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)電經K1～K4及其相應阻(zu)容元件組成的(de)(de)4條并列支路選擇或組合，再(zai)經整流(liu)堆D整流(liu)后，通(tong)(tong)過(guo)電流(liu)表A，給蓄(xu)(xu)電池(chi)充電。在充電過(guo)程中，由于回路中蓄(xu)(xu)電池(chi)兩端電壓的(de)(de)變(bian)(bian)化量相對于220V交流(liu)電壓來說很小，電容兩端的(de)(de)電壓降幾乎(hu)可認為是(shi)不(bu)(bu)變(bian)(bian)的(de)(de)，所以，通(tong)(tong)過(guo)電容器的(de)(de)電流(liu)也是(shi)不(bu)(bu)變(bian)(bian)的(de)(de)，通(tong)(tong)過(guo)蓄(xu)(xu)電池(chi)內部(bu)的(de)(de)充電電流(liu)自(zi)然也是(shi)恒定(ding)的(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(shi)，能及時(shi)將電(dian)(dian)(dian)(dian)容器上積(ji)存的(de)(de)電(dian)(dian)(dian)(dian)荷放掉；K1、K2、K3、K4是(shi)支路控制開(kai)(kai)關，通(tong)過開(kai)(kai)關通(tong)斷控制可(ke)以(yi)決定支路是(shi)否并入電(dian)(dian)(dian)(dian)路；R5、LED組(zu)成空(kong)載(zai)報警指示電(dian)(dian)(dian)(dian)路(為(wei)了(le)安(an)全，充電(dian)(dian)(dian)(dian)器不可(ke)在(zai)空(kong)載(zai)狀態(tai)下插入220V交流(liu)電(dian)(dian)(dian)(dian)源)，LED亮時(shi)，說明空(kong)載(zai)。電(dian)(dian)(dian)(dian)流(liu)表(biao)A指示充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)的(de)(de)大小：電(dian)(dian)(dian)(dian)壓(ya)表(biao)V指示蓄電(dian)(dian)(dian)(dian)池兩端的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(為(wei)防止(zhi)空(kong)載(zai)時(shi)電(dian)(dian)(dian)(dian)壓(ya)高燒壞(huai)電(dian)(dian)(dian)(dian)壓(ya)表(biao)，電(dian)(dian)(dian)(dian)壓(ya)表(biao)的(de)(de)接入與否受開(kai)(kai)關K5的(de)(de)控制)。

　　二、電路設計

　　該充(chong)電(dian)(dian)(dian)(dian)(dian)器的(de)限(xian)流電(dian)(dian)(dian)(dian)(dian)容器容量越(yue)大，容抗(kang)越(yue)小(xiao)(xiao)，充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流越(yue)大。反之，充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流越(yue)小(xiao)(xiao)。根據該原理，可采用(yong)調(diao)整(zheng)(zheng)并(bing)聯(lian)(lian)電(dian)(dian)(dian)(dian)(dian)容的(de)方法來達(da)到調(diao)整(zheng)(zheng)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流大小(xiao)(xiao)的(de)目(mu)的(de)。以汽車(che)、摩托車(che)、電(dian)(dian)(dian)(dian)(dian)動自行車(che)常用(yong)的(de)蓄電(dian)(dian)(dian)(dian)(dian)池(chi)為例，該充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路設置了相鄰(lin)級差為1A的(de)1～15A的(de)15級可調(diao)充(chong)電(dian)(dian)(dian)(dian)(dian)，通過四條支路的(de)不同并(bing)聯(lian)(lian)組合實現對畜(chu)電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的(de)調(diao)整(zheng)(zheng)。

　　由(you)純電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)路中(zhong)(圖中(zhong)各分(fen)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)阻的(de)(de)(de)分(fen)流(liu)(liu)(liu)很小，可忽略不計)電(dian)(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)、容(rong)(rong)(rong)(rong)抗(kang)之(zhi)間的(de)(de)(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)，Xc表(biao)示(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的(de)(de)(de)容(rong)(rong)(rong)(rong)抗(kang)，其(qi)(qi)(qi)單位(wei)(wei)為(wei)歐姆；U表(biao)示(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)兩端的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)，其(qi)(qi)(qi)單位(wei)(wei)為(wei)伏特，其(qi)(qi)(qi)值為(wei)：交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)總電(dian)(dian)(dian)(dian)(dian)壓(ya)220V-蓄電(dian)(dian)(dian)(dian)(dian)池放電(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)下限(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)10V=210V；C表(biao)示(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的(de)(de)(de)容(rong)(rong)(rong)(rong)量，其(qi)(qi)(qi)單位(wei)(wei)為(wei)法拉：f表(biao)示(shi)交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)頻率(lv)，其(qi)(qi)(qi)單位(wei)(wei)為(wei)赫(he)(he)茲，我國公共電(dian)(dian)(dian)(dian)(dian)網的(de)(de)(de)頻率(lv)為(wei)50赫(he)(he)茲；I表(biao)示(shi)通過電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，其(qi)(qi)(qi)單位(wei)(wei)為(wei)安(an)培；π取3．14)。

