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，這在實際使用(yong)(yong)中有諸多不(bu)便。本文設計了一種通用(yong)(yong)型(xing)的(de)充(chong)(chong)(chong)電(dian)器，可(ke)對電(dian)壓等(deng)級為(wei)1.2V～48V的(de)鎳鎘(ge)、鎳氫、鉛(qian)蓄電(dian)池和(he)鋰電(dian)池進行充(chong)(chong)(chong)電(dian)。為(wei)達到(dao)如此寬的(de)充(chong)(chong)(chong)電(dian)范圍(wei)，充(chong)(chong)(chong)電(dian)電(dian)源(yuan)采(cai)用(yong)(yong)二級電(dian)路(lu)拓撲，并使用(yong)(yong)同一PWM信號(hao)源(yuan)對兩級電(dian)路(lu)進行聯動控(kong)制(zhi)(zhi)。該電(dian)源(yuan)在 85VAC～265VAC的(de)通用(yong)(yong)輸(shu)入范圍(wei)內均可(ke)實現1.2V（0.3A）～60V（1.6A）的(de)寬范圍(wei)輸(shu)出。同時使用(yong)(yong)單(dan)片機進行充(chong)(chong)(chong)電(dian)控(kong)制(zhi)(zhi)，先進的(de)慢脈(mo)沖(chong)快(kuai)速充(chong)(chong)(chong)電(dian)法［4］，并綜合(he)使用(yong)(yong)定時控(kong)制(zhi)(zhi)、電(dian)壓控(kong)制(zhi)(zhi)和(he)溫度控(kong)制(zhi)(zhi)來(lai)中止快(kuai)速充(chong)(chong)(chong)電(dian)，確保不(bu)會因過(guo)充(chong)(chong)(chong)電(dian)而損傷(shang)電(dian)池。

　　2 充電電源的拓撲結構和控制方案

　　由于(yu)(yu)要(yao)求充電(dian)(dian)電(dian)(dian)源的(de)(de)輸(shu)出變(bian)化范圍為1.2V（0.3A）～60V（1.6A），采用(yong)單(dan)級變(bian)換器很難實現(xian)這(zhe) 么(me)大的(de)(de)變(bian)化范圍，故采用(yong)了(le)兩級結(jie)構(gou)，電(dian)(dian)源主電(dian)(dian)路(lu)如圖1所(suo)示，交流(liu)輸(shu)入(ru)經整(zheng)流(liu)濾波(bo)得(de)到穩(wen)定的(de)(de)直流(liu)電(dian)(dian)壓(ya)DCin，首先經單(dan)端反激(ji)變(bian)換器預穩(wen)壓(ya)，并實現(xian)輸(shu)入(ru)級與(yu)輸(shu)出級的(de)(de)隔(ge)離，然后再經BUCK變(bian)換器進(jin)一步降壓(ya)，得(de)到所(suo)需輸(shu)出電(dian)(dian)壓(ya)。為了(le)保證單(dan)端反激(ji)變(bian)換器能(neng)穩(wen)定工作，加入(ru)了(le)假(jia)負載R2。由于(yu)(yu)電(dian)(dian)池等效于(yu)(yu)一個大電(dian)(dian)容，故輸(shu)出端可不加濾波(bo)電(dian)(dian)容。

　　為簡化控(kong)(kong)制，采用(yong)(yong)同(tong)一(yi)PWM信(xin)號(hao)對(dui)兩(liang)級(ji)(ji)變(bian)換(huan)器進行(xing)聯動控(kong)(kong)制。單(dan)端反激變(bian)換(huan)器的的占(zhan)(zhan)空比一(yi)般應(ying)不超過0.5，以減小開關管(guan)電壓應(ying)力，而BUCK變(bian)換(huan)器則希望盡量提高占(zhan)(zhan)空比，以改善(shan)輸(shu)出電壓波形和(he)動態響應(ying)，因此(ci)，在保證能夠(gou)實現所(suo)要求的輸(shu)出變(bian)化范圍的情況下(xia)，應(ying)盡量提高BUCK變(bian)換(huan)器的占(zhan)(zhan)空比，這樣(yang)就不能采用(yong)(yong)完(wan)全相同(tong)的PWM信(xin)號(hao)同(tong)時控(kong)(kong)制兩(liang)級(ji)(ji)變(bian)換(huan)器。為此(ci)，本(ben)文給出了一(yi)種相對(dui)簡單(dan)的控(kong)(kong)制策略，使用(yong)(yong)同(tong)一(yi) PWM信(xin)號(hao)變(bian)換(huan)出占(zhan)(zhan)空比不同(tong)的兩(liang)路PWM信(xin)號(hao)，分別控(kong)(kong)制兩(liang)級(ji)(ji)變(bian)換(huan)器，具體實現方法(fa)如下(xia)所(suo)述。

