一、電路原理

　　如圖所示，該充電器屬于電容限流式無電源變壓器恒流充電器。220V交流(liu)(liu)電(dian)(dian)經K1～K4及其相(xiang)應阻(zu)容元件組(zu)成的(de)(de)(de)4條(tiao)并列(lie)支路選擇或組(zu)合，再經整(zheng)流(liu)(liu)堆D整(zheng)流(liu)(liu)后，通(tong)過(guo)電(dian)(dian)流(liu)(liu)表A，給蓄(xu)電(dian)(dian)池(chi)充電(dian)(dian)。在充電(dian)(dian)過(guo)程中，由于回路中蓄(xu)電(dian)(dian)池(chi)兩(liang)端(duan)電(dian)(dian)壓的(de)(de)(de)變化量相(xiang)對(dui)于220V交流(liu)(liu)電(dian)(dian)壓來(lai)說很小，電(dian)(dian)容兩(liang)端(duan)的(de)(de)(de)電(dian)(dian)壓降幾乎可認為(wei)是(shi)不變的(de)(de)(de)，所以(yi)，通(tong)過(guo)電(dian)(dian)容器(qi)的(de)(de)(de)電(dian)(dian)流(liu)(liu)也(ye)是(shi)不變的(de)(de)(de)，通(tong)過(guo)蓄(xu)電(dian)(dian)池(chi)內(nei)部的(de)(de)(de)充電(dian)(dian)電(dian)(dian)流(liu)(liu)自然也(ye)是(shi)恒定的(de)(de)(de)。

　　圖中，L為220V交流電源指示燈，R1、R2、R3、R4分別是電容器C1、C2、C3、C4的泄放電阻，在不用充電器時，能及時將電(dian)(dian)(dian)(dian)(dian)容器(qi)上積存的電(dian)(dian)(dian)(dian)(dian)荷放掉(diao)；K1、K2、K3、K4是(shi)支路(lu)控(kong)制(zhi)開(kai)關(guan)，通過開(kai)關(guan)通斷(duan)控(kong)制(zhi)可(ke)以決(jue)定支路(lu)是(shi)否并(bing)入(ru)電(dian)(dian)(dian)(dian)(dian)路(lu)；R5、LED組成(cheng)空(kong)(kong)載報(bao)警(jing)指(zhi)示(shi)電(dian)(dian)(dian)(dian)(dian)路(lu)(為了安全，充電(dian)(dian)(dian)(dian)(dian)器(qi)不可(ke)在空(kong)(kong)載狀態下插入(ru)220V交(jiao)流電(dian)(dian)(dian)(dian)(dian)源(yuan))，LED亮時，說明空(kong)(kong)載。電(dian)(dian)(dian)(dian)(dian)流表A指(zhi)示(shi)充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的大小(xiao)：電(dian)(dian)(dian)(dian)(dian)壓表V指(zhi)示(shi)蓄電(dian)(dian)(dian)(dian)(dian)池兩端的電(dian)(dian)(dian)(dian)(dian)壓(為防止(zhi)空(kong)(kong)載時電(dian)(dian)(dian)(dian)(dian)壓高燒壞電(dian)(dian)(dian)(dian)(dian)壓表，電(dian)(dian)(dian)(dian)(dian)壓表的接入(ru)與否受開(kai)關(guan)K5的控(kong)制(zhi))。

　　二、電路設計

　　該(gai)充電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)的(de)(de)(de)限流電(dian)(dian)(dian)(dian)(dian)(dian)容器(qi)容量越(yue)大，容抗越(yue)小，充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流越(yue)大。反(fan)之，充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流越(yue)小。根(gen)據該(gai)原理，可采用調整(zheng)并聯電(dian)(dian)(dian)(dian)(dian)(dian)容的(de)(de)(de)方法來達到調整(zheng)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流大小的(de)(de)(de)目的(de)(de)(de)。以汽車、摩托車、電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)自行車常用的(de)(de)(de)蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)為(wei)例，該(gai)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)路設置了(le)相鄰級(ji)(ji)差為(wei)1A的(de)(de)(de)1～15A的(de)(de)(de)15級(ji)(ji)可調充電(dian)(dian)(dian)(dian)(dian)(dian)，通過(guo)四條支路的(de)(de)(de)不(bu)同并聯組合實現對畜電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)調整(zheng)。

　　由純電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(圖中(zhong)各分流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)阻的(de)分流(liu)很小，可(ke)忽略不計)電(dian)(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)、容(rong)(rong)(rong)抗之間(jian)的(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)，Xc表(biao)(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)的(de)容(rong)(rong)(rong)抗，其單(dan)位(wei)(wei)為(wei)(wei)歐姆；U表(biao)(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)兩端的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓，其單(dan)位(wei)(wei)為(wei)(wei)伏特(te)，其值為(wei)(wei)：交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)源的(de)總電(dian)(dian)(dian)(dian)(dian)(dian)壓220V-蓄電(dian)(dian)(dian)(dian)(dian)(dian)池放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)下限(xian)電(dian)(dian)(dian)(dian)(dian)(dian)壓10V=210V；C表(biao)(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)的(de)容(rong)(rong)(rong)量，其單(dan)位(wei)(wei)為(wei)(wei)法拉(la)：f表(biao)(biao)示交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)頻率，其單(dan)位(wei)(wei)為(wei)(wei)赫茲，我國公(gong)共(gong)電(dian)(dian)(dian)(dian)(dian)(dian)網的(de)頻率為(wei)(wei)50赫茲；I表(biao)(biao)示通過電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，其單(dan)位(wei)(wei)為(wei)(wei)安(an)培；π取3．14)。

