铝电解电容的使用寿命.doc

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1、铝电解电容的寿命电源产品中经常用到铝电解电容，他的寿命往往决定了整个产品的寿命。因此，了解如何计算铝电解电容的寿命很有必要。Chapter1铝电解电容的特性1.1Circuitmodel（等效模型）Thefollowingcircuitmodelsthealuminiumelectrolyticcapacitor’snormaloperationaswellastheovervoltageandreversevoltagebehavior.（此模型包含正常运行，过压，反压时的特性）CACcRPESRLD=Anodecapacitance(阳极电容)=Cathodec

2、apacitance(阴极电容)=Parallelresistance,duetodielectric(并联电阻)=Seriesresistance,asaresultofconnections,paper,electrolyte,ect.等效串联电阻=Windinginductanceandconnections等效串联电感=Overandreversevoltage等效稳压管ThecapacitanceCaandCcarethecapacitanceofthecapacitorandisfrequencyandtemperaturedepended.（Caand

3、Cc，它的容量是频率及温度的函数）TheresistanceESRistheequivalentseriesresistancewhichisfrequencyandtemperaturedepended.Italsoincreaseswiththeratedvoltage.（ESR是频率及温度的函数，随着额定电压的增加而增加）TheinductanceListheequivalentseriesinductance,andit’sindependentforbothfrequencyandtemperature.Itincreaseswithterminalspa

4、cing.（L是频率及温度的函数）TheresistanceRpistheequivalentparallelresistanceandaccountsforleakagecurrentinthecapacitor.Itdecreaseswithincreasingthecapacitance,temperatureandvoltageanditincreaseswithtime.（Rp的大小决定了漏电流的大小，随着容量温度电压的增加而降低，随着使用时间的延长而增加）ThezenerdiodeDmodelstheovervoltageandreversevoltag

5、ebehavior.Applicationofovervoltageontheorderof50Vbeyondthecapacitor’ssurgevoltageratingcauseshigh。（D模拟过压及加反向电压时特性）Leakagecurrentandaconstantvoltage-operatingmodequitelikethereverseconductionofazenerdiode.Applicationsofreversevoltagemuchbeyond1.5Vcauseshighleakagecurrentquiteliketheforw

6、ardconductionofadiode.Neitheroftheseoperatingmodescanbemaintainedforlongbecausehydrogengasisproduced,andthepressurebuiltupwillcausefailure.（加到电容两端的反向电压不能大于1.5V）1.2Capacitance（电容的容量）Theratedcapacitanceisthenominalcapacitanceanditisspecifiedat120Hzandatemperatureof25°C.Capacitanceisameas

7、ureoftheenergystoragecapabilityofacapacitoratagivenvoltage.（额定容量：标称电压，120Hz,25°C时测量）。Thecapacitancedecreasesunderloadconditionsandincreasesundernoloadconditionsovertime.Whenreversevoltageorexcessiveripplecurrentisapplied,orwhenthecapacitorisrepeatedlychargedanddischarged,analuminiumo