锂电池保护板均衡原理

成组锂电(dian)(dian)(dian)(dian)池(chi)(chi)串联充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)时(shi)，应保证(zheng)每(mei)节(jie)电(dian)(dian)(dian)(dian)池(chi)(chi)均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)，否则使用过(guo)程中会影响整组电(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)性(xing)能(neng)(neng)和寿(shou)命。常(chang)用的(de)(de)均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)技术(shu)有恒定分流(liu)电(dian)(dian)(dian)(dian)阻均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)、通(tong)断分流(liu)电(dian)(dian)(dian)(dian)阻均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)、平均(jun)电(dian)(dian)(dian)(dian)池(chi)(chi)电(dian)(dian)(dian)(dian)压均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)、开关电(dian)(dian)(dian)(dian)容均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)、降压型变换(huan)器均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)、电(dian)(dian)(dian)(dian)感均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)等(deng)。而现有的(de)(de)单节(jie)锂电(dian)(dian)(dian)(dian)池(chi)(chi)保护(hu)芯(xin)片均(jun)不(bu)含(han)均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)控(kong)制功能(neng)(neng);多节(jie)锂电(dian)(dian)(dian)(dian)池(chi)(chi)保护(hu)芯(xin)片均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)控(kong)制功能(neng)(neng)需要外接CPU，通(tong)过(guo)和保护(hu)芯(xin)片的(de)(de)串行通(tong)讯（如I2C总线）来实现，加(jia)大了(le)保护(hu)电(dian)(dian)(dian)(dian)路(lu)的(de)(de)复杂(za)程度和设计难度、降低了(le)系统的(de)(de)效率和可靠性(xing)、增加(jia)了(le)功耗(hao)。

本文针(zhen)对(dui)(dui)动力(li)锂(li)电(dian)池(chi)(chi)成组使用(yong)锂(li)电(dian)池(chi)(chi)保(bao)(bao)护(hu)(hu)板均衡原理(li)，各节(jie)锂(li)电(dian)池(chi)(chi)均要求充电(dian)过(guo)电(dian)压(ya)、放电(dian)欠(qian)电(dian)压(ya)、过(guo)流、短路(lu)的(de)(de)保(bao)(bao)护(hu)(hu)，充电(dian)过(guo)程中要实现整组电(dian)池(chi)(chi)均衡充电(dian)的(de)(de)问题，介(jie)绍(shao)了一种采用(yong)单节(jie)锂(li)电(dian)池(chi)(chi)保(bao)(bao)护(hu)(hu)芯片对(dui)(dui)任意串联(lian)数的(de)(de)成组锂(li)电(dian)池(chi)(chi)进行保(bao)(bao)护(hu)(hu)的(de)(de)含(han)均衡充电(dian)功(gong)能的(de)(de)电(dian)池(chi)(chi)组保(bao)(bao)护(hu)(hu)板的(de)(de)设(she)计方案。经过(guo)仿真结果和工(gong)业生产应(ying)用(yong)证(zheng)明，该保(bao)(bao)护(hu)(hu)板的(de)(de)保(bao)(bao)护(hu)(hu)功(gong)能完善(shan)，工(gong)作稳定，性价比高。

锂(li)电(dian)(dian)(dian)(dian)(dian)(dian)池保护(hu)(hu)板(ban)均(jun)(jun)衡原(yuan)理常用的(de)(de)(de)(de)均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)技术包括(kuo)恒定分(fen)(fen)流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)阻均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)、通(tong)断分(fen)(fen)流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)阻均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)、平均(jun)(jun)电(dian)(dian)(dian)(dian)(dian)(dian)池电(dian)(dian)(dian)(dian)(dian)(dian)压均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)、开关电(dian)(dian)(dian)(dian)(dian)(dian)容均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)、降压型变换器均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)、电(dian)(dian)(dian)(dian)(dian)(dian)感均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)等。成(cheng)组的(de)(de)(de)(de)锂(li)电(dian)(dian)(dian)(dian)(dian)(dian)池串联(lian)充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)时，应保证每节(jie)电(dian)(dian)(dian)(dian)(dian)(dian)池均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)，否则使用过程(cheng)中会(hui)影响(xiang)整(zheng)组电(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)(de)性(xing)能(neng)和寿(shou)命(ming)。而现(xian)有(you)的(de)(de)(de)(de)单节(jie)锂(li)电(dian)(dian)(dian)(dian)(dian)(dian)池保护(hu)(hu)芯(xin)(xin)片(pian)均(jun)(jun)不含均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)控制功能(neng)，多节(jie)锂(li)电(dian)(dian)(dian)(dian)(dian)(dian)池保护(hu)(hu)芯(xin)(xin)片(pian)均(jun)(jun)衡充(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)控制功能(neng)需(xu)要外接CPU;通(tong)过和保护(hu)(hu)芯(xin)(xin)片(pian)的(de)(de)(de)(de)串行通(tong)讯（如I2C总线）来实现(xian)，加大了保护(hu)(hu)电(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)复杂程(cheng)度和设计难度、降低了系(xi)统(tong)的(de)(de)(de)(de)效率和可(ke)靠性(xing)、增加了功耗。

