C8051F310器(qi)件(jian)設計鋰離子電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)。利用(yong)PWM脈寬調制產生(sheng)可用(yong)軟件(jian)控制的充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)源，以(yi)適應不同階段的充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的要求。溫度(du)傳感器(qi)對電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)溫度(du)進行監測(ce)(ce)，并通過AD轉換和(he)相(xiang)關計算檢(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓和(he)電(dian)(dian)(dian)(dian)(dian)流，以(yi)判斷電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)到達(da)哪個(ge)階段。使(shi)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)具有更長的使(shi)用(yong)壽命。

設計過程

1  充電原理

　　電(dian)池的(de)(de)特(te)性唯一地決(jue)定(ding)其安全性能和充電(dian)的(de)(de)效率。電(dian)池的(de)(de)最佳充電(dian)方(fang)法是由電(dian)池的(de)(de)化(hua)學成分決(jue)定(ding)的(de)(de)（鋰(li)離子、鎳(nie)氫、鎳(nie)鎘還是SLA電(dian)池等(deng)）。盡管如此，大多數充電(dian)方(fang)案都(dou)包(bao)含下面的(de)(de)三個階段：

　　低電流調節階段

　　恒流階段

　　恒壓階(jie)段/充電(dian)終止

　　所有電(dian)(dian)(dian)(dian)(dian)池都是通過(guo)向(xiang)自身傳輸電(dian)(dian)(dian)(dian)(dian)能的(de)方法(fa)進行充(chong)電(dian)(dian)(dian)(dian)(dian)的(de)，一(yi)節電(dian)(dian)(dian)(dian)(dian)池的(de)最大(da)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)取(qu)決(jue)于電(dian)(dian)(dian)(dian)(dian)池的(de)額定容量(liang)（C）例如，一(yi)節容量(liang)為(wei)1000mAh的(de)電(dian)(dian)(dian)(dian)(dian)池在(zai)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)為(wei)1000mA時，可以(yi)充(chong)電(dian)(dian)(dian)(dian)(dian)1C（電(dian)(dian)(dian)(dian)(dian)池容量(liang)的(de)1倍）也(ye)可以(yi)用(yong)1/50C（20mA）或(huo)更低的(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)給(gei)電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)。

　　現在使用的大多數充電器在(zai)(zai)給電池(chi)充(chong)(chong)電時(shi)都是(shi)既(ji)使(shi)用低(di)電流(liu)充(chong)(chong)電方(fang)式(shi)又使(shi)用額定(ding)充(chong)(chong)電電流(liu)的方(fang)法，即容積充(chong)(chong)電，低(di)充(chong)(chong)電電流(liu)通(tong)常使(shi)用在(zai)(zai)充(chong)(chong)電的初始階段(duan)。在(zai)(zai)這一階段(duan)，需要將會導致(zhi)充(chong)(chong)電過程終止的芯片初期(qi)的自熱效應減小(xiao)到最低(di)程度，容積充(chong)(chong)電通(tong)常用在(zai)(zai)充(chong)(chong)電的中級階段(duan)，電池(chi)的大部分能(neng)量(liang)都是(shi)在(zai)(zai)這一階段(duan)存儲的。

　　充(chong)(chong)(chong)電(dian)(dian)(dian)時(shi)(shi)(shi)部(bu)分電(dian)(dian)(dian)能(neng)被(bei)(bei)轉(zhuan)換成(cheng)熱(re)能(neng)，直至電(dian)(dian)(dian)池充(chong)(chong)(chong)滿。而充(chong)(chong)(chong)滿后，所有(you)的電(dian)(dian)(dian)能(neng)將全(quan)部(bu)被(bei)(bei)轉(zhuan)換成(cheng)熱(re)能(neng)。如果此時(shi)(shi)(shi)不終止(zhi)充(chong)(chong)(chong)電(dian)(dian)(dian)，電(dian)(dian)(dian)池就會(hui)被(bei)(bei)損壞或(huo)燒毀。快速充(chong)(chong)(chong)電(dian)(dian)(dian)器電(dian)(dian)(dian)池則(ze)可以解決(jue)這個問題，因為這些充(chong)(chong)(chong)電(dian)(dian)(dian)器是使用(yong)高充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流來縮短充(chong)(chong)(chong)電(dian)(dian)(dian)時(shi)(shi)(shi)間的。

