capacitor selection

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1、Forhalf-waveCockcroft-Waltonvoltagemultipliercircuit,wecangettheoutputvoltagewhenconnectingwithload.ܫ௟௢௔ௗܸൌ2ܸ݊െሺ4݊ଷ൅3݊ଶെ݊ሻ݊ൌ1,2,3…௢௨௧,௠௔௫௜௡,௣௘௔௞6ܥ݂Oneoftheproblemsisthatweshoulddeterminecapacitors.Thisiswhatwillbediscussed.Howtoselectappropriatecapacitors?Whatshouldbetookintoc

2、onsideration?Howdotherespectiveparametersaffectthefinaloutput?SelectionTips1.RatingVoltageThecircuitisappliedtothoseoccasionswherehighvoltageisneeded.Sowemustconsiderwhetheronecapacitorhastheabilityofwithdrawingsuchhighvoltage,usuallyseveralhundredvolts.Theanalysisisnotverycom

3、plicated.Forhalf-waveCWvolttaagemultipliercircuit,thecapacitorsmustwithdrrawatleasts2ܸ௜௡,௣௘௔௞.Ifthevoltageontheelectrodeexceedscapacitor’sratingvoltage,thecapacitormaybedamagepermanently.DielectricmayloseitsDCblockspecificationandthewholecapacitoractsshort.2.ESRThere’reanother

4、twoconcepts,phasedifferenceanddielectriicloss.Ithinktheyareusedtointerpretthesammething.Weusuallyestablishthecapacitor’smodelasabove.ABBREVIATIONEXPLANATATIONSOURCEANDDETAILSESREquivalentSeriesWireandconnectiiontoResistancetheplateProducesheatESLEquivalentSeriesDependsonpackag

5、etypeInductanceSurfacemountbettterSmallerSMDbetterRleakLeakageResistanceTypeofdielectricCIdealCapacitorAstoidealcapacitors,thecurrentisܸሶܫூௗ௘௔௟ሶൌ݆߱ܥIfthesupplyvoltageisn’ttoohighandthefrequencyislow,wecannegateESLandRleak.Thustherealisticcurrentisܸሶܫሶൌܧܴܵ൅݆߱ܥThereisananglebetw

6、eenܫandሶܫூௗ௘௔௟ሶ.Drawagraphtodemonstratetheirrelationship.IidealIrealsiticΦθESRΦiscalleddielectriclossangle.ܧܴܵtanΦൌܺ஼WenametanΦasdielectriclossangletangentvalue.It’salsocalleddielectriclossfactor.ObviouslytanΦincreasesifcapacitorhasabiggerESR.Andcosθ(ݏ݅݊ߔ)iscalledpowerfactor.T

7、hepowerlossܲൌܸሶܫݏ݅݊ߔሶWhereܸሶisavoltageappliedtothecondenser,ܫሶisthecurrentthroughthecondenserandѰisthephasedifferenceofthedielectric.Wealsocallݏ݅݊ߔaspowerfactor.Forsmallangles,itcanberewrittenasܲൌܸሶܫߔሶSupposeܸൌܸ௠sinሺ2ߨ݂ݐሻܸ݀݅஼ൌܥൌ2ߨ݂ܥܸ௠ܿ݋ݏሺ2ߨ݂ݐሻ݀ݐLetܫሶൌ2ߨ݂ܥܸሶܲൌ2ߨ݂ܥܸଶሶߔInordertog

8、ettheminimumcapacitor’spowerloss,wesshouldselectcapacitorswit