsassignedtoelectronics canbeper formedinnootherway,whereasforfunctionsthatcanalter nativelybeaccomplished usingpneumatics, mechanics, or hydraulics, ithasrecentlybecomeapparentthatcontemporary electronics canbecompetitive. Antiskid isafunctionbestac complished electronically, forinstance,andrecentlegislation willmakeitsapplication toheavy-duty trucksmandatory. Speedcontrol,ontheotherhand,canbeaccomplished using eitherelectromechanical orelectronic elements. Recently electronics hasbeenmadetoperformthespeedcontrolfunc tioninasuperiorfashion,whileremaining competitive in termsofcostandreliability. Aselectronic equipments proliferate, moreandmoreelec tronicdesignersencounter thepeculiarenvironment ofthe automobile. Theautomotive powersupplyischaracterized byvoltagefluctuation, noise,andsevereelectricaltransients. Mis handlinganddegradation ofelectricalcomponents oftheauto motivepowersupplyexaggerates theseconditions. Electro magneticinterference arisesfromenergyradiatedfromsources bothexternal andinternaltothevehicle. Devicessuchascom munications transmitters installedinthevehiclemaypresenta hazardtotheproperoperation ofelectronic equipment. Thispaperexaminessomemeasurements ofthesetypesof electricaldisturbances oncontemporary automobiles anddis cussestheeffectofthesephenomena ontheperformance of electronic equipment. Causesfortemporary andpermanent degradation ofelectronic equipment andfailuremechanisms onelectronic devicesareinvestigated, andasystemsapproach totheproblemisrecommended. Possibleimprovements to theelectrical environment aredirectedtothesourceofthe variousdisturbances, unlikethepresentmethodofdealing withthedisturbances attheinterfacebetweenthepowersup plyandeachelectronic package. VOLTAGE FLUCTUATIONS Typicalspecifications forwhatmightbecalledthesteady statecondition forthesupplyvoltagerangeinpassenger cars ABSTRACT Theincreasing useofelectronics inautomotive controland inmeasurement anddisplayfunctionsrequiresanexamination oftheautomotive electricalpowersupplycharacteristics. This environment ischaracterized byvoltagefluctuations, noise, andseveretransients. Mishandling anddegradation ofelectri calcomponents oftheautomotive powersupplyexaggerate theseconditions. Electromagnetic interference arisesfrom energyradiatedfromsourceswithinandoutsidethevehicle. Thispaperpresentssomemeasurements ofthesetypesofelectricaldisturbances oncontemporary automobiles anddis cussestheeffectofthephenomena ontheperformance of electronic equipment. Causesfortemporary andpermanent degradation ofelectronicequipment areinvestigated, anda systemsapproachtotheproblemisrecommended. Attention isdrawntopossibleimprovements totheelectricalenviron ment,directedtothesourceofthevariousdisturbances, asop posedtothepresentmethodofdealingwiththedisturbances attheinterfacebetweenthepowersupplyandeachelectronic package. Downloaded from SAE International by University of New South Wales, Sunday, September 16, 20182 placetheuppervoltagelimitat16V.Thelowervoltagelimit requirement dependsso