本文介紹一款電路簡單、性能可靠的多用恒流充電器。

　　一(yi)、電(dian)(dian)(dian)(dian)路(lu)(lu)原(yuan)理　　如圖所(suo)示，該(gai)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)屬于(yu)電(dian)(dian)(dian)(dian)容限流(liu)式無電(dian)(dian)(dian)(dian)源(yuan)變壓(ya)器(qi)恒流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)。220V交流(liu)電(dian)(dian)(dian)(dian)經K1～K4及其相應阻(zu)容元件組成的(de)4條并列支路(lu)(lu)選(xuan)擇(ze)或組合，再經整流(liu)堆D整流(liu)后，通過電(dian)(dian)(dian)(dian)流(liu)表(biao)A，給蓄電(dian)(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)(dian)。在充(chong)(chong)電(dian)(dian)(dian)(dian)過程中(zhong)，由(you)于(yu)回(hui)路(lu)(lu)中(zhong)蓄電(dian)(dian)(dian)(dian)池兩(liang)端(duan)電(dian)(dian)(dian)(dian)的(de)變化量相對于(yu)220V交流(liu)電(dian)(dian)(dian)(dian)壓(ya)來說很小，電(dian)(dian)(dian)(dian)容兩(liang)端(duan)的(de)電(dian)(dian)(dian)(dian)壓(ya)降幾乎可(ke)認為是不變的(de)，所(suo)以，通過電(dian)(dian)(dian)(dian)容器(qi)的(de)電(dian)(dian)(dian)(dian)流(liu)也是不變的(de)，通過蓄電(dian)(dian)(dian)(dian)池內部的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)自然也是恒定的(de)。 　　

     L為220V交流電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)指示(shi)燈，R1、R2、R3、R4分(fen)別是電(dian)(dian)(dian)(dian)(dian)容(rong)器C1、C2、C3、C4的泄放電(dian)(dian)(dian)(dian)(dian)阻，在(zai)不(bu)用充電(dian)(dian)(dian)(dian)(dian)器時，能及時將電(dian)(dian)(dian)(dian)(dian)容(rong)器上積(ji)存的電(dian)(dian)(dian)(dian)(dian)荷放掉；K1、K2、K3、K4是支路(lu)控制(zhi)開關，通過開關通斷控制(zhi)可以(yi)決(jue)定支路(lu)是否并(bing)入電(dian)(dian)(dian)(dian)(dian)路(lu)；R5、LED組(zu)成空(kong)(kong)載(zai)(zai)(zai)報警指示(shi)電(dian)(dian)(dian)(dian)(dian)路(lu)(為了安全，充電(dian)(dian)(dian)(dian)(dian)器不(bu)可在(zai)空(kong)(kong)載(zai)(zai)(zai)狀(zhuang)態下插入220V交流電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan))，LED亮時，說(shuo)明(ming)空(kong)(kong)載(zai)(zai)(zai)。電(dian)(dian)(dian)(dian)(dian)流表A指示(shi)充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的大小：電(dian)(dian)(dian)(dian)(dian)壓表V指示(shi)蓄電(dian)(dian)(dian)(dian)(dian)池(chi)兩端(duan)的電(dian)(dian)(dian)(dian)(dian)壓(為防止空(kong)(kong)載(zai)(zai)(zai)時電(dian)(dian)(dian)(dian)(dian)壓高燒壞(huai)電(dian)(dian)(dian)(dian)(dian)壓表，電(dian)(dian)(dian)(dian)(dian)壓表的接(jie)入與否受開關K5的控制(zhi))。

　　二、電路設計　　該充電器的(de)(de)限流電(dian)(dian)(dian)容(rong)器容(rong)量越大(da)，容(rong)抗越小(xiao)，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流越大(da)。反之，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流越小(xiao)。根(gen)據(ju)該原(yuan)理，可(ke)采(cai)用(yong)調(diao)整并聯電(dian)(dian)(dian)容(rong)的(de)(de)方法來達到調(diao)整充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流大(da)小(xiao)的(de)(de)目的(de)(de)。以(yi)汽車(che)、摩托車(che)、電(dian)(dian)(dian)動自行(xing)車(che)常用(yong)的(de)(de)蓄電(dian)(dian)(dian)池為(wei)例，該充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)路(lu)設(she)置了相鄰級(ji)差為(wei)1A的(de)(de)1～15A的(de)(de)15級(ji)可(ke)調(diao)充(chong)(chong)電(dian)(dian)(dian)，通過四條支路(lu)的(de)(de)不同并聯組合實現對畜電(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流的(de)(de)調(diao)整。

