太阳能手机充电器英文文献.docx
《太阳能手机充电器英文文献.docx》由会员分享,可在线阅读,更多相关《太阳能手机充电器英文文献.docx(17页珍藏版)》请在冰豆网上搜索。
太阳能手机充电器英文文献
DesignofaLead-AcidBatteryChargingandProtectingICinPhotovoltaicSystem
ZENGDe-you,LINGChao-dong,LIGuo-gang
(YuanshunICDesignR&DCenter,HuaqiaoUniversity,Quanzhou362021,China)
Source:
MicroelectronicDevice&Technology,June2007
1.Introduction
Solarenergyasaninexhaustible,inexhaustiblesourceofenergymoreandmoreattention.Solarpowerhasbecomepopularinmanycountriesandregions,solarlightinghasalsobeenputintouseinmanycitiesinChina.Asakeypartofthesolarlighting,batterychargingandprotectionisparticularlyimportant.Sealedmaintenance-freelead-acidbatteryhasasealed,leak-free,pollution-free,maintenance-free,low-cost,reliablepowersupplyduringtheentirelifeofthebatteryvoltageisstableandnomaintenance,theneedforuninterruptedforthevarioustypesofhaswideapplicationinpowerelectronicequipment,andportableinstrumentation.Appropriatefloatvoltage,innormaluse(topreventover-discharge,overcharge,over-current),maintenance-freelead-acidbatteryfloatlifeofupto12~16yearsfloatvoltagedeviationof5%shortenthelifeof1/2.Thus,thechargehasamajorimpactonthistypeofbatterylife.Photovoltaic,batterydoesnotneedregularmaintenance,thecorrectchargeandreasonableprotection,caneffectivelyextendbatterylife.ChargingandprotectionICistheseparationoftheoccupiedareaandtheperipheralcircuitcomplexity.Currently,themarkethasnotyetreal,chargedwiththeprotectionfunctionisintegratedonasinglechip.Forthisproblem,designasetofbatterychargingandprotectionfunctionsinoneICisverynecessary.
2.Systemdesignandconsiderations
Thesystemmainlyincludestwoparts:
thebatterychargermoduleandtheprotectionmodule.Ofgreatsignificanceforthebatteryasstandbypoweruseoftheoccasion,Itcanensurethattheexternalpowersupplytothebattery-powered,butalsointhebatteryovercharge,over-currentandanexternalpowersupplyisdisconnectedthebatteryistoputthestatetoprovideprotection,thechargeandprotectionrolledintoonetomakethecircuittosimplifyandreducevaluableproductwasteofresources.Figure1isaspecificapplicationofthisIcinthephotovoltaicpowergenerationsystem,butalsothesourceofthisdesign.
accumulator
Figure1Photovoltaiccircuitsystemblockdiagram
Maintenance-freelead-acidbatterylifeisusuallythecyclelifeandfloatlifefactorsaffectingthelifeofthebatterychargerate,dischargerate,andfloatvoltage.Somemanufacturerssaidthatiftheoverchargeprotectioncircuit,thechargingratecanbeachievedevenmorethan2C(Cistheratedcapacityofthebattery),batterymanufacturersrecommendchargingrateofC/20~C/3.Batteryvoltageandtemperature,thetemperatureisincreasedby1°C,singlecellbatteryvoltagedrops4mV,negativetemperaturecoefficientof-4mV/°Cmeansthatthebatteryfloatvoltage.Ordinarychargerforthebestworkingconditionat25°C;chargelessthantheambienttemperatureof0°C;at45°Cmayshortenthebatterylifeduetosevereovercharge.Tomakethebatterytoextendtheworkinglife,haveacertainunderstandingandanalysisoftheworkingstatusofthebattery,inordertoachievethepurposeofprotectionofthebattery.Battery,therearefourstates:
normalstate,over-currentstateoverthestateofcharge,overdischargestate.However,duetotheimpactofthedifferentdischargecurrentover-capacityandlifetimeofthebatteryisnotthesame,sothebatteryoverdischargecurrentdetectionshouldbetreatedseparately.Whenthebatteryischargingthestatealongtime,wouldseverelyreducethecapacityofthebatteryandshortenbatterylife.Whenthebatteryisthetimeofdischargestatusexceedstheallottedtime,thebattery,thebatteryvoltageistoolowmaynotbeabletorecharge,makingthebatterylifeislower.
Basedontheabove,thechargeonthelifeofmaintenance-freelead-acidbatterieshaveasignificantimpact,whilethebatteryisalwaysingoodworkingcondition,batteryprotectioncircuitmustbeabletodetectthenormalworkingconditionofthebatteryandmaketheactionthebatterycannevernormalworkingstatebacktonormaloperation,inordertoachievetheprotectionofthebattery.
3.Unitsmodulardesign
3.1Thechargingmodule
Chip,chargingmoduleblockdiagramshowninFigure2.Thecircuitryincludescurrentlimiting,currentsensingcomparator,referencevoltagesource,under-voltagedetectioncircuit,voltagesamplingcircuitandlogiccontrolcircuit.