2  總體設計

　　充電(dian)電(dian)路由(you)三部分(fen)：控(kong)制部分(fen)，檢測部分(fen)及充電(dian)部分(fen)組(zu)成。

　　如圖1所示，采用F310單片機(ji)進行充電(dian)控制(zhi)，單片機(ji)本身具有(you)脈(mo)寬調制(zhi)PWM型開關穩(wen)壓(ya)電(dian)源所需的全部功能，具有(you)10位A/D轉換器。

　　利用單片(pian)機A/D端口(kou)，構成(cheng)電池電壓，電流，溫度檢(jian)測電路。

 

 

 

    圖(tu)1  鋰離子電(dian)池充(chong)電(dian)模塊(kuai)圖(tu)

    單片機通(tong)過(guo)電(dian)壓反饋(kui)和(he)電(dian)流反饋(kui)信(xin)號，直接利用PWM輸(shu)出將數(shu)字電(dian)壓信(xin)號并(bing)轉化成模擬(ni)電(dian)壓信(xin)號，能夠保證控(kong)制精度。

3  控制部分電路設計

　　C8051F310單片機

　　①模擬外設

　　a.10位ADC：轉換速度(du)可(ke)達200ks/s,可(ke)多達21或(huo)(huo)17個(ge)外(wai)部(bu)單端或(huo)(huo)差(cha)分(fen)輸(shu)入，VREF可(ke)在(zai)外(wai)部(bu)引腳或(huo)(huo)VDD中選擇，內置溫度(du)傳感器（±3℃），外(wai)部(bu)轉換啟(qi)動輸(shu)入；

　　b.兩個模擬比較器：可編(bian)程回差電壓和響應時間，可配置為中斷或復位源(yuan)，小(xiao)電流（〈0.5μA）。

　　②供電電壓

　　a.典(dian)型工作電流：5mA、25MHz；

　　b.典型停(ting)機電流：0.1μA；

　　c.溫度范圍(wei)：-40～+85℃。

　　③高速8051微控制(zhi)器(qi)內(nei)核

　　a.流水線指(zhi)令結構：70%的(de)指(zhi)令的(de)執行時間為(wei)一(yi)個(ge)或兩個(ge)系統時鐘(zhong)周期(qi)；

　　b.速度可達25MI/s（時鐘頻率為25MHz時）；

　　c.擴展(zhan)的中斷系統。

　　④數字外設

　　a.29/25個端口I/O：所有的口線(xian)均耐5V電壓；

　　b.4個通用16位(wei)計數(shu)器/定時器；

　　c.16位可編(bian)程(cheng)計數器/定時器陣列（PCA），有(you)5個捕捉/比(bi)較(jiao)模塊；

　　d.使用PCA或定時器和外(wai)部(bu)時鐘(zhong)源(yuan)的實時時鐘(zhong)方式。

　　控(kong)制(zhi)電(dian)(dian)路(lu)中(zhong)如(ru)圖2所示，P0.3口(kou)提供充電(dian)(dian)電(dian)(dian)源，P0.6口(kou)檢(jian)(jian)測充電(dian)(dian)電(dian)(dian)壓的大(da)小(xiao)，P0.5口(kou)檢(jian)(jian)測充電(dian)(dian)電(dian)(dian)流的大(da)小(xiao)，P0.4口(kou)檢(jian)(jian)測電(dian)(dian)池的溫(wen)度。

  

 

    圖2  控制電(dian)路接線圖

　　充電電流(liu)(liu)由(you)單片(pian)機脈寬調制(zhi)PWM產生(sheng)，充電電流(liu)(liu)由(you)AD轉換再經過計算得出。

  

4  充電(dian)(dian)部分及檢(jian)測部分電(dian)(dian)路設計

　　圖3為充電電路(lu)與檢(jian)測(ce)電路(lu)圖。

  

 