　　由純電(dian)(dian)(dian)(dian)容(rong)交(jiao)流(liu)電(dian)(dian)(dian)(dian)路(lu)中(圖中各(ge)分流(liu)電(dian)(dian)(dian)(dian)阻的(de)(de)分流(liu)很小，可忽略不計)電(dian)(dian)(dian)(dian)壓(ya)(ya)、電(dian)(dian)(dian)(dian)流(liu)、容(rong)抗之間的(de)(de)關(guan)系(xi)得：I=U／Xc=2πfcU=2×3．14×50×210C=65940C(式中，Xc表(biao)示(shi)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)的(de)(de)容(rong)抗，其單(dan)(dan)位(wei)為(wei)(wei)(wei)歐姆；U表(biao)示(shi)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)兩端的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)，其單(dan)(dan)位(wei)為(wei)(wei)(wei)伏特，其值為(wei)(wei)(wei)：交(jiao)流(liu)電(dian)(dian)(dian)(dian)源的(de)(de)總電(dian)(dian)(dian)(dian)壓(ya)(ya)220V-蓄電(dian)(dian)(dian)(dian)池放電(dian)(dian)(dian)(dian)的(de)(de)下限電(dian)(dian)(dian)(dian)壓(ya)(ya)10V=210V；C表(biao)示(shi)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)的(de)(de)容(rong)量，其單(dan)(dan)位(wei)為(wei)(wei)(wei)法拉：f表(biao)示(shi)交(jiao)流(liu)電(dian)(dian)(dian)(dian)的(de)(de)頻(pin)率(lv)，其單(dan)(dan)位(wei)為(wei)(wei)(wei)赫(he)茲，我國公(gong)共電(dian)(dian)(dian)(dian)網的(de)(de)頻(pin)率(lv)為(wei)(wei)(wei)50赫(he)茲；I表(biao)示(shi)通(tong)過電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)，其單(dan)(dan)位(wei)為(wei)(wei)(wei)安(an)培；π取3．14)。

　　由以上(shang)計算結(jie)果可(ke)(ke)(ke)知(zhi)，當電(dian)(dian)容(rong)(rong)器C取(qu)15微(wei)(wei)法(fa)(fa)(fa)(即0．000015法(fa)(fa)(fa)拉)時，I=65940C=65940×0．000015≈1(A)。C1=15微(wei)(wei)法(fa)(fa)(fa)、C2=30微(wei)(wei)法(fa)(fa)(fa)、C3=60微(wei)(wei)法(fa)(fa)(fa)、C4=120微(wei)(wei)法(fa)(fa)(fa)，對應的(de)(de)(de)(de)各支(zhi)路(lu)電(dian)(dian)流分(fen)別為1A、2A、4A、8A。通過各控(kong)(kong)(kong)制(zhi)(zhi)開關(guan)將以上(shang)四(si)個(ge)電(dian)(dian)容(rong)(rong)器進行(xing)適當的(de)(de)(de)(de)并聯(lian)組合便可(ke)(ke)(ke)得到(dao)(dao)1A、2A、3A……15A的(de)(de)(de)(de)15組可(ke)(ke)(ke)調充電(dian)(dian)電(dian)(dian)流。如果想將電(dian)(dian)流調得更精細些，可(ke)(ke)(ke)增加(jia)并聯(lian)支(zhi)路(lu)。如增加(jia)7．5微(wei)(wei)法(fa)(fa)(fa)支(zhi)路(lu)可(ke)(ke)(ke)得到(dao)(dao)相鄰級差(cha)為0．5A的(de)(de)(de)(de)0．5A～15．5A的(de)(de)(de)(de)31級可(ke)(ke)(ke)調充電(dian)(dian)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)(xi)統，上(shang)述各支(zhi)路(lu)電(dian)(dian)容(rong)(rong)器的(de)(de)(de)(de)容(rong)(rong)量若(ruo)只(zhi)取(qu)其(qi)十分(fen)之(zhi)一(yi)，便可(ke)(ke)(ke)得到(dao)(dao)相鄰級差(cha)為O．1A的(de)(de)(de)(de)0．1～1．5A的(de)(de)(de)(de)15級可(ke)(ke)(ke)調并聯(lian)組合充電(dian)(dian)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)(xi)統；若(ruo)只(zhi)取(qu)其(qi)容(rong)(rong)量的(de)(de)(de)(de)百分(fen)之(zhi)一(yi)，便可(ke)(ke)(ke)得到(dao)(dao)相鄰級差(cha)為140mA的(de)(de)(de)(de)15級可(ke)(ke)(ke)調并聯(lian)組合充電(dian)(dian)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)(xi)統。

