C8051F310器件設計鋰(li)離子電(dian)(dian)(dian)池充電(dian)(dian)(dian)器。利用PWM脈寬調(diao)制產生可用軟件控制的充電(dian)(dian)(dian)電(dian)(dian)(dian)源，以適應(ying)不同階段的充電(dian)(dian)(dian)電(dian)(dian)(dian)流的要(yao)求。溫度(du)(du)傳感器對電(dian)(dian)(dian)池溫度(du)(du)進(jin)行監(jian)測，并通(tong)過AD轉換和相關計算檢測電(dian)(dian)(dian)池充電(dian)(dian)(dian)電(dian)(dian)(dian)壓和電(dian)(dian)(dian)流，以判斷電(dian)(dian)(dian)池到達哪個階段。使(shi)電(dian)(dian)(dian)池具(ju)有更長的使(shi)用壽命(ming)。

設計過程

1  充電原理

　　電(dian)(dian)(dian)池的特性唯一地決(jue)(jue)定其(qi)安全(quan)性能和充電(dian)(dian)(dian)的效率。電(dian)(dian)(dian)池的最(zui)佳充電(dian)(dian)(dian)方法是(shi)由電(dian)(dian)(dian)池的化學成分決(jue)(jue)定的（鋰離子(zi)、鎳(nie)氫、鎳(nie)鎘還是(shi)SLA電(dian)(dian)(dian)池等）。盡(jin)管如(ru)此，大多(duo)數(shu)充電(dian)(dian)(dian)方案都包含下面(mian)的三個階段：

　　低電流調節階段

　　恒流階段

　　恒壓階段/充(chong)電終止

　　所(suo)有電(dian)(dian)(dian)(dian)(dian)(dian)池都是通(tong)過向自身傳(chuan)輸電(dian)(dian)(dian)(dian)(dian)(dian)能的(de)方法進行充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)，一節(jie)電(dian)(dian)(dian)(dian)(dian)(dian)池的(de)最(zui)大(da)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)取決于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)池的(de)額定容量（C）例如，一節(jie)容量為(wei)1000mAh的(de)電(dian)(dian)(dian)(dian)(dian)(dian)池在充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為(wei)1000mA時(shi)，可以充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)1C（電(dian)(dian)(dian)(dian)(dian)(dian)池容量的(de)1倍）也可以用1/50C（20mA）或更低的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)給電(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)。

　　現在使用的大多數充電器在(zai)給(gei)電(dian)(dian)池充(chong)電(dian)(dian)時都是既(ji)使(shi)(shi)用低電(dian)(dian)流(liu)充(chong)電(dian)(dian)方式又使(shi)(shi)用額定充(chong)電(dian)(dian)電(dian)(dian)流(liu)的方法(fa)，即容積充(chong)電(dian)(dian)，低充(chong)電(dian)(dian)電(dian)(dian)流(liu)通常使(shi)(shi)用在(zai)充(chong)電(dian)(dian)的初始階(jie)段(duan)。在(zai)這(zhe)(zhe)一階(jie)段(duan)，需(xu)要將會導致充(chong)電(dian)(dian)過程終(zhong)止的芯片初期的自(zi)熱效應(ying)減小到(dao)最低程度，容積充(chong)電(dian)(dian)通常用在(zai)充(chong)電(dian)(dian)的中(zhong)級階(jie)段(duan)，電(dian)(dian)池的大部分能量都是在(zai)這(zhe)(zhe)一階(jie)段(duan)存儲(chu)的。

　　充(chong)電時部分(fen)電能(neng)(neng)被(bei)轉換(huan)成(cheng)熱能(neng)(neng)，直至電池充(chong)滿。而充(chong)滿后，所有的電能(neng)(neng)將全部被(bei)轉換(huan)成(cheng)熱能(neng)(neng)。如果此時不(bu)終(zhong)止充(chong)電，電池就會被(bei)損壞或燒毀(hui)。快速(su)充(chong)電器電池則可以解決這(zhe)個(ge)問題，因(yin)為這(zhe)些(xie)充(chong)電器是使用高(gao)充(chong)電電流來縮短充(chong)電時間(jian)的。

