本文介紹一款電路簡單、性能可靠的多用恒流充電器。

　　一、電(dian)(dian)(dian)(dian)路原理　　如圖所示，該充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)(qi)屬于(yu)電(dian)(dian)(dian)(dian)容(rong)限流(liu)式無電(dian)(dian)(dian)(dian)源(yuan)變壓(ya)器(qi)(qi)恒(heng)流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)(qi)。220V交流(liu)電(dian)(dian)(dian)(dian)經K1～K4及其相應阻容(rong)元件(jian)組成的(de)4條(tiao)并列支路選擇或組合，再經整流(liu)堆D整流(liu)后，通(tong)過電(dian)(dian)(dian)(dian)流(liu)表(biao)A，給蓄電(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)。在充(chong)(chong)電(dian)(dian)(dian)(dian)過程中(zhong)，由于(yu)回路中(zhong)蓄電(dian)(dian)(dian)(dian)池(chi)(chi)兩端電(dian)(dian)(dian)(dian)的(de)變化量相對于(yu)220V交流(liu)電(dian)(dian)(dian)(dian)壓(ya)來說很(hen)小，電(dian)(dian)(dian)(dian)容(rong)兩端的(de)電(dian)(dian)(dian)(dian)壓(ya)降(jiang)幾乎可(ke)認為是(shi)不變的(de)，所以(yi)，通(tong)過電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)的(de)電(dian)(dian)(dian)(dian)流(liu)也是(shi)不變的(de)，通(tong)過蓄電(dian)(dian)(dian)(dian)池(chi)(chi)內(nei)部(bu)的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)自然(ran)也是(shi)恒(heng)定(ding)的(de)。 　　

     L為(wei)(wei)220V交流(liu)(liu)電(dian)(dian)(dian)(dian)源(yuan)指(zhi)示燈，R1、R2、R3、R4分別(bie)是電(dian)(dian)(dian)(dian)容器C1、C2、C3、C4的泄放電(dian)(dian)(dian)(dian)阻，在(zai)不用充電(dian)(dian)(dian)(dian)器時，能及(ji)時將電(dian)(dian)(dian)(dian)容器上(shang)積存(cun)的電(dian)(dian)(dian)(dian)荷放掉；K1、K2、K3、K4是支路控(kong)制開關，通過開關通斷控(kong)制可以決定支路是否并入電(dian)(dian)(dian)(dian)路；R5、LED組成空(kong)(kong)載報警指(zhi)示電(dian)(dian)(dian)(dian)路(為(wei)(wei)了安全(quan)，充電(dian)(dian)(dian)(dian)器不可在(zai)空(kong)(kong)載狀態下插入220V交流(liu)(liu)電(dian)(dian)(dian)(dian)源(yuan))，LED亮(liang)時，說明空(kong)(kong)載。電(dian)(dian)(dian)(dian)流(liu)(liu)表A指(zhi)示充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)的大小：電(dian)(dian)(dian)(dian)壓表V指(zhi)示蓄(xu)電(dian)(dian)(dian)(dian)池兩端的電(dian)(dian)(dian)(dian)壓(為(wei)(wei)防(fang)止空(kong)(kong)載時電(dian)(dian)(dian)(dian)壓高燒(shao)壞電(dian)(dian)(dian)(dian)壓表，電(dian)(dian)(dian)(dian)壓表的接入與否受開關K5的控(kong)制)。

　　二、電路設計　　該充電器的限流(liu)(liu)電(dian)容(rong)器容(rong)量越大(da)，容(rong)抗(kang)越小(xiao)，充電(dian)電(dian)流(liu)(liu)越大(da)。反之，充電(dian)電(dian)流(liu)(liu)越小(xiao)。根據該原理，可采用(yong)(yong)調(diao)整并聯(lian)電(dian)容(rong)的方法來達到調(diao)整充電(dian)電(dian)流(liu)(liu)大(da)小(xiao)的目的。以(yi)汽車、摩托(tuo)車、電(dian)動自行車常用(yong)(yong)的蓄電(dian)池為(wei)例，該充電(dian)電(dian)路(lu)(lu)設置了相鄰級差為(wei)1A的1～15A的15級可調(diao)充電(dian)，通過四條支路(lu)(lu)的不同并聯(lian)組合實現(xian)對(dui)畜電(dian)池充電(dian)電(dian)流(liu)(liu)的調(diao)整。