Figure2Chargingmoduleblockdiagram
Themodulecontainsastand-alonelimitingamplifierandvoltagecontrolcircuit,itcancontroloff-chipdrive,20~30mA,providedbythedriveoutputcurrentcandirectlydriveanexternalseriesofadjustmenttube,soastoadjustthechargeroutputvoltageandcurrent.Voltageandcurrentdetectioncomparatordetectsthebatterychargestatus,andcontrolthestateoftheinputsignalofthelogiccircuit.Whenthebatteryvoltageorcurrentistoolow,thechargetostartthecomparatorcontrolthecharging.Appliancesintothetricklechargestatewhenthecut-offofthedrive,thecomparatorcanoutputabout20mAintothetricklechargecurrent.Thus,whenthebatteryshort-circuitorreverse,thechargercanonlychargeasmallcurrent,toavoiddamagetothebatterychargingcurrentistoolarge.Thismoduleconstitutesachargingcircuitchargingprocessisdividedintotwochargingstatus:
high-currentconstant-currentchargestate,high-voltagechargestatusandlow-voltageconstantvoltagefloatingstate.Thechargingprocessfromtheconstantcurrentchargingstatus,theconstantchargingcurrentofthechargeroutputinthisstate.Andthechargercontinuouslymonitorsthevoltageacrossthebatterypack,thebatterypowerhasbeenrestoredto70%to90%ofthereleasedcapacitywhenthebatteryvoltagereachestheswitchingvoltagetochargeconversionvoltageVsamchargermovestothestateofcharge.Inthisstate,thechargeroutputvoltageisincreasedtooverchargepressureVocisduetothechargeroutputvoltageremainsconstant,sothechargingcurrentisacontinuousdecline.CurrentdowntochargeandsuspendthecurrentIoct,thebatterycapacityhasreached100%ofratedcapacity,thechargeroutputvoltagedropstoalowerfloatvoltageVF.
3.2ProtectionModule
ChipblockdiagramoftheinternalprotectioncircuitshowninFigure3.Thecircuitincludescontrollogiccircuit,samplingcircuit,overchargedetectioncircuit,over-dischargedetectioncomparator,overcurrentdetectioncomparator,loadshort-circuitdetectioncircuit,level-shiftingcircuitandreferencecircuit(BGR).
Over-current
detectioncomparator2
Loadshortdetectioncircuit
Over-current
detectioncircuit
Over-current
detectioncomparator1
Overchargedetectioncomparator
Levelconversion
circuit
Controllogiccircuit
Overdischarge
detectioncomparator
Samplingcircuit
Figure3Blockdiagramofbatteryprotection
ThismoduleconstitutesaprotectioncircuitshowninFigure4.Underthechipsupplyvoltagewithinthenormalscopeofwork,andtheVMpinvoltageattheovercurrentdetectionvoltage,thebatteryisinnormaloperation,thechargeanddischargecontrolofthechiphighpowerendoftheCOandDOarelevel,whenthechipisinnormalworkingmode.LargerwhenthebatterydischargecurrentwillcausevoltageriseoftheVMpinattheVMpinvoltageatabovethecurrentdetectionvoltageViov,thenthebatteryisthecurrentstatus,ifthisstatetomaintainthetiovovercurrentdelaytime,thechipbanonbatterydischarge,thenthechargetocontroltheendofCOishigh,thedischargecontrolsideDOislow,thechipisinthecurrentmode,generalinordertoplayonthebatterysaferandmorereasonableprotection,thechipwillbatteryover-dischargecurrenttotakeoverthedischargecurrentdelaytimeprotection.Thegeneralruleisthattheover-dischargecurrentislarger,overtheshorterthedischargecurrentdelaytime.AboveOverchargedetectionvoltage,thechipsupplyvoltage(Vdd>Vcu),thebatteryisinoverchargestate,thisstateistomaintainthecorrespondingoverchargedelaytimetcuchipwillbeprohibitedfromchargingthebattery,thendischargecontrolendDOishigh,andchargingcontrolterminalCOislow,thechipisinchargingmode.Whenthesupplyvoltageofthechipundertheoverdischargedetectionvoltage(VddProtection
module
Figure4Protectioncircuitapplicationschematicdiagram
4.CircuitDesign
Twochargeprotectionmodulestructurediagram,thecircuitcanbedividedintofourparts:
thepowerdetectioncircuit(under-voltagedetectioncircuit),partofthebiascircuit(samplingcircuit,thereferencecircuitandbiascircuit),thecomparator(includingtheoverchargedetection/overdischargedetectioncomparator,over-currentdetectionandloadshort-circuitdetectioncircuit)andthelogiccontrolpart.
Thispaperdescribestheunder-voltagedetectioncircuit(Figure5),andgivesthebandgapreferencecircuit(Figure6).
Figure5Under-voltagedetectioncircuit
Amplifier
Amplifier
Figure6Areferencepowersupplycircuitdiagram
Batterycharging,voltagestabilityisparticularlyimportant,undervoltage,overvoltageprotectionisessential,thereforeintegratedovervoltage,undervoltageprotectioncircuitinsidethechip,toimprovepowersupplyreliabilityandsecurity.Andprotectioncircu