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為什么原因導致開關電源的輸出電壓不足?
時間:2022-06-26 字號

1、開(kai)關電源電壓輸出低的原(yuan)因

(1)220V交流(liu)電壓輸入和整(zheng)流(liu)濾波(bo)電路對(dui)開關(guan)管供給的作業電壓不行,超出脈寬(kuan)調整(zheng)電路控(kong)制(zhi)規劃。

(2)負(fu)載電路存在過(guo)流(liu)引起開關電源(yuan)負(fu)載加重而導致(zhi)輸(shu)出電壓下(xia)降(jiang)。

(3)開(kai)/關(guan)機切換錯誤(wu),行掃描電(dian)(dian)路剛(gang)開(kai)始作業(ye)瞬(shun)間(jian),開(kai)關(guan)電(dian)(dian)源即處于(yu)待機狀況,此類缺點適(shi)用(yong)于(yu)無準備(bei)電(dian)(dian)源的(de)機器,CPU電(dian)(dian)源取自同(tong)一個電(dian)(dian)源,非副(fu)電(dian)(dian)源供(gong)給。

(4)開/關機(ji)接口電路結(jie)束因(yin)缺點處(chu)于(yu)開機(ji)與待(dai)機(ji)之間的狀況(kuang),然(ran)后導致開關電源輸出電壓低于(yu)正常值高于(yu)待(dai)機(ji)值。

(5)保(bao)護電路結(jie)束因缺點進入導(dao)通狀況,使電源進入弱振狀況,引起(qi)開關(guan)電源輸出(chu)電壓下降。

(6)整(zheng)流輸(shu)出(chu)電路中二極管和(he)濾波電容、限(xian)流電阻損壞引起輸(shu)出(chu)電壓低。

(7)脈寬(kuan)調制電路缺點,不能對(dui)開(kai)關(guan)電源(yuan)輸出電壓(ya)(ya)的(de)改變作出正確的(de)呼(hu)應(ying),對(dui)開(kai)關(guan)管基(ji)極電壓(ya)(ya)調整(zheng)方向不對(dui),然后構成開(kai)關(guan)電源(yuan)輸出電壓(ya)(ya)低。

(8)正(zheng)反饋電(dian)路中的正(zheng)反饋電(dian)阻(zu)值(zhi)改變,續(xu)流二極管性能蛻(tui)變或恒流源缺點(dian),使正(zheng)反饋量缺乏,導(dao)致振(zhen)動(dong)周期變長,振(zhen)動(dong)頻率下(xia)降,然后引起開(kai)關電(dian)源輸出(chu)電(dian)壓低。

(9)它激式開關電源因未(wei)得到行逆(ni)程脈沖而作(zuo)業于低(di)頻狀況,構成輸出(chu)電壓低(di)。

2、判別(bie)問題(ti)的(de)方法與過程

從(cong)上述(shu)剖析的(de)原因(yin)看出,引起電(dian)壓低的(de)原因(yin)涉(she)及到了開關電(dian)源本身的(de)各(ge)個(ge)部分和(he)與開關電(dian)源相關的(de)全(quan)部電(dian)路(lu),在檢修(xiu)時應先縮小缺點規劃。