　　由(you)以上計算結果(guo)可知，當(dang)電(dian)(dian)容(rong)(rong)器C取(qu)(qu)15微(wei)法(fa)(fa)(即(ji)0．000015法(fa)(fa)拉(la))時，I=65940C=65940×0．000015≈1(A)。C1=15微(wei)法(fa)(fa)、C2=30微(wei)法(fa)(fa)、C3=60微(wei)法(fa)(fa)、C4=120微(wei)法(fa)(fa)，對應的(de)(de)各支路(lu)電(dian)(dian)流(liu)分(fen)別(bie)為1A、2A、4A、8A。通(tong)過各控制(zhi)(zhi)開關將以上四個電(dian)(dian)容(rong)(rong)器進行適當(dang)的(de)(de)并(bing)(bing)聯(lian)(lian)組合(he)便(bian)可得(de)到(dao)1A、2A、3A……15A的(de)(de)15組可調充電(dian)(dian)電(dian)(dian)流(liu)。如果(guo)想(xiang)將電(dian)(dian)流(liu)調得(de)更精細些，可增加(jia)并(bing)(bing)聯(lian)(lian)支路(lu)。如增加(jia)7．5微(wei)法(fa)(fa)支路(lu)可得(de)到(dao)相(xiang)鄰級(ji)差(cha)(cha)為0．5A的(de)(de)0．5A～15．5A的(de)(de)31級(ji)可調充電(dian)(dian)控制(zhi)(zhi)系(xi)統(tong)，上述各支路(lu)電(dian)(dian)容(rong)(rong)器的(de)(de)容(rong)(rong)量若只取(qu)(qu)其十分(fen)之一(yi)，便(bian)可得(de)到(dao)相(xiang)鄰級(ji)差(cha)(cha)為O．1A的(de)(de)0．1～1．5A的(de)(de)15級(ji)可調并(bing)(bing)聯(lian)(lian)組合(he)充電(dian)(dian)控制(zhi)(zhi)系(xi)統(tong)；若只取(qu)(qu)其容(rong)(rong)量的(de)(de)百分(fen)之一(yi)，便(bian)可得(de)到(dao)相(xiang)鄰級(ji)差(cha)(cha)為140mA的(de)(de)15級(ji)可調并(bing)(bing)聯(lian)(lian)組合(he)充電(dian)(dian)控制(zhi)(zhi)系(xi)統(tong)。

　　三、制作方法

　　指示燈(deng)L應選(xuan)用(yong)(yong)額定(ding)工(gong)作(zuo)電(dian)(dian)(dian)壓(ya)為(wei)(wei)220V的(de)(de)(de)(de)(de)(de)(de)體積較小(xiao)(xiao)些的(de)(de)(de)(de)(de)(de)(de)燈(deng)泡，也可以用(yong)(yong)10kΩ的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)阻(zu)和一個小(xiao)(xiao)功率(lv)發光二極管(guan)串聯代(dai)替；控制開(kai)(kai)關(guan)K1、K2、K3、K4應分別選(xuan)用(yong)(yong)額定(ding)工(gong)作(zuo)電(dian)(dian)(dian)流不(bu)小(xiao)(xiao)于1．5A、3A、6A、12A的(de)(de)(de)(de)(de)(de)(de)；電(dian)(dian)(dian)容器C1、C2、C3、C4均選(xuan)用(yong)(yong)耐壓(ya)不(bu)小(xiao)(xiao)于400V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)(de)(de)(de)；泄(xie)放電(dian)(dian)(dian)阻(zu)R1、R2、R3、R4均選(xuan)用(yong)(yong)220kΩ，1／2W規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)(de)(de)(de)；整流堆(dui)D應選(xuan)用(yong)(yong)額定(ding)工(gong)作(zuo)電(dian)(dian)(dian)流不(bu)小(xiao)(xiao)于50A，耐壓(ya)不(bu)小(xiao)(xiao)于400V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)(de)(de)(de)；電(dian)(dian)(dian)流表(biao)(biao)(biao)A選(xuan)用(yong)(yong)量(liang)程為(wei)(wei)20A或30A規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)(de)(de)(de)直流電(dian)(dian)(dian)流表(biao)(biao)(biao)；電(dian)(dian)(dian)壓(ya)表(biao)(biao)(biao)V應選(xuan)用(yong)(yong)量(liang)程為(wei)(wei)50V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)(de)(de)(de)直流電(dian)(dian)(dian)壓(ya)表(biao)(biao)(biao)；R5選(xuan)用(yong)(yong)10kΩ／6W的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)阻(zu)；LED選(xuan)用(yong)(yong)普(pu)通(tong)小(xiao)(xiao)功率(lv)發光二極管(guan)；K5選(xuan)用(yong)(yong)普(pu)通(tong)按鍵式開(kai)(kai)關(guan)，工(gong)作(zuo)電(dian)(dian)(dian)流大小(xiao)(xiao)不(bu)作(zuo)要求。將(jiang)控制開(kai)(kai)關(guan)K1