有關鋰電池組保護板均衡充電基本工作原理了解
電(dian)動車充電(dian)器(qi)的有關(guan)知識
充電(dian)器的(de)分類：用有、無工頻（
50
赫茲）變壓器區分(fen)，可分(fen)為(wei)兩大(da)類(lei)。貨運三輪充電器一(yi)
般使用帶工頻變壓器的充電(dian)機，體(ti)積(ji)大、重量大，費電(dian)，但是(shi)可靠，便宜；電(dian)動自行車和(he)電(dian)
摩則使(shi)用所(suo)謂開關電(dian)源式充電(dian)器，省電(dian)，效率高(gao)，但是易壞。
開(kai)關(guan)電源(yuan)式充電器的正確操(cao)作是：
充電時，
先插電池，
后加市電；
充足后，
先切斷市電，
后(hou)拔電(dian)池插頭。如(ru)果在(zai)充(chong)電(dian)時先(xian)拔電(dian)池插頭，特(te)別是充(chong)電(dian)電(dian)流大（紅燈）時，非常容(rong)易損壞
充電器。
常用的開關(guan)電源式(shi)充電器(qi)又分(fen)半橋式(shi)和單激(ji)式(shi)兩大類，
單激(ji)(ji)類又分為正激(ji)(ji)式和反激(ji)(ji)式
兩類(lei)。半橋式成本(ben)高(gao)，性能好，常(chang)用于帶(dai)負(fu)脈(mo)沖的充電器；單激式成本(ben)低，市場占有率高(gao)。
關于負脈沖充電器
鉛酸電池已經有
100
多年的歷史了，
開始全(quan)球普(pu)遍沿引老(lao)的觀點和操(cao)作規程：
充、
放
電率為
0.1C(C
是電池容量
)
壽命較長。
美國人麥(mai)斯先生為解決快速充電問(wen)題，
1967
年向全世
界公(gong)布了(le)他的研(yan)究(jiu)成(cheng)果，用大于
1C
率(lv)脈沖電(dian)(dian)(dian)流充電(dian)(dian)(dian)，充電(dian)(dian)(dian)間歇(xie)時對電(dian)(dian)(dian)池(chi)放(fang)電(dian)(dian)(dian)。放(fang)電(dian)(dian)(dian)有利于
消除極化(hua)、降低電(dian)解液(ye)溫度、提高極板接(jie)受(shou)電(dian)荷的(de)能力。
我國(guo)一些科技工作者(zhe)在
1969
年前后，根(gen)據(ju)麥(mai)斯(si)先生的(de)三定律(lv)制作成(cheng)功(gong)了多(duo)種(zhong)品牌的(de)
快速充電機。
充電循環過程是：
大電(dian)(dian)(dian)流脈沖充(chong)電(dian)(dian)(dian)→切斷(duan)充(chong)電(dian)(dian)(dian)通路→對電(dian)(dian)(dian)池短暫(zan)放電(dian)(dian)(dian)→停止放
電(dian)→接通(tong)充電(dian)通(tong)路→大電(dian)流脈沖充電(dian)??
2000
年前后(hou)，有人將這一原理用到了電動車(che)充電器中，充電過(guo)程中，不切斷充電通
路(lu)，用小(xiao)電阻將電池短路(lu)瞬間，
進(jin)行(xing)放(fang)電(dian)(dian)。短路時由于(yu)不切斷(duan)充電(dian)(dian)通路，在充電(dian)(dian)通路中串連
了電感。一般在
1
秒內短路
3
－
5
毫秒（
1
秒＝
1000
毫秒）
，由于電(dian)感里的電(dian)流不能(neng)跳變，
短
路時間短促，
可(ke)以保護充電器的電源轉(zhuan)換部(bu)分。
如果把充電電流方向(xiang)叫正，
放電自然為負了，
電動(dong)車(che)業就(jiu)出現了名詞“負脈沖(chong)充電器”
，而且稱可以延長電池壽命(ming)等(deng)等(deng)。
關于三段式充電器
近幾年，
電動車普遍(bian)使用(yong)了所謂三段式充電器，
第一個(ge)階段叫恒流階段，
第二個階段
叫恒壓階段，
第三個階(jie)段(duan)叫涓流階(jie)段(duan)。
從電子技術角度針對(dui)電池而言(yan)：
第一個階段叫充電限
流階段，
第二個階(jie)段(duan)叫高(gao)恒(heng)壓階(jie)段(duan)，
第三個階段(duan)叫(jiao)低恒壓階段(duan)比較貼(tie)切。
第二階段和第三階
段轉換(huan)時，面(mian)板指示燈相應變換(huan)，大(da)多數(shu)充電器第一、二階段是紅(hong)燈，第三階段變綠燈。第
二階段(duan)和(he)第三(san)階段(duan)的(de)相互轉換是由充電電流決定的(de)，
大于某電流進(jin)入第一第二階(jie)段，
小于某
電流進入第(di)三階段。這(zhe)個電流叫(jiao)轉換電流，也叫(jiao)轉折電流。
早期充電器，
包括名(ming)牌車配套的充電器，雖然也(ye)變燈，
但實際是恒壓(ya)限(xian)流充電器，并
不是三(san)階段充電器。一般這類(lei)就一個穩定電壓(ya)值，
44.2V
左右，對當時(shi)的高比重硫酸的電池
還湊合。