　　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)；電(dian)(dian)(dian)容(rong)器(qi)C1、C2、C3、C4均選用(yong)耐(nai)(nai)壓不小(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)；泄放電(dian)(dian)(dian)阻R1、R2、R3、R4均選用(yong)220kΩ，1／2W規(gui)格(ge)的(de)(de)；整(zheng)流(liu)(liu)(liu)堆D應(ying)選用(yong)額(e)定(ding)工作電(dian)(dian)(dian)流(liu)(liu)(liu)不小(xiao)(xiao)于50A，耐(nai)(nai)壓不小(xiao)(xiao)于400V規(gui)格(ge)的(de)(de)；電(dian)(dian)(dian)流(liu)(liu)(liu)表(biao)A選用(yong)量程為(wei)(wei)20A或30A規(gui)格(ge)的(de)(de)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)流(liu)(liu)(liu)表(biao)；電(dian)(dian)(dian)壓表(biao)V應(ying)選用(yong)量程為(wei)(wei)50V規(gui)格(ge)的(de)(de)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)壓表(biao)；R5選用(yong)10kΩ／6W的(de)(de)電(dian)(dian)(dian)阻；LED選用(yong)普(pu)通小(xiao)(xiao)功率發(fa)光(guang)二極管；K5選用(yong)普(pu)通按(an)鍵式開關，工作電(dian)(dian)(dian)流(liu)(liu)(liu)大小(xiao)(xiao)不作要(yao)求。將控(kong)制(zhi)開關K1、K2、K3、K4并排(pai)裝在機殼(ke)面板上適當(dang)的(de)(de)位置，并在K1、K2、K3、K4的(de)(de)位置旁邊分別標注上1A、2A、4A、8A的(de)(de)字樣，以便控(kong)制(zhi)計算調(diao)整(zheng)。蓄電(dian)(dian)(dian)池(chi)接線柱的(de)(de)工作電(dian)(dian)(dian)流(liu)(liu)(liu)不小(xiao)(xiao)于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(ren)身安全(quan)，充電(dian)(dian)(dian)時應(ying)嚴格(ge)照下列程序進行操作：　　1．檢查各個開關應(ying)處(chu)于斷開狀態(tai)，將(jiang)蓄(xu)電(dian)(dian)(dian)池的正、負極與接(jie)(jie)(jie)線柱連接(jie)(jie)(jie)可靠(kao)，然后(hou)閉合(he)K5，電(dian)(dian)(dian)壓表指(zhi)示出(chu)蓄(xu)電(dian)(dian)(dian)池兩端的電(dian)(dian)(dian)壓。　　2．將(jiang)電(dian)(dian)(dian)源插頭插入220V交流電(dian)(dian)(dian)源，接(jie)(jie)(jie)通K1，此時，觀(guan)察(cha)電(dian)(dian)(dian)源指(zhi)示燈亮(liang)，空(kong)載報警指(zhi)示發光二極管不應(ying)亮(liang)。若發光二極管亮(liang)，說明蓄(xu)電(dian)(dian)(dian)池正、負極與充電(dian)(dian)(dian)器接(jie)(jie)(jie)線柱之(zhi)間接(jie)(jie)(jie)觸不良，應(ying)除掉接(jie)(jie)(jie)點之(zhi)間的臟物后(hou)再進行連接(jie)(jie)(jie)。　　3．根據蓄(xu)電(dian)(dian)(dian)池對(dui)充電(dian)(dian)(dian)電(dian)(dian)(dian)流的要(yao)求，選(xuan)擇合(he)適的控(kong)制(zhi)開關接(jie)(jie)(jie)通并聯調(diao)整(zheng)充電(dian)(dian)(dian)電(dian)(dian)(dian)流，充電(dian)(dian)(dian)電(dian)(dian)(dian)流數(shu)值為接(jie)(jie)(jie)通的開關電(dian)(dian)(dian)流數(shu)之(zhi)和(he)。

　　該充(chong)(chong)電(dian)(dian)器的(de)唯一(yi)缺陷是，不(bu)具(ju)備充(chong)(chong)滿(man)電(dian)(dian)后自動停充(chong)(chong)的(de)功能。因各種蓄電(dian)(dian)池的(de)電(dian)(dian)壓(ya)及(ji)容量都(dou)不(bu)一(yi)樣，讀者應根據不(bu)同蓄電(dian)(dian)池的(de)要求(qiu)決定(ding)充(chong)(chong)電(dian)(dian)的(de)電(dian)(dian)流(liu)和充(chong)(chong)電(dian)(dian)時間，通過電(dian)(dian)壓(ya)表(biao)監視(shi)充(chong)(chong)電(dian)(dian)程度(du)。