有關鋰電池組保護板均衡充電基本工作原理了解
電動車充電器的有關知(zhi)識
充電器的分(fen)類：用有、無工(gong)頻（
50
赫茲(zi)）變壓器區分(fen)，可分(fen)為兩大類。貨運三(san)輪充(chong)電(dian)器一(yi)
般使用(yong)帶工(gong)頻(pin)變壓器的充電(dian)機，體積(ji)大(da)、重(zhong)量(liang)大(da)，費電(dian)，但(dan)是可靠，便宜；電(dian)動自行(xing)車和(he)電(dian)
摩則使用所謂(wei)開關(guan)電源(yuan)式(shi)充電器，省(sheng)電，效率(lv)高(gao)，但是易壞。
開(kai)關(guan)電源式充電器的正(zheng)確操作是：
充電時，
先插電池，
后加市電；
充足后，
先切斷市電，
后拔電(dian)池(chi)插頭(tou)。如果在充電(dian)時先拔電(dian)池(chi)插頭(tou)，特別(bie)是充電(dian)電(dian)流大（紅(hong)燈）時，非常(chang)容易損壞
充電器。
常用(yong)的開關電源式(shi)充(chong)電器(qi)又分半橋式(shi)和單激式(shi)兩(liang)大類，
單激類又分為(wei)正激式(shi)和反激式(shi)
兩類。半(ban)橋式(shi)成(cheng)本高，性能好，常用于帶負(fu)脈(mo)沖的充電器；單激(ji)式(shi)成(cheng)本低，市(shi)場占(zhan)有(you)率高。
關于負脈沖充電器
鉛酸電池已經有
100
多年的歷史了，
開(kai)始全球(qiu)普遍沿引(yin)老的(de)觀點和操作規程(cheng)：
充、
放
電率為
0.1C(C
是電池容量
)
壽命較長。
美(mei)國(guo)人麥(mai)斯先生(sheng)為解(jie)決快速充電問題，
1967
年向全世
界公布了他(ta)的研究(jiu)成(cheng)果(guo)，用大(da)于
1C
率(lv)脈沖電(dian)(dian)流充電(dian)(dian)，充電(dian)(dian)間歇時(shi)對(dui)電(dian)(dian)池放(fang)電(dian)(dian)。放(fang)電(dian)(dian)有利(li)于
消除(chu)極(ji)化、降(jiang)低電解液(ye)溫度(du)、提高(gao)極(ji)板接受電荷的能力。
我國一些科技工作者在
1969
年前后，根據(ju)麥斯先生的三定律(lv)制作(zuo)成(cheng)功了多種品牌的
快速充電機。
充電循環過程是：
大電流脈(mo)沖充電→切斷(duan)充電通路→對電池短暫放電→停止放
電(dian)→接通充(chong)電(dian)通路→大電(dian)流脈(mo)沖充(chong)電(dian)??
2000
年前后(hou)，有人將這一原理用到了電動車充電器中，充電過程(cheng)中，不切斷充電通
路，用小電(dian)(dian)阻(zu)將電(dian)(dian)池短路瞬間，
進(jin)行放電(dian)(dian)。短(duan)路(lu)時由于不切斷充電(dian)(dian)通(tong)路(lu)，在(zai)充電(dian)(dian)通(tong)路(lu)中(zhong)串連
了電感。一般在
1
秒內短路
3
－
5
毫秒（
1
秒＝
1000
毫秒）
，由于電感里的電流不(bu)能跳變，
短
路時間短促，
可以保護(hu)充電器(qi)的電源(yuan)轉(zhuan)換部分。
如果(guo)把充電(dian)電(dian)流方(fang)向叫正，
放電自然為負了，
電動(dong)車業就出現(xian)了名詞“負脈沖充(chong)電器(qi)”
，而且稱可以延長電(dian)池壽命等等。
關于三段式充電器
近幾年，
電(dian)動車(che)普遍使(shi)用了所謂三段(duan)式充(chong)電(dian)器，
第一個階段(duan)(duan)叫(jiao)恒流階段(duan)(duan)，
第二個階段
叫恒壓階段，
第三(san)個階段(duan)叫(jiao)涓流階段(duan)。
從電(dian)子技(ji)術角度(du)針對(dui)電(dian)池而言：
第一個階段叫充電限
流階段，
第二(er)個階(jie)(jie)段叫高恒壓階(jie)(jie)段，
第三個階段(duan)叫低恒(heng)壓階段(duan)比較(jiao)貼切(qie)。
第二階段和第三階
段轉(zhuan)換時，面板指示燈(deng)相應變換，大多數(shu)充電器第一、二(er)階(jie)段是紅燈(deng)，第三階(jie)段變綠燈(deng)。第
二階段和第三(san)階段的相互轉(zhuan)換是由充電電流(liu)決定的，
大于某(mou)電流(liu)進(jin)入第一第二(er)階(jie)段，
小于某
電流進入第三階段。這(zhe)個電流叫轉(zhuan)換電流，也叫轉(zhuan)折電流。
早期充電器，
包括名牌車配(pei)套的充電器，雖然也變燈，
但實際是恒(heng)壓限流充電器，并(bing)
不是三(san)階段(duan)充電器。一般(ban)這類就一個穩(wen)定電壓值，
44.2V
左右，對當時(shi)的高比重硫酸的電池
還湊合。
關于(yu)三(san)段(duan)式充電器(qi)的三(san)個關鍵(jian)參數(shu)
第(di)一個重要參數是(shi)涓流階(jie)段的低恒壓值，
第(di)二個重要(yao)參數是(shi)第(di)二階段的(de)高(gao)恒壓值，
第
三個(ge)重要(yao)參數(shu)(shu)是轉換電流。這(zhe)三個(ge)重要(yao)參數(shu)(shu)與電池數(shu)(shu)目有關，與電池的容量
Ah
有關，與溫
度有(you)關，與電池種類有(you)關。為了方便大家記憶，下面以最常見(jian)的電動自(zi)行車（三塊
12V
串
聯的
10Ah
電池）所(suo)用的三段(duan)式充電器為(wei)例(li)簡單介(jie)紹一下：
首(shou)先討論(lun)涓流階段的低恒壓值(zhi)，
參考電壓為
42.5V
左右。
此值高將使電池失(shi)水，
容易
使(shi)電(dian)池(chi)發熱變形；此值低(di)不利(li)于電(dian)池(chi)充足電(dian)。此值在南方要低(di)于
41.5V
；膠體電池要低于
41.5V
，如在南方還(huan)要低一(yi)點兒。這(zhe)個參(can)數是相對(dui)嚴格(ge)的，不可以大于(yu)參(can)考值。
其次討論第二(er)階(jie)段的(de)高(gao)恒壓值，參(can)考電壓為
44.5V
左右(you)。此值高有(you)利于快速充(chong)足電，
但(dan)是容易使電池失水，
充電后期電流下不來，
結果使電池(chi)發(fa)熱變形；
此值低不利于電池快速(su)
充足(zu)電，有利于向涓流階段轉換。這(zhe)個(ge)值(zhi)雖然沒(mei)有第(di)一個(ge)值(zhi)那樣嚴(yan)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(zhi)高(gao)有(you)利(li)于電池壽(shou)命(ming)，