關于三段式(shi)充(chong)電器的(de)三個(ge)關鍵參數(shu)
第一個重要參數是涓(juan)流(liu)階段的低恒壓(ya)值，
第(di)二個重要(yao)參數是第(di)二階段的(de)高(gao)恒(heng)壓值，
第
三個重要(yao)參數(shu)是轉換(huan)電流。這三個重要(yao)參數(shu)與(yu)(yu)電池(chi)(chi)數(shu)目有關(guan)，與(yu)(yu)電池(chi)(chi)的容量
Ah
有關，與溫
度有關(guan)(guan)，與電池種類有關(guan)(guan)。為了方便大家記(ji)憶，下面以最常見(jian)的(de)電動自行車（三塊
12V
串
聯的
10Ah
電池）所用的三(san)段(duan)式充(chong)電器(qi)為例簡單介紹一下：
首先討論涓流階段(duan)的低(di)恒壓值，
參考電壓為
42.5V
左右。
此值高(gao)將(jiang)使(shi)電池失水，
容易
使電(dian)池(chi)發熱變形；此值(zhi)低不利(li)于(yu)電(dian)池(chi)充(chong)足電(dian)。此值(zhi)在南方要(yao)低于(yu)
41.5V
；膠體電池要低于
41.5V
，如在(zai)南方還要低一點兒。這個參(can)數是(shi)相對(dui)嚴格的，不可以(yi)大于參(can)考值。
其次討論(lun)第二階段的高恒壓值，參考電壓為
44.5V
左(zuo)右(you)。此(ci)值高(gao)有(you)利于快速充足電，
但(dan)是容易使電池失(shi)水(shui)，
充(chong)電(dian)后期電(dian)流下不(bu)來，
結果使電池(chi)發(fa)熱變形；
此值(zhi)低不利于電池快速
充足電(dian)，有利于向涓流階段轉換。這個值(zhi)雖然沒有第(di)一(yi)個值(zhi)那樣嚴格，但是也不要過高。
最后討論轉換電流，
參考電流為
300
毫安左右。
此值高有利于(yu)電池壽命(ming)，
不容易發熱
本(ben)文介(jie)紹(shao)的(de)(de)是(shi)有(you)關鋰電(dian)池組(zu)保護板均衡(heng)充電(dian)基本(ben)工作(zuo)原理，在采用單節鋰電(dian)池保護芯片設計的(de)(de)且(qie)具備均衡(heng)充電(dian)能(neng)力的(de)(de)鋰電(dian)池組(zu)保護板，示意圖(tu)如圖(tu)1所示。
其中：1為單節鋰離子電池；2為充電過電壓分流放電支路電阻；3 為分流放電支路控制用開關器件；4為過流檢測保護電阻；5為省略的鋰電池保護芯片及電路連接部分；6為單節鋰電池保護芯片(一般包括充電控制引腳CO,放電控制引腳DO，放電過電流及短路檢測引腳VM，電池正端VDD，電池負端VSS等)；7為充電過電壓保護信號經光耦隔離后形成并聯關系驅動主電路中充電控制用MOS管柵極；8為放電欠電壓、過流、短路保護信號經光耦隔離后形成串聯關系驅動主電路中放電控制用MOS管柵極；9為充電控制開關器件；10為放電控制開關器件；11為控制電路；12為主電路；13為分流放電支路。單節鋰電池保護芯片數目依據鋰電池組電池(chi)數目確定，串聯(lian)使用(yong)(yong)，分別對所對應(ying)單節鋰(li)電池(chi)的(de)(de)(de)充(chong)(chong)(chong)(chong)放電、過流(liu)、短路狀態進行保護。該系統在充(chong)(chong)(chong)(chong)電保護的(de)(de)(de)同時，通過保護芯(xin)片(pian)控制分流(liu)放電支路開關器件(jian)的(de)(de)(de)通斷實現均衡充(chong)(chong)(chong)(chong)電，該方案(an)有別于傳統的(de)(de)(de)在充(chong)(chong)(chong)(chong)電器端實現均衡充(chong)(chong)(chong)(chong)電的(de)(de)(de)做法，降低了(le)鋰(li)電池(chi)組(zu)充(chong)(chong)(chong)(chong)電器設計(ji)應(ying)用(yong)(yong)的(de)(de)(de)成本(ben)。
圖1 具(ju)備均衡充電能力的鋰電池組(zu)保護板示意圖
當鋰電池組充電時，外接電源正負極分別接電池組正負極BAT+和BAT-兩端，充電電流流經電池組正極BAT+、電池組中單節鋰電池1～N、放電控制開關器件、充電控制開關器件、電池組負極BAT-,電流流向如圖2所示。
圖2 充電過程
系統中控制電路部分單節鋰電池保護芯片的充電過電壓保護控制信號經光耦隔離后并聯輸出，為主電路中充電開關器件的導通提供柵極電壓；如某一節或幾節鋰電池在充電過程中先進入過電壓保護狀態，則由過電壓保護信號控制并聯在單節鋰電池正負極兩端的分(fen)流(liu)放電(dian)(dian)支路(lu)放電(dian)(dian)，同時(shi)將串接在充(chong)(chong)電(dian)(dian)回路(lu)中(zhong)的對應單體鋰電(dian)(dian)池斷離出充(chong)(chong)電(dian)(dian)回路(lu)。
