220v交流電經T0雙向濾波抑制干擾，D1整流為脈動直流，再經C11濾波形成穩定的300V左右的直流電。U1 為TL3842脈寬調制集成電路。其5腳為電源負極，7腳為電源正極，6腳為脈沖輸出直接驅動場效應管Q1(K1358) 3腳為***大電流限制，調整R25(2.5歐姆)的阻值可以調整充電器的***大電流。
電動車充電器原理圖
2腳為電壓反饋，可以調節充電器的輸出電壓。4腳外接振蕩電阻R1,和振蕩電容C1。T1為高頻脈沖變壓器，其作用有三個。
第一是把高壓脈沖降壓為低壓脈沖。
第二是起到隔離高壓的作用，以防觸電。
第三是為uc3842提供工作電源。D4為高頻整流管（16A60V）C10為低壓濾波電容,D5為12V穩壓二極管， U3(TL431)為精密基準電壓源，配合U2(光耦合器4N35) 起到自動調節充電器電壓的作用。調整w2(微調電阻)可以細調充電器的電壓。D10是電源指示燈。D6為充電指示燈。
R27是電流取樣電阻（0.1歐姆，5w）改變W1的阻值可以調整充電器轉浮充的拐點電流
電動車充電器原理圖
（200－300 mA）通電開始時，C11上有300v左右電壓。此電壓一路經T1加載到Q1。
第二路經R5,C8,C3, 達到U1的第7腳。強迫U1啟動。U1的6腳輸出方波脈沖，Q1工作，電流經R25到地。同時T1副線圈產生感應電壓，經D3,R12給U1提供可靠電源。T1輸出線圈的電壓經D4,C10整流濾波得到穩定的電壓。此電壓一路經D7（D7起到防止電池的電流倒灌給充電器的作用）給電池充電。
第二路經R14,D5,C9, 為LM358(雙運算放大器，1腳為電源地，8腳為電源正)及其外圍電路提供12V工作電源。D9為LM358提供基準電壓，經R26,R4分壓達到LM358的第二腳和第5腳。正常充電時，R27上端有0.15－0.18V左右電壓，此電壓經R17加到LM358第三腳，從1腳送出高電壓。此電壓一路經R18,強迫Q2導通，
電動車充電器原理圖
D6（紅(hong)燈）點亮，第(di)二路(lu)注入LM358的(de)(de)6腳(jiao)(jiao)(jiao)，7腳(jiao)(jiao)(jiao)輸(shu)出低電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，迫使(shi)Q3關斷(duan)，D10(綠燈)熄滅(mie)，充(chong)電(dian)(dian)(dian)(dian)器(qi)進入恒(heng)流充(chong)電(dian)(dian)(dian)(dian)階段(duan)。當電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)上升到44.2V左右(you)時,充(chong)電(dian)(dian)(dian)(dian)器(qi)進入恒(heng)壓(ya)(ya)(ya)充(chong)電(dian)(dian)(dian)(dian)階段(duan)，輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)維持在44.2V左右(you)，充(chong)電(dian)(dian)(dian)(dian)器(qi)進入恒(heng)壓(ya)(ya)(ya)充(chong)電(dian)(dian)(dian)(dian)階段(duan)，電(dian)(dian)(dian)(dian)流逐漸減小。當充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流減小到200mA—300mA時，R27上端的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)下降，LM358的(de)(de)3腳(jiao)(jiao)(jiao)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低于2腳(jiao)(jiao)(jiao)，1腳(jiao)(jiao)(jiao)輸(shu)出低電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，Q2關斷(duan)，D6熄滅(mie)。同時7腳(jiao)(jiao)(jiao)輸(shu)出高(gao)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，此電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)一路(lu)使(shi)Q3導通，D10點亮。另一路(lu)經D8，W1到達反(fan)饋電(dian)(dian)(dian)(dian)路(lu)，使(shi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)降低。充(chong)電(dian)(dian)(dian)(dian)器(qi)進入涓(juan)流充(chong)電(dian)(dian)(dian)(dian)階段(duan)。1－2小時后充(chong)電(dian)(dian)(dian)(dian)結束(shu)。
