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)經K1～K4及其(qi)相(xiang)應阻容元件組成的(de)(de)(de)4條并列支路(lu)選擇或組合，再(zai)經整(zheng)流(liu)堆D整(zheng)流(liu)后，通(tong)過電(dian)(dian)流(liu)表A，給蓄(xu)電(dian)(dian)池(chi)充(chong)電(dian)(dian)。在充(chong)電(dian)(dian)過程(cheng)中，由于(yu)回路(lu)中蓄(xu)電(dian)(dian)池(chi)兩端(duan)電(dian)(dian)壓(ya)的(de)(de)(de)變(bian)化量相(xiang)對于(yu)220V交流(liu)電(dian)(dian)壓(ya)來說(shuo)很小，電(dian)(dian)容兩端(duan)的(de)(de)(de)電(dian)(dian)壓(ya)降(jiang)幾(ji)乎可認(ren)為是(shi)不(bu)變(bian)的(de)(de)(de)，所以，通(tong)過電(dian)(dian)容器(qi)的(de)(de)(de)電(dian)(dian)流(liu)也是(shi)不(bu)變(bian)的(de)(de)(de)，通(tong)過蓄(xu)電(dian)(dian)池(chi)內部的(de)(de)(de)充(chong)電(dian)(dian)電(dian)(dian)流(liu)自然也是(shi)恒定(ding)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(shi)，能(neng)及時(shi)將(jiang)電(dian)(dian)(dian)(dian)(dian)容器上(shang)積存的電(dian)(dian)(dian)(dian)(dian)荷(he)放掉(diao)；K1、K2、K3、K4是支(zhi)路(lu)控(kong)制開(kai)關，通過開(kai)關通斷控(kong)制可以決(jue)定支(zhi)路(lu)是否并入(ru)電(dian)(dian)(dian)(dian)(dian)路(lu)；R5、LED組(zu)成空載(zai)報警指示電(dian)(dian)(dian)(dian)(dian)路(lu)(為了安全(quan)，充電(dian)(dian)(dian)(dian)(dian)器不可在空載(zai)狀態下插入(ru)220V交流電(dian)(dian)(dian)(dian)(dian)源(yuan))，LED亮時(shi)，說明空載(zai)。電(dian)(dian)(dian)(dian)(dian)流表(biao)A指示充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的大小：電(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)V指示蓄電(dian)(dian)(dian)(dian)(dian)池兩端的電(dian)(dian)(dian)(dian)(dian)壓(ya)(為防止空載(zai)時(shi)電(dian)(dian)(dian)(dian)(dian)壓(ya)高(gao)燒壞電(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)，電(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)的接入(ru)與否受開(kai)關K5的控(kong)制)。

　　二、電路設計

　　該(gai)充(chong)電(dian)(dian)器的(de)(de)限流電(dian)(dian)容(rong)器容(rong)量越(yue)(yue)大，容(rong)抗越(yue)(yue)小(xiao)，充(chong)電(dian)(dian)電(dian)(dian)流越(yue)(yue)大。反之，充(chong)電(dian)(dian)電(dian)(dian)流越(yue)(yue)小(xiao)。根據該(gai)原(yuan)理(li)，可采用(yong)調整(zheng)并聯電(dian)(dian)容(rong)的(de)(de)方法來達(da)到調整(zheng)充(chong)電(dian)(dian)電(dian)(dian)流大小(xiao)的(de)(de)目的(de)(de)。以汽車(che)、摩托車(che)、電(dian)(dian)動(dong)自行車(che)常用(yong)的(de)(de)蓄電(dian)(dian)池(chi)為(wei)例，該(gai)充(chong)電(dian)(dian)電(dian)(dian)路設置了相(xiang)鄰級(ji)差為(wei)1A的(de)(de)1～15A的(de)(de)15級(ji)可調充(chong)電(dian)(dian)，通過四條支路的(de)(de)不同并聯組合實現對畜電(dian)(dian)池(chi)充(chong)電(dian)(dian)電(dian)(dian)流的(de)(de)調整(zheng)。

　　由(you)純電(dian)(dian)(dian)容(rong)交流(liu)電(dian)(dian)(dian)路中(圖中各(ge)分(fen)流(liu)電(dian)(dian)(dian)阻的(de)(de)分(fen)流(liu)很小，可忽略(lve)不(bu)計)電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流(liu)、容(rong)抗之(zhi)間的(de)(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中，Xc表示(shi)電(dian)(dian)(dian)容(rong)器的(de)(de)容(rong)抗，其單位(wei)為(wei)歐姆；U表示(shi)電(dian)(dian)(dian)容(rong)器兩端的(de)(de)電(dian)(dian)(dian)壓，其單位(wei)為(wei)伏特，其值為(wei)：交流(liu)電(dian)(dian)(dian)源的(de)(de)總電(dian)(dian)(dian)壓220V-蓄電(dian)(dian)(dian)池放電(dian)(dian)(dian)的(de)(de)下限電(dian)(dian)(dian)壓10V=210V；C表示(shi)電(dian)(dian)(dian)容(rong)器的(de)(de)容(rong)量，其單位(wei)為(wei)法拉：f表示(shi)交流(liu)電(dian)(dian)(dian)的(de)(de)頻率(lv)，其單位(wei)為(wei)赫茲(zi)，我國公共(gong)電(dian)(dian)(dian)網(wang)的(de)(de)頻率(lv)為(wei)50赫茲(zi)；I表示(shi)通過電(dian)(dian)(dian)容(rong)器的(de)(de)電(dian)(dian)(dian)流(liu)，其單位(wei)為(wei)安培(pei)；π取3．14)。

