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)(liu)電(dian)(dian)(dian)經K1～K4及其相應阻(zu)容元件組成的(de)(de)(de)(de)4條并(bing)列支路選(xuan)擇或組合，再經整流(liu)(liu)(liu)堆D整流(liu)(liu)(liu)后，通(tong)過(guo)電(dian)(dian)(dian)流(liu)(liu)(liu)表A，給蓄電(dian)(dian)(dian)池充電(dian)(dian)(dian)。在(zai)充電(dian)(dian)(dian)過(guo)程中(zhong)，由于回路中(zhong)蓄電(dian)(dian)(dian)池兩(liang)端(duan)電(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)(de)變化量相對于220V交流(liu)(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)來說很小，電(dian)(dian)(dian)容兩(liang)端(duan)的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)(ya)降幾乎可認為(wei)是(shi)不變的(de)(de)(de)(de)，所以，通(tong)過(guo)電(dian)(dian)(dian)容器的(de)(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)(liu)也是(shi)不變的(de)(de)(de)(de)，通(tong)過(guo)蓄電(dian)(dian)(dian)池內部的(de)(de)(de)(de)充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)(liu)自然也是(shi)恒定的(de)(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(shi)(shi)，能(neng)及時(shi)(shi)將電(dian)(dian)容器上積存的(de)電(dian)(dian)荷放掉(diao)；K1、K2、K3、K4是(shi)支路(lu)(lu)控(kong)制(zhi)開(kai)關，通過(guo)開(kai)關通斷控(kong)制(zhi)可以決(jue)定支路(lu)(lu)是(shi)否(fou)并入電(dian)(dian)路(lu)(lu)；R5、LED組(zu)成(cheng)空載(zai)報(bao)警指示(shi)電(dian)(dian)路(lu)(lu)(為(wei)了安全，充(chong)電(dian)(dian)器不(bu)可在空載(zai)狀態下插入220V交流電(dian)(dian)源)，LED亮時(shi)(shi)，說明(ming)空載(zai)。電(dian)(dian)流表A指示(shi)充(chong)電(dian)(dian)電(dian)(dian)流的(de)大小(xiao)：電(dian)(dian)壓(ya)表V指示(shi)蓄電(dian)(dian)池兩端的(de)電(dian)(dian)壓(ya)(為(wei)防止空載(zai)時(shi)(shi)電(dian)(dian)壓(ya)高燒壞電(dian)(dian)壓(ya)表，電(dian)(dian)壓(ya)表的(de)接(jie)入與否(fou)受開(kai)關K5的(de)控(kong)制(zhi))。

　　二、電路設計

　　該(gai)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器的(de)限流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容器容量越(yue)大(da)，容抗越(yue)小(xiao)，充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流越(yue)大(da)。反之(zhi)，充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流越(yue)小(xiao)。根(gen)據該(gai)原理，可(ke)采(cai)用調(diao)(diao)整并聯電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容的(de)方法來達到調(diao)(diao)整充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流大(da)小(xiao)的(de)目的(de)。以汽車、摩托(tuo)車、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動自(zi)行(xing)車常(chang)用的(de)蓄電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池為例，該(gai)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)設置了(le)相(xiang)鄰級(ji)差為1A的(de)1～15A的(de)15級(ji)可(ke)調(diao)(diao)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，通過四條支(zhi)路(lu)的(de)不同并聯組合實現(xian)對畜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)調(diao)(diao)整。

　　由(you)純電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)交流電(dian)(dian)(dian)路中(zhong)(zhong)(圖中(zhong)(zhong)各分流電(dian)(dian)(dian)阻(zu)的分流很小，可忽略不計(ji))電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流、容(rong)(rong)(rong)(rong)抗之間的關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)(zhong)，Xc表示(shi)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的容(rong)(rong)(rong)(rong)抗，其(qi)單(dan)位(wei)(wei)(wei)為(wei)歐姆(mu)；U表示(shi)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)兩端的電(dian)(dian)(dian)壓，其(qi)單(dan)位(wei)(wei)(wei)為(wei)伏特，其(qi)值為(wei)：交流電(dian)(dian)(dian)源的總電(dian)(dian)(dian)壓220V-蓄電(dian)(dian)(dian)池放(fang)電(dian)(dian)(dian)的下限電(dian)(dian)(dian)壓10V=210V；C表示(shi)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的容(rong)(rong)(rong)(rong)量，其(qi)單(dan)位(wei)(wei)(wei)為(wei)法拉(la)：f表示(shi)交流電(dian)(dian)(dian)的頻(pin)率(lv)，其(qi)單(dan)位(wei)(wei)(wei)為(wei)赫茲，我國(guo)公共電(dian)(dian)(dian)網(wang)的頻(pin)率(lv)為(wei)50赫茲；I表示(shi)通過電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)的電(dian)(dian)(dian)流，其(qi)單(dan)位(wei)(wei)(wei)為(wei)安培；π取3．14)。