　　由(you)以上計算結果可(ke)(ke)知，當(dang)電容(rong)(rong)器C取(qu)15微(wei)法(即0．000015法拉)時，I=65940C=65940×0．000015≈1(A)。C1=15微(wei)法、C2=30微(wei)法、C3=60微(wei)法、C4=120微(wei)法，對應的(de)(de)(de)各支路(lu)電流(liu)(liu)分(fen)別為1A、2A、4A、8A。通(tong)過各控制開關(guan)將(jiang)以上四(si)個電容(rong)(rong)器進行(xing)適當(dang)的(de)(de)(de)并(bing)聯(lian)組合(he)便(bian)可(ke)(ke)得(de)到(dao)1A、2A、3A……15A的(de)(de)(de)15組可(ke)(ke)調(diao)充電電流(liu)(liu)。如果想將(jiang)電流(liu)(liu)調(diao)得(de)更(geng)精細些，可(ke)(ke)增(zeng)加并(bing)聯(lian)支路(lu)。如增(zeng)加7．5微(wei)法支路(lu)可(ke)(ke)得(de)到(dao)相鄰(lin)級(ji)(ji)差為0．5A的(de)(de)(de)0．5A～15．5A的(de)(de)(de)31級(ji)(ji)可(ke)(ke)調(diao)充電控制系(xi)統(tong)，上述各支路(lu)電容(rong)(rong)器的(de)(de)(de)容(rong)(rong)量若(ruo)只(zhi)取(qu)其十分(fen)之一(yi)，便(bian)可(ke)(ke)得(de)到(dao)相鄰(lin)級(ji)(ji)差為O．1A的(de)(de)(de)0．1～1．5A的(de)(de)(de)15級(ji)(ji)可(ke)(ke)調(diao)并(bing)聯(lian)組合(he)充電控制系(xi)統(tong)；若(ruo)只(zhi)取(qu)其容(rong)(rong)量的(de)(de)(de)百(bai)分(fen)之一(yi)，便(bian)可(ke)(ke)得(de)到(dao)相鄰(lin)級(ji)(ji)差為140mA的(de)(de)(de)15級(ji)(ji)可(ke)(ke)調(diao)并(bing)聯(lian)組合(he)充電控制系(xi)統(tong)。

　　三、制作方法

　　指示燈L應(ying)選(xuan)用(yong)(yong)額定工(gong)(gong)作(zuo)電(dian)(dian)(dian)壓為(wei)220V的(de)體積較小(xiao)些的(de)燈泡，也可(ke)以用(yong)(yong)10kΩ的(de)電(dian)(dian)(dian)阻(zu)和一個小(xiao)功(gong)率(lv)發光(guang)(guang)二極管串聯代(dai)替；控制開(kai)關K1、K2、K3、K4應(ying)分別選(xuan)用(yong)(yong)額定工(gong)(gong)作(zuo)電(dian)(dian)(dian)流(liu)不小(xiao)于(yu)1．5A、3A、6A、12A的(de)；電(dian)(dian)(dian)容器C1、C2、C3、C4均(jun)選(xuan)用(yong)(yong)耐壓不小(xiao)于(yu)400V規格(ge)的(de)；泄放電(dian)(dian)(dian)阻(zu)R1、R2、R3、R4均(jun)選(xuan)用(yong)(yong)220kΩ，1／2W規格(ge)的(de)；整流(liu)堆D應(ying)選(xuan)用(yong)(yong)額定工(gong)(gong)作(zuo)電(dian)(dian)(dian)流(liu)不小(xiao)于(yu)50A，耐壓不小(xiao)于(yu)400V規格(ge)的(de)；電(dian)(dian)(dian)流(liu)表(biao)A選(xuan)用(yong)(yong)量程為(wei)20A或30A規格(ge)的(de)直流(liu)電(dian)(dian)(dian)流(liu)表(biao)；電(dian)(dian)(dian)壓表(biao)V應(ying)選(xuan)用(yong)(yong)量程為(wei)50V規格(ge)的(de)直流(liu)電(dian)(dian)(dian)壓表(biao)；R5選(xuan)用(yong)(yong)10kΩ／6W的(de)電(dian)(dian)(dian)阻(zu)；LED選(xuan)用(yong)(yong)普通(tong)小(xiao)功(gong)率(lv)發光(guang)(guang)二極管；K5選(xuan)用(yong)(yong)普通(tong)按鍵式開(kai)關，工(gong)(gong)作(zuo)電(dian)(dian)(dian)流(liu)大小(xiao)不作(zuo)要求(qiu)。將(jiang)控制開(kai)關K1