　　對于(yu)任一方波信(xin)號(hao)(hao)，要改變(bian)(bian)其占(zhan)空(kong)比(bi)（對應于(yu)導通時(shi)(shi)間(jian)，即信(xin)號(hao)(hao)處于(yu)高電(dian)(dian)平狀態的(de)時(shi)(shi)間(jian)），一般有(you)兩種(zhong)實(shi)(shi)現途徑(jing)：一是改變(bian)(bian)其導通時(shi)(shi)間(jian)而頻(pin)(pin)(pin)率(lv)(lv)保持(chi)(chi)不變(bian)(bian)，二是改變(bian)(bian)其頻(pin)(pin)(pin)率(lv)(lv)而導通時(shi)(shi)間(jian)保持(chi)(chi)不變(bian)(bian)。本文采用后一種(zhong)途徑(jing)，即用PWM控制(zhi)器(qi)輸(shu)出的(de)信(xin)號(hao)(hao)直(zhi)接(jie)控制(zhi)BUCK變(bian)(bian)換器(qi)，而在(zai)保持(chi)(chi)導通時(shi)(shi)間(jian)不變(bian)(bian)的(de)情況下將其信(xin)號(hao)(hao)進(jin)行二分(fen)(fen)頻(pin)(pin)(pin)，得(de)到占(zhan)空(kong)比(bi)減半(ban)的(de)信(xin)號(hao)(hao)來控制(zhi)單端反激變(bian)(bian)換器(qi)。具體實(shi)(shi)現電(dian)(dian)路如(ru)圖2（a）所(suo)示(shi)，源信(xin)號(hao)(hao)經分(fen)(fen)頻(pin)(pin)(pin)器(qi)二分(fen)(fen)頻(pin)(pin)(pin)，得(de)到頻(pin)(pin)(pin)率(lv)(lv)減半(ban)的(de)信(xin)號(hao)(hao)，再(zai)與(yu)源信(xin)號(hao)(hao)相與(yu)，即得(de)到導通時(shi)(shi)間(jian)不變(bian)(bian)而頻(pin)(pin)(pin)率(lv)(lv)減半(ban)的(de)信(xin)號(hao)(hao)。電(dian)(dian)路中(zhong)各(ge)點波形參見圖2（b）。

 3 充電控制方案

　　近年來，如何對電(dian)(dian)池高(gao)效、快速(su)地充(chong)(chong)電(dian)(dian)成為充(chong)(chong)電(dian)(dian)技術研究的(de)(de)熱點，國內(nei)外研究人(ren)員也提(ti)出了不少快速(su)充(chong)(chong)電(dian)(dian)方(fang)法，本文即參考了其中一種(zhong)較實用的(de)(de)慢脈沖快速(su)充(chong)(chong)電(dian)(dian)法，這種(zhong)方(fang)法能確(que)保在充(chong)(chong)電(dian)(dian)過程中及時消(xiao)除或降低電(dian)(dian)池極化(hua)，電(dian)(dian)池析氣量少，溫升低，充(chong)(chong)電(dian)(dian)效率高(gao)。整個充(chong)(chong)電(dian)(dian)過程由恒(heng)流和恒(heng)壓(ya)充(chong)(chong)電(dian)(dian)兩個階(jie)段(duan)組成，在每一階(jie)段(duan)均以周期為幾秒到幾十秒的(de)(de)電(dian)(dian)流或電(dian)(dian)壓(ya)脈沖進(jin)行充(chong)(chong)電(dian)(dian)。而兩階(jie)段(duan)的(de)(de)轉換時刻則(ze)由電(dian)(dian)池的(de)(de)充(chong)(chong)電(dian)(dian)狀態所決定(ding)。