本文针对动力锂电(dian)池(chi)(chi)成组(zu)使用，各节(jie)锂电(dian)池(chi)(chi)均要(yao)求充(chong)(chong)电(dian)过(guo)电(dian)压(ya)、放电(dian)欠电(dian)压(ya)、过(guo)流、短路的(de)(de)保护(hu)，充(chong)(chong)电(dian)过(guo)程(cheng)中要(yao)实现整(zheng)组(zu)电(dian)池(chi)(chi)均衡(heng)充(chong)(chong)电(dian)的(de)(de)问(wen)题，介绍了(le)一种(zhong)采用单节(jie)锂电(dian)池(chi)(chi)保护(hu)芯片对任意(yi)串(chuan)联数的(de)(de)成组(zu)锂电(dian)池(chi)(chi)进行保护(hu)的(de)(de)含均衡(heng)充(chong)(chong)电(dian)功能(neng)的(de)(de)电(dian)池(chi)(chi)组(zu)保护(hu)板的(de)(de)设计方案。仿(fang)真(zhen)结果(guo)和工(gong)业生产应用证(zheng)明，该保护(hu)板保护(hu)功能(neng)完善，工(gong)作稳定，性价比高，均衡(heng)充(chong)(chong)电(dian)误(wu)差小于50mV。

1、锂电池组保护板均衡充电原理结构

采(cai)用单节锂电池保(bao)护(hu)芯(xin)片设(she)计的(de)具备均(jun)衡充电能(neng)力的(de)锂电池组保(bao)护(hu)板结构框图如(ru)下图1所示。

图1锂电(dian)池组保护板结构(gou)框图

其中(zhong)：1为(wei)单(dan)节锂(li)(li)(li)离(li)子电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)；2为(wei)充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压分流(liu)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)；3为(wei)分流(liu)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)控(kong)制(zhi)(zhi)(zhi)(zhi)用开关(guan)(guan)(guan)器件；4为(wei)过流(liu)检测保(bao)护(hu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)；5为(wei)省略的锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)护(hu)芯(xin)(xin)片(pian)及(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)连接部分；6为(wei)单(dan)节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)护(hu)芯(xin)(xin)片(pian)（一般包括充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)引脚(jiao)CO,放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)引脚(jiao)DO,放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)及(ji)短路(lu)检测引脚(jiao)VM,电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)正端(duan)VDD,电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)负端(duan)VSS等）；7为(wei)充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压保(bao)护(hu)信号(hao)经(jing)(jing)光耦(ou)隔离(li)后形(xing)成并联关(guan)(guan)(guan)系驱(qu)动(dong)主(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)用MOS管栅极(ji)；锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)护(hu)板均(jun)衡原理8为(wei)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)欠电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压、过流(liu)、短路(lu)保(bao)护(hu)信号(hao)经(jing)(jing)光耦(ou)隔离(li)后形(xing)成串(chuan)联关(guan)(guan)(guan)系驱(qu)动(dong)主(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)用MOS管栅极(ji)；9为(wei)充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)开关(guan)(guan)(guan)器件；10为(wei)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)(zhi)开关(guan)(guan)(guan)器件；11为(wei)控(kong)制(zhi)(zhi)(zhi)(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)；12为(wei)主(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)；13为(wei)分流(liu)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)。锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)护(hu)板均(jun)衡原理单(dan)节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)护(hu)芯(xin)(xin)片(pian)数目依据锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)组(zu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)数目确定，串(chuan)联使用，分别对(dui)所对(dui)应单(dan)节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的充(chong)(chong)(chong)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)、过流(liu)、短路(lu)状态进(jin)行(xing)保(bao)护(hu)。该(gai)系统(tong)在充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)护(hu)的同时，通过保(bao)护(hu)芯(xin)(xin)片(pian)控(kong)制(zhi)(zhi)(zhi)(zhi)分流(liu)放(fang)(fang)(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支路(lu)开关(guan)(guan)(guan)器件的通断实现均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，该(gai)方案有别于(yu)传统(tong)的在充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器端(duan)实现均(jun)衡充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的做法，降低了锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)组(zu)充(chong)(chong)(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器设计(ji)应用的成本。

2 硬件设计
2.1充电电路

当(dang)锂电(dian)(dian)池(chi)(chi)保护板均衡原(yuan)理(li)锂电(dian)(dian)池(chi)(chi)组(zu)(zu)充电(dian)(dian)时(shi)，外接(jie)电(dian)(dian)源正(zheng)负极(ji)(ji)分别接(jie)电(dian)(dian)池(chi)(chi)组(zu)(zu)正(zheng)负极(ji)(ji)BAT+和BAT-两端，充电(dian)(dian)电(dian)(dian)流流经电(dian)(dian)池(chi)(chi)组(zu)(zu)正(zheng)极(ji)(ji)BAT+、电(dian)(dian)池(chi)(chi)组(zu)(zu)中单(dan)节锂电(dian)(dian)池(chi)(chi)1~N、放(fang)电(dian)(dian)控制开关器(qi)件(jian)、充电(dian)(dian)控制开关器(qi)件(jian)、电(dian)(dian)池(chi)(chi)组(zu)(zu)负极(ji)(ji)BAT-,电(dian)(dian)流流向如图(tu)2所示(shi)。

图2锂电池组充电电路

系统中控制(zhi)电(dian)(dian)路(lu)部分(fen)单节(jie)锂(li)(li)电(dian)(dian)池(chi)(chi)保(bao)(bao)护(hu)(hu)(hu)芯片的充(chong)电(dian)(dian)过(guo)(guo)电(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)(hu)控制(zhi)信号经光耦隔(ge)离后并联输出(chu)，为主电(dian)(dian)路(lu)中充(chong)电(dian)(dian)开关器件的导通提供栅极电(dian)(dian)压(ya)；如某一节(jie)或(huo)几节(jie)锂(li)(li)电(dian)(dian)池(chi)(chi)在充(chong)电(dian)(dian)过(guo)(guo)程中先(xian)进入过(guo)(guo)电(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)(hu)状态，锂(li)(li)电(dian)(dian)池(chi)(chi)保(bao)(bao)护(hu)(hu)(hu)板均衡原理则由(you)过(guo)(guo)电(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)(hu)信号控制(zhi)并联在单节(jie)锂(li)(li)电(dian)(dian)池(chi)(chi)正负极两(liang)端的分(fen)流放电(dian)(dian)支路(lu)放电(dian)(dian)，同时将(jiang)串接(jie)在充(chong)电(dian)(dian)回(hui)路(lu)中的对应单体锂(li)(li)电(dian)(dian)池(chi)(chi)断离出(chu)充(chong)电(dian)(dian)回(hui)路(lu)。