2  總體設計

　　充電電路由三(san)部(bu)分(fen)：控制部(bu)分(fen)，檢測(ce)部(bu)分(fen)及充電部(bu)分(fen)組成。

　　如圖1所示，采用F310單片機進(jin)行充電控制(zhi)，單片機本身具有脈(mo)寬調制(zhi)PWM型開關(guan)穩壓電源所需的全部功能(neng)，具有10位A/D轉換器。

　　利用單(dan)片機(ji)A/D端(duan)口(kou)，構成電池電壓，電流，溫度檢測電路(lu)。

 

 

 

    圖(tu)1  鋰離子電(dian)池充(chong)電(dian)模(mo)塊圖(tu)

    單片(pian)機通過電壓反饋和電流反饋信號，直接利用PWM輸(shu)出將數(shu)字電壓信號并(bing)轉化成模(mo)擬電壓信號，能(neng)夠保證控制精度。

3  控制部分電路設計

　　C8051F310單片機

　　①模擬外設

　　a.10位ADC：轉(zhuan)(zhuan)換速度可達200ks/s,可多達21或(huo)17個外部單端或(huo)差分輸(shu)(shu)入(ru)，VREF可在外部引腳(jiao)或(huo)VDD中選擇，內置(zhi)溫(wen)度傳感(gan)器（±3℃），外部轉(zhuan)(zhuan)換啟動(dong)輸(shu)(shu)入(ru)；

　　b.兩個(ge)模(mo)擬比較器：可編程回差電壓和(he)響應時間，可配置為(wei)中斷或復位源，小電流（〈0.5μA）。

　　②供電電壓

　　a.典型工(gong)作(zuo)電(dian)流：5mA、25MHz；

　　b.典型停機電流：0.1μA；

　　c.溫度(du)范圍：-40～+85℃。

　　③高速8051微(wei)控制器內核

　　a.流水線指令結構：70%的(de)指令的(de)執(zhi)行時(shi)(shi)間為一個或兩(liang)個系統(tong)時(shi)(shi)鐘(zhong)周期；

　　b.速度(du)可達25MI/s（時鐘(zhong)頻(pin)率(lv)為25MHz時）；

　　c.擴展的(de)中斷系統。

　　④數字外設

　　a.29/25個端口I/O：所有的口線均耐(nai)5V電(dian)壓；

　　b.4個通用16位計數器(qi)/定時器(qi)；

　　c.16位(wei)可編程計數器/定時器陣列（PCA），有5個捕捉(zhuo)/比較模塊；

　　d.使用PCA或定時(shi)器和(he)外部時(shi)鐘源的實時(shi)時(shi)鐘方(fang)式。

　　控制電(dian)路中如圖2所示，P0.3口(kou)提供充(chong)電(dian)電(dian)源(yuan)，P0.6口(kou)檢(jian)(jian)測(ce)充(chong)電(dian)電(dian)壓的大小，P0.5口(kou)檢(jian)(jian)測(ce)充(chong)電(dian)電(dian)流(liu)的大小，P0.4口(kou)檢(jian)(jian)測(ce)電(dian)池的溫度。

  

 

    圖2  控制(zhi)電路(lu)接線(xian)圖

　　充(chong)電(dian)(dian)電(dian)(dian)流由單片機(ji)脈寬調制(zhi)PWM產生，充(chong)電(dian)(dian)電(dian)(dian)流由AD轉(zhuan)換再經過計(ji)算得出。

  

4  充電(dian)部(bu)(bu)分(fen)及檢測部(bu)(bu)分(fen)電(dian)路設計

　　圖(tu)3為(wei)充(chong)電電路(lu)(lu)與(yu)檢測電路(lu)(lu)圖(tu)。

  

