T型客車充電器的基本原理BUSELECTRICALINST

T型客車充電器的基本原理ZHENGZHOURAILWAYVOCATIONAL&TECHNICALCOLLEGE客車電氣裝置/BUSELECTRICALINSTALLATIONSpeaker主講人Zhangjia張嘉一、充電器基本原理從系統(tǒng)的安全性和可靠性來考慮，充電器是供電系統(tǒng)中最重要的設(shè)備之一，一旦充電器發(fā)生故障，蓄電池?zé)o法充電，電壓會(huì)放到很低，有可能使本車掛在蓄電池上的所有設(shè)備都無法啟動(dòng)和工作。Consideredfromthesafetyandreliabilityofthesystem,thechargerisoneofthemostimportantequipmentinthepowersupplysystem,oncethechargerfails,thebatterycannotbecharged,thevoltagewillbeverylow,maymakethecar’salltheequipmentrelatingtothebatterycannotstartandwork.25T客車無論兼容供電還是DC600V供電，都需要充電器，將DC600V或AC380V變換成DC110V供給蓄電池和照明等負(fù)載。Whetherthe25TpassengercariscompatiblewithpowersupplyorDC600Vpowersupply,itneedsachargertoconvertDC600VorAC380VintoDC110Vtosupplybatteriesandlightingandotherloads.一、充電器基本原理PWM橋式DC/DC變換電路圖PWMbridgeDC/DCconversioncircuitisshowninthefigure.充電器的輸入隔離、濾波和緩沖電路與逆變器相同，逆變橋由4只IGBT組成，功率的傳遞靠高頻變壓器傳遞，變壓器的輸出經(jīng)過高頻整流和濾波后，供給直流負(fù)載和蓄電池。Theinputisolation,filteringandbufferingcircuitofthechargeristhesameasthatoftheinverter,theinverterbridgeiscomposedoffourIGBTs,andthepowertransmissionistransmittedbythehigh-frequencytransformer,andtheoutputofthetransformerisprovidedwiththeDCloadandthebatteryafterhigh-frequencyrectificationandfiltering.1.高頻橋式逆變主電路V1～V4構(gòu)成DC/DC變換的主電路，V1～V4的控制邏輯和變壓器原副邊電壓波形如圖4－18所示。V1toV4formthemaincircuitoftheDC/DCconversion.Figure4-18showsthecontrollogicofV1toV4andthevoltagewaveformoftheprimaryandsecondarysidesofthetransformer.t1～t2區(qū)間內(nèi)，V1和V4導(dǎo)通，變壓器原邊電壓為正相電壓；Intherangeoft1~t2,V1andV4areswitchedon,andtheprimaryvoltageofthetransformerisapositivephasevoltage.t3～t4區(qū)間內(nèi)，V2和V3導(dǎo)通，變壓器原邊電壓為反相電壓。Intherangeoft3tot4,V2andV3areon,andtheprimarysidevoltageofthetransformeristhereversephasevoltage.