2.2主电路及分流放电支路

锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组串联充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)时(shi)(shi)，忽略单(dan)节电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)容量差别的(de)(de)(de)影响，一(yi)般(ban)内(nei)阻(zu)较小(xiao)的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)先(xian)充满(man)。此(ci)时(shi)(shi)，相(xiang)(xiang)应的(de)(de)(de)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)信号(hao)控(kong)制(zhi)分流(liu)(liu)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支(zhi)路(lu)(lu)的(de)(de)(de)开关(guan)(guan)器件(jian)闭合，在原(yuan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)两(liang)端并(bing)联上一(yi)个分流(liu)(liu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)。根据(ju)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)PNGV等(deng)效电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)模型，此(ci)时(shi)(shi)分流(liu)(liu)支(zhi)路(lu)(lu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)相(xiang)(xiang)当于先(xian)充满(man)的(de)(de)(de)单(dan)节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)负载，该电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)通过其放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，使电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)端电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)维持在充满(man)状态(tai)附近(jin)一(yi)个极(ji)小(xiao)的(de)(de)(de)范(fan)围(wei)内(nei)。假设第1节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)先(xian)充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)完成(cheng)，进(jin)入(ru)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)状态(tai)，则(ze)主(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)及分流(liu)(liu)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)支(zhi)路(lu)(lu)中电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向(xiang)如图3所示。锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)保(bao)(bao)护(hu)(hu)板均衡原(yuan)理当所有单(dan)节电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)均充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)进(jin)入(ru)过电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)护(hu)(hu)状态(tai)时(shi)(shi)，全部单(dan)节锂(li)(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)大小(xiao)在误差范(fan)围(wei)内(nei)完全相(xiang)(xiang)等(deng)，各节保(bao)(bao)护(hu)(hu)芯片充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)护(hu)(hu)控(kong)制(zhi)信号(hao)均变低，无(wu)法为主(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中的(de)(de)(de)充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)制(zhi)开关(guan)(guan)器件(jian)提供(gong)栅(zha)极(ji)偏压(ya)，使其关(guan)(guan)断(duan)，主(zhu)回(hui)路(lu)(lu)断(duan)开，即实现均衡充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)过程完成(cheng)。

图3主电路(lu)及分流放电支路(lu)

单(dan)节电(dian)(dian)池(chi)(chi)两端(duan)并(bing)接的放(fang)电(dian)(dian)支(zhi)路电(dian)(dian)阻可(ke)根据(ju)锂(li)电(dian)(dian)池(chi)(chi)充电(dian)(dian)器的充电(dian)(dian)电(dian)(dian)压(ya)大小以及锂(li)电(dian)(dian)池(chi)(chi)的参数(shu)和放(fang)电(dian)(dian)电(dian)(dian)流的大小计(ji)算(suan)得出。均衡(heng)电(dian)(dian)流应合理选择，如果(guo)太小，均衡(heng)效(xiao)果(guo)不明显；如果(guo)太大，系统的能量(liang)损耗大，均衡(heng)效(xiao)率低(di)，对锂(li)电(dian)(dian)池(chi)(chi)组热管理要求高(gao)，一般电(dian)(dian)流大小可(ke)设计(ji)在(zai)50~100mA之(zhi)间(jian)。

2.3放电电路

当电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)时，外接(jie)负载分(fen)别接(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组正(zheng)负极(ji)(ji)BAT+和(he)(he)BAT-两端，放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)经电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组负极(ji)(ji)BAT-、充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制开关器(qi)件(jian)、放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制开关器(qi)件(jian)、电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组中单节锂(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)N~1和(he)(he)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组正(zheng)极(ji)(ji)BAT+,电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向如图4所示。锂(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)保护板均衡原理系统中控(kong)(kong)制电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)部分(fen)单节锂(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)保护芯片(pian)的(de)放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)欠电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压保护、过流(liu)(liu)和(he)(he)短路(lu)(lu)保护控(kong)(kong)制信(xin)(xin)号经光耦隔离后(hou)串联输出，为主(zhu)(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)开关器(qi)件(jian)的(de)导通(tong)提供栅极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压；一旦电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)组在放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)过程中遇到单节锂(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)欠电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压或(huo)者过流(liu)(liu)和(he)(he)短路(lu)(lu)等(deng)特(te)殊情况，对(dui)应的(de)单节锂(li)(li)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)保护控(kong)(kong)制信(xin)(xin)号变低，无法(fa)为主(zhu)(zhu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中的(de)放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)控(kong)(kong)制开关器(qi)件(jian)提供栅极(ji)(ji)偏压，使(shi)其关断，主(zhu)(zhu)回路(lu)(lu)断开，即结束放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)使(shi)用过程。

