本文介紹一款電路簡單、性能可靠的多用恒流充電器。

　　一(yi)、電(dian)(dian)路原理　　如(ru)圖所示，該充(chong)電(dian)(dian)器(qi)屬于電(dian)(dian)容(rong)(rong)(rong)限流(liu)(liu)式無(wu)電(dian)(dian)源變(bian)壓器(qi)恒流(liu)(liu)充(chong)電(dian)(dian)器(qi)。220V交流(liu)(liu)電(dian)(dian)經K1～K4及其(qi)相應阻容(rong)(rong)(rong)元件組(zu)成的(de)(de)4條并(bing)列(lie)支路選擇或(huo)組(zu)合，再經整(zheng)流(liu)(liu)堆D整(zheng)流(liu)(liu)后，通過(guo)(guo)電(dian)(dian)流(liu)(liu)表(biao)A，給(gei)蓄電(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)。在充(chong)電(dian)(dian)過(guo)(guo)程中，由(you)于回路中蓄電(dian)(dian)池(chi)(chi)兩端電(dian)(dian)的(de)(de)變(bian)化量相對(dui)于220V交流(liu)(liu)電(dian)(dian)壓來說很小，電(dian)(dian)容(rong)(rong)(rong)兩端的(de)(de)電(dian)(dian)壓降幾乎可認為(wei)是不變(bian)的(de)(de)，所以，通過(guo)(guo)電(dian)(dian)容(rong)(rong)(rong)器(qi)的(de)(de)電(dian)(dian)流(liu)(liu)也是不變(bian)的(de)(de)，通過(guo)(guo)蓄電(dian)(dian)池(chi)(chi)內部的(de)(de)充(chong)電(dian)(dian)電(dian)(dian)流(liu)(liu)自然也是恒定(ding)的(de)(de)。 　　

     L為(wei)220V交(jiao)流(liu)電(dian)(dian)源(yuan)指示燈，R1、R2、R3、R4分別(bie)是電(dian)(dian)容器(qi)(qi)(qi)C1、C2、C3、C4的(de)(de)泄放電(dian)(dian)阻，在不(bu)用充電(dian)(dian)器(qi)(qi)(qi)時，能及時將電(dian)(dian)容器(qi)(qi)(qi)上積存的(de)(de)電(dian)(dian)荷放掉；K1、K2、K3、K4是支路控制(zhi)開關，通(tong)過開關通(tong)斷控制(zhi)可以決定(ding)支路是否(fou)并(bing)入(ru)電(dian)(dian)路；R5、LED組成空(kong)載(zai)(zai)(zai)(zai)報(bao)警指示電(dian)(dian)路(為(wei)了安(an)全，充電(dian)(dian)器(qi)(qi)(qi)不(bu)可在空(kong)載(zai)(zai)(zai)(zai)狀態下(xia)插入(ru)220V交(jiao)流(liu)電(dian)(dian)源(yuan))，LED亮時，說明空(kong)載(zai)(zai)(zai)(zai)。電(dian)(dian)流(liu)表(biao)(biao)A指示充電(dian)(dian)電(dian)(dian)流(liu)的(de)(de)大小：電(dian)(dian)壓(ya)表(biao)(biao)V指示蓄電(dian)(dian)池兩端(duan)的(de)(de)電(dian)(dian)壓(ya)(為(wei)防止空(kong)載(zai)(zai)(zai)(zai)時電(dian)(dian)壓(ya)高燒壞(huai)電(dian)(dian)壓(ya)表(biao)(biao)，電(dian)(dian)壓(ya)表(biao)(biao)的(de)(de)接(jie)入(ru)與否(fou)受開關K5的(de)(de)控制(zhi))。

　　二、電路設計　　該充電器的(de)(de)(de)(de)限流電(dian)(dian)(dian)容器容量越(yue)(yue)大(da)(da)，容抗越(yue)(yue)小，充電(dian)(dian)(dian)電(dian)(dian)(dian)流越(yue)(yue)大(da)(da)。反(fan)之，充電(dian)(dian)(dian)電(dian)(dian)(dian)流越(yue)(yue)小。根據該(gai)原(yuan)理，可(ke)采(cai)用調(diao)整并(bing)聯(lian)電(dian)(dian)(dian)容的(de)(de)(de)(de)方法(fa)來達到(dao)調(diao)整充電(dian)(dian)(dian)電(dian)(dian)(dian)流大(da)(da)小的(de)(de)(de)(de)目(mu)的(de)(de)(de)(de)。以汽車(che)、摩托車(che)、電(dian)(dian)(dian)動自行車(che)常用的(de)(de)(de)(de)蓄電(dian)(dian)(dian)池為例，該(gai)充電(dian)(dian)(dian)電(dian)(dian)(dian)路(lu)設置了相(xiang)鄰級差為1A的(de)(de)(de)(de)1～15A的(de)(de)(de)(de)15級可(ke)調(diao)充電(dian)(dian)(dian)，通過四(si)條支路(lu)的(de)(de)(de)(de)不(bu)同并(bing)聯(lian)組合實現對畜電(dian)(dian)(dian)池充電(dian)(dian)(dian)電(dian)(dian)(dian)流的(de)(de)(de)(de)調(diao)整。