　　由(you)以上(shang)(shang)計算結果(guo)可(ke)(ke)(ke)知，當電(dian)(dian)(dian)容器(qi)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(de)(de)(de)各支(zhi)路(lu)(lu)電(dian)(dian)(dian)流(liu)分別(bie)為1A、2A、4A、8A。通(tong)過各控(kong)制開關將以上(shang)(shang)四個電(dian)(dian)(dian)容器(qi)進行適當的(de)(de)(de)并(bing)聯(lian)組合便可(ke)(ke)(ke)得(de)到1A、2A、3A……15A的(de)(de)(de)15組可(ke)(ke)(ke)調充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)。如果(guo)想將電(dian)(dian)(dian)流(liu)調得(de)更(geng)精細些，可(ke)(ke)(ke)增加并(bing)聯(lian)支(zhi)路(lu)(lu)。如增加7．5微(wei)法支(zhi)路(lu)(lu)可(ke)(ke)(ke)得(de)到相(xiang)鄰(lin)級(ji)差為0．5A的(de)(de)(de)0．5A～15．5A的(de)(de)(de)31級(ji)可(ke)(ke)(ke)調充電(dian)(dian)(dian)控(kong)制系(xi)統(tong)，上(shang)(shang)述各支(zhi)路(lu)(lu)電(dian)(dian)(dian)容器(qi)的(de)(de)(de)容量(liang)若(ruo)只取其(qi)十分之(zhi)一，便可(ke)(ke)(ke)得(de)到相(xiang)鄰(lin)級(ji)差為O．1A的(de)(de)(de)0．1～1．5A的(de)(de)(de)15級(ji)可(ke)(ke)(ke)調并(bing)聯(lian)組合充電(dian)(dian)(dian)控(kong)制系(xi)統(tong)；若(ruo)只取其(qi)容量(liang)的(de)(de)(de)百分之(zhi)一，便可(ke)(ke)(ke)得(de)到相(xiang)鄰(lin)級(ji)差為140mA的(de)(de)(de)15級(ji)可(ke)(ke)(ke)調并(bing)聯(lian)組合充電(dian)(dian)(dian)控(kong)制系(xi)統(tong)。

　　三、制作方法

　　指示燈L應選(xuan)用(yong)(yong)(yong)(yong)額定(ding)工(gong)(gong)作(zuo)(zuo)電(dian)(dian)(dian)(dian)壓為(wei)220V的(de)(de)(de)體積(ji)較小(xiao)(xiao)些的(de)(de)(de)燈泡，也可以用(yong)(yong)(yong)(yong)10kΩ的(de)(de)(de)電(dian)(dian)(dian)(dian)阻和一個小(xiao)(xiao)功(gong)率發(fa)光二(er)極管串(chuan)聯代替；控(kong)制開關(guan)K1、K2、K3、K4應分(fen)別選(xuan)用(yong)(yong)(yong)(yong)額定(ding)工(gong)(gong)作(zuo)(zuo)電(dian)(dian)(dian)(dian)流(liu)(liu)不(bu)小(xiao)(xiao)于(yu)1．5A、3A、6A、12A的(de)(de)(de)；電(dian)(dian)(dian)(dian)容器(qi)C1、C2、C3、C4均(jun)選(xuan)用(yong)(yong)(yong)(yong)耐壓不(bu)小(xiao)(xiao)于(yu)400V規格(ge)的(de)(de)(de)；泄放電(dian)(dian)(dian)(dian)阻R1、R2、R3、R4均(jun)選(xuan)用(yong)(yong)(yong)(yong)220kΩ，1／2W規格(ge)的(de)(de)(de)；整流(liu)(liu)堆(dui)D應選(xuan)用(yong)(yong)(yong)(yong)額定(ding)工(gong)(gong)作(zuo)(zuo)電(dian)(dian)(dian)(dian)流(liu)(liu)不(bu)小(xiao)(xiao)于(yu)50A，耐壓不(bu)小(xiao)(xiao)于(yu)400V規格(ge)的(de)(de)(de)；電(dian)(dian)(dian)(dian)流(liu)(liu)表(biao)(biao)A選(xuan)用(yong)(yong)(yong)(yong)量程(cheng)為(wei)20A或(huo)30A規格(ge)的(de)(de)(de)直流(liu)(liu)電(dian)(dian)(dian)(dian)流(liu)(liu)表(biao)(biao)；電(dian)(dian)(dian)(dian)壓表(biao)(biao)V應選(xuan)用(yong)(yong)(yong)(yong)量程(cheng)為(wei)50V規格(ge)的(de)(de)(de)直流(liu)(liu)電(dian)(dian)(dian)(dian)壓表(biao)(biao)；R5選(xuan)用(yong)(yong)(yong)(yong)10kΩ／6W的(de)(de)(de)電(dian)(dian)(dian)(dian)阻；LED選(xuan)用(yong)(yong)(yong)(yong)普通小(xiao)(xiao)功(gong)率發(fa)光二(er)極管；K5選(xuan)用(yong)(yong)(yong)(yong)普通按(an)鍵(jian)式開關(guan)，工(gong)(gong)作(zuo)(zuo)電(dian)(dian)(dian)(dian)流(liu)(liu)大小(xiao)(xiao)不(bu)作(zuo)(zuo)要(yao)求。將控(kong)制開關(guan)K1