 

    圖(tu)3  充電電路(lu)與檢測電路(lu)圖(tu)

 　　①充電(dian)過程(cheng)曲(qu)線(xian)

　　如圖4所(suo)示，充電(dian)過程由預充狀(zhuang)態，恒流充電(dian)狀(zhuang)態和恒壓充電(dian)狀(zhuang)態組成。

  

 

    圖4  鋰電(dian)池(chi)充電(dian)曲(qu)線(xian)

　　②快速轉換器

　　實現漸弱終止充電器(qi)的最經濟的方(fang)法就是(shi)用一個(ge)(ge)快速轉換器(qi)。快速轉換器(qi)是(shi)用一個(ge)(ge)電感和(he)/或一個(ge)(ge)變壓(ya)器(qi)（需要隔離(li)的時候用變壓(ya)器(qi)）作(zuo)為能(neng)量(liang)存儲單元(yuan)以離(li)散的能(neng)量(liang)包的形式將能(neng)量(liang)從輸(shu)入傳(chuan)輸(shu)至輸(shu)出的開(kai)關(guan)調節器(qi)反饋電路，通過(guo)晶體管來調節能(neng)量(liang)的傳(chuan)輸(shu)，同(tong)時也作(zuo)為過(guo)濾開(kai)關(guan)，以確保電壓(ya)或電流(liu)在負載時保持恒定。

　　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(guan)閉合(he)

 

  

b  開(kai)關打開(kai)

    圖(tu)5  快速(su)轉換器(qi)操作(zuo)

　　③電感的確定

　　電(dian)(dian)感對交流電(dian)(dian)是有阻礙作用的(de)(de)。在(zai)交流電(dian)(dian)頻率一定的(de)(de)情(qing)況下，電(dian)(dian)感量越(yue)大(da)，對交流電(dian)(dian)的(de)(de)阻礙能力(li)越(yue)強，電(dian)(dian)感量越(yue)小(xiao)，其(qi)阻礙能力(li)越(yue)小(xiao)。

　　其工作原理是這樣的(de)：當(dang)負(fu)載兩(liang)端的(de)電(dian)(dian)(dian)(dian)(dian)壓要(yao)降低(di)時(shi)，通過(guo)MOSFET場(chang)效(xiao)應(ying)管的(de)開(kai)關(guan)作用，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)(dian)源(yuan)對(dui)電(dian)(dian)(dian)(dian)(dian)感(gan)進行充電(dian)(dian)(dian)(dian)(dian)并達(da)到所需的(de)額(e)定電(dian)(dian)(dian)(dian)(dian)壓。當(dang)負(fu)載兩(liang)端地電(dian)(dian)(dian)(dian)(dian)壓升高時(shi)，通過(guo)MOSFET場(chang)效(xiao)應(ying)管的(de)開(kai)關(guan)作用，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)(dian)源(yuan)供(gong)電(dian)(dian)(dian)(dian)(dian)斷開(kai)，電(dian)(dian)(dian)(dian)(dian)感(gan)釋放出剛(gang)才充入的(de)能量(liang)，這時(shi)電(dian)(dian)(dian)(dian)(dian)感(gan)就變成(cheng)了電(dian)(dian)(dian)(dian)(dian)源(yuan)繼續對(dui)負(fu)載供(gong)電(dian)(dian)(dian)(dian)(dian)。隨(sui)著電(dian)(dian)(dian)(dian)(dian)感(gan)上存儲的(de)能量(liang)地消耗。負(fu)載兩(liang)端的(de)電(dian)(dian)(dian)(dian)(dian)壓開(kai)始逐(zhu)漸降低(di)，外(wai)部(bu)(bu)電(dian)(dian)(dian)(dian)(dian)源(yuan)通過(guo)MOSFET場(chang)效(xiao)應(ying)管的(de)開(kai)關(guan)作用又要(yao)充電(dian)(dian)(dian)(dian)(dian)。