图(tu)4电(dian)(dian)(dian)池组(zu)放(fang)电(dian)(dian)(dian)电(dian)(dian)(dian)路

一(yi)般锂电(dian)池(chi)采用恒流(liu)-恒压（TAPER）型(xing)充(chong)电(dian)控制(zhi)，恒压充(chong)电(dian)时，充(chong)电(dian)电(dian)流(liu)近(jin)似指数规律(lv)减小。系统中(zhong)充(chong)放电(dian)主回路(lu)(lu)的开关器件可(ke)根据外(wai)部电(dian)路(lu)(lu)要求满足的最(zui)大工作电(dian)流(liu)和工作电(dian)压选(xuan)型(xing)。

锂(li)电(dian)(dian)(dian)池(chi)保护板均(jun)衡原理(li)控制电(dian)(dian)(dian)路的单(dan)节锂(li)电(dian)(dian)(dian)池(chi)保护芯片可根据待保护的单(dan)节锂(li)电(dian)(dian)(dian)池(chi)的电(dian)(dian)(dian)压等级、保护延(yan)迟(chi)时间等选(xuan)型。分(fen)流放(fang)电(dian)(dian)(dian)支路电(dian)(dian)(dian)阻(zu)(zu)(zu)可采(cai)用功率电(dian)(dian)(dian)阻(zu)(zu)(zu)或电(dian)(dian)(dian)阻(zu)(zu)(zu)网络实现。这里采(cai)用电(dian)(dian)(dian)阻(zu)(zu)(zu)网络实现分(fen)流放(fang)电(dian)(dian)(dian)支路电(dian)(dian)(dian)阻(zu)(zu)(zu)较为合理(li)，可以(yi)有(you)效消除电(dian)(dian)(dian)阻(zu)(zu)(zu)偏差的影响(xiang)，此外(wai)，还能(neng)起(qi)到降(jiang)低热功耗的作(zuo)用。

3 均衡充电保护板电路仿真

根据上述锂(li)电(dian)池(chi)保护板均衡原理，在(zai)Matlab/Simulink环境下搭(da)建了系统仿(fang)真模型，模拟锂(li)电(dian)池(chi)组充放电(dian)过程中保护板工作(zuo)的情(qing)况，验证该设计(ji)方案的可行性。为简单起见，给(ji)出了锂(li)电(dian)池(chi)组仅由2节锂(li)电(dian)池(chi)串联的仿(fang)真模型，如图5所示。

图5 2节锂电池(chi)串联均充保护仿真模(mo)型(xing)

模型中用(yong)受控(kong)电(dian)(dian)(dian)(dian)压(ya)源代替(ti)单节(jie)锂电(dian)(dian)(dian)(dian)池，模拟电(dian)(dian)(dian)(dian)池充放电(dian)(dian)(dian)(dian)的(de)(de)情(qing)况。图(tu)5中，Rs为(wei)(wei)串(chuan)联电(dian)(dian)(dian)(dian)池组的(de)(de)电(dian)(dian)(dian)(dian)池总内阻(zu)，RL为(wei)(wei)负载电(dian)(dian)(dian)(dian)阻(zu)，Rd为(wei)(wei)分流放电(dian)(dian)(dian)(dian)支(zhi)路电(dian)(dian)(dian)(dian)阻(zu)。所采用(yong)的(de)(de)单节(jie)锂电(dian)(dian)(dian)(dian)池保护芯片S28241封装为(wei)(wei)一个子系统，使(shi)整体(ti)模型表达时(shi)更为(wei)(wei)简洁。

锂电(dian)(dian)(dian)池保护(hu)板均衡原(yuan)理保护(hu)芯片子系(xi)(xi)统模(mo)(mo)(mo)型(xing)主要(yao)用逻辑(ji)运算模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、符(fu)号函(han)数(shu)(shu)模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、一维查表模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、积分模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、延时(shi)模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、开关模(mo)(mo)(mo)块(kuai)(kuai)(kuai)、数(shu)(shu)学运算模(mo)(mo)(mo)块(kuai)(kuai)(kuai)等模(mo)(mo)(mo)拟了保护(hu)动作的(de)(de)(de)(de)时(shi)序(xu)与逻辑(ji)。由于仿(fang)(fang)真环境(jing)与真实(shi)电(dian)(dian)(dian)路存(cun)在一定的(de)(de)(de)(de)差别(bie)，仿(fang)(fang)真时(shi)不需要(yao)滤(lv)波和(he)强弱电(dian)(dian)(dian)隔离(li)，而且多余的(de)(de)(de)(de)模(mo)(mo)(mo)块(kuai)(kuai)(kuai)容易导致仿(fang)(fang)真时(shi)间(jian)的(de)(de)(de)(de)冗(rong)长(zhang)。因此(ci)，在实(shi)际仿(fang)(fang)真过程(cheng)中，去除(chu)了滤(lv)波、光耦隔离(li)、电(dian)(dian)(dian)平调理等电(dian)(dian)(dian)路，并把为(wei)大电(dian)(dian)(dian)流(liu)分流(liu)设(she)计的(de)(de)(de)(de)电(dian)(dian)(dian)阻网络改为(wei)单电(dian)(dian)(dian)阻，降低(di)了仿(fang)(fang)真系(xi)(xi)统的(de)(de)(de)(de)复杂程(cheng)度。建立完整的(de)(de)(de)(de)系(xi)(xi)统仿(fang)(fang)真模(mo)(mo)(mo)型(xing)时(shi)，要(yao)注意不同模(mo)(mo)(mo)块(kuai)(kuai)(kuai)的(de)(de)(de)(de)输入输出数(shu)(shu)据和(he)信号类(lei)型(xing)可能存(cun)在差异，必须正确排列模(mo)(mo)(mo)块(kuai)(kuai)(kuai)的(de)(de)(de)(de)连(lian)接(jie)顺序(xu)，必要(yao)时(shi)进行数(shu)(shu)据类(lei)型(xing)的(de)(de)(de)(de)转(zhuan)换，模(mo)(mo)(mo)型(xing)中用电(dian)(dian)(dian)压检(jian)测模(mo)(mo)(mo)块(kuai)(kuai)(kuai)实(shi)现了强弱信号的(de)(de)(de)(de)转(zhuan)换连(lian)接(jie)问题。

