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)(dian)(dian)(dian)(dian)經K1～K4及其相(xiang)應阻容(rong)(rong)(rong)元件組成的(de)4條并(bing)列支(zhi)路選(xuan)擇或組合，再經整流(liu)(liu)堆D整流(liu)(liu)后(hou)，通過電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)表A，給蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)。在充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程中，由(you)于(yu)(yu)回路中蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)兩(liang)端電(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)變化量相(xiang)對于(yu)(yu)220V交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓來說很(hen)小，電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)兩(liang)端的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓降(jiang)幾乎可認為(wei)是(shi)不變的(de)，所以，通過電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)也是(shi)不變的(de)，通過蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)內部(bu)的(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)自(zi)然(ran)也是(shi)恒定的(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)(dian)(dian)容器(qi)(qi)上積存的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)荷(he)放(fang)掉；K1、K2、K3、K4是支(zhi)路(lu)控制開關，通過開關通斷控制可以決(jue)定支(zhi)路(lu)是否(fou)并(bing)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)；R5、LED組成(cheng)空載報警(jing)指(zhi)示電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(為了安全，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)不(bu)可在空載狀(zhuang)態下插入(ru)220V交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)源)，LED亮(liang)時(shi)，說明空載。電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)表(biao)A指(zhi)示充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)的(de)(de)大(da)小(xiao)：電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)V指(zhi)示蓄電(dian)(dian)(dian)(dian)(dian)(dian)池兩(liang)端的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(為防止空載時(shi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)高燒壞(huai)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)，電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)的(de)(de)接入(ru)與否(fou)受開關K5的(de)(de)控制)。

　　二、電路設計

　　該充(chong)(chong)電(dian)器的限(xian)流(liu)電(dian)容器容量越(yue)大(da)，容抗越(yue)小，充(chong)(chong)電(dian)電(dian)流(liu)越(yue)大(da)。反之(zhi)，充(chong)(chong)電(dian)電(dian)流(liu)越(yue)小。根據該原理，可采(cai)用(yong)(yong)調整并聯電(dian)容的方法來達到(dao)調整充(chong)(chong)電(dian)電(dian)流(liu)大(da)小的目的。以汽車、摩托車、電(dian)動自行車常用(yong)(yong)的蓄電(dian)池為(wei)例，該充(chong)(chong)電(dian)電(dian)路設置了相鄰級差為(wei)1A的1～15A的15級可調充(chong)(chong)電(dian)，通過四條(tiao)支路的不同(tong)并聯組合實(shi)現對畜電(dian)池充(chong)(chong)電(dian)電(dian)流(liu)的調整。

　　由純電(dian)容(rong)(rong)交流(liu)(liu)電(dian)路中(zhong)(圖中(zhong)各分(fen)流(liu)(liu)電(dian)阻的(de)(de)分(fen)流(liu)(liu)很小，可忽略不計)電(dian)壓、電(dian)流(liu)(liu)、容(rong)(rong)抗之(zhi)間的(de)(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)，Xc表示電(dian)容(rong)(rong)器的(de)(de)容(rong)(rong)抗，其(qi)(qi)(qi)(qi)單位(wei)為(wei)歐姆(mu)；U表示電(dian)容(rong)(rong)器兩端的(de)(de)電(dian)壓，其(qi)(qi)(qi)(qi)單位(wei)為(wei)伏(fu)特，其(qi)(qi)(qi)(qi)值為(wei)：交流(liu)(liu)電(dian)源的(de)(de)總電(dian)壓220V-蓄電(dian)池放電(dian)的(de)(de)下(xia)限電(dian)壓10V=210V；C表示電(dian)容(rong)(rong)器的(de)(de)容(rong)(rong)量，其(qi)(qi)(qi)(qi)單位(wei)為(wei)法拉：f表示交流(liu)(liu)電(dian)的(de)(de)頻率，其(qi)(qi)(qi)(qi)單位(wei)為(wei)赫(he)茲，我國公共電(dian)網的(de)(de)頻率為(wei)50赫(he)茲；I表示通過電(dian)容(rong)(rong)器的(de)(de)電(dian)流(liu)(liu)，其(qi)(qi)(qi)(qi)單位(wei)為(wei)安(an)培；π取3．14)。

