本文介紹一款電路簡單、性能可靠的多用恒流充電器。

　　一、電(dian)(dian)(dian)(dian)(dian)路(lu)原理　　如圖所(suo)示，該充電(dian)(dian)(dian)(dian)(dian)器(qi)屬于電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)限流(liu)(liu)(liu)式無(wu)電(dian)(dian)(dian)(dian)(dian)源變壓器(qi)恒(heng)流(liu)(liu)(liu)充電(dian)(dian)(dian)(dian)(dian)器(qi)。220V交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)經K1～K4及其相(xiang)應阻容(rong)(rong)元(yuan)件組成(cheng)的(de)4條并(bing)列(lie)支路(lu)選擇或組合，再經整流(liu)(liu)(liu)堆D整流(liu)(liu)(liu)后，通(tong)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)表A，給蓄電(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)。在(zai)充電(dian)(dian)(dian)(dian)(dian)過(guo)(guo)程中(zhong)，由于回路(lu)中(zhong)蓄電(dian)(dian)(dian)(dian)(dian)池兩(liang)(liang)端電(dian)(dian)(dian)(dian)(dian)的(de)變化量相(xiang)對(dui)于220V交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)壓來說(shuo)很小，電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)兩(liang)(liang)端的(de)電(dian)(dian)(dian)(dian)(dian)壓降幾乎可認為是(shi)不(bu)(bu)變的(de)，所(suo)以(yi)，通(tong)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)的(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)也是(shi)不(bu)(bu)變的(de)，通(tong)過(guo)(guo)蓄電(dian)(dian)(dian)(dian)(dian)池內部的(de)充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)自然也是(shi)恒(heng)定的(de)。 　　

     L為220V交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)源指(zhi)示(shi)(shi)燈，R1、R2、R3、R4分別是電(dian)(dian)(dian)(dian)(dian)容器C1、C2、C3、C4的(de)泄放(fang)電(dian)(dian)(dian)(dian)(dian)阻，在(zai)不用充電(dian)(dian)(dian)(dian)(dian)器時，能及時將電(dian)(dian)(dian)(dian)(dian)容器上積存(cun)的(de)電(dian)(dian)(dian)(dian)(dian)荷放(fang)掉；K1、K2、K3、K4是支(zhi)路(lu)控(kong)制(zhi)(zhi)開(kai)(kai)關(guan)，通(tong)過(guo)開(kai)(kai)關(guan)通(tong)斷控(kong)制(zhi)(zhi)可以決定支(zhi)路(lu)是否(fou)(fou)并入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)路(lu)；R5、LED組(zu)成空載報警指(zhi)示(shi)(shi)電(dian)(dian)(dian)(dian)(dian)路(lu)(為了安全，充電(dian)(dian)(dian)(dian)(dian)器不可在(zai)空載狀態下(xia)插入(ru)(ru)220V交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)源)，LED亮時，說明空載。電(dian)(dian)(dian)(dian)(dian)流(liu)表(biao)A指(zhi)示(shi)(shi)充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)的(de)大小：電(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)V指(zhi)示(shi)(shi)蓄(xu)電(dian)(dian)(dian)(dian)(dian)池兩端的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(為防止空載時電(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(de)接入(ru)(ru)與否(fou)(fou)受開(kai)(kai)關(guan)K5的(de)控(kong)制(zhi)(zhi))。

　　二、電路設計　　該充電器的(de)(de)限流電(dian)(dian)(dian)(dian)容器(qi)容量越大，容抗越小，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流越大。反之，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流越小。根據該原(yuan)理(li)，可采用調(diao)(diao)整并聯(lian)電(dian)(dian)(dian)(dian)容的(de)(de)方法(fa)來達(da)到調(diao)(diao)整充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流大小的(de)(de)目的(de)(de)。以汽車(che)、摩托車(che)、電(dian)(dian)(dian)(dian)動自行車(che)常用的(de)(de)蓄電(dian)(dian)(dian)(dian)池(chi)為例，該充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)路設置(zhi)了相鄰級(ji)差為1A的(de)(de)1～15A的(de)(de)15級(ji)可調(diao)(diao)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)，通過四條支(zhi)路的(de)(de)不同并聯(lian)組合(he)實現(xian)對畜電(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流的(de)(de)調(diao)(diao)整。