锂电池(chi)保护板均衡原理(li)仿(fang)真(zhen)模型中受控电压(ya)源的(de)(de)给(ji)定信号在波(bo)形(xing)大(da)体(ti)一致的(de)(de)前提(ti)下可(ke)有微小差别，以代表(biao)电池(chi)个(ge)体(ti)充(chong)放(fang)电的(de)(de)差异。图6为(wei)电池(chi)组(zu)中单(dan)节电池(chi)电压(ya)检测(ce)仿(fang)真(zhen)结果(guo)，可(ke)见采用过(guo)流放(fang)电支(zhi)路均充(chong)的(de)(de)办法，该电路可(ke)正常工作。

图6 锂电池(chi)电压(ya)检测仿真结果

4系统实验

实际(ji)应用中(zhong)，针对某(mou)品牌电(dian)动(dong)自(zi)行(xing)车(che)生产厂的需求，设(she)计实现了2组并(bing)联、10节串(chuan)联的36V8A.h锰酸锂动(dong)力电(dian)池(chi)组保护(hu)(hu)板，其中(zhong)单节锂电(dian)池(chi)保护(hu)(hu)芯片采用日本精工(gong)公司的S28241,保护(hu)(hu)板主(zhu)要由主(zhu)电(dian)路(lu)、控制(zhi)电(dian)路(lu)、分(fen)流(liu)放(fang)电(dian)支(zhi)路(lu)以及(ji)滤波(bo)、光(guang)耦隔离和电(dian)平调理电(dian)路(lu)等部分(fen)组成，锂电(dian)池(chi)保护(hu)(hu)板均衡原理其基本结(jie)构如(ru)图7所(suo)示。放(fang)电(dian)支(zhi)路(lu)电(dian)流(liu)选择在800mA左右，采用510Ω电(dian)阻串(chuan)并(bing)联构成电(dian)阻网(wang)络(luo)。

图7 锂电池组保(bao)护板调试

调试(shi)工(gong)作(zuo)(zuo)(zuo)主要分(fen)为(wei)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)测(ce)(ce)试(shi)和电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)测(ce)(ce)试(shi)两部(bu)分(fen)。电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)测(ce)(ce)试(shi)包(bao)括(kuo)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)性(xing)(xing)能(neng)检(jian)测(ce)(ce)过(guo)(guo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)、均(jun)(jun)充(chong)以(yi)(yi)及放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)性(xing)(xing)能(neng)检(jian)测(ce)(ce)欠电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)两步。可(ke)以(yi)(yi)选择采用电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)模拟(ni)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源供应器代替实际的(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组(zu)进行测(ce)(ce)试(shi)，由于(yu)(yu)多节(jie)(jie)(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)串联，该方(fang)案一(yi)次投(tou)入(ru)的(de)测(ce)(ce)试(shi)成本(ben)较(jiao)高。也(ye)可(ke)以(yi)(yi)使用装配好的(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组(zu)直接(jie)进行测(ce)(ce)试(shi)，对电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组(zu)循(xun)环充(chong)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，观测(ce)(ce)过(guo)(guo)压(ya)(ya)(ya)和欠压(ya)(ya)(ya)时(shi)(shi)(shi)保护装置是否正(zheng)(zheng)(zheng)常动作(zuo)(zuo)(zuo)，记录过(guo)(guo)充(chong)保护时(shi)(shi)(shi)各(ge)节(jie)(jie)(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)实时(shi)(shi)(shi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)，判断(duan)均(jun)(jun)衡(heng)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)性(xing)(xing)能(neng)。但此方(fang)案一(yi)次测(ce)(ce)试(shi)耗费时(shi)(shi)(shi)间较(jiao)长(zhang)。对电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组(zu)作(zuo)(zuo)(zuo)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)性(xing)(xing)能(neng)检(jian)测(ce)(ce)时(shi)(shi)(shi)，采用3位半(ban)精度(du)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)表对10节(jie)(jie)(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)监测(ce)(ce)，可(ke)见各(ge)节(jie)(jie)(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)都在正(zheng)(zheng)(zheng)常工(gong)作(zuo)(zuo)(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)范围(wei)内，并且单体之(zhi)间的(de)差(cha)异很小(xiao)，充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)过(guo)(guo)程中(zhong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)偏差(cha)小(xiao)于(yu)(yu)100mV,满充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)4.2V、电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)偏差(cha)小(xiao)于(yu)(yu)50mV.电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)测(ce)(ce)试(shi)部(bu)分(fen)包(bao)括(kuo)过(guo)(guo)流(liu)检(jian)测(ce)(ce)和短路检(jian)测(ce)(ce)两步。过(guo)(guo)流(liu)检(jian)测(ce)(ce)可(ke)在电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻负载与(yu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源回路间串接(jie)一(yi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)表，缓慢减小(xiao)负载，当电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)增(zeng)大到(dao)过(guo)(guo)流(liu)值(zhi)时(shi)(shi)(shi)，看电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)表是否指示断(duan)流(liu)。短路检(jian)测(ce)(ce)可(ke)直接(jie)短接(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)组(zu)正(zheng)(zheng)(zheng)负极来(lai)观测(ce)(ce)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)表状态。在确定(ding)器件完(wan)好，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路焊(han)接(jie)无(wu)误的(de)前提下，也(ye)可(ke)直接(jie)通过(guo)(guo)保护板(ban)上电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源指示灯(deng)的(de)状态进行电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)测(ce)(ce)试(shi)。