2、電壓變換的實(shí)現(xiàn)DC600V供電客車的DC/DC變換，主要是通過IGBT橋式逆變電路將直流600V電壓變換成占空比可調(diào)的高頻方波電壓，經(jīng)變壓器隔離后整流濾波成DC110V電壓。TheDC/DCconversionofDC600VpoweredpassengercarismainlythroughIGBTbridgeinvertercircuittoconvertDC600Vvoltageintohighfrequencysquarewavevoltagewithadjustabledutycycle,andthenrectifiedandfilteredintoDC110Vvoltageafterisolationbytransformer.兼容供電客車則是先將AC380V整流后，變成DC540V,然后采取與DC600V相同的DC/DC變換。ThecompatiblepowerpassengercarisfirstlyrectifiedAC380VintoDC540V,andthenadoptsthesameDC/DCconversionastheDC600V.所謂占空比是指一個(gè)半波內(nèi)，驅(qū)動(dòng)IGBT的脈沖寬度占整個(gè)半波周期的比例。Theso-calleddutycyclereferstotheproportionofthepulsewidthdrivingtheIGBTtothewholehalfwaveperiodwithinonehalfwave.為了調(diào)整輸出電壓，占空比是可變化的，屬于脈沖寬度可調(diào)模式即PWM方式。Inordertoadjusttheoutputvoltage,thedutycycleisvariable,belongingtothepulsewidthadjustablemode,thatis,PWMmode.在這種控制方式下，脈沖的幅值是不變的，當(dāng)負(fù)載發(fā)生變化時(shí),依靠改變脈沖的寬度來保證輸出電壓的穩(wěn)定;如果輸入電壓發(fā)生變化，也可以通過改變脈沖寬度來保證輸出的穩(wěn)定，如圖所示。Inthiscontrolmode,theamplitudeofthepulseisconstant.Whentheloadchanges,thepulsewidthischangedtoensurethestabilityoftheoutputvoltage.Iftheinputvoltagechanges,youcanalsochangethepulsewidthtoensurethestabilityoftheoutput,asshowninthefigure.3、高頻的影響采用20kHz的工作頻率，主要是為了減小變壓器、濾波器的體積。Theoperatingfrequencyof20kHzismainlyusedtoreducethevolumeoftransformersandfilters.變壓器的原邊或副邊的感應(yīng)電壓有一個(gè)基本公式：Theinducedvoltageoftheprimaryorsecondarysideofthetransformerhasabasicformula:U=kfW1BS其中U為變壓器線圈端電壓，f為工作頻率，W1為線圈匝數(shù)，B為磁通密度，S為磁路面積。WhereUisthetransformercoilendvoltage,fistheoperatingfrequency,W1isthenumberofcoilturns,Bisthemagneticfluxdensity,andSisthemagneticcircuitarea.從公式U=kfW1BS中可以看出，相同的輸出電壓和磁密時(shí)，當(dāng)頻率f提高，W1和S可相對(duì)減小，W1的減小即線圈繞組的匝數(shù)減少，亦即變壓器的銅重可以減??；Itcanbeseenfromtheformulathatwhentheoutputvoltageandmagneticdensityarethesame,W1andScanberelativelyreducedwhenthefrequencyfisincreased,andthereductionofW1meansthatthenumberofturnsofthecoilwindingisreduced,thatis,thecopperweightofthetransformercanbereduced.S的減小即變壓器鐵心面積減小，亦即鐵重減少，而銅線和鐵心是決定變壓器的主要有效體積和重量。ThereductionofSisthatthetransformercoreareaisreduced,thatis,theironweightisreduced,andthecopperwireandtheironcorearethemaineffectivevolumeandweightofthetransformer.當(dāng)頻率提高到20kHz時(shí)，變壓器的鐵心非常小，線圈匝數(shù)大幅減小。Whenthefrequencyisincreasedto20kHz,thecoreofthetransformerisverysmall,andthenumberofturnsofthecoilisgreatlyreduced.同樣，高頻輸出脈沖（對(duì)應(yīng)40kHz）的濾波電感和電容也明顯減小，這就是高頻化的效果。Similarly,thefilterinductanceandcapacitanceofthehigh-frequencyoutputpulsearealsosignificantlyreduced,whichistheeffectofhigh-frequency.

4、DC/DC變換器的功能和保護(hù)功能Function保護(hù)ProtectionDC/DC充電器的主要功能是將輸入DC600V或AC380V變換成適合蓄電池充電和直流負(fù)載使用的DC110V，并在輸入電壓和負(fù)載變化時(shí)，保持輸出穩(wěn)定即穩(wěn)壓功能。ThemainfunctionoftheDC/DCchargeristoconverttheinputDC600VorAC380VintoDC110VsuitableforbatterychargingandDCload,andkeeptheoutputstablewhentheinputvoltageandloadchange.DC/DC充電器的輸入保護(hù)和工作原理與逆變器相同。TheinputprotectionandworkingprincipleoftheDC/DCchargeristhesameasthatoftheinverter.5、限流定壓充電功能充電器的輸出電流分三個(gè)部分Theoutputcurrentofthechargerisdividedintothreesections部分向本車蓄電池充電,someofwhichchargethecarbattery,另有部分供給本車照明、控制等負(fù)載，someofwhichsupplythecarlighting,controlandotherloads,還有部分通過二極管向列車母線供電。andsomeofwhichsupplypowertothetrainbusthroughthediode.DC/DC充電器的工作原理圖DC/DC變換器采用雙閉環(huán)即電流環(huán)和電壓環(huán)控制。TheDC/DCconverteradoptsdoubleclosedloopcontrol,thatis,currentloopandvoltageloop.圖中，電壓反饋靠電壓傳感器U/V輸出測(cè)量信號(hào)，充電電流反饋靠電流傳感器I2/V的輸出信號(hào),而電流傳感器I1/V的反饋則提供輸出總電流的檢測(cè)信號(hào)。ThevoltagefeedbackdependsontheoutputmeasurementsignalofthevoltagesensorU,thechargingcurrentfeedbackdependsontheoutputsignalofthecurrentsensorI2,an