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(dian)(dian)(dian)(dian)經K1～K4及其相(xiang)應阻(zu)容元件組(zu)(zu)成(cheng)的(de)(de)4條并列(lie)支路選擇或(huo)組(zu)(zu)合，再經整(zheng)流(liu)堆(dui)D整(zheng)流(liu)后，通過(guo)電(dian)(dian)(dian)(dian)流(liu)表A，給蓄電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)。在(zai)充電(dian)(dian)(dian)(dian)過(guo)程(cheng)中，由(you)于回路中蓄電(dian)(dian)(dian)(dian)池(chi)兩端電(dian)(dian)(dian)(dian)壓的(de)(de)變(bian)化量相(xiang)對于220V交流(liu)電(dian)(dian)(dian)(dian)壓來(lai)說很小，電(dian)(dian)(dian)(dian)容兩端的(de)(de)電(dian)(dian)(dian)(dian)壓降(jiang)幾乎(hu)可認為是(shi)不變(bian)的(de)(de)，所以，通過(guo)電(dian)(dian)(dian)(dian)容器的(de)(de)電(dian)(dian)(dian)(dian)流(liu)也是(shi)不變(bian)的(de)(de)，通過(guo)蓄電(dian)(dian)(dian)(dian)池(chi)內部的(de)(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)自然(ran)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)容器上積存的(de)電(dian)(dian)(dian)荷放掉；K1、K2、K3、K4是支(zhi)(zhi)路控制(zhi)開關，通(tong)過開關通(tong)斷控制(zhi)可以決定支(zhi)(zhi)路是否并入(ru)電(dian)(dian)(dian)路；R5、LED組(zu)成(cheng)空(kong)(kong)載(zai)報警指(zhi)示電(dian)(dian)(dian)路(為了安全，充電(dian)(dian)(dian)器不可在空(kong)(kong)載(zai)狀態下插入(ru)220V交流(liu)電(dian)(dian)(dian)源(yuan))，LED亮時(shi)，說明空(kong)(kong)載(zai)。電(dian)(dian)(dian)流(liu)表(biao)A指(zhi)示充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)的(de)大小：電(dian)(dian)(dian)壓(ya)表(biao)V指(zhi)示蓄電(dian)(dian)(dian)池兩端的(de)電(dian)(dian)(dian)壓(ya)(為防止空(kong)(kong)載(zai)時(shi)電(dian)(dian)(dian)壓(ya)高燒壞(huai)電(dian)(dian)(dian)壓(ya)表(biao)，電(dian)(dian)(dian)壓(ya)表(biao)的(de)接入(ru)與(yu)否受開關K5的(de)控制(zhi))。

　　二、電路設計

　　該(gai)充(chong)電(dian)(dian)(dian)器(qi)的(de)(de)限(xian)流(liu)電(dian)(dian)(dian)容(rong)(rong)器(qi)容(rong)(rong)量(liang)越大(da)，容(rong)(rong)抗越小(xiao)(xiao)(xiao)，充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)越大(da)。反之，充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)越小(xiao)(xiao)(xiao)。根據該(gai)原理，可采用(yong)調整并(bing)聯(lian)電(dian)(dian)(dian)容(rong)(rong)的(de)(de)方法來達到調整充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)大(da)小(xiao)(xiao)(xiao)的(de)(de)目的(de)(de)。以(yi)汽車(che)、摩托車(che)、電(dian)(dian)(dian)動自行車(che)常用(yong)的(de)(de)蓄電(dian)(dian)(dian)池為例，該(gai)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)路設(she)置了相鄰級(ji)差為1A的(de)(de)1～15A的(de)(de)15級(ji)可調充(chong)電(dian)(dian)(dian)，通過四條支路的(de)(de)不同(tong)并(bing)聯(lian)組合實現對畜電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)的(de)(de)調整。

　　由純電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)交流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(圖中(zhong)各(ge)分流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻的(de)(de)分流(liu)(liu)(liu)(liu)很(hen)小，可(ke)忽略(lve)不計)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)、容(rong)抗之間的(de)(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)，Xc表(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器的(de)(de)容(rong)抗，其(qi)(qi)單(dan)(dan)位(wei)為(wei)歐(ou)姆；U表(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器兩(liang)端(duan)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，其(qi)(qi)單(dan)(dan)位(wei)為(wei)伏(fu)特，其(qi)(qi)值為(wei)：交流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源的(de)(de)總電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)220V-蓄電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)下限電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)10V=210V；C表(biao)示電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器的(de)(de)容(rong)量，其(qi)(qi)單(dan)(dan)位(wei)為(wei)法拉：f表(biao)示交流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)頻率，其(qi)(qi)單(dan)(dan)位(wei)為(wei)赫(he)茲，我(wo)國公共電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)網(wang)的(de)(de)頻率為(wei)50赫(he)茲；I表(biao)示通過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，其(qi)(qi)單(dan)(dan)位(wei)為(wei)安培；π取3．14)。