实际(ji)使用中，考虑到外(wai)部干扰(rao)可(ke)能会(hui)引起电(dian)(dian)池(chi)电(dian)(dian)压不稳定的情况，这样会(hui)造(zao)成电(dian)(dian)压极短时(shi)(shi)(shi)间(jian)(jian)的过(guo)压或欠压，从(cong)而导致电(dian)(dian)池(chi)保(bao)护(hu)电(dian)(dian)路(lu)错误判断，因此在保(bao)护(hu)芯片配有(you)相(xiang)应的延时(shi)(shi)(shi)逻(luo)辑，必(bi)要(yao)时(shi)(shi)(shi)可(ke)在保(bao)护(hu)板上添加延时(shi)(shi)(shi)电(dian)(dian)路(lu)，这样将(jiang)有(you)效降低外(wai)部干扰(rao)造(zao)成保(bao)护(hu)电(dian)(dian)路(lu)误动(dong)作的可(ke)能性。由于(yu)电(dian)(dian)池(chi)组(zu)不工(gong)作时(shi)(shi)(shi)，保(bao)护(hu)板上各开关器件(jian)处于(yu)断开状(zhuang)(zhuang)态(tai)(tai)，故静态(tai)(tai)损(sun)(sun)耗(hao)几乎为0.当系统工(gong)作时(shi)(shi)(shi)，主要(yao)损(sun)(sun)耗(hao)为主电(dian)(dian)路(lu)中2个MOS管上的通(tong)态(tai)(tai)损(sun)(sun)耗(hao)，当充(chong)电(dian)(dian)状(zhuang)(zhuang)态(tai)(tai)下均衡电(dian)(dian)路(lu)工(gong)作时(shi)(shi)(shi)，分流(liu)支路(lu)中电(dian)(dian)阻热损(sun)(sun)耗(hao)较(jiao)大，但时(shi)(shi)(shi)间(jian)(jian)较(jiao)短，整体动(dong)态(tai)(tai)损(sun)(sun)耗(hao)在电(dian)(dian)池(chi)组(zu)正常工(gong)作的周期内处于(yu)可(ke)以接受的水平。

经测试，该保护(hu)电路(lu)的设计能够满(man)足(zu)串联锂电池组保护(hu)的需要，保护(hu)功能齐全，能可靠地进(jin)行过充电、过放电的保护(hu)，同时实现(xian)均衡充电功能。

锂电池(chi)保(bao)(bao)护(hu)(hu)板均(jun)衡原理根据应用的需要(yao)，在(zai)改变(bian)保(bao)(bao)护(hu)(hu)芯片型号和(he)(he)串联数，电路中开关器件和(he)(he)能耗元(yuan)件的功率等级(ji)之后(hou)，可对任意结构和(he)(he)电压等级(ji)的动力锂电池(chi)组(zu)(zu)实(shi)现保(bao)(bao)护(hu)(hu)和(he)(he)均(jun)充。如采用台湾(wan)富晶公司(si)的FS361A单节(jie)锂电池(chi)保(bao)(bao)护(hu)(hu)芯片可实(shi)现3组(zu)(zu)并联、12串磷酸铁(tie)锂电池(chi)组(zu)(zu)保(bao)(bao)护(hu)(hu)板设计等。

锂(li)电(dian)(dian)池(chi)(chi)(可充型(xing))之所以(yi)需(xu)要保护，是由它本身特(te)性决定的(de)。由于锂(li)电(dian)(dian)池(chi)(chi)本身的(de)材料决定了它不能被过充、过放(fang)、过流(liu)、短路及超高温(wen)充放(fang)电(dian)(dian)，因(yin)此锂(li)电(dian)(dian)池(chi)(chi)锂(li)电(dian)(dian)组件总会跟(gen)着一块(kuai)精致(zhi)的(de)保护板和一片电(dian)(dian)流(liu)保险(xian)器出现(xian)。

1、正常状态

在正常状态下电(dian)路中(zhong)N1的(de)“CO”与(yu)“DO”脚都(dou)输出高电(dian)压，两个MOSFET都(dou)处(chu)于(yu)导通状态，电(dian)池可(ke)以自由(you)地进行充(chong)电(dian)和放电(dian)，由(you)于(yu)MOSFET的(de)导通阻抗很(hen)小(xiao)，通常小(xiao)于(yu)30毫(hao)欧，因(yin)此其(qi)导通电(dian)阻对(dui)电(dian)路的(de)性能影响很(hen)小(xiao)。

此状态(tai)下(xia)保护电路的消耗电流(liu)为μA级，通常小于7μA。

2、过(guo)充(chong)电保护

锂(li)离(li)子电(dian)(dian)(dian)池要求的充(chong)电(dian)(dian)(dian)方式为(wei)恒流/恒压(ya)(ya)，在(zai)充(chong)电(dian)(dian)(dian)初(chu)期，为(wei)恒流充(chong)电(dian)(dian)(dian)，随(sui)着充(chong)电(dian)(dian)(dian)过(guo)程，电(dian)(dian)(dian)压(ya)(ya)会上升到4.2V(根据正极材料不同，有(you)的电(dian)(dian)(dian)池要求恒压(ya)(ya)值为(wei)4.1V)，转为(wei)恒压(ya)(ya)充(chong)电(dian)(dian)(dian)，直至电(dian)(dian)(dian)流越(yue)来越(yue)小(xiao)。

