C8051F310器件設計鋰離子電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)器。利(li)用PWM脈寬調制產生可(ke)用軟件控制的(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源，以適應不(bu)同(tong)階段(duan)的(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流的(de)要求。溫(wen)度(du)傳感器對電(dian)(dian)(dian)(dian)池(chi)溫(wen)度(du)進行(xing)監測(ce)，并通過AD轉換和相關計算檢測(ce)電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)和電(dian)(dian)(dian)(dian)流，以判斷(duan)電(dian)(dian)(dian)(dian)池(chi)到達哪(na)個階段(duan)。使(shi)電(dian)(dian)(dian)(dian)池(chi)具有更長的(de)使(shi)用壽命。

設計過程

1  充電原理

　　電(dian)池(chi)的特性唯一(yi)地決定其(qi)安(an)全(quan)性能和充(chong)電(dian)的效率。電(dian)池(chi)的最佳(jia)充(chong)電(dian)方(fang)法是由電(dian)池(chi)的化學成分決定的（鋰(li)離子、鎳(nie)氫、鎳(nie)鎘還是SLA電(dian)池(chi)等）。盡管如此(ci)，大多數充(chong)電(dian)方(fang)案(an)都包含(han)下(xia)面的三(san)個階段：

　　低電流調節階段

　　恒流階段

　　恒(heng)壓階段/充(chong)電(dian)終(zhong)止

　　所有電(dian)(dian)(dian)(dian)池(chi)都是通過向(xiang)自身傳輸電(dian)(dian)(dian)(dian)能的(de)方法進行充(chong)電(dian)(dian)(dian)(dian)的(de)，一(yi)節(jie)電(dian)(dian)(dian)(dian)池(chi)的(de)最(zui)大充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)取決于電(dian)(dian)(dian)(dian)池(chi)的(de)額定容量（C）例如，一(yi)節(jie)容量為1000mAh的(de)電(dian)(dian)(dian)(dian)池(chi)在充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)為1000mA時，可(ke)以(yi)充(chong)電(dian)(dian)(dian)(dian)1C（電(dian)(dian)(dian)(dian)池(chi)容量的(de)1倍）也可(ke)以(yi)用1/50C（20mA）或更低的(de)電(dian)(dian)(dian)(dian)流(liu)給電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)。

　　現在使用的大多數充電器在(zai)給電(dian)(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)(dian)時(shi)都是既使(shi)用(yong)低(di)電(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)方式(shi)又(you)使(shi)用(yong)額定充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)的(de)(de)方法，即容(rong)積充(chong)(chong)電(dian)(dian)(dian)(dian)，低(di)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)通常(chang)使(shi)用(yong)在(zai)充(chong)(chong)電(dian)(dian)(dian)(dian)的(de)(de)初始階(jie)段(duan)。在(zai)這一階(jie)段(duan)，需要將會(hui)導致充(chong)(chong)電(dian)(dian)(dian)(dian)過程(cheng)終止(zhi)的(de)(de)芯片(pian)初期的(de)(de)自(zi)熱效應(ying)減小到最(zui)低(di)程(cheng)度，容(rong)積充(chong)(chong)電(dian)(dian)(dian)(dian)通常(chang)用(yong)在(zai)充(chong)(chong)電(dian)(dian)(dian)(dian)的(de)(de)中(zhong)級階(jie)段(duan)，電(dian)(dian)(dian)(dian)池的(de)(de)大部分能量都是在(zai)這一階(jie)段(duan)存儲(chu)的(de)(de)。

　　充(chong)電(dian)時部(bu)(bu)分(fen)電(dian)能被轉(zhuan)換成(cheng)熱能，直至電(dian)池(chi)(chi)充(chong)滿。而充(chong)滿后，所(suo)有的(de)電(dian)能將(jiang)全部(bu)(bu)被轉(zhuan)換成(cheng)熱能。如果此時不終止充(chong)電(dian)，電(dian)池(chi)(chi)就會被損(sun)壞或燒(shao)毀。快(kuai)速充(chong)電(dian)器電(dian)池(chi)(chi)則可以解決這(zhe)(zhe)個問題，因(yin)為這(zhe)(zhe)些充(chong)電(dian)器是(shi)使用高(gao)充(chong)電(dian)電(dian)流來(lai)縮短充(chong)電(dian)時間的(de)。

2  總體設計

　　充電(dian)電(dian)路(lu)由三部分(fen)：控(kong)制部分(fen)，檢測部分(fen)及充電(dian)部分(fen)組成。

　　如(ru)圖1所示，采用F310單片機(ji)進行充電控制(zhi)，單片機(ji)本身(shen)具有脈寬調制(zhi)PWM型開關穩壓電源所需的全部功能，具有10位(wei)A/D轉換器。

　　利(li)用單片機A/D端口，構成(cheng)電(dian)池電(dian)壓，電(dian)流，溫度檢測電(dian)路。

 

 

 

    圖(tu)1  鋰離子電池(chi)充電模(mo)塊圖(tu)

