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(de)有關知識
充電器的分類：用有、無工(gong)頻（
50
赫(he)茲(zi)）變(bian)壓器區分，可分為兩大類。貨運三輪充電器一
般使用帶工頻(pin)變壓器的(de)充(chong)電(dian)機，體積大、重量大，費(fei)電(dian)，但是可靠(kao)，便宜；電(dian)動(dong)自行車和電(dian)
摩則使用所(suo)謂開關電(dian)源式充電(dian)器，省電(dian)，效率高，但是(shi)易壞。
開關電源式(shi)充(chong)電器的正確操作是：
充電時，
先插電池，
后加市電；
充足后，
先切斷市電，
后拔電(dian)池插頭。如(ru)果在充電(dian)時先拔電(dian)池插頭，特(te)別(bie)是充電(dian)電(dian)流大（紅燈）時，非常(chang)容易損壞(huai)
充電器。
常用的開關(guan)電源式充(chong)電器又分(fen)半(ban)橋式和(he)單激式兩大類，
單激(ji)類又分(fen)為正激(ji)式(shi)和反激(ji)式(shi)
兩類(lei)。半(ban)橋式(shi)成(cheng)本高(gao)，性能(neng)好(hao)，常用于帶負脈沖的充(chong)電器；單激(ji)式(shi)成(cheng)本低，市(shi)場(chang)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(shi)全球普(pu)遍(bian)沿引老的觀點和(he)操作規程：
充、
放
電率為
0.1C(C
是電池容量
)
壽命較長。
美國人麥斯先生為解(jie)決快速(su)充(chong)電問題，
1967
年向全世
界公布了他的研(yan)究(jiu)成果，用大于
1C
率(lv)脈沖電(dian)(dian)流充電(dian)(dian)，充電(dian)(dian)間歇時對(dui)電(dian)(dian)池放電(dian)(dian)。放電(dian)(dian)有(you)利于(yu)
消除極化(hua)、降低(di)電解液溫度、提高(gao)極板接受電荷的能力(li)。
我國一(yi)些科技工作者在
1969
年前后(hou)，根(gen)據麥斯先生的(de)三(san)定律(lv)制作成功了多(duo)種品牌的(de)
快速充電機。
充電循環過程是：
大電流脈沖充電→切斷充電通路→對電池(chi)短暫放(fang)電→停止(zhi)放(fang)
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，有人將這一(yi)原(yuan)理用到了電(dian)動車充(chong)(chong)電(dian)器中，充(chong)(chong)電(dian)過程(cheng)中，不切斷(duan)充(chong)(chong)電(dian)通(tong)
路(lu)，用小(xiao)電阻(zu)將電池(chi)短路(lu)瞬(shun)間，
進行放電(dian)。短路時(shi)由于不切斷充電(dian)通(tong)路，在充電(dian)通(tong)路中串連
了電感。一般在
1
秒內短路
3
－
5
毫秒（
1
秒＝
1000
毫秒）
，由于電感里的電流不能跳變，
短
路時間短促，
可以保護充(chong)電(dian)器的電(dian)源轉換部(bu)分(fen)。
如(ru)果把充電(dian)電(dian)流方(fang)向叫正(zheng)，
放電自然為負了，
電(dian)動車業就出現了名詞“負(fu)脈沖充(chong)電(dian)器(qi)”
，而且稱可(ke)以延長電(dian)池壽命等等。
關于三段式充電器
近幾年，
電動車普遍使用(yong)了所謂三(san)段式充電器(qi)，
第一個階段叫(jiao)恒流階段，
第二個階段
叫恒壓階段，
第三個階(jie)段(duan)叫(jiao)涓流階(jie)段(duan)。
從電子(zi)技術角(jiao)度針對電池而言：
第一個階段叫充電限
流階段，
第(di)二個階段(duan)叫(jiao)高恒(heng)壓階段(duan)，
第三個階段(duan)叫低恒壓階段(duan)比較(jiao)貼切。
第二階段和第三階
段轉換(huan)時，面板指示燈(deng)相應變(bian)換(huan)，大(da)多(duo)數充電(dian)器第一、二階(jie)段是紅燈(deng)，第三階(jie)段變(bian)綠燈(deng)。第
二階(jie)段和第三階(jie)段的(de)相互(hu)轉換是由充電電流(liu)決定的(de)，
大于(yu)某(mou)電流進入第(di)一第(di)二階段，
小于某
電流進(jin)入(ru)第(di)三階段(duan)。這個電流叫轉換(huan)電流，也叫轉折電流。
早期充電器，
包括名牌車配套的充電器，雖然也變(bian)燈，
但實際(ji)是恒壓限流充電(dian)器，并
不是三階段充電器。一般這類(lei)就一個穩定(ding)電壓值，
44.2V
左右，對當時(shi)的高比(bi)重硫酸的電池
還湊合。
關(guan)(guan)于三段式充電(dian)器的三個(ge)關(guan)(guan)鍵參數
第一(yi)個重要(yao)參(can)數(shu)是(shi)涓(juan)流(liu)階段的低恒(heng)壓值，
第(di)二個重要參數是(shi)第(di)二階段的高(gao)恒壓(ya)值，
第
三個重(zhong)要參數是(shi)轉換電(dian)流。這三個重(zhong)要參數與電(dian)池(chi)數目有關，與電(dian)池(chi)的容量(liang)
Ah
有關，與溫
度有(you)(you)關，與電(dian)池種類有(you)(you)關。為了(le)方便大家記憶，下(xia)面以最(zui)常見的電(dian)動自行車(che)（三塊
12V
串
聯的
10Ah
電池(chi)）所(suo)用的三段式充(chong)電器為(wei)例簡單介紹一下(xia)：
首先(xian)討(tao)論涓流階段的低(di)恒壓(ya)值，
參考電壓為
42.5V
左右。
此值高將使電池失水，
容易
使電池發熱變形(xing)；此值低不(bu)利于電池充足電。此值在南方要低于
41.5V
；膠體電池要低于
41.5V
，如在南(nan)方還要低一點兒。這個參數(shu)是相對(dui)嚴格的，不可以大(da)于參考值。
其次討(tao)論第二階段的高(gao)恒壓值(zhi)，參考(kao)電壓為
44.5V
左右。此(ci)值高有利于快速充(chong)足電，
但是容(rong)易使電(dian)池失(shi)水，
充電后(hou)期(qi)電流下不(bu)來，
結(jie)果(guo)使電池(chi)發熱(re)變(bian)形；
此值低(di)不(bu)利于電池快速
充足(zu)電，有利于向涓流階段轉換。這個值雖然沒有第一個值那樣嚴格，但(dan)是也不(bu)要過高。
最后討論轉換電流，
參考電流為
300
毫安左右。