　　由于充電(dian)(dian)(dian)方法(fa)相對較(jiao)復雜，且需(xu)要對多種(zhong)類(lei)型和規(gui)格的(de)(de)(de)(de)(de)電(dian)(dian)(dian)池進行(xing)充電(dian)(dian)(dian)，故需(xu)要采用(yong)(yong)可(ke)編程器件(jian)進行(xing)控制(zhi)，而單(dan)(dan)片機以其相對強大的(de)(de)(de)(de)(de)功能和低廉的(de)(de)(de)(de)(de)價格成(cheng)為(wei)首選。本文選用(yong)(yong)Motorola公司推出(chu)的(de)(de)(de)(de)(de) MC68HC908GP32作為(wei)主控元件(jian)，整個(ge)系統的(de)(de)(de)(de)(de)組成(cheng)框(kuang)圖(tu)如(ru)圖(tu)3所示，反映(ying)電(dian)(dian)(dian)池充電(dian)(dian)(dian)狀態的(de)(de)(de)(de)(de)充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)、電(dian)(dian)(dian)池電(dian)(dian)(dian)壓(ya)和溫度信(xin)號(hao)經采樣電(dian)(dian)(dian)路送入單(dan)(dan)片機的(de)(de)(de)(de)(de)A/D 轉換口，單(dan)(dan)片機根據充電(dian)(dian)(dian)算法(fa)，通(tong)過D/A轉換口輸出(chu)信(xin)號(hao)控制(zhi)充電(dian)(dian)(dian)電(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)或(huo)電(dian)(dian)(dian)流(liu)給(gei)定，從而達(da)到控制(zhi)充電(dian)(dian)(dian)電(dian)(dian)(dian)源(yuan)輸出(chu)的(de)(de)(de)(de)(de)目的(de)(de)(de)(de)(de)。

　　軟(ruan)件系統采用(yong)(yong)模塊(kuai)化設計方(fang)法(fa)，整(zheng)(zheng)個(ge)程序(xu)(xu)由主程序(xu)(xu)模塊(kuai)、各類電(dian)(dian)池充電(dian)(dian)子程序(xu)(xu)模塊(kuai)以及錯誤處理模塊(kuai)組成，各模塊(kuai)相對獨立，以便于(yu)算法(fa)改進及功能擴(kuo)充，其(qi)中主程序(xu)(xu)模塊(kuai)構架了軟(ruan)件系統的(de)骨架，通過其(qi)對其(qi)他模塊(kuai)的(de)調用(yong)(yong)來實現(xian)完整(zheng)(zheng)的(de)充電(dian)(dian)過程控(kong)制，其(qi)流程圖見圖4。

　　為確保(bao)充(chong)(chong)電(dian)(dian)(dian)(dian)安全，在開始充(chong)(chong)電(dian)(dian)(dian)(dian)前檢(jian)(jian)測(ce)電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和(he)(he)溫度，以排(pai)除(chu)電(dian)(dian)(dian)(dian)池(chi)(chi)接反、用戶(hu)選擇的電(dian)(dian)(dian)(dian)池(chi)(chi)規格有(you)誤等錯誤，并判(pan)斷電(dian)(dian)(dian)(dian)池(chi)(chi)的狀(zhuang)態是否適(shi)合快(kuai)速(su)充(chong)(chong)電(dian)(dian)(dian)(dian)，如電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)或(huo)溫度過低，則(ze)需(xu)要進行小電(dian)(dian)(dian)(dian)流預充(chong)(chong)電(dian)(dian)(dian)(dian)，待電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)、溫度達(da)到正(zheng)常(chang)范圍后(hou)再開始快(kuai)速(su)充(chong)(chong)電(dian)(dian)(dian)(dian)。在整個充(chong)(chong)電(dian)(dian)(dian)(dian)過程中均實時檢(jian)(jian)測(ce)電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和(he)(he)溫度，并綜(zong)合采用最高電(dian)(dian)(dian)(dian)壓(ya)(ya)控(kong)制、電(dian)(dian)(dian)(dian)壓(ya)(ya)零增量控(kong)制、最高溫度控(kong)制和(he)(he)定時控(kong)制等方法來(lai)終止(zhi)快(kuai)速(su)充(chong)(chong)電(dian)(dian)(dian)(dian)，以確保(bao)電(dian)(dian)(dian)(dian)池(chi)(chi)不被過充(chong)(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(shi)驗測(ce)試(shi)，在整個(ge)負載范圍(wei)內均有穩定的(de)輸出，開關(guan)管的(de)最小導通時間（對應(ying)于最小負載）約為1.2us，而開關(guan)管（MTP4N80）的(de)開關(guan)時間和反向恢復時間之和小于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)寬范圍(wei)充電(dian)電(dian)源的一種(zhong)實(shi)現(xian)方法，并(bing)充分(fen)利用了(le)單片機強(qiang)大(da)的控制功(gong)能(neng)(neng)，絕大(da)部分(fen)功(gong)能(neng)(neng)由軟件編(bian)程實(shi)現(xian)，使得系統對硬件的依賴性較小，便于功(gong)能(neng)(neng)的擴充及(ji)改進(jin)。