　　由以上(shang)計算結果可(ke)(ke)知，當電容(rong)器C取15微法(fa)(fa)(即0．000015法(fa)(fa)拉(la))時，I=65940C=65940×0．000015≈1(A)。C1=15微法(fa)(fa)、C2=30微法(fa)(fa)、C3=60微法(fa)(fa)、C4=120微法(fa)(fa)，對(dui)應的(de)(de)(de)各支(zhi)路(lu)(lu)電流(liu)分(fen)別為1A、2A、4A、8A。通過(guo)各控(kong)(kong)制開(kai)關將以上(shang)四個(ge)電容(rong)器進行適當的(de)(de)(de)并(bing)(bing)聯(lian)組合便(bian)(bian)可(ke)(ke)得到(dao)1A、2A、3A……15A的(de)(de)(de)15組可(ke)(ke)調(diao)充(chong)(chong)電電流(liu)。如果想將電流(liu)調(diao)得更精細些，可(ke)(ke)增(zeng)加(jia)并(bing)(bing)聯(lian)支(zhi)路(lu)(lu)。如增(zeng)加(jia)7．5微法(fa)(fa)支(zhi)路(lu)(lu)可(ke)(ke)得到(dao)相鄰(lin)級差(cha)為0．5A的(de)(de)(de)0．5A～15．5A的(de)(de)(de)31級可(ke)(ke)調(diao)充(chong)(chong)電控(kong)(kong)制系(xi)統(tong)，上(shang)述各支(zhi)路(lu)(lu)電容(rong)器的(de)(de)(de)容(rong)量若只取其(qi)十分(fen)之一，便(bian)(bian)可(ke)(ke)得到(dao)相鄰(lin)級差(cha)為O．1A的(de)(de)(de)0．1～1．5A的(de)(de)(de)15級可(ke)(ke)調(diao)并(bing)(bing)聯(lian)組合充(chong)(chong)電控(kong)(kong)制系(xi)統(tong)；若只取其(qi)容(rong)量的(de)(de)(de)百分(fen)之一，便(bian)(bian)可(ke)(ke)得到(dao)相鄰(lin)級差(cha)為140mA的(de)(de)(de)15級可(ke)(ke)調(diao)并(bing)(bing)聯(lian)組合充(chong)(chong)電控(kong)(kong)制系(xi)統(tong)。

　　三、制作方法

　　指示燈L應(ying)選(xuan)用(yong)額定(ding)工作(zuo)電(dian)(dian)壓為220V的(de)(de)(de)體積較小(xiao)(xiao)些(xie)的(de)(de)(de)燈泡(pao)，也(ye)可以(yi)用(yong)10kΩ的(de)(de)(de)電(dian)(dian)阻(zu)(zu)和(he)一個小(xiao)(xiao)功(gong)率發光二極管串聯(lian)代(dai)替；控制開關K1、K2、K3、K4應(ying)分別選(xuan)用(yong)額定(ding)工作(zuo)電(dian)(dian)流(liu)(liu)(liu)不小(xiao)(xiao)于1．5A、3A、6A、12A的(de)(de)(de)；電(dian)(dian)容器C1、C2、C3、C4均(jun)選(xuan)用(yong)耐(nai)壓不小(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)(de)；泄放電(dian)(dian)阻(zu)(zu)R1、R2、R3、R4均(jun)選(xuan)用(yong)220kΩ，1／2W規(gui)格(ge)的(de)(de)(de)；整流(liu)(liu)(liu)堆D應(ying)選(xuan)用(yong)額定(ding)工作(zuo)電(dian)(dian)流(liu)(liu)(liu)不小(xiao)(xiao)于50A，耐(nai)壓不小(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)(de)；電(dian)(dian)流(liu)(liu)(liu)表(biao)A選(xuan)用(yong)量程(cheng)為20A或30A規(gui)格(ge)的(de)(de)(de)直流(liu)(liu)(liu)電(dian)(dian)流(liu)(liu)(liu)表(biao)；電(dian)(dian)壓表(biao)V應(ying)選(xuan)用(yong)量程(cheng)為50V規(gui)格(ge)的(de)(de)(de)直流(liu)(liu)(liu)電(dian)(dian)壓表(biao)；R5選(xuan)用(yong)10kΩ／6W的(de)(de)(de)電(dian)(dian)阻(zu)(zu)；LED選(xuan)用(yong)普通小(xiao)(xiao)功(gong)率發光二極管；K5選(xuan)用(yong)普通按鍵(jian)式開關，工作(zuo)電(dian)(dian)流(liu)(liu)(liu)大(da)小(xiao)(xiao)不作(zuo)要求。將控制開關K1