    圖(tu)3  充電(dian)(dian)電(dian)(dian)路與檢測電(dian)(dian)路圖(tu)

 　　①充電過程曲線

　　如圖4所示(shi)，充(chong)電(dian)(dian)過(guo)程由預充(chong)狀(zhuang)態，恒流充(chong)電(dian)(dian)狀(zhuang)態和恒壓充(chong)電(dian)(dian)狀(zhuang)態組成。

  

 

    圖4  鋰電池充電曲線

　　②快速轉換器

　　實現(xian)漸(jian)弱終止充電(dian)器(qi)的(de)最(zui)經(jing)濟(ji)的(de)方(fang)法就是(shi)用一個快速(su)轉(zhuan)換(huan)器(qi)。快速(su)轉(zhuan)換(huan)器(qi)是(shi)用一個電(dian)感和/或一個變壓器(qi)（需要隔離的(de)時候用變壓器(qi)）作為(wei)能量(liang)存儲單元以離散的(de)能量(liang)包的(de)形式(shi)將能量(liang)從輸入傳輸至輸出的(de)開(kai)關(guan)調節器(qi)反饋電(dian)路，通過晶體(ti)管(guan)來調節能量(liang)的(de)傳輸，同(tong)時也作為(wei)過濾開(kai)關(guan)，以確保(bao)電(dian)壓或電(dian)流(liu)在負載時保(bao)持恒定。

　　快速調節器的操作是通過控制一個晶體管開關的占空比來實現的。占空比會自動增加以使電池流入更多的電流。當VBATT

 

 

  

a  開關閉(bi)合(he)

 

  

b  開關打開

    圖5  快速轉換(huan)器操(cao)作(zuo)

　　③電感的確定

　　電(dian)(dian)(dian)感對(dui)交流(liu)電(dian)(dian)(dian)是有阻(zu)礙作用(yong)的(de)(de)。在(zai)交流(liu)電(dian)(dian)(dian)頻(pin)率一定的(de)(de)情(qing)況下(xia)，電(dian)(dian)(dian)感量越(yue)大(da)，對(dui)交流(liu)電(dian)(dian)(dian)的(de)(de)阻(zu)礙能力越(yue)強(qiang)，電(dian)(dian)(dian)感量越(yue)小，其阻(zu)礙能力越(yue)小。

　　其工作(zuo)(zuo)原(yuan)理(li)是這(zhe)樣的(de)：當負(fu)載(zai)兩端的(de)電(dian)(dian)(dian)(dian)壓要降低時，通(tong)過(guo)MOSFET場(chang)效應管的(de)開(kai)(kai)關(guan)作(zuo)(zuo)用(yong)，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)源(yuan)對電(dian)(dian)(dian)(dian)感(gan)(gan)進行充電(dian)(dian)(dian)(dian)并(bing)達到(dao)所需的(de)額定電(dian)(dian)(dian)(dian)壓。當負(fu)載(zai)兩端地電(dian)(dian)(dian)(dian)壓升高(gao)時，通(tong)過(guo)MOSFET場(chang)效應管的(de)開(kai)(kai)關(guan)作(zuo)(zuo)用(yong)，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)源(yuan)供電(dian)(dian)(dian)(dian)斷開(kai)(kai)，電(dian)(dian)(dian)(dian)感(gan)(gan)釋放出剛(gang)才充入的(de)能量，這(zhe)時電(dian)(dian)(dian)(dian)感(gan)(gan)就(jiu)變成了(le)電(dian)(dian)(dian)(dian)源(yuan)繼續(xu)對負(fu)載(zai)供電(dian)(dian)(dian)(dian)。隨著(zhu)電(dian)(dian)(dian)(dian)感(gan)(gan)上存儲(chu)的(de)能量地消耗。負(fu)載(zai)兩端的(de)電(dian)(dian)(dian)(dian)壓開(kai)(kai)始逐漸降低，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)源(yuan)通(tong)過(guo)MOSFET場(chang)效應管的(de)開(kai)(kai)關(guan)作(zuo)(zuo)用(yong)又要充電(dian)(dian)(dian)(dian)。