C8051F310器件設計(ji)(ji)鋰離子電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器。利用(yong)(yong)(yong)PWM脈寬調制(zhi)產生可(ke)用(yong)(yong)(yong)軟(ruan)件控(kong)制(zhi)的(de)充電(dian)(dian)(dian)電(dian)(dian)(dian)源，以適應不(bu)同階段的(de)充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)的(de)要求。溫度傳(chuan)感器對電(dian)(dian)(dian)池(chi)溫度進行監(jian)測(ce)，并通過AD轉(zhuan)換和相關計(ji)(ji)算檢測(ce)電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)電(dian)(dian)(dian)壓和電(dian)(dian)(dian)流(liu)，以判斷(duan)電(dian)(dian)(dian)池(chi)到達哪(na)個階段。使電(dian)(dian)(dian)池(chi)具有更(geng)長的(de)使用(yong)(yong)(yong)壽命。

設計過程

1  充電原理

　　電池的(de)特性唯一地(di)決(jue)(jue)定其安全性能和充(chong)(chong)電的(de)效率。電池的(de)最佳充(chong)(chong)電方法是(shi)由電池的(de)化學(xue)成分(fen)決(jue)(jue)定的(de)（鋰離子、鎳氫(qing)、鎳鎘還是(shi)SLA電池等）。盡管(guan)如此，大(da)多數充(chong)(chong)電方案都包含(han)下面的(de)三(san)個(ge)階段(duan)：

　　低電流調節階段

　　恒流階段

　　恒壓階段/充(chong)電終止

　　所有(you)電(dian)(dian)池都是通過(guo)向自身傳輸電(dian)(dian)能的方法進行充(chong)電(dian)(dian)的，一節電(dian)(dian)池的最大充(chong)電(dian)(dian)電(dian)(dian)流取決于電(dian)(dian)池的額定容(rong)量(liang)（C）例如(ru)，一節容(rong)量(liang)為1000mAh的電(dian)(dian)池在(zai)充(chong)電(dian)(dian)電(dian)(dian)流為1000mA時，可以充(chong)電(dian)(dian)1C（電(dian)(dian)池容(rong)量(liang)的1倍）也可以用1/50C（20mA）或更低的電(dian)(dian)流給電(dian)(dian)池充(chong)電(dian)(dian)。

　　現在使用的大多數充電器在(zai)給電(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)時都(dou)是(shi)(shi)既(ji)使用(yong)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)方式又(you)使用(yong)額定充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的方法，即容積(ji)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，低(di)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)通常使用(yong)在(zai)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的初(chu)始階段。在(zai)這(zhe)一階段，需(xu)要將會導致(zhi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程終(zhong)止的芯(xin)片初(chu)期的自熱效應減小到最低(di)程度，容積(ji)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)通常用(yong)在(zai)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的中級階段，電(dian)(dian)(dian)(dian)(dian)(dian)池的大部分能量都(dou)是(shi)(shi)在(zai)這(zhe)一階段存(cun)儲(chu)的。

　　充(chong)(chong)電(dian)(dian)時部分(fen)電(dian)(dian)能(neng)被轉換(huan)(huan)成熱能(neng)，直(zhi)至電(dian)(dian)池(chi)充(chong)(chong)滿。而充(chong)(chong)滿后，所(suo)有的電(dian)(dian)能(neng)將全部被轉換(huan)(huan)成熱能(neng)。如果此(ci)時不終止充(chong)(chong)電(dian)(dian)，電(dian)(dian)池(chi)就會被損壞或燒毀。快速充(chong)(chong)電(dian)(dian)器(qi)電(dian)(dian)池(chi)則(ze)可以解決這個問題，因(yin)為(wei)這些充(chong)(chong)電(dian)(dian)器(qi)是使用高(gao)充(chong)(chong)電(dian)(dian)電(dian)(dian)流來縮短充(chong)(chong)電(dian)(dian)時間的。

2  總體設計

　　充(chong)電電路由三部分(fen)：控(kong)制部分(fen)，檢測部分(fen)及充(chong)電部分(fen)組成。

　　如圖1所示，采(cai)用F310單片機(ji)(ji)進行充電(dian)控制，單片機(ji)(ji)本身(shen)具(ju)有脈寬調制PWM型開關穩壓電(dian)源(yuan)所需(xu)的全部功(gong)能，具(ju)有10位A/D轉(zhuan)換器。

　　利用單片機A/D端口，構成電(dian)池(chi)電(dian)壓，電(dian)流，溫度檢測電(dian)路。

 

 

 

    圖1  鋰離子電池充電模塊圖

    單(dan)片機通(tong)過電(dian)(dian)壓(ya)反饋和電(dian)(dian)流反饋信(xin)號，直接(jie)利(li)用PWM輸出(chu)將數字電(dian)(dian)壓(ya)信(xin)號并轉化成模擬(ni)電(dian)(dian)壓(ya)信(xin)號，能(neng)夠保(bao)證(zheng)控(kong)制精度(du)。