鋰電(dian)(dian)(dian)(dian)池(chi)(chi)組串聯充電(dian)(dian)(dian)(dian)時，忽略單節(jie)(jie)電(dian)(dian)(dian)(dian)池(chi)(chi)容(rong)量差(cha)別的(de)(de)(de)(de)影(ying)響，一(yi)般內阻較小的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)池(chi)(chi)先充滿(man)。此時，相(xiang)應的(de)(de)(de)(de)過電(dian)(dian)(dian)(dian)壓(ya)保(bao)護信(xin)號控(kong)制(zhi)分(fen)流(liu)(liu)放電(dian)(dian)(dian)(dian)支(zhi)路的(de)(de)(de)(de)開關器件閉合，在原電(dian)(dian)(dian)(dian)池(chi)(chi)兩端(duan)并聯上一(yi)個分(fen)流(liu)(liu)電(dian)(dian)(dian)(dian)阻。根據電(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)PNGV等效電(dian)(dian)(dian)(dian)路模型，此時分(fen)流(liu)(liu)支(zhi)路電(dian)(dian)(dian)(dian)阻相(xiang)當(dang)于先充滿(man)的(de)(de)(de)(de)單節(jie)(jie)鋰電(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)負載，該電(dian)(dian)(dian)(dian)池(chi)(chi)通(tong)過其放電(dian)(dian)(dian)(dian)，使(shi)(shi)電(dian)(dian)(dian)(dian)池(chi)(chi)端(duan)電(dian)(dian)(dian)(dian)壓(ya)維持在充滿(man)狀態附近一(yi)個極小的(de)(de)(de)(de)范(fan)圍內。假設(she)第1節(jie)(jie)鋰電(dian)(dian)(dian)(dian)池(chi)(chi)先充電(dian)(dian)(dian)(dian)完成，進入過電(dian)(dian)(dian)(dian)壓(ya)保(bao)護狀態，則主(zhu)電(dian)(dian)(dian)(dian)路及分(fen)流(liu)(liu)放電(dian)(dian)(dian)(dian)支(zhi)路中電(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向如圖3所(suo)示。當(dang)所(suo)有單節(jie)(jie)電(dian)(dian)(dian)(dian)池(chi)(chi)均(jun)充電(dian)(dian)(dian)(dian)進入過電(dian)(dian)(dian)(dian)壓(ya)保(bao)護狀態時，全部單節(jie)(jie)鋰電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)大小在誤差(cha)范(fan)圍內完全相(xiang)等，各節(jie)(jie)保(bao)護芯片充電(dian)(dian)(dian)(dian)保(bao)護控(kong)制(zhi)信(xin)號均(jun)變低，無法為主(zhu)電(dian)(dian)(dian)(dian)路中的(de)(de)(de)(de)充電(dian)(dian)(dian)(dian)控(kong)制(zhi)開關器件提供柵極偏壓(ya)，使(shi)(shi)其關斷(duan)，主(zhu)回路斷(duan)開，即實現均(jun)衡充電(dian)(dian)(dian)(dian)，充電(dian)(dian)(dian)(dian)過程完成。
圖3 分流均衡過程
當電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組放電(dian)(dian)(dian)(dian)(dian)(dian)時，外接(jie)負(fu)載分別接(jie)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組正(zheng)負(fu)極(ji)BAT+和(he)BAT-兩(liang)端(duan)，放電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流流經電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組負(fu)極(ji)BAT-、充電(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)(kai)關器件(jian)、放電(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)(kai)關器件(jian)、電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組中單節鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)N～1和(he)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組正(zheng)極(ji)BAT+,電(dian)(dian)(dian)(dian)(dian)(dian)流流向如圖4所示。