此值高有利于電池壽命，
不容易發熱
本文介紹的(de)是有(you)關鋰(li)電池(chi)(chi)(chi)組保(bao)護(hu)板(ban)均(jun)衡(heng)充電基本工(gong)作原理，在(zai)采(cai)用單節鋰(li)電池(chi)(chi)(chi)保(bao)護(hu)芯(xin)片設計的(de)且具備(bei)均(jun)衡(heng)充電能力的(de)鋰(li)電池(chi)(chi)(chi)組保(bao)護(hu)板(ban)，示(shi)意圖如圖1所示(shi)。
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)池數(shu)目(mu)確定，串(chuan)聯使用，分別(bie)對(dui)所(suo)對(dui)應單節鋰電(dian)池的(de)(de)充放電(dian)、過(guo)(guo)流、短路狀態進行保護。該系統在(zai)充電(dian)保護的(de)(de)同時，通過(guo)(guo)保護芯片控制分流放電(dian)支路開(kai)關器件的(de)(de)通斷實現均衡充電(dian)，該方案有(you)別(bie)于(yu)傳統的(de)(de)在(zai)充電(dian)器端(duan)實現均衡充電(dian)的(de)(de)做法(fa)，降(jiang)低了鋰電(dian)池組充電(dian)器設計應用的(de)(de)成本。
圖1 具備均衡充電(dian)能力(li)的鋰電(dian)池組保護板示意圖
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負極兩(liang)端的(de)分流放(fang)電(dian)(dian)(dian)(dian)(dian)支路放(fang)電(dian)(dian)(dian)(dian)(dian)，同時(shi)將串接在充電(dian)(dian)(dian)(dian)(dian)回路中的(de)對應單體鋰電(dian)(dian)(dian)(dian)(dian)池斷離(li)出(chu)充電(dian)(dian)(dian)(dian)(dian)回路。
鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池組串(chuan)聯充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)，忽略單(dan)節(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池容量差(cha)別的(de)(de)(de)影(ying)響，一般內阻較小的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池先充(chong)(chong)(chong)滿。此(ci)時(shi)，相(xiang)應(ying)的(de)(de)(de)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)保(bao)護(hu)信號控制分流(liu)(liu)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支(zhi)路的(de)(de)(de)開關(guan)器(qi)件閉合，在原電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池兩端并聯上(shang)一個(ge)分流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻。根據電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)PNGV等效電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路模型(xing)，此(ci)時(shi)分流(liu)(liu)支(zhi)路電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻相(xiang)當于先充(chong)(chong)(chong)滿的(de)(de)(de)單(dan)節(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)負載，該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池通過(guo)其放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)維持在充(chong)(chong)(chong)滿狀態(tai)(tai)附近一個(ge)極(ji)小的(de)(de)(de)范(fan)(fan)圍內。假設第1節(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池先充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)完(wan)成(cheng)，進(jin)入過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)保(bao)護(hu)狀態(tai)(tai)，則主電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路及分流(liu)(liu)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支(zhi)路中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向(xiang)如圖3所(suo)示(shi)。當所(suo)有單(dan)節(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池均充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)進(jin)入過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)保(bao)護(hu)狀態(tai)(tai)時(shi)，全部單(dan)節(jie)(jie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)大(da)小在誤(wu)差(cha)范(fan)(fan)圍內完(wan)全相(xiang)等，各節(jie)(jie)保(bao)護(hu)芯片充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)護(hu)控制信號均變低，無法為主電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路中的(de)(de)(de)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控制開關(guan)器(qi)件提供(gong)柵(zha)極(ji)偏壓(ya)(ya)(ya)(ya)，使其關(guan)斷(duan)，主回路斷(duan)開，即實現(xian)均衡充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程(cheng)完(wan)成(cheng)。