　　由純電(dian)(dian)(dian)(dian)(dian)容(rong)交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)路中(圖中各分(fen)流(liu)電(dian)(dian)(dian)(dian)(dian)阻的分(fen)流(liu)很小，可忽略不計)電(dian)(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)(dian)流(liu)、容(rong)抗(kang)之間的關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中，Xc表(biao)示(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)的容(rong)抗(kang)，其單(dan)位(wei)為(wei)歐姆；U表(biao)示(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)兩端的電(dian)(dian)(dian)(dian)(dian)壓(ya)，其單(dan)位(wei)為(wei)伏特(te)，其值(zhi)為(wei)：交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)源的總(zong)電(dian)(dian)(dian)(dian)(dian)壓(ya)220V-蓄電(dian)(dian)(dian)(dian)(dian)池放電(dian)(dian)(dian)(dian)(dian)的下限電(dian)(dian)(dian)(dian)(dian)壓(ya)10V=210V；C表(biao)示(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)的容(rong)量，其單(dan)位(wei)為(wei)法拉：f表(biao)示(shi)(shi)(shi)交(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)的頻率(lv)，其單(dan)位(wei)為(wei)赫茲，我國公共電(dian)(dian)(dian)(dian)(dian)網(wang)的頻率(lv)為(wei)50赫茲；I表(biao)示(shi)(shi)(shi)通過電(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)的電(dian)(dian)(dian)(dian)(dian)流(liu)，其單(dan)位(wei)為(wei)安培(pei)；π取(qu)3．14)。