系(xi)統中控(kong)(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)部(bu)分單節鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保護(hu)芯片的放電(dian)(dian)(dian)(dian)(dian)(dian)欠電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)保護(hu)、過流和(he)短(duan)路(lu)保護(hu)控(kong)(kong)制(zhi)信號(hao)經光耦(ou)隔(ge)離后串聯輸出(chu)，為主電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中放電(dian)(dian)(dian)(dian)(dian)(dian)開(kai)(kai)關器件(jian)的導(dao)通提供(gong)柵(zha)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya);一(yi)旦電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組在放電(dian)(dian)(dian)(dian)(dian)(dian)過程中遇到單節鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)欠電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)或者過流和(he)短(duan)路(lu)等(deng)特(te)殊情(qing)況，對應的單節鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)放電(dian)(dian)(dian)(dian)(dian)(dian)保護(hu)控(kong)(kong)制(zhi)信號(hao)變低，無法(fa)為主電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中的放電(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)(kai)關器件(jian)提供(gong)柵(zha)極(ji)偏壓(ya)，使(shi)(shi)其關斷，主回路(lu)斷開(kai)(kai)，即結(jie)束放電(dian)(dian)(dian)(dian)(dian)(dian)使(shi)(shi)用過程。
圖4 放電過程
一般鋰電(dian)池采(cai)用恒流-恒壓(TAPER)型充(chong)電(dian)控制，恒壓充(chong)電(dian)時，充(chong)電(dian)電(dian)流近似指數規律減小。系統中充(chong)放電(dian)主回路的(de)開關器件(jian)可根(gen)據外部電(dian)路要(yao)求(qiu)滿足(zu)的(de)最大工作(zuo)電(dian)流和(he)工作(zuo)電(dian)壓選型。
控制電(dian)(dian)路的(de)單(dan)(dan)節鋰電(dian)(dian)池保護芯片可根據(ju)待保護的(de)單(dan)(dan)節鋰電(dian)(dian)池的(de)電(dian)(dian)壓(ya)等(deng)級、保護延遲(chi)時間等(deng)選(xuan)型。
單節電池兩端并接的放電支路電阻可根據鋰電池充電器的(de)(de)充電電壓大(da)小(xiao)(xiao)以及鋰電池(chi)的(de)(de)參(can)數和放電電流的(de)(de)大(da)小(xiao)(xiao)計(ji)算得出。均(jun)衡(heng)電流應合(he)理選(xuan)擇，如(ru)(ru)果(guo)太(tai)小(xiao)(xiao)，均(jun)衡(heng)效(xiao)果(guo)不明顯；如(ru)(ru)果(guo)太(tai)大(da)，系統的(de)(de)能量損耗大(da)，均(jun)衡(heng)效(xiao)率(lv)低，對鋰電池(chi)組熱管理要(yao)求高，一般(ban)電流大(da)小(xiao)(xiao)可設計(ji)在50～100mA之(zhi)間(jian)。
分流放電(dian)(dian)支路(lu)電(dian)(dian)阻(zu)(zu)可采(cai)用功率電(dian)(dian)阻(zu)(zu)或電(dian)(dian)阻(zu)(zu)網絡(luo)實(shi)現。這里采(cai)用電(dian)(dian)阻(zu)(zu)網絡(luo)實(shi)現分流放電(dian)(dian)支路(lu)電(dian)(dian)阻(zu)(zu)較為合理，可以有效消除電(dian)(dian)阻(zu)(zu)偏差的影響，此外，還(huan)能起到降低熱(re)功耗(hao)的作用。