　　由純電(dian)(dian)容(rong)交(jiao)流(liu)(liu)(liu)電(dian)(dian)路中(zhong)(圖(tu)中(zhong)各分流(liu)(liu)(liu)電(dian)(dian)阻(zu)的(de)分流(liu)(liu)(liu)很小，可忽略(lve)不(bu)計(ji))電(dian)(dian)壓、電(dian)(dian)流(liu)(liu)(liu)、容(rong)抗之間的(de)關系得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中(zhong)，Xc表示(shi)電(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)容(rong)抗，其單(dan)(dan)位(wei)為歐姆；U表示(shi)電(dian)(dian)容(rong)器(qi)(qi)(qi)兩端(duan)的(de)電(dian)(dian)壓，其單(dan)(dan)位(wei)為伏特，其值為：交(jiao)流(liu)(liu)(liu)電(dian)(dian)源的(de)總(zong)電(dian)(dian)壓220V-蓄電(dian)(dian)池放電(dian)(dian)的(de)下(xia)限電(dian)(dian)壓10V=210V；C表示(shi)電(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)容(rong)量，其單(dan)(dan)位(wei)為法(fa)拉：f表示(shi)交(jiao)流(liu)(liu)(liu)電(dian)(dian)的(de)頻(pin)率(lv)(lv)，其單(dan)(dan)位(wei)為赫茲，我國公共電(dian)(dian)網(wang)的(de)頻(pin)率(lv)(lv)為50赫茲；I表示(shi)通(tong)過(guo)電(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)電(dian)(dian)流(liu)(liu)(liu)，其單(dan)(dan)位(wei)為安培；π取3．14)。

　　由以上(shang)計算(suan)結(jie)果可(ke)(ke)知，當電(dian)(dian)容(rong)(rong)器C取(qu)15微法(即0．000015法拉(la))時(shi)，I=65940C=65940×0．000015≈1(A)。C1=15微法、C2=30微法、C3=60微法、C4=120微法，對(dui)應的(de)(de)(de)(de)(de)各支路電(dian)(dian)流分別(bie)為1A、2A、4A、8A。通(tong)過各控(kong)制開關將以上(shang)四個電(dian)(dian)容(rong)(rong)器進行(xing)適(shi)當的(de)(de)(de)(de)(de)并(bing)聯(lian)組合(he)便可(ke)(ke)得到(dao)1A、2A、3A……15A的(de)(de)(de)(de)(de)15組可(ke)(ke)調充電(dian)(dian)電(dian)(dian)流。如(ru)果想將電(dian)(dian)流調得更精(jing)細些，可(ke)(ke)增加(jia)并(bing)聯(lian)支路。如(ru)增加(jia)7．5微法支路可(ke)(ke)得到(dao)相鄰級(ji)差(cha)為0．5A的(de)(de)(de)(de)(de)0．5A～15．5A的(de)(de)(de)(de)(de)31級(ji)可(ke)(ke)調充電(dian)(dian)控(kong)制系統(tong)，上(shang)述各支路電(dian)(dian)容(rong)(rong)器的(de)(de)(de)(de)(de)容(rong)(rong)量若(ruo)只取(qu)其十分之一，便可(ke)(ke)得到(dao)相鄰級(ji)差(cha)為O．1A的(de)(de)(de)(de)(de)0．1～1．5A的(de)(de)(de)(de)(de)15級(ji)可(ke)(ke)調并(bing)聯(lian)組合(he)充電(dian)(dian)控(kong)制系統(tong)；若(ruo)只取(qu)其容(rong)(rong)量的(de)(de)(de)(de)(de)百(bai)分之一，便可(ke)(ke)得到(dao)相鄰級(ji)差(cha)為140mA的(de)(de)(de)(de)(de)15級(ji)可(ke)(ke)調并(bing)聯(lian)組合(he)充電(dian)(dian)控(kong)制系統(tong)。