3  控制部分電路設計

　　C8051F310單片(pian)機

　　①模擬外設

　　a.10位ADC：轉(zhuan)換(huan)速度可(ke)達200ks/s,可(ke)多(duo)達21或(huo)17個(ge)外(wai)(wai)部(bu)單端或(huo)差分輸(shu)入，VREF可(ke)在外(wai)(wai)部(bu)引腳(jiao)或(huo)VDD中選擇，內置溫度傳感(gan)器（±3℃），外(wai)(wai)部(bu)轉(zhuan)換(huan)啟(qi)動輸(shu)入；

　　b.兩個模擬比較器：可(ke)編程回差(cha)電壓和響應時間，可(ke)配置(zhi)為(wei)中斷或復(fu)位源，小電流（〈0.5μA）。

　　②供電電壓

　　a.典(dian)型工作電流：5mA、25MHz；

　　b.典(dian)型(xing)停機電(dian)流：0.1μA；

　　c.溫度(du)范圍：-40～+85℃。

　　③高速8051微控制器(qi)內核

　　a.流(liu)水(shui)線指令結構：70%的指令的執行(xing)時(shi)間為一(yi)個或(huo)兩個系統時(shi)鐘周期(qi)；

　　b.速度可達25MI/s（時(shi)鐘(zhong)頻率為(wei)25MHz時(shi)）；

　　c.擴展(zhan)的中斷系(xi)統。

　　④數字外設

　　a.29/25個(ge)端口I/O：所有的口線均(jun)耐(nai)5V電壓；

　　b.4個通用16位(wei)計數器(qi)/定時器(qi)；

　　c.16位可編程計數器/定時器陣(zhen)列(lie)（PCA），有5個捕捉/比(bi)較(jiao)模(mo)塊；

　　d.使(shi)用PCA或定時器和外(wai)部時鐘(zhong)源的實時時鐘(zhong)方式。

　　控制電(dian)(dian)路中(zhong)如圖2所示，P0.3口提供充(chong)電(dian)(dian)電(dian)(dian)源，P0.6口檢測(ce)充(chong)電(dian)(dian)電(dian)(dian)壓的(de)大小，P0.5口檢測(ce)充(chong)電(dian)(dian)電(dian)(dian)流的(de)大小，P0.4口檢測(ce)電(dian)(dian)池的(de)溫度。

  

 

    圖2  控制電路接線圖

　　充(chong)電電流(liu)由單(dan)片機脈寬(kuan)調(diao)制PWM產生(sheng)，充(chong)電電流(liu)由AD轉(zhuan)換再經過計算得出。

  

4  充電部分及檢測部分電路(lu)設計

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

  

 

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

 　　①充(chong)電過(guo)程(cheng)曲線

　　如圖4所(suo)示，充電過程由(you)預(yu)充狀態(tai)，恒流(liu)充電狀態(tai)和(he)恒壓充電狀態(tai)組成。

  

 

    圖4  鋰電(dian)池充電(dian)曲線

　　②快速轉換器

　　實現漸弱(ruo)終止充電(dian)(dian)(dian)器的最經濟(ji)的方(fang)法就是用一個快(kuai)速轉換器。快(kuai)速轉換器是用一個電(dian)(dian)(dian)感和/或一個變壓(ya)(ya)器（需要隔離(li)的時候(hou)用變壓(ya)(ya)器）作(zuo)為(wei)能(neng)量存儲單元(yuan)以離(li)散的能(neng)量包(bao)的形式將能(neng)量從(cong)輸入(ru)傳輸至(zhi)輸出的開(kai)(kai)關(guan)調節(jie)器反(fan)饋電(dian)(dian)(dian)路，通過(guo)晶體管來調節(jie)能(neng)量的傳輸，同(tong)時也作(zuo)為(wei)過(guo)濾開(kai)(kai)關(guan)，以確保(bao)電(dian)(dian)(dian)壓(ya)(ya)或電(dian)(dian)(dian)流(liu)在(zai)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  開關閉合(he)

 

  

b  開(kai)關打開(kai)

    圖5  快(kuai)速(su)轉換器(qi)操(cao)作

　　③電感的確定

　　電感(gan)(gan)對交(jiao)(jiao)流(liu)電是有阻(zu)(zu)礙(ai)(ai)作用(yong)的(de)。在交(jiao)(jiao)流(liu)電頻率一定的(de)情(qing)況下，電感(gan)(gan)量(liang)越(yue)大，對交(jiao)(jiao)流(liu)電的(de)阻(zu)(zu)礙(ai)(ai)能力(li)越(yue)強(qiang)，電感(gan)(gan)量(liang)越(yue)小，其阻(zu)(zu)礙(ai)(ai)能力(li)越(yue)小。

　　其工作原理是這樣的(de)：當負(fu)載兩(liang)端的(de)電(dian)(dian)(dian)壓要降低(di)時(shi)(shi)，通過(guo)MOSFET場效(xiao)應管(guan)的(de)開關(guan)作用，外部電(dian)(dian)(dian)源對電(dian)(dian)(dian)感進行(xing)充(chong)電(dian)(dian)(dian)并達到所需的(de)額(e)定(ding)電(dian)(dian)(dian)壓。當負(fu)載兩(liang)端地電(dian)(dian)(dian)壓升高時(shi)(shi)，通過(guo)MOSFET場效(xiao)應管(guan)的(de)開關(guan)作用，外部電(dian)(dian)(dian)源供電(dian)(dian)(dian)斷開，電(dian)(dian)(dian)感釋放(fang)出剛(gang)才充(chong)入的(de)能量，這時(shi)(shi)電(dian)(dian)(dian)感就變成了(le)電(dian)(dian)(dian)源繼續對負(fu)載供電(dian)(dian)(dian)。隨著電(dian)(dian)(dian)感上(shang)存儲的(de)能量地消耗。負(fu)載兩(liang)端的(de)電(dian)(dian)(dian)壓開始逐漸(jian)降低(di)，外部電(dian)(dian)(dian)源通過(guo)MOSFET場效(xiao)應管(guan)的(de)開關(guan)作用又要充(chong)電(dian)(dian)(dian)。