　　由以上計算結果可(ke)(ke)(ke)(ke)知，當(dang)電(dian)容(rong)器C取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，對應的各支(zhi)(zhi)路電(dian)流分別(bie)為(wei)(wei)1A、2A、4A、8A。通(tong)過各控制開關將以上四個電(dian)容(rong)器進行適當(dang)的并(bing)聯(lian)(lian)(lian)組合便(bian)可(ke)(ke)(ke)(ke)得到1A、2A、3A……15A的15組可(ke)(ke)(ke)(ke)調(diao)(diao)充(chong)電(dian)電(dian)流。如(ru)果想將電(dian)流調(diao)(diao)得更精細(xi)些，可(ke)(ke)(ke)(ke)增加(jia)并(bing)聯(lian)(lian)(lian)支(zhi)(zhi)路。如(ru)增加(jia)7．5微(wei)法支(zhi)(zhi)路可(ke)(ke)(ke)(ke)得到相(xiang)鄰級(ji)(ji)差(cha)為(wei)(wei)0．5A的0．5A～15．5A的31級(ji)(ji)可(ke)(ke)(ke)(ke)調(diao)(diao)充(chong)電(dian)控制系統(tong)，上述各支(zhi)(zhi)路電(dian)容(rong)器的容(rong)量若(ruo)只取其十(shi)分之一，便(bian)可(ke)(ke)(ke)(ke)得到相(xiang)鄰級(ji)(ji)差(cha)為(wei)(wei)O．1A的0．1～1．5A的15級(ji)(ji)可(ke)(ke)(ke)(ke)調(diao)(diao)并(bing)聯(lian)(lian)(lian)組合充(chong)電(dian)控制系統(tong)；若(ruo)只取其容(rong)量的百分之一，便(bian)可(ke)(ke)(ke)(ke)得到相(xiang)鄰級(ji)(ji)差(cha)為(wei)(wei)140mA的15級(ji)(ji)可(ke)(ke)(ke)(ke)調(diao)(diao)并(bing)聯(lian)(lian)(lian)組合充(chong)電(dian)控制系統(tong)。

　　三、制作方法

　　指示燈(deng)(deng)L應選(xuan)(xuan)用(yong)(yong)(yong)額(e)定(ding)工作(zuo)(zuo)(zuo)電(dian)(dian)壓為(wei)220V的(de)(de)體積較(jiao)小(xiao)(xiao)(xiao)些的(de)(de)燈(deng)(deng)泡(pao)，也(ye)可以(yi)用(yong)(yong)(yong)10kΩ的(de)(de)電(dian)(dian)阻(zu)(zu)(zu)和一(yi)個小(xiao)(xiao)(xiao)功率發(fa)(fa)光二(er)極管(guan)串聯代(dai)替；控制(zhi)開關K1、K2、K3、K4應分(fen)別選(xuan)(xuan)用(yong)(yong)(yong)額(e)定(ding)工作(zuo)(zuo)(zuo)電(dian)(dian)流(liu)(liu)不(bu)(bu)小(xiao)(xiao)(xiao)于1．5A、3A、6A、12A的(de)(de)；電(dian)(dian)容器C1、C2、C3、C4均選(xuan)(xuan)用(yong)(yong)(yong)耐(nai)壓不(bu)(bu)小(xiao)(xiao)(xiao)于400V規(gui)(gui)(gui)格(ge)(ge)的(de)(de)；泄放電(dian)(dian)阻(zu)(zu)(zu)R1、R2、R3、R4均選(xuan)(xuan)用(yong)(yong)(yong)220kΩ，1／2W規(gui)(gui)(gui)格(ge)(ge)的(de)(de)；整(zheng)流(liu)(liu)堆D應選(xuan)(xuan)用(yong)(yong)(yong)額(e)定(ding)工作(zuo)(zuo)(zuo)電(dian)(dian)流(liu)(liu)不(bu)(bu)小(xiao)(xiao)(xiao)于50A，耐(nai)壓不(bu)(bu)小(xiao)(xiao)(xiao)于400V規(gui)(gui)(gui)格(ge)(ge)的(de)(de)；電(dian)(dian)流(liu)(liu)表A選(xuan)(xuan)用(yong)(yong)(yong)量程為(wei)20A或30A規(gui)(gui)(gui)格(ge)(ge)的(de)(de)直(zhi)流(liu)(liu)電(dian)(dian)流(liu)(liu)表；電(dian)(dian)壓表V應選(xuan)(xuan)用(yong)(yong)(yong)量程為(wei)50V規(gui)(gui)(gui)格(ge)(ge)的(de)(de)直(zhi)流(liu)(liu)電(dian)(dian)壓表；R5選(xuan)(xuan)用(yong)(yong)(yong)10kΩ／6W的(de)(de)電(dian)(dian)阻(zu)(zu)(zu)；LED選(xuan)(xuan)用(yong)(yong)(yong)普通小(xiao)(xiao)(xiao)功率發(fa)(fa)光二(er)極管(guan)；K5選(xuan)(xuan)用(yong)(yong)(yong)普通按(an)鍵(jian)式開關，工作(zuo)(zuo)(zuo)電(dian)(dian)流(liu)(liu)大小(xiao)(xiao)(xiao)不(bu)(bu)作(zuo)(zuo)(zuo)要求(qiu)。將控制(zhi)開關K1