　　由以上計算結(jie)果(guo)可(ke)(ke)(ke)(ke)知，當(dang)電(dian)容器C取(qu)15微法(即0．000015法拉(la))時，I=65940C=65940×0．000015≈1(A)。C1=15微法、C2=30微法、C3=60微法、C4=120微法，對應的(de)(de)(de)(de)(de)各(ge)支(zhi)路(lu)(lu)電(dian)流分別(bie)為(wei)1A、2A、4A、8A。通過各(ge)控(kong)制(zhi)(zhi)(zhi)開(kai)關將以上四個(ge)電(dian)容器進(jin)行(xing)適當(dang)的(de)(de)(de)(de)(de)并(bing)(bing)聯組合便可(ke)(ke)(ke)(ke)得到1A、2A、3A……15A的(de)(de)(de)(de)(de)15組可(ke)(ke)(ke)(ke)調(diao)充(chong)電(dian)電(dian)流。如(ru)果(guo)想將電(dian)流調(diao)得更精細些，可(ke)(ke)(ke)(ke)增(zeng)加并(bing)(bing)聯支(zhi)路(lu)(lu)。如(ru)增(zeng)加7．5微法支(zhi)路(lu)(lu)可(ke)(ke)(ke)(ke)得到相(xiang)鄰(lin)級差(cha)為(wei)0．5A的(de)(de)(de)(de)(de)0．5A～15．5A的(de)(de)(de)(de)(de)31級可(ke)(ke)(ke)(ke)調(diao)充(chong)電(dian)控(kong)制(zhi)(zhi)(zhi)系(xi)統，上述(shu)各(ge)支(zhi)路(lu)(lu)電(dian)容器的(de)(de)(de)(de)(de)容量若只(zhi)(zhi)取(qu)其十(shi)分之一，便可(ke)(ke)(ke)(ke)得到相(xiang)鄰(lin)級差(cha)為(wei)O．1A的(de)(de)(de)(de)(de)0．1～1．5A的(de)(de)(de)(de)(de)15級可(ke)(ke)(ke)(ke)調(diao)并(bing)(bing)聯組合充(chong)電(dian)控(kong)制(zhi)(zhi)(zhi)系(xi)統；若只(zhi)(zhi)取(qu)其容量的(de)(de)(de)(de)(de)百(bai)分之一，便可(ke)(ke)(ke)(ke)得到相(xiang)鄰(lin)級差(cha)為(wei)140mA的(de)(de)(de)(de)(de)15級可(ke)(ke)(ke)(ke)調(diao)并(bing)(bing)聯組合充(chong)電(dian)控(kong)制(zhi)(zhi)(zhi)系(xi)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)；電(dian)容(rong)器C1、C2、C3、C4均選(xuan)用(yong)(yong)耐壓不(bu)小(xiao)于400V規(gui)格(ge)(ge)的(de)；泄放(fang)電(dian)阻(zu)R1、R2、R3、R4均選(xuan)用(yong)(yong)220kΩ，1／2W規(gui)格(ge)(ge)的(de)；整流(liu)堆D應(ying)選(xuan)用(yong)(yong)額定工(gong)作電(dian)流(liu)不(bu)小(xiao)于50A，耐壓不(bu)小(xiao)于400V規(gui)格(ge)(ge)的(de)；電(dian)流(liu)表A選(xuan)用(yong)(yong)量(liang)程為20A或30A規(gui)格(ge)(ge)的(de)直(zhi)流(liu)電(dian)流(liu)表；電(dian)壓表V應(ying)選(xuan)用(yong)(yong)量(liang)程為50V規(gui)格(ge)(ge)的(de)直(zhi)流(liu)電(dian)壓表；R5選(xuan)用(yong)(yong)10kΩ／6W的(de)電(dian)阻(zu)；LED選(xuan)用(yong)(yong)普(pu)(pu)通小(xiao)功(gong)率發光(guang)二(er)極管；K5選(xuan)用(yong)(yong)普(pu)(pu)通按鍵式開關，工(gong)作電(dian)流(liu)大(da)小(xiao)不(bu)作要求。將(jiang)控(kong)(kong)制開關K1、K2、K3、K4并(bing)(bing)排裝(zhuang)在(zai)機殼(ke)面板(ban)上適當的(de)位置，并(bing)(bing)在(zai)K1、K2、K3、K4的(de)位置旁(pang)邊分別標注(zhu)上1A、2A、4A、8A的(de)字樣，以便控(kong)(kong)制計算調整。蓄電(dian)池接線柱(zhu)的(de)工(gong)作電(dian)流(liu)不(bu)小(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(wei)了人身安全，充電(dian)(dian)(dian)時應嚴格照下列程序(xu)進(jin)行操作：　　1．檢查各個(ge)開(kai)關(guan)應處于(yu)斷開(kai)狀(zhuang)態，將蓄電(dian)(dian)(dian)池(chi)的正、負(fu)極(ji)與接(jie)(jie)線柱(zhu)連(lian)接(jie)(jie)可靠，然后(hou)(hou)閉合K5，電(dian)(dian)(dian)壓表指示(shi)出蓄電(dian)(dian)(dian)池(chi)兩端的電(dian)(dian)(dian)壓。　　2．將電(dian)(dian)(dian)源(yuan)(yuan)插頭插入220V交流電(dian)(dian)(dian)源(yuan)(yuan)，接(jie)(jie)通(tong)K1，此(ci)時，觀察電(dian)(dian)(dian)源(yuan)(yuan)指示(shi)燈亮(liang)(liang)，空載報(bao)警指示(shi)發(fa)光二(er)(er)極(ji)管不應亮(liang)(liang)。若發(fa)光二(er)(er)極(ji)管亮(liang)(liang)，說明蓄電(dian)(dian)(dian)池(chi)正、負(fu)極(ji)與充電(dian)(dian)(dian)器接(jie)(jie)線柱(zhu)之(zhi)間(jian)接(jie)(jie)觸不良，應除掉接(jie)(jie)點之(zhi)間(jian)的臟物后(hou)(hou)再(zai)進(jin)行連(lian)接(jie)(jie)。　　3．根(gen)據蓄電(dian)(dian)(dian)池(chi)對充電(dian)(dian)(dian)電(dian)(dian)(dian)流的要求，選擇合適的控制開(kai)關(guan)接(jie)(jie)通(tong)并聯調整充電(dian)(dian)(dian)電(dian)(dian)(dian)流，充電(dian)(dian)(dian)電(dian)(dian)(dian)流數值為(wei)接(jie)(jie)通(tong)的開(kai)關(guan)電(dian)(dian)(dian)流數之(zhi)和。

　　該充(chong)(chong)電(dian)(dian)(dian)(dian)器的(de)唯一(yi)缺陷是，不具備(bei)充(chong)(chong)滿電(dian)(dian)(dian)(dian)后自動(dong)停充(chong)(chong)的(de)功(gong)能。因各種蓄電(dian)(dian)(dian)(dian)池(chi)的(de)電(dian)(dian)(dian)(dian)壓(ya)及(ji)容(rong)量都(dou)不一(yi)樣，讀者應根據不同蓄電(dian)(dian)(dian)(dian)池(chi)的(de)要求決定充(chong)(chong)電(dian)(dian)(dian)(dian)的(de)電(dian)(dian)(dian)(dian)流和(he)充(chong)(chong)電(dian)(dian)(dian)(dian)時間，通過(guo)電(dian)(dian)(dian)(dian)壓(ya)表(biao)監視充(chong)(chong)電(dian)(dian)(dian)(dian)程度。