　　由純電(dian)(dian)(dian)容交流(liu)(liu)電(dian)(dian)(dian)路中(圖中各分流(liu)(liu)電(dian)(dian)(dian)阻的(de)(de)(de)分流(liu)(liu)很小，可忽(hu)略不計(ji))電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流(liu)(liu)、容抗之間(jian)的(de)(de)(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中，Xc表(biao)示電(dian)(dian)(dian)容器(qi)(qi)的(de)(de)(de)容抗，其(qi)(qi)單(dan)位(wei)為歐姆；U表(biao)示電(dian)(dian)(dian)容器(qi)(qi)兩端(duan)的(de)(de)(de)電(dian)(dian)(dian)壓，其(qi)(qi)單(dan)位(wei)為伏特(te)，其(qi)(qi)值為：交流(liu)(liu)電(dian)(dian)(dian)源的(de)(de)(de)總電(dian)(dian)(dian)壓220V-蓄電(dian)(dian)(dian)池放電(dian)(dian)(dian)的(de)(de)(de)下限電(dian)(dian)(dian)壓10V=210V；C表(biao)示電(dian)(dian)(dian)容器(qi)(qi)的(de)(de)(de)容量，其(qi)(qi)單(dan)位(wei)為法拉：f表(biao)示交流(liu)(liu)電(dian)(dian)(dian)的(de)(de)(de)頻(pin)率，其(qi)(qi)單(dan)位(wei)為赫茲(zi)，我國公(gong)共電(dian)(dian)(dian)網的(de)(de)(de)頻(pin)率為50赫茲(zi)；I表(biao)示通過電(dian)(dian)(dian)容器(qi)(qi)的(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)，其(qi)(qi)單(dan)位(wei)為安培；π取3．14)。

　　由以上(shang)計算結(jie)果(guo)可(ke)(ke)(ke)(ke)知(zhi)，當電(dian)(dian)(dian)容(rong)器(qi)C取(qu)15微(wei)(wei)法(即0．000015法拉)時，I=65940C=65940×0．000015≈1(A)。C1=15微(wei)(wei)法、C2=30微(wei)(wei)法、C3=60微(wei)(wei)法、C4=120微(wei)(wei)法，對(dui)應的(de)(de)各(ge)支路(lu)(lu)電(dian)(dian)(dian)流(liu)(liu)分(fen)別(bie)為1A、2A、4A、8A。通過各(ge)控制開(kai)關將以上(shang)四(si)個電(dian)(dian)(dian)容(rong)器(qi)進行適當的(de)(de)并聯組(zu)(zu)合便可(ke)(ke)(ke)(ke)得(de)到(dao)1A、2A、3A……15A的(de)(de)15組(zu)(zu)可(ke)(ke)(ke)(ke)調(diao)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)。如果(guo)想將電(dian)(dian)(dian)流(liu)(liu)調(diao)得(de)更(geng)精(jing)細些(xie)，可(ke)(ke)(ke)(ke)增加并聯支路(lu)(lu)。如增加7．5微(wei)(wei)法支路(lu)(lu)可(ke)(ke)(ke)(ke)得(de)到(dao)相(xiang)鄰(lin)級差為0．5A的(de)(de)0．5A～15．5A的(de)(de)31級可(ke)(ke)(ke)(ke)調(diao)充(chong)電(dian)(dian)(dian)控制系統，上(shang)述各(ge)支路(lu)(lu)電(dian)(dian)(dian)容(rong)器(qi)的(de)(de)容(rong)量若(ruo)只取(qu)其十分(fen)之(zhi)一，便可(ke)(ke)(ke)(ke)得(de)到(dao)相(xiang)鄰(lin)級差為O．1A的(de)(de)0．1～1．5A的(de)(de)15級可(ke)(ke)(ke)(ke)調(diao)并聯組(zu)(zu)合充(chong)電(dian)(dian)(dian)控制系統；若(ruo)只取(qu)其容(rong)量的(de)(de)百(bai)分(fen)之(zhi)一，便可(ke)(ke)(ke)(ke)得(de)到(dao)相(xiang)鄰(lin)級差為140mA的(de)(de)15級可(ke)(ke)(ke)(ke)調(diao)并聯組(zu)(zu)合充(chong)電(dian)(dian)(dian)控制系統。