圖3 分流均衡過程
當電(dian)(dian)(dian)(dian)(dian)池(chi)組放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)時，外(wai)接(jie)負(fu)載分別接(jie)電(dian)(dian)(dian)(dian)(dian)池(chi)組正(zheng)負(fu)極BAT+和(he)(he)BAT-兩端(duan)，放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)經電(dian)(dian)(dian)(dian)(dian)池(chi)組負(fu)極BAT-、充電(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)開(kai)(kai)(kai)關(guan)(guan)器件(jian)(jian)、放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)開(kai)(kai)(kai)關(guan)(guan)器件(jian)(jian)、電(dian)(dian)(dian)(dian)(dian)池(chi)組中單節(jie)(jie)鋰(li)電(dian)(dian)(dian)(dian)(dian)池(chi)N～1和(he)(he)電(dian)(dian)(dian)(dian)(dian)池(chi)組正(zheng)極BAT+,電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向如圖4所示。系統中控(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)路部分單節(jie)(jie)鋰(li)電(dian)(dian)(dian)(dian)(dian)池(chi)保護芯片(pian)的放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)欠(qian)(qian)電(dian)(dian)(dian)(dian)(dian)壓(ya)保護、過流(liu)(liu)和(he)(he)短路保護控(kong)制(zhi)信號(hao)經光(guang)耦隔離后串聯輸出，為主電(dian)(dian)(dian)(dian)(dian)路中放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)開(kai)(kai)(kai)關(guan)(guan)器件(jian)(jian)的導通提(ti)供(gong)柵極電(dian)(dian)(dian)(dian)(dian)壓(ya);一旦電(dian)(dian)(dian)(dian)(dian)池(chi)組在放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)過程(cheng)中遇到單節(jie)(jie)鋰(li)電(dian)(dian)(dian)(dian)(dian)池(chi)欠(qian)(qian)電(dian)(dian)(dian)(dian)(dian)壓(ya)或者過流(liu)(liu)和(he)(he)短路等特殊(shu)情(qing)況，對應的單節(jie)(jie)鋰(li)電(dian)(dian)(dian)(dian)(dian)池(chi)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)保護控(kong)制(zhi)信號(hao)變低，無法為主電(dian)(dian)(dian)(dian)(dian)路中的放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)開(kai)(kai)(kai)關(guan)(guan)器件(jian)(jian)提(ti)供(gong)柵極偏壓(ya)，使(shi)其(qi)關(guan)(guan)斷(duan)，主回路斷(duan)開(kai)(kai)(kai)，即結(jie)束(shu)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)使(shi)用過程(cheng)。
圖4 放電過程
一(yi)般(ban)鋰電(dian)池采用恒(heng)流(liu)-恒(heng)壓(TAPER)型充(chong)(chong)(chong)電(dian)控制，恒(heng)壓充(chong)(chong)(chong)電(dian)時，充(chong)(chong)(chong)電(dian)電(dian)流(liu)近(jin)似指(zhi)數(shu)規律減小。系統(tong)中充(chong)(chong)(chong)放電(dian)主回路(lu)的開關器(qi)件可(ke)根據外部電(dian)路(lu)要求(qiu)滿足的最大工作電(dian)流(liu)和工作電(dian)壓選型。
控制電(dian)路的(de)單節(jie)鋰(li)電(dian)池(chi)保護(hu)(hu)(hu)芯(xin)片可根據待(dai)保護(hu)(hu)(hu)的(de)單節(jie)鋰(li)電(dian)池(chi)的(de)電(dian)壓等級、保護(hu)(hu)(hu)延遲時(shi)間等選型。
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(chong)電電壓大小以及(ji)鋰電池(chi)的(de)參數和(he)放(fang)電電流(liu)(liu)的(de)大小計算(suan)得出。均衡(heng)電流(liu)(liu)應(ying)合理(li)選擇，如果(guo)太小，均衡(heng)效(xiao)果(guo)不明顯；如果(guo)太大，系統的(de)能量(liang)損耗(hao)大，均衡(heng)效(xiao)率低(di)，對(dui)鋰電池(chi)組(zu)熱管理(li)要(yao)求高，一(yi)般電流(liu)(liu)大小可設(she)計在50～100mA之間(jian)。
分流(liu)放(fang)電支路(lu)電阻(zu)可采用(yong)功率電阻(zu)或電阻(zu)網絡(luo)實(shi)現。這里采用(yong)電阻(zu)網絡(luo)實(shi)現分流(liu)放(fang)電支路(lu)電阻(zu)較為合(he)理，可以有(you)效消除電阻(zu)偏(pian)差的影響，此外，還能起到降低熱(re)功耗的作用(yong)。
