從再生能(neng)(neng)源(yuan)（如光電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)面板或(huo)風力(li)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)）接收能(neng)(neng)量(liang)(liang)的(de)系統一般會將能(neng)(neng)量(liang)(liang)保存在可(ke)(ke)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)中,再提供(gong)給負(fu)載(zai)。通常情況下(xia),兩個過程是同時(shi)發(fa)生的(de)。對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)剩余電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)的(de)周期性評估可(ke)(ke)以(yi)保證(zheng)延長電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)性能(neng)(neng)和壽命,同時(shi)控制電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)供(gong)給負(fu)載(zai)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)剩余電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)包括(kuo)前次計算的(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang),加上新增電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang),或(huo)者(zhe)減去消耗的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)。根據Coulomb定律,可(ke)(ke)以(yi)用(yong)下(xia)式計算出(chu)累積(ji)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)：

　　其中QACC是電池最新的(de)累積(ji)電量,i表示在時間間隔Δt期間累積(ji)的(de)電流(liu)量。

　　在不(bu)連續的情(qing)況(kuang)下,該(gai)式變(bian)成

　　其中n表示在(zai)時間間隔(ge)Δt內電流Ik的(de)測量次數。雖(sui)然Δt值可以任意選擇,但選等(deng)于(yu)一小時的(de)值比較方便,因為電池制造商標定容量的(de)單位是安(an)培小時。

　　為(wei)了(le)簡化(hua)微(wei)控(kong)制器(qi)的(de)(de)硬件,降低算(suan)(suan)術(shu)運算(suan)(suan)所需內存數量(liang),可(ke)以(yi)將1小時劃分為(wei)128個測(ce)量(liang)周期,并用(yong)寄存器(qi)移位方法完(wan)成(cheng)公式中所需的(de)(de)分割。可(ke)以(yi)從(cong)32個電(dian)(dian)(dian)(dian)流采樣取平均值(zhi)(zhi)作為(wei)每次(ci)充電(dian)(dian)(dian)(dian)測(ce)量(liang)值(zhi)(zhi),采樣值(zhi)(zhi)經微(wei)處理器(qi)內部ADC轉換(huan)。一個ADC的(de)(de)輸入通道用(yong)于轉換(huan)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流,另一個ADC用(yong)于轉換(huan)放(fang)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流。因此,剩(sheng)余電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)量(liang)的(de)(de)公式就簡化(hua)為(wei) QREM=QPREV±QACC,其中QREM 是(shi)剩(sheng)余電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)量(liang),QPREV是(shi)前次(ci)計算(suan)(suan)的(de)(de)充電(dian)(dian)(dian)(dian)量(liang),加(jia)號表明是(shi)凈充電(dian)(dian)(dian)(dian),而減(jian)號則表明是(shi)凈放(fang)電(dian)(dian)(dian)(dian)。

　　如圖(tu)1所(suo)示,電(dian)(dian)(dian)路(lu)包括一個(ge)8腳的(de)(de)(de)(de)飛思卡爾(Freescale)公司(si)低(di)成本MC68HC908QT2微控制器IC3。電(dian)(dian)(dian)流采(cai)樣(yang)電(dian)(dian)(dian)阻R1兩(liang)(liang)端的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)會根據電(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)還是(shi)放(fang)電(dian)(dian)(dian)而轉換極性。IC2A和IC2B分別接成相(xiang)(xiang)(xiang)(xiang)同(tong)增益的(de)(de)(de)(de)非(fei)反(fan)(fan)相(xiang)(xiang)(xiang)(xiang)和反(fan)(fan)相(xiang)(xiang)(xiang)(xiang)放(fang)大(da)器,用于檢測R1兩(liang)(liang)端的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)。非(fei)反(fan)(fan)相(xiang)(xiang)(xiang)(xiang)放(fang)大(da)器IC2A只響應(ying)充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流產生(sheng)的(de)(de)(de)(de)正向電(dian)(dian)(dian)壓(ya),而對(dui)放(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)流產生(sheng)的(de)(de)(de)(de)負輸入(ru)電(dian)(dian)(dian)壓(ya)則提供零輸出。反(fan)(fan)相(xiang)(xiang)(xiang)(xiang)放(fang)大(da)器IC2B則只響應(ying)負輸入(ru),而對(dui)正充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流提供0V。兩(liang)(liang)個(ge)運放(fang)的(de)(de)(de)(de)輸出都是(shi)正的(de)(de)(de)(de),范圍從(cong)0 V至約5V,從(cong)而簡化了(le)與ADC多路(lu)輸入(ru)的(de)(de)(de)(de)接口設計。IC2采(cai)用德(de)州儀器(Texas Instruments)公司(si)的(de)(de)(de)(de)TLC277,它(ta)的(de)(de)(de)(de)優(you)點是(shi)占用印制電(dian)(dian)(dian)路(lu)板面積小,并有(you)低(di)的(de)(de)(de)(de)輸入(ru)失調(diao)電(dian)(dian)(dian)壓(ya)。

　　確定了最低、最高期望的充、放電電流后,就可以計算出檢測電阻R₁的值和放大器(qi)增益G,公式(shi)如下：

　　其中I_MAX是最大放電電流,V_IN(MAX)是最大ADC輸入。在本例中,最大充、放電電流均約為1A。

　　因此,對1A充電或放電電流和最大ADC輸入為5V時,可以選擇0.5Ω的R₁,增益為10或100。一旦計算出了電池的充電能力,就可以通過單線接口SIP、I²C、CAN（控制器局域網絡）或其它工業標準方法,將數據發送給主控處理器或其它目標（參考文獻1）。為使電池壽命最長,可以用微處理器的輸出來控制外部負載吸入的電流。

　　制造商一般交付充滿電的鉛酸電池,這是為了防止出現硫酸鉛沉淀問題,本設計假定一塊電池開始時處于滿充電狀態。如要將此電路用于鉛酸電池以外的其它化學性質電池,必須修改電池最大可充能量值,該值保存在一個專用的(de)硬件寄(ji)存器內。