　　三、制作方法　　指示燈L應選用額定工作電壓為220V的體積較小些的燈泡，也可以用10kΩ的電阻和一個小功率發光二極管串聯代替；控制開關K1、K2、K3、K4應分別選用額定工作電流不小于1．5A、3A、6A、12A的(de)(de)(de)；電(dian)(dian)容器C1、C2、C3、C4均選用(yong)(yong)耐壓(ya)(ya)不(bu)小于(yu)400V規(gui)格的(de)(de)(de)；泄放電(dian)(dian)阻(zu)R1、R2、R3、R4均選用(yong)(yong)220kΩ，1／2W規(gui)格的(de)(de)(de)；整流(liu)(liu)堆D應選用(yong)(yong)額定工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)(liu)不(bu)小于(yu)50A，耐壓(ya)(ya)不(bu)小于(yu)400V規(gui)格的(de)(de)(de)；電(dian)(dian)流(liu)(liu)表A選用(yong)(yong)量(liang)程為(wei)20A或(huo)30A規(gui)格的(de)(de)(de)直(zhi)流(liu)(liu)電(dian)(dian)流(liu)(liu)表；電(dian)(dian)壓(ya)(ya)表V應選用(yong)(yong)量(liang)程為(wei)50V規(gui)格的(de)(de)(de)直(zhi)流(liu)(liu)電(dian)(dian)壓(ya)(ya)表；R5選用(yong)(yong)10kΩ／6W的(de)(de)(de)電(dian)(dian)阻(zu)；LED選用(yong)(yong)普通小功率發光二極管；K5選用(yong)(yong)普通按鍵式開關(guan)，工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)(liu)大小不(bu)作(zuo)(zuo)要求。將(jiang)控制(zhi)開關(guan)K1、K2、K3、K4并(bing)排裝在機殼面板上適當的(de)(de)(de)位置(zhi)，并(bing)在K1、K2、K3、K4的(de)(de)(de)位置(zhi)旁邊分別標注上1A、2A、4A、8A的(de)(de)(de)字樣，以便控制(zhi)計算調整。蓄電(dian)(dian)池接線柱的(de)(de)(de)工(gong)作(zuo)(zuo)電(dian)(dian)流(liu)(liu)不(bu)小于(yu)20A。

　　四、使用方法　　該充電器屬于無電源變壓器隔離式充電器，為了人身安全，充(chong)電(dian)(dian)(dian)(dian)(dian)時應嚴格照(zhao)下列程(cheng)序進(jin)行操作(zuo)：　　1．檢查各個開關應處于斷開狀態(tai)，將蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)正、負(fu)極(ji)與接(jie)線(xian)(xian)柱(zhu)連接(jie)可靠(kao)，然(ran)后閉(bi)合(he)K5，電(dian)(dian)(dian)(dian)(dian)壓(ya)表指示出(chu)蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)兩端的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)。　　2．將電(dian)(dian)(dian)(dian)(dian)源(yuan)插頭插入220V交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)源(yuan)，接(jie)通(tong)K1，此時，觀察電(dian)(dian)(dian)(dian)(dian)源(yuan)指示燈(deng)亮，空載報警指示發(fa)光二極(ji)管不應亮。若發(fa)光二極(ji)管亮，說明蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)正、負(fu)極(ji)與充(chong)電(dian)(dian)(dian)(dian)(dian)器接(jie)線(xian)(xian)柱(zhu)之間接(jie)觸不良(liang)，應除掉接(jie)點之間的(de)臟物后再進(jin)行連接(jie)。　　3．根據蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)對充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)的(de)要求，選(xuan)擇(ze)合(he)適(shi)的(de)控制(zhi)開關接(jie)通(tong)并聯(lian)調整充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)數值為接(jie)通(tong)的(de)開關電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)數之和。

　　該(gai)充電(dian)器的(de)唯一缺陷是，不具備(bei)充滿電(dian)后自動(dong)停(ting)充的(de)功能。因(yin)各(ge)種(zhong)蓄(xu)電(dian)池(chi)的(de)電(dian)壓(ya)(ya)及容量都不一樣，讀者應根據不同蓄(xu)電(dian)池(chi)的(de)要(yao)求決定充電(dian)的(de)電(dian)流和充電(dian)時間，通(tong)過(guo)電(dian)壓(ya)(ya)表監視(shi)充電(dian)程度。