    單(dan)片機(ji)通過電(dian)壓反(fan)饋和電(dian)流反(fan)饋信號，直接利用PWM輸出將數字(zi)電(dian)壓信號并轉(zhuan)化成模(mo)擬(ni)電(dian)壓信號，能夠(gou)保證控制精(jing)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)換(huan)速度(du)可(ke)(ke)達200ks/s,可(ke)(ke)多達21或(huo)17個外部單端或(huo)差分輸入，VREF可(ke)(ke)在外部引腳(jiao)或(huo)VDD中選(xuan)擇(ze)，內置溫(wen)度(du)傳感器（±3℃），外部轉(zhuan)換(huan)啟(qi)動(dong)輸入；

　　b.兩個模擬(ni)比較器：可(ke)編程回差電壓和(he)響應時間(jian)，可(ke)配置為中斷或復位源，小電流（〈0.5μA）。

　　②供電電壓

　　a.典型工作電流(liu)：5mA、25MHz；

　　b.典(dian)型停機電流(liu)：0.1μA；

　　c.溫(wen)度范圍：-40～+85℃。

　　③高速8051微(wei)控制(zhi)器內核

　　a.流水線指令(ling)結構(gou)：70%的(de)(de)指令(ling)的(de)(de)執行時間為一個或兩個系統時鐘周期；

　　b.速度(du)可達25MI/s（時(shi)鐘頻率(lv)為25MHz時(shi)）；

　　c.擴展的中斷系(xi)統(tong)。

　　④數字外設

　　a.29/25個端(duan)口(kou)I/O：所有(you)的口(kou)線均(jun)耐5V電壓(ya)；

　　b.4個通(tong)用16位計(ji)數器(qi)(qi)/定時(shi)器(qi)(qi)；

　　c.16位可編(bian)程計數器/定(ding)時(shi)器陣列（PCA），有5個捕捉(zhuo)/比較模塊；

　　d.使用PCA或(huo)定(ding)時(shi)器(qi)和外(wai)部時(shi)鐘源的實(shi)時(shi)時(shi)鐘方式。

　　控制(zhi)電(dian)(dian)路(lu)中(zhong)如圖2所示，P0.3口(kou)(kou)提供充電(dian)(dian)電(dian)(dian)源，P0.6口(kou)(kou)檢(jian)測(ce)充電(dian)(dian)電(dian)(dian)壓的大小，P0.5口(kou)(kou)檢(jian)測(ce)充電(dian)(dian)電(dian)(dian)流(liu)的大小，P0.4口(kou)(kou)檢(jian)測(ce)電(dian)(dian)池的溫度。

  

 

    圖2  控制電路(lu)接線圖

　　充電電流由(you)單片(pian)機脈(mo)寬調制PWM產(chan)生，充電電流由(you)AD轉換再經過(guo)計算得出。

  

4  充電(dian)部分及檢測(ce)部分電(dian)路設計

　　圖3為充(chong)電電路與檢測電路圖。

  

 

    圖3  充電(dian)電(dian)路與檢(jian)測電(dian)路圖

 　　①充(chong)電(dian)過程曲(qu)線

　　如圖4所(suo)示，充(chong)電(dian)過程由預(yu)充(chong)狀態，恒(heng)流充(chong)電(dian)狀態和恒(heng)壓(ya)充(chong)電(dian)狀態組成(cheng)。

  

 

    圖4  鋰電(dian)池充(chong)電(dian)曲(qu)線

　　②快速轉換器

　　實現(xian)漸弱(ruo)終止充電器(qi)(qi)的(de)(de)最經濟的(de)(de)方(fang)法(fa)就是用一個(ge)(ge)快速(su)轉換器(qi)(qi)。快速(su)轉換器(qi)(qi)是用一個(ge)(ge)電感和/或(huo)一個(ge)(ge)變壓器(qi)(qi)（需要隔離的(de)(de)時候用變壓器(qi)(qi)）作(zuo)為(wei)能(neng)量存儲單元以離散的(de)(de)能(neng)量包(bao)的(de)(de)形式將能(neng)量從輸入傳輸至(zhi)輸出的(de)(de)開關調(diao)節(jie)器(qi)(qi)反饋電路，通過晶體管來調(diao)節(jie)能(neng)量的(de)(de)傳輸，同時也作(zuo)為(wei)過濾開關，以確保(bao)電壓或(huo)電流在(zai)負載時保(bao)持恒定(ding)。

　　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

 

  

b  開關(guan)打開

    圖5  快(kuai)速轉換器操(cao)作

　　③電感的確定

　　電(dian)感(gan)對交流(liu)電(dian)是有阻礙(ai)作(zuo)用的(de)(de)。在交流(liu)電(dian)頻率一(yi)定的(de)(de)情況下，電(dian)感(gan)量越大(da)，對交流(liu)電(dian)的(de)(de)阻礙(ai)能力(li)越強，電(dian)感(gan)量越小(xiao)，其阻礙(ai)能力(li)越小(xiao)。

　　其(qi)工作(zuo)原理是這樣(yang)的：當負(fu)載兩端的電(dian)(dian)(dian)(dian)壓(ya)要降(jiang)低時，通(tong)過MOSFET場效(xiao)應(ying)管的開關作(zuo)用(yong)(yong)，外部(bu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)對(dui)電(dian)(dian)(dian)(dian)感進(jin)行充(chong)電(dian)(dian)(dian)(dian)并達到(dao)所需的額定電(dian)(dian)(dian)(dian)壓(ya)。當負(fu)載兩端地電(dian)(dian)(dian)(dian)壓(ya)升高時，通(tong)過MOSFET場效(xiao)應(ying)管的開關作(zuo)用(yong)(yong)，外部(bu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)供電(dian)(dian)(dian)(dian)斷開，電(dian)(dian)(dian)(dian)感釋放出剛才充(chong)入的能量，這時電(dian)(dian)(dian)(dian)感就變(bian)成了電(dian)(dian)(dian)(dian)源(yuan)(yuan)繼續(xu)對(dui)負(fu)載供電(dian)(dian)(dian)(dian)。隨著電(dian)(dian)(dian)(dian)感上存儲的能量地消(xiao)耗。負(fu)載兩端的電(dian)(dian)(dian)(dian)壓(ya)開始逐漸降(jiang)低，外部(bu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)通(tong)過MOSFET場效(xiao)應(ying)管的開關作(zuo)用(yong)(yong)又要充(chong)電(dian)(dian)(dian)(dian)。