不容易發熱
本文介(jie)紹的(de)是(shi)有關鋰電(dian)池(chi)組保護(hu)板均衡充(chong)電(dian)基本工作原理，在采用單(dan)節鋰電(dian)池(chi)保護(hu)芯(xin)片(pian)設(she)計的(de)且具(ju)備均衡充(chong)電(dian)能力的(de)鋰電(dian)池(chi)組保護(hu)板，示意(yi)圖如圖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(dian)(dian)池(chi)數(shu)目確定，串聯使用，分(fen)別(bie)對(dui)所對(dui)應(ying)(ying)單節鋰電(dian)(dian)池(chi)的充(chong)(chong)放電(dian)(dian)、過(guo)流、短路(lu)狀態進(jin)行保(bao)(bao)(bao)護(hu)。該(gai)系統在(zai)充(chong)(chong)電(dian)(dian)保(bao)(bao)(bao)護(hu)的同時，通(tong)過(guo)保(bao)(bao)(bao)護(hu)芯片(pian)控(kong)制(zhi)分(fen)流放電(dian)(dian)支路(lu)開關器件(jian)的通(tong)斷(duan)實(shi)現均(jun)(jun)衡充(chong)(chong)電(dian)(dian)，該(gai)方案(an)有別(bie)于傳統的在(zai)充(chong)(chong)電(dian)(dian)器端實(shi)現均(jun)(jun)衡充(chong)(chong)電(dian)(dian)的做法，降低了鋰電(dian)(dian)池(chi)組充(chong)(chong)電(dian)(dian)器設計(ji)應(ying)(ying)用的成本(ben)。
圖1 具備均衡充電能(neng)力的鋰(li)電池(chi)組保護板示意圖
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(zheng)負極兩(liang)端的分流放電(dian)(dian)支(zhi)路放電(dian)(dian)，同時將串接在充電(dian)(dian)回(hui)路中的對應單體鋰電(dian)(dian)池斷離(li)出充電(dian)(dian)回(hui)路。
鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組串聯充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)，忽略單(dan)節(jie)(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)容量差(cha)別的(de)(de)影響，一(yi)(yi)般(ban)內阻較(jiao)小的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)先充(chong)(chong)(chong)(chong)滿(man)。此時(shi)，相應的(de)(de)過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)保(bao)護信號(hao)控(kong)(kong)(kong)制分(fen)(fen)流(liu)(liu)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)的(de)(de)開(kai)關(guan)器件(jian)(jian)閉合，在(zai)原電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)兩端(duan)并聯上一(yi)(yi)個分(fen)(fen)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻。根據電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)PNGV等效(xiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)模型，此時(shi)分(fen)(fen)流(liu)(liu)支路(lu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻相當于先充(chong)(chong)(chong)(chong)滿(man)的(de)(de)單(dan)節(jie)(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)負(fu)載，該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)通過其放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)端(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)維持在(zai)充(chong)(chong)(chong)(chong)滿(man)狀態附近(jin)一(yi)(yi)個極小的(de)(de)范(fan)圍內。假(jia)設第1節(jie)(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)先充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)完成，進入過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)保(bao)護狀態，則主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)及(ji)分(fen)(fen)流(liu)(liu)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向如圖3所(suo)示。當所(suo)有單(dan)節(jie)(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)均充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)進入過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)保(bao)護狀態時(shi)，全部單(dan)節(jie)(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)大(da)小在(zai)誤差(cha)范(fan)圍內完全相等，各(ge)節(jie)(jie)(jie)保(bao)護芯片充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)護控(kong)(kong)(kong)制信號(hao)均變低(di)，無法為主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)的(de)(de)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)(kong)制開(kai)關(guan)器件(jian)(jian)提供(gong)柵極偏壓(ya)(ya)，使其關(guan)斷，主(zhu)回路(lu)斷開(kai)，即實現均衡(heng)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)完成。