电(dian)(dian)(dian)(dian)池(chi)(chi)在被充(chong)电(dian)(dian)(dian)(dian)过程中，如(ru)果(guo)充(chong)电(dian)(dian)(dian)(dian)器电(dian)(dian)(dian)(dian)路失去控制(zhi)，会使电(dian)(dian)(dian)(dian)池(chi)(chi)电(dian)(dian)(dian)(dian)压超过4.2V后继续恒流充(chong)电(dian)(dian)(dian)(dian)，此(ci)时电(dian)(dian)(dian)(dian)池(chi)(chi)电(dian)(dian)(dian)(dian)压仍会继续上升(sheng)，当电(dian)(dian)(dian)(dian)池(chi)(chi)电(dian)(dian)(dian)(dian)压被充(chong)电(dian)(dian)(dian)(dian)至超过4.3V时，电(dian)(dian)(dian)(dian)池(chi)(chi)的化(hua)学副反(fan)应将加剧，会导致(zhi)电(dian)(dian)(dian)(dian)池(chi)(chi)损坏或出现安(an)全问(wen)题。

锂电(dian)(dian)(dian)(dian)池保护(hu)板均衡原理在带有(you)保护(hu)电(dian)(dian)(dian)(dian)路的电(dian)(dian)(dian)(dian)池中，当控制IC检测到(dao)电(dian)(dian)(dian)(dian)池电(dian)(dian)(dian)(dian)压(ya)(ya)达到(dao)4.28V（该值由(you)(you)控制IC决(jue)定，不同的IC有(you)不同的值）时，其“CO”脚(jiao)将由(you)(you)高电(dian)(dian)(dian)(dian)压(ya)(ya)转变为(wei) 零(ling)电(dian)(dian)(dian)(dian)压(ya)(ya)，使T1由(you)(you)导(dao)通(tong)转为(wei)关断(duan)，从而切断(duan)了充(chong)(chong)电(dian)(dian)(dian)(dian)回路，使充(chong)(chong)电(dian)(dian)(dian)(dian)器无法再对(dui)电(dian)(dian)(dian)(dian)池进行充(chong)(chong)电(dian)(dian)(dian)(dian)，起(qi)到(dao)过充(chong)(chong)电(dian)(dian)(dian)(dian)保护(hu)作(zuo)用。而此(ci)时由(you)(you)于T1自(zi)带的体二极(ji)管VD1的存在，电(dian)(dian)(dian)(dian) 池可以(yi)通(tong)过该二极(ji)管对(dui)外部负载进行放电(dian)(dian)(dian)(dian)。

在控制IC检测到电(dian)池(chi)电(dian)压(ya)超过4.28V至(zhi)发出关断(duan)T1信号之间(jian)，还有一段延时时间(jian)，该延时时间(jian)的长短由C2决定，通常设为1秒左右，以(yi)避(bi)免因干扰而造成(cheng)误(wu)判断(duan)。

3、过(guo)放电保护(hu)

电(dian)池(chi)在对外部负(fu)(fu)载放(fang)(fang)电(dian)过(guo)程中(zhong)，其电(dian)压会(hui)随着放(fang)(fang)电(dian)过(guo)程逐(zhu)渐降低，当电(dian)池(chi)电(dian)压降至2.5V时，其容量已(yi)被完全放(fang)(fang)光，此(ci)时如(ru)果让电(dian)池(chi)继续对负(fu)(fu)载放(fang)(fang)电(dian)，将造成电(dian)池(chi)的永久性损坏。

在电(dian)(dian)(dian)(dian)池(chi)(chi)放电(dian)(dian)(dian)(dian)过(guo)程中(zhong)，当控(kong)(kong)制IC检测到电(dian)(dian)(dian)(dian)池(chi)(chi)电(dian)(dian)(dian)(dian)压(ya)低于2.3V（该值(zhi)由(you)控(kong)(kong)制IC决定(ding)，不同的(de)IC有不同的(de)值(zhi)）时，其“DO”脚将由(you)高电(dian)(dian)(dian)(dian)压(ya)转变为(wei)零(ling)电(dian)(dian)(dian)(dian)压(ya)， 使T2由(you)导通转为(wei)关断，从(cong)而切断了(le)放电(dian)(dian)(dian)(dian)回路，使电(dian)(dian)(dian)(dian)池(chi)(chi)无法再对(dui)负载进(jin)行(xing)放电(dian)(dian)(dian)(dian)，起到过(guo)放电(dian)(dian)(dian)(dian)保护作用。而此时由(you)于T2自带的(de)体二(er)极管VD2的(de)存在，充(chong)电(dian)(dian)(dian)(dian)器可以通 过(guo)该二(er)极管对(dui)电(dian)(dian)(dian)(dian)池(chi)(chi)进(jin)行(xing)充(chong)电(dian)(dian)(dian)(dian)。

由于在过放电(dian)保护(hu)(hu)状态下电(dian)池电(dian)压不能再降低(di)，因此(ci)要求保护(hu)(hu)电(dian)路的消耗电(dian)流极小，此(ci)时(shi)(shi)控制(zhi)IC会进(jin)入低(di)功耗状态，整个保护(hu)(hu)电(dian)路耗电(dian)会小于0.1μA。 在控制(zhi)IC检测到电(dian)池电(dian)压低(di)于2.3V至发出(chu)关断T2信号之间，也有一段延时(shi)(shi)时(shi)(shi)间，该延时(shi)(shi)时(shi)(shi)间的长短由C2决(jue)定(ding)，通(tong)常设(she)为100毫秒左右，以避免因干扰而(er) 造成误(wu)判断。

