1 概 述

　　電子信息技術的快速發展使得各種各樣的電子產品不斷涌現，并朝著便攜和小型輕量化的趨勢發展，這也使得更多的電氣化產品采用基于電池的供電系統。目前，較多使用的電池有鎳鎘、鎳氫、鉛蓄電池和鋰電池，由于它們各自的優缺點使得它們在相當長的時期內將共存發展［4］。由于不同類型的電池的充電特性不同，目前通常對不同類型，甚至不同電壓、容量等級的電池使用不同的充電器，這在實(shi)際使用中有諸多(duo)不便(bian)。本文設(she)計(ji)了一(yi)(yi)種(zhong)通用型的(de)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器，可對電(dian)(dian)(dian)(dian)壓等級(ji)為1.2V～48V的(de)鎳(nie)鎘(ge)、鎳(nie)氫、鉛蓄電(dian)(dian)(dian)(dian)池和鋰電(dian)(dian)(dian)(dian)池進(jin)行(xing)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)。為達到如此寬(kuan)的(de)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)范圍(wei)，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源采用二級(ji)電(dian)(dian)(dian)(dian)路拓撲，并使用同(tong)一(yi)(yi)PWM信號源對兩級(ji)電(dian)(dian)(dian)(dian)路進(jin)行(xing)聯動控制。該電(dian)(dian)(dian)(dian)源在 85VAC～265VAC的(de)通用輸入范圍(wei)內均可實(shi)現1.2V（0.3A）～60V（1.6A）的(de)寬(kuan)范圍(wei)輸出。同(tong)時使用單片(pian)機進(jin)行(xing)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)控制，先(xian)進(jin)的(de)慢脈(mo)沖快速(su)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)法［4］，并綜合使用定(ding)時控制、電(dian)(dian)(dian)(dian)壓控制和溫度控制來中止快速(su)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)，確保不會因過充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)而損傷電(dian)(dian)(dian)(dian)池。

　　2 充電電源的拓撲結構和控制方案

　　由(you)于要求充(chong)電(dian)電(dian)源的(de)輸(shu)(shu)(shu)出(chu)(chu)(chu)變(bian)化(hua)范(fan)圍為1.2V（0.3A）～60V（1.6A），采(cai)用單級(ji)變(bian)換(huan)器(qi)很難實(shi)現這 么大的(de)變(bian)化(hua)范(fan)圍，故采(cai)用了(le)兩級(ji)結構，電(dian)源主電(dian)路如圖1所示，交流(liu)輸(shu)(shu)(shu)入經整(zheng)流(liu)濾波得(de)到穩(wen)定的(de)直流(liu)電(dian)壓DCin，首先(xian)經單端反(fan)激變(bian)換(huan)器(qi)預穩(wen)壓，并(bing)實(shi)現輸(shu)(shu)(shu)入級(ji)與輸(shu)(shu)(shu)出(chu)(chu)(chu)級(ji)的(de)隔(ge)離(li)，然(ran)后再經BUCK變(bian)換(huan)器(qi)進(jin)一步降壓，得(de)到所需輸(shu)(shu)(shu)出(chu)(chu)(chu)電(dian)壓。為了(le)保證單端反(fan)激變(bian)換(huan)器(qi)能穩(wen)定工作，加(jia)入了(le)假負載R2。由(you)于電(dian)池(chi)等效(xiao)于一個大電(dian)容(rong)，故輸(shu)(shu)(shu)出(chu)(chu)(chu)端可(ke)不加(jia)濾波電(dian)容(rong)。

　　為(wei)簡(jian)化控(kong)(kong)制，采用(yong)同一PWM信號對(dui)兩級變(bian)(bian)(bian)換(huan)器(qi)進行(xing)聯動控(kong)(kong)制。單端反激變(bian)(bian)(bian)換(huan)器(qi)的(de)的(de)占(zhan)空(kong)比(bi)一般應不(bu)(bu)超過0.5，以(yi)減(jian)小開關(guan)管(guan)電(dian)壓應力(li)，而BUCK變(bian)(bian)(bian)換(huan)器(qi)則希望盡(jin)量(liang)提高占(zhan)空(kong)比(bi)，以(yi)改善輸出電(dian)壓波形和動態響應，因此，在保證(zheng)能夠實現(xian)所(suo)要求的(de)輸出變(bian)(bian)(bian)化范圍(wei)的(de)情況下(xia)，應盡(jin)量(liang)提高BUCK變(bian)(bian)(bian)換(huan)器(qi)的(de)占(zhan)空(kong)比(bi)，這樣就(jiu)不(bu)(bu)能采用(yong)完全相同的(de)PWM信號同時(shi)控(kong)(kong)制兩級變(bian)(bian)(bian)換(huan)器(qi)。為(wei)此，本文給出了一種相對(dui)簡(jian)單的(de)控(kong)(kong)制策略，使用(yong)同一 PWM信號變(bian)(bian)(bian)換(huan)出占(zhan)空(kong)比(bi)不(bu)(bu)同的(de)兩路PWM信號，分別控(kong)(kong)制兩級變(bian)(bian)(bian)換(huan)器(qi)，具體實現(xian)方法如下(xia)所(suo)述。