圖3 分流均衡過程
當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時，外(wai)接負載分別接電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)正負極(ji)BAT+和BAT-兩端(duan)，放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)流(liu)經電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)負極(ji)BAT-、充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)關(guan)器件、放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)關(guan)器件、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)中單(dan)節(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)N～1和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)正極(ji)BAT+,電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)流(liu)向如圖4所(suo)示。系(xi)統中控(kong)(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路部分單(dan)節(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)保護芯片的(de)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)欠(qian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓保護、過(guo)流(liu)和短(duan)路保護控(kong)(kong)制(zhi)信(xin)號經光耦隔離后串聯(lian)輸出，為主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路中放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)開(kai)關(guan)器件的(de)導(dao)通提供(gong)柵極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓;一旦(dan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)在放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程中遇到單(dan)節(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)欠(qian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓或者過(guo)流(liu)和短(duan)路等特殊情(qing)況，對(dui)應的(de)單(dan)節(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保護控(kong)(kong)制(zhi)信(xin)號變低，無(wu)法為主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路中的(de)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制(zhi)開(kai)關(guan)器件提供(gong)柵極(ji)偏(pian)壓，使(shi)其關(guan)斷(duan)，主(zhu)回路斷(duan)開(kai)，即結(jie)束放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)使(shi)用(yong)過(guo)程。
圖4 放電過程
一般鋰(li)電(dian)池采用恒(heng)流-恒(heng)壓(TAPER)型充電(dian)控(kong)制，恒(heng)壓充電(dian)時，充電(dian)電(dian)流近似指數規律減小(xiao)。系統中(zhong)充放電(dian)主回路的(de)開關(guan)器(qi)件可根據(ju)外部電(dian)路要(yao)求(qiu)滿足的(de)最大工作電(dian)流和工作電(dian)壓選型。
控(kong)制電(dian)路(lu)的單節(jie)(jie)鋰電(dian)池(chi)保(bao)護(hu)(hu)芯片可根據待保(bao)護(hu)(hu)的單節(jie)(jie)鋰電(dian)池(chi)的電(dian)壓(ya)等級、保(bao)護(hu)(hu)延(yan)遲時間(jian)等選型。
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)充電(dian)電(dian)壓大(da)小以及(ji)鋰電(dian)池(chi)(chi)的(de)參(can)數(shu)和放電(dian)電(dian)流(liu)的(de)大(da)小計算得出。均衡(heng)電(dian)流(liu)應合理(li)選(xuan)擇(ze)，如果(guo)太(tai)小，均衡(heng)效(xiao)(xiao)果(guo)不(bu)明(ming)顯；如果(guo)太(tai)大(da)，系(xi)統的(de)能量損耗大(da)，均衡(heng)效(xiao)(xiao)率低，對鋰電(dian)池(chi)(chi)組(zu)熱管理(li)要求(qiu)高，一般電(dian)流(liu)大(da)小可設計在(zai)50～100mA之(zhi)間(jian)。
分流放(fang)電(dian)(dian)支路電(dian)(dian)阻可(ke)采(cai)用(yong)功(gong)率電(dian)(dian)阻或電(dian)(dian)阻網絡(luo)實現。這(zhe)里(li)采(cai)用(yong)電(dian)(dian)阻網絡(luo)實現分流放(fang)電(dian)(dian)支路電(dian)(dian)阻較為(wei)合理，可(ke)以有(you)效消除(chu)電(dian)(dian)阻偏差的影響，此(ci)外(wai)，還能起到降低熱功(gong)耗的作用(yong)。