4、过电流保护

由(you)于锂(li)离(li)子电(dian)(dian)(dian)池(chi)(chi)(chi)的化(hua)学特性，电(dian)(dian)(dian)池(chi)(chi)(chi)生产厂家规(gui)定(ding)了其放(fang)电(dian)(dian)(dian)电(dian)(dian)(dian)流(liu)最(zui)大不能超(chao)过2C（C=电(dian)(dian)(dian)池(chi)(chi)(chi)容量/小时(shi)(shi)），当电(dian)(dian)(dian)池(chi)(chi)(chi)超(chao)过2C电(dian)(dian)(dian)流(liu)放(fang)电(dian)(dian)(dian)时(shi)(shi)，将会(hui)导致电(dian)(dian)(dian)池(chi)(chi)(chi)的永久性损坏(huai)或出现安全问题(ti)。

电(dian)(dian)池在对(dui)负(fu)载正常放(fang)电(dian)(dian)过程(cheng)中，放(fang)电(dian)(dian)电(dian)(dian)流在经过串联的(de)(de)(de)2个(ge)MOSFET时，由(you)于MOSFET的(de)(de)(de)导(dao)(dao)通阻(zu)抗(kang)(kang)，会在其两(liang)端产生一个(ge)电(dian)(dian)压，该(gai)(gai)电(dian)(dian)压值 U=I*RDS*2, RDS为单(dan)个(ge)MOSFET导(dao)(dao)通阻(zu)抗(kang)(kang)，控制(zhi)IC上的(de)(de)(de)“V-”脚对(dui)该(gai)(gai)电(dian)(dian)压值进行检测(ce)，若负(fu)载因某种原因导(dao)(dao)致异常，使回路(lu)电(dian)(dian)流增大(da)，当回路(lu)电(dian)(dian)流大(da)到使 U>0.1V（该(gai)(gai)值由(you)控制(zhi)IC决定，不同(tong)的(de)(de)(de)IC有不同(tong)的(de)(de)(de)值）时，其“DO”脚将由(you)高电(dian)(dian)压转(zhuan)变为零电(dian)(dian)压，使T2由(you)导(dao)(dao)通转(zhuan)为关断(duan)，从而切断(duan)了放(fang)电(dian)(dian)回路(lu)， 使回路(lu)中电(dian)(dian)流为零，起到过电(dian)(dian)流保护作用。

在控(kong)制IC检测到过电流(liu)发(fa)生(sheng)至发(fa)出(chu)关断(duan)T2信号之间(jian)，也有一段延时(shi)(shi)时(shi)(shi)间(jian)，该延时(shi)(shi)时(shi)(shi)间(jian)的长短(duan)由C2决定，通(tong)常(chang)为13毫秒左右，以避免因干扰而造成(cheng)误判断(duan)。

在上述(shu)控(kong)制(zhi)过程中可知(zhi)，其过电(dian)流检测值大小不仅取(qu)决于控(kong)制(zhi)IC的(de)(de)控(kong)制(zhi)值，还取(qu)决于MOSFET的(de)(de)导(dao)通(tong)阻(zu)抗，当(dang)MOSFET导(dao)通(tong)阻(zu)抗越大时，对(dui)同样(yang)的(de)(de)控(kong)制(zhi)IC，其过电(dian)流保护值越小。

5、短路保护

电(dian)池(chi)在对(dui)负载放(fang)电(dian)过程中，若(ruo)回(hui)路(lu)(lu)(lu)电(dian)流大到使U>0.9V（该(gai)值由(you)控制(zhi)IC决(jue)定，不(bu)同(tong)的(de)(de)IC有不(bu)同(tong)的(de)(de)值）时，控制(zhi)IC则判(pan)断(duan)为负载短路(lu)(lu)(lu)，其 “DO”脚(jiao)将迅速由(you)高电(dian)压(ya)转变为零(ling)电(dian)压(ya)，使T2由(you)导通(tong)(tong)转为关断(duan)，从(cong)而切断(duan)放(fang)电(dian)回(hui)路(lu)(lu)(lu)，起(qi)到短路(lu)(lu)(lu)保(bao)(bao)(bao)护(hu)(hu)作用。短路(lu)(lu)(lu)保(bao)(bao)(bao)护(hu)(hu)的(de)(de)延(yan)时时间极(ji)短，通(tong)(tong)常(chang)小于7微秒。其工作原 理与过电(dian)流保(bao)(bao)(bao)护(hu)(hu)类似，只是(shi)判(pan)断(duan)方法不(bu)同(tong)，保(bao)(bao)(bao)护(hu)(hu)延(yan)时时间也不(bu)一样。

6 结论

本文(wen)采用单节(jie)锂(li)电(dian)池保护芯片设计(ji)实(shi)现(xian)了多节(jie)锂(li)电(dian)池串联的(de)电(dian)池组保护板(ban)，除可完成(cheng)必要的(de)过电(dian)压、欠电(dian)压、过电(dian)流和短路保护功(gong)能外，还可以实(shi)现(xian)均衡充电(dian)功(gong)能。仿真和实(shi)验(yan)(yan)结果(guo)验(yan)(yan)证(zheng)了该(gai)方案的(de)可行性，市场使用情况检验(yan)(yan)了该(gai)设计(ji)的(de)稳定(ding)性。

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