　　對(dui)于(yu)任(ren)一(yi)(yi)方波信號(hao)(hao)(hao)(hao)(hao)，要(yao)改(gai)變(bian)(bian)其(qi)(qi)占空(kong)比(bi)（對(dui)應于(yu)導通時(shi)(shi)間，即信號(hao)(hao)(hao)(hao)(hao)處于(yu)高電(dian)平狀態的時(shi)(shi)間），一(yi)(yi)般(ban)有兩(liang)種實(shi)(shi)現途(tu)徑(jing)：一(yi)(yi)是改(gai)變(bian)(bian)其(qi)(qi)導通時(shi)(shi)間而(er)頻率保持(chi)不變(bian)(bian)，二是改(gai)變(bian)(bian)其(qi)(qi)頻率而(er)導通時(shi)(shi)間保持(chi)不變(bian)(bian)。本文(wen)采用后一(yi)(yi)種途(tu)徑(jing)，即用PWM控(kong)制(zhi)器輸出(chu)的信號(hao)(hao)(hao)(hao)(hao)直接(jie)控(kong)制(zhi)BUCK變(bian)(bian)換器，而(er)在保持(chi)導通時(shi)(shi)間不變(bian)(bian)的情況下(xia)將(jiang)其(qi)(qi)信號(hao)(hao)(hao)(hao)(hao)進行二分頻，得(de)到占空(kong)比(bi)減半的信號(hao)(hao)(hao)(hao)(hao)來(lai)控(kong)制(zhi)單端反激(ji)變(bian)(bian)換器。具體實(shi)(shi)現電(dian)路如(ru)圖2（a）所示，源信號(hao)(hao)(hao)(hao)(hao)經分頻器二分頻，得(de)到頻率減半的信號(hao)(hao)(hao)(hao)(hao)，再與(yu)源信號(hao)(hao)(hao)(hao)(hao)相與(yu)，即得(de)到導通時(shi)(shi)間不變(bian)(bian)而(er)頻率減半的信號(hao)(hao)(hao)(hao)(hao)。電(dian)路中各(ge)點波形參見圖2（b）。

 3 充(chong)電控制方案

　　近年來(lai)，如何對電(dian)(dian)(dian)(dian)池(chi)高(gao)效、快速(su)地充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)成為(wei)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)技術研(yan)究(jiu)的熱點，國內外研(yan)究(jiu)人員也提出(chu)了不少(shao)快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)方(fang)法(fa)，本文即參考(kao)了其中(zhong)一種較(jiao)實用的慢脈(mo)沖(chong)快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)法(fa)，這種方(fang)法(fa)能確保在充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過(guo)(guo)程(cheng)中(zhong)及時消(xiao)除或(huo)降低電(dian)(dian)(dian)(dian)池(chi)極化，電(dian)(dian)(dian)(dian)池(chi)析(xi)氣(qi)量(liang)少(shao)，溫升(sheng)低，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)效率(lv)高(gao)。整個充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過(guo)(guo)程(cheng)由(you)恒流和(he)恒壓(ya)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)兩個階段(duan)組(zu)成，在每一階段(duan)均以周期為(wei)幾秒到幾十(shi)秒的電(dian)(dian)(dian)(dian)流或(huo)電(dian)(dian)(dian)(dian)壓(ya)脈(mo)沖(chong)進行充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)。而兩階段(duan)的轉換(huan)時刻則(ze)由(you)電(dian)(dian)(dian)(dian)池(chi)的充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)狀態所(suo)決定。