　　三、制作方法　　指示燈L應選用額定工作電壓為220V的體積較小些的燈泡，也可以用10kΩ的電阻和一個小功率發光二極管串聯代替；控制開關K1、K2、K3、K4應分別選用額定工作電流不小于1．5A、3A、6A、12A的(de)(de)(de)；電(dian)(dian)容(rong)器C1、C2、C3、C4均選(xuan)(xuan)用耐壓(ya)不(bu)小(xiao)(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)(de)；泄放電(dian)(dian)阻R1、R2、R3、R4均選(xuan)(xuan)用220kΩ，1／2W規(gui)格(ge)的(de)(de)(de)；整(zheng)流(liu)堆D應(ying)選(xuan)(xuan)用額(e)定(ding)工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)不(bu)小(xiao)(xiao)(xiao)于50A，耐壓(ya)不(bu)小(xiao)(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)(de)；電(dian)(dian)流(liu)表(biao)A選(xuan)(xuan)用量程為20A或(huo)30A規(gui)格(ge)的(de)(de)(de)直流(liu)電(dian)(dian)流(liu)表(biao)；電(dian)(dian)壓(ya)表(biao)V應(ying)選(xuan)(xuan)用量程為50V規(gui)格(ge)的(de)(de)(de)直流(liu)電(dian)(dian)壓(ya)表(biao)；R5選(xuan)(xuan)用10kΩ／6W的(de)(de)(de)電(dian)(dian)阻；LED選(xuan)(xuan)用普(pu)通小(xiao)(xiao)(xiao)功率發光二極管；K5選(xuan)(xuan)用普(pu)通按鍵式開關，工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)大小(xiao)(xiao)(xiao)不(bu)作(zuo)(zuo)要求。將控(kong)制開關K1、K2、K3、K4并(bing)排裝在(zai)機(ji)殼(ke)面(mian)板(ban)上(shang)適當的(de)(de)(de)位(wei)(wei)置，并(bing)在(zai)K1、K2、K3、K4的(de)(de)(de)位(wei)(wei)置旁邊分別標注上(shang)1A、2A、4A、8A的(de)(de)(de)字(zi)樣，以(yi)便控(kong)制計算調(diao)整(zheng)。蓄電(dian)(dian)池接線柱的(de)(de)(de)工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)不(bu)小(xiao)(xiao)(xiao)于20A。

　　四、使用方法　　該充電器屬于無電源變壓器隔離式充電器，為了人身(shen)安全，充(chong)電(dian)(dian)時(shi)應(ying)嚴格照下列(lie)程序進行操作：　　1．檢查各個開(kai)(kai)關應(ying)處于斷開(kai)(kai)狀態(tai)，將(jiang)(jiang)蓄電(dian)(dian)池的(de)正、負極(ji)與接線(xian)柱(zhu)連接可靠，然(ran)后(hou)閉合K5，電(dian)(dian)壓表指示(shi)出蓄電(dian)(dian)池兩端的(de)電(dian)(dian)壓。　　2．將(jiang)(jiang)電(dian)(dian)源插頭插入220V交流電(dian)(dian)源，接通K1，此時(shi)，觀察電(dian)(dian)源指示(shi)燈亮(liang)，空載報警指示(shi)發(fa)光(guang)二極(ji)管不(bu)應(ying)亮(liang)。若發(fa)光(guang)二極(ji)管亮(liang)，說明蓄電(dian)(dian)池正、負極(ji)與充(chong)電(dian)(dian)器接線(xian)柱(zhu)之(zhi)間接觸不(bu)良，應(ying)除掉接點之(zhi)間的(de)臟物(wu)后(hou)再進行連接。　　3．根據蓄電(dian)(dian)池對充(chong)電(dian)(dian)電(dian)(dian)流的(de)要(yao)求，選擇(ze)合適的(de)控制開(kai)(kai)關接通并聯調整充(chong)電(dian)(dian)電(dian)(dian)流，充(chong)電(dian)(dian)電(dian)(dian)流數(shu)值(zhi)為接通的(de)開(kai)(kai)關電(dian)(dian)流數(shu)之(zhi)和。

　　該充(chong)(chong)電(dian)(dian)器的(de)(de)唯一缺陷是，不(bu)具備充(chong)(chong)滿(man)電(dian)(dian)后自動停充(chong)(chong)的(de)(de)功能。因各種蓄電(dian)(dian)池的(de)(de)電(dian)(dian)壓及容量都不(bu)一樣，讀者應根據不(bu)同(tong)蓄電(dian)(dian)池的(de)(de)要求決定(ding)充(chong)(chong)電(dian)(dian)的(de)(de)電(dian)(dian)流和充(chong)(chong)電(dian)(dian)時間，通(tong)過電(dian)(dian)壓表監視充(chong)(chong)電(dian)(dian)程度。