　　由(you)以(yi)上(shang)(shang)計算(suan)結果(guo)可(ke)知(zhi)，當電(dian)(dian)(dian)(dian)容(rong)器(qi)C取(qu)(qu)15微法(fa)(即0．000015法(fa)拉)時，I=65940C=65940×0．000015≈1(A)。C1=15微法(fa)、C2=30微法(fa)、C3=60微法(fa)、C4=120微法(fa)，對應的(de)各支(zhi)路(lu)電(dian)(dian)(dian)(dian)流(liu)分(fen)別為1A、2A、4A、8A。通過各控制開(kai)關將(jiang)以(yi)上(shang)(shang)四(si)個電(dian)(dian)(dian)(dian)容(rong)器(qi)進行適當的(de)并(bing)(bing)聯(lian)組(zu)合(he)(he)便可(ke)得(de)(de)到(dao)1A、2A、3A……15A的(de)15組(zu)可(ke)調充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)。如果(guo)想將(jiang)電(dian)(dian)(dian)(dian)流(liu)調得(de)(de)更精細(xi)些，可(ke)增加并(bing)(bing)聯(lian)支(zhi)路(lu)。如增加7．5微法(fa)支(zhi)路(lu)可(ke)得(de)(de)到(dao)相鄰(lin)級(ji)差(cha)(cha)為0．5A的(de)0．5A～15．5A的(de)31級(ji)可(ke)調充(chong)(chong)電(dian)(dian)(dian)(dian)控制系統(tong)，上(shang)(shang)述(shu)各支(zhi)路(lu)電(dian)(dian)(dian)(dian)容(rong)器(qi)的(de)容(rong)量(liang)若只取(qu)(qu)其(qi)十分(fen)之一(yi)，便可(ke)得(de)(de)到(dao)相鄰(lin)級(ji)差(cha)(cha)為O．1A的(de)0．1～1．5A的(de)15級(ji)可(ke)調并(bing)(bing)聯(lian)組(zu)合(he)(he)充(chong)(chong)電(dian)(dian)(dian)(dian)控制系統(tong)；若只取(qu)(qu)其(qi)容(rong)量(liang)的(de)百分(fen)之一(yi)，便可(ke)得(de)(de)到(dao)相鄰(lin)級(ji)差(cha)(cha)為140mA的(de)15級(ji)可(ke)調并(bing)(bing)聯(lian)組(zu)合(he)(he)充(chong)(chong)電(dian)(dian)(dian)(dian)控制系統(tong)。

　　三、制作方法

　　指示燈(deng)L應選(xuan)(xuan)(xuan)(xuan)用額定(ding)工(gong)作電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)220V的(de)(de)(de)(de)體(ti)積較小(xiao)(xiao)些(xie)的(de)(de)(de)(de)燈(deng)泡，也可以用10kΩ的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻(zu)和(he)一(yi)個小(xiao)(xiao)功率發(fa)光二極管串聯代(dai)替；控制(zhi)開(kai)關(guan)K1、K2、K3、K4應分別選(xuan)(xuan)(xuan)(xuan)用額定(ding)工(gong)作電(dian)(dian)(dian)(dian)(dian)流不小(xiao)(xiao)于(yu)(yu)1．5A、3A、6A、12A的(de)(de)(de)(de)；電(dian)(dian)(dian)(dian)(dian)容器C1、C2、C3、C4均(jun)選(xuan)(xuan)(xuan)(xuan)用耐壓(ya)(ya)(ya)(ya)不小(xiao)(xiao)于(yu)(yu)400V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)；泄放電(dian)(dian)(dian)(dian)(dian)阻(zu)R1、R2、R3、R4均(jun)選(xuan)(xuan)(xuan)(xuan)用220kΩ，1／2W規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)；整(zheng)流堆D應選(xuan)(xuan)(xuan)(xuan)用額定(ding)工(gong)作電(dian)(dian)(dian)(dian)(dian)流不小(xiao)(xiao)于(yu)(yu)50A，耐壓(ya)(ya)(ya)(ya)不小(xiao)(xiao)于(yu)(yu)400V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)；電(dian)(dian)(dian)(dian)(dian)流表A選(xuan)(xuan)(xuan)(xuan)用量(liang)程(cheng)為(wei)20A或30A規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)直流電(dian)(dian)(dian)(dian)(dian)流表；電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)表V應選(xuan)(xuan)(xuan)(xuan)用量(liang)程(cheng)為(wei)50V規(gui)(gui)(gui)格(ge)的(de)(de)(de)(de)直流電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)表；R5選(xuan)(xuan)(xuan)(xuan)用10kΩ／6W的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻(zu)；LED選(xuan)(xuan)(xuan)(xuan)用普(pu)通小(xiao)(xiao)功率發(fa)光二極管；K5選(xuan)(xuan)(xuan)(xuan)用普(pu)通按鍵(jian)式開(kai)關(guan)，工(gong)作電(dian)(dian)(dian)(dian)(dian)流大小(xiao)(xiao)不作要求。將控制(zhi)開(kai)關(guan)K1