　　由于充(chong)電(dian)(dian)(dian)(dian)(dian)方(fang)法相(xiang)(xiang)對較復(fu)雜(za)，且需要對多種類(lei)型和規格(ge)的(de)(de)電(dian)(dian)(dian)(dian)(dian)池進行充(chong)電(dian)(dian)(dian)(dian)(dian)，故需要采用可編程器件進行控(kong)制(zhi)，而(er)(er)單片機以其相(xiang)(xiang)對強大的(de)(de)功能和低(di)廉的(de)(de)價(jia)格(ge)成為首選。本文選用Motorola公司(si)推出(chu)的(de)(de) MC68HC908GP32作為主(zhu)控(kong)元件，整個系統的(de)(de)組(zu)成框圖如圖3所(suo)示，反映電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)狀態的(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流、電(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)壓和溫(wen)度信號經采樣電(dian)(dian)(dian)(dian)(dian)路送(song)入單片機的(de)(de)A/D 轉換口，單片機根據充(chong)電(dian)(dian)(dian)(dian)(dian)算法，通(tong)過(guo)D/A轉換口輸(shu)出(chu)信號控(kong)制(zhi)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)源的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓或電(dian)(dian)(dian)(dian)(dian)流給定，從而(er)(er)達(da)到(dao)控(kong)制(zhi)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)源輸(shu)出(chu)的(de)(de)目的(de)(de)。

　　軟(ruan)件系統采用(yong)(yong)模(mo)(mo)(mo)(mo)塊(kuai)化設計方(fang)法，整個程序由主程序模(mo)(mo)(mo)(mo)塊(kuai)、各(ge)類電(dian)(dian)池充電(dian)(dian)子程序模(mo)(mo)(mo)(mo)塊(kuai)以及(ji)錯誤(wu)處理模(mo)(mo)(mo)(mo)塊(kuai)組成，各(ge)模(mo)(mo)(mo)(mo)塊(kuai)相(xiang)對獨立，以便于(yu)算(suan)法改進及(ji)功能擴(kuo)充，其中主程序模(mo)(mo)(mo)(mo)塊(kuai)構架了軟(ruan)件系統的骨架，通過其對其他模(mo)(mo)(mo)(mo)塊(kuai)的調用(yong)(yong)來(lai)實現(xian)完(wan)整的充電(dian)(dian)過程控制(zhi)，其流程圖見圖4。

　　為確保充(chong)電(dian)(dian)(dian)(dian)安全(quan)，在開始充(chong)電(dian)(dian)(dian)(dian)前檢測電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和溫(wen)(wen)度(du)(du)(du)，以(yi)排除電(dian)(dian)(dian)(dian)池(chi)接反、用戶選擇的電(dian)(dian)(dian)(dian)池(chi)規格有誤等錯(cuo)誤，并(bing)判斷電(dian)(dian)(dian)(dian)池(chi)的狀態是(shi)否適(shi)合快速(su)充(chong)電(dian)(dian)(dian)(dian)，如(ru)電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)或溫(wen)(wen)度(du)(du)(du)過(guo)(guo)低，則需要(yao)進行小電(dian)(dian)(dian)(dian)流預充(chong)電(dian)(dian)(dian)(dian)，待電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)、溫(wen)(wen)度(du)(du)(du)達到正常范圍后再(zai)開始快速(su)充(chong)電(dian)(dian)(dian)(dian)。在整個充(chong)電(dian)(dian)(dian)(dian)過(guo)(guo)程中均實時檢測電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和溫(wen)(wen)度(du)(du)(du)，并(bing)綜合采用最(zui)高電(dian)(dian)(dian)(dian)壓(ya)(ya)控制、電(dian)(dian)(dian)(dian)壓(ya)(ya)零增量控制、最(zui)高溫(wen)(wen)度(du)(du)(du)控制和定(ding)時控制等方法(fa)來終止(zhi)快速(su)充(chong)電(dian)(dian)(dian)(dian)，以(yi)確保電(dian)(dian)(dian)(dian)池(chi)不被(bei)過(guo)(guo)充(chong)。

　　4 實驗及結論

　　本文采用清華大學Motorola單片機應用開發研究中心推出的MC68HC908GP32IDK作為開發系統［2］，對該充電器進行了實驗測試(shi)，在整個負載范圍內均有穩定的輸出，開(kai)(kai)關管的最小導(dao)通(tong)時(shi)間(jian)（對應于(yu)最小負載）約為(wei)1.2us，而開(kai)(kai)關管（MTP4N80）的開(kai)(kai)關時(shi)間(jian)和反向恢復時(shi)間(jian)之和小于(yu)0.7us，故充電電源能穩定工作(zuo)。

　　本文設計了一個通用型智能充電器，給出了(le)寬范(fan)圍(wei)充(chong)電電源的(de)一種(zhong)實現方(fang)法，并充(chong)分(fen)利用了(le)單片機強大(da)的(de)控制功能，絕大(da)部分(fen)功能由軟件(jian)編程實現，使得(de)系統對硬件(jian)的(de)依賴性較小，便于功能的(de)擴充(chong)及改進。