(1)檢(jian)測開關(guan)管(guan)c極電(dian)壓,承認開關(guan)管(guan)供(gong)電(dian)正常。

(2)依據開關(guan)電(dian)源(yuan)各個輸(shu)出端電(dian)壓判別缺(que)點。

開(kai)(kai)關電(dian)(dian)(dian)(dian)源(yuan)(yuan)有(you)(you)(you)的(de)輸(shu)出(chu)(chu)端(duan)電(dian)(dian)(dian)(dian)壓正(zheng)常(chang),有(you)(you)(you)的(de)低于正(zheng)常(chang)值(zhi)。缺(que)點在(zai)(zai)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓低的(de)這個整(zheng)流(liu)(liu)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu),應對電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中的(de)限流(liu)(liu)電(dian)(dian)(dian)(dian)阻、整(zheng)流(liu)(liu)二極管、濾(lv)波(bo)電(dian)(dian)(dian)(dian)容進(jin)行(xing)檢查(cha)代換,若限流(liu)(liu)電(dian)(dian)(dian)(dian)阻發燙,說(shuo)明(ming)負載(zai)過流(liu)(liu),查(cha)負載(zai)。開(kai)(kai)關電(dian)(dian)(dian)(dian)源(yuan)(yuan)各(ge)(ge)路(lu)(lu)(lu)輸(shu)出(chu)(chu)均低。這種狀(zhuang)況說(shuo)明(ming)負載(zai)和整(zheng)流(liu)(liu)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)均正(zheng)常(chang),缺(que)點在(zai)(zai)開(kai)(kai)關電(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)正(zheng)反饋電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)、脈(mo)寬(kuan)調(diao)整(zheng)、開(kai)(kai)/待(dai)機(ji)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)、保護電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)。輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓有(you)(you)(you)的(de)下(xia)降(jiang)份額大(da),有(you)(you)(you)的(de)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓下(xia)降(jiang)份額小。測(ce)量效果說(shuo)明(ming)缺(que)點在(zai)(zai)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓下(xia)降(jiang)份額大(da)的(de)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)。此刻可斷(duan)開(kai)(kai)此路(lu)(lu)(lu)負載(zai),假設斷(duan)開(kai)(kai)的(de)是行(xing)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu),應接(jie)假負載(zai)。在(zai)(zai)斷(duan)開(kai)(kai)負載(zai)后,再測(ce)開(kai)(kai)關電(dian)(dian)(dian)(dian)源(yuan)(yuan)各(ge)(ge)輸(shu)出(chu)(chu)端(duan)電(dian)(dian)(dian)(dian)壓,若恢復正(zheng)常(chang),可判別(bie)所(suo)斷(duan)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)的(de)負載(zai)有(you)(you)(you)過流(liu)(liu)現象。若仍不(bu)正(zheng)常(chang),說(shuo)明(ming)缺(que)點在(zai)(zai)該(gai)整(zheng)流(liu)(liu)濾(lv)波(bo)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)。

3、斷開主負載、接上(shang)燈泡,判(pan)別是否(fou)負載缺點

有些收臺圖閃、帶負(fu)載后電(dian)壓(ya)不穩的機器,難(nan)于鑒(jian)別缺點是在電(dian)源或是負(fu)載時,能夠(gou)選用“借(jie)法”,用此電(dian)源帶同等標(biao)準、相(xiang)同B+電(dian)壓(ya)的另一臺機器行負(fu)載,進行判別。

4、保存(cun)發動、正反饋、軟(ruan)發動及負反饋電路

逐個吊銷各種(zhong)保護電(dian)(dian)(dian)路(lu)、待(dai)機(ji)控(kong)制電(dian)(dian)(dian)路(lu)結束三極管。開機(ji)查詢缺(que)點是否(fou)消除,來逐漸縮(suo)小缺(que)點規(gui)劃。留心:兼(jian)有穩壓效(xiao)果的電(dian)(dian)(dian)路(lu)不能斷(duan)開(例如(ru)光(guang)電(dian)(dian)(dian)耦合器)。斷(duan)開保護電(dian)(dian)(dian)路(lu)時,須慎重,并采(cai)納防(fang)止電(dian)(dian)(dian)壓升高(gao)的辦法。

5、選用替(ti)代法、檢修脈寬調整(zheng)電路(用克己取(qu)樣電路替(ti)代原取(qu)樣電路,判別(bie)缺點規(gui)劃)

(1)代換后,電(dian)壓(ya)恢復正(zheng)常,說(shuo)明缺點(dian)在取樣電(dian)路(lu)(lu)及光耦(ou)電(dian)路(lu)(lu)。

(2)電(dian)(dian)壓仍(reng)(reng)低,則(ze)(ze)斷開原取樣電(dian)(dian)路(lu)(lu)B+接(jie)入點(dian),假設(she)電(dian)(dian)壓還低,則(ze)(ze)檢查(cha)B+濾波電(dian)(dian)容,承認良(liang)好后,能夠圈定(ding)缺點(dian)在熱(re)底(di)板(ban)部(bu)分。先查(cha)軟發動電(dian)(dian)路(lu)(lu)是否(fou)對開關管B極分流了。仍(reng)(reng)不(bu)可,查(cha)正反饋(kui)、負(fu)反饋(kui)電(dian)(dian)路(lu)(lu)。查(cha)熱(re)底(di)板(ban)部(bu)分的(de)負(fu)反饋(kui)方(fang)法同檢查(cha)電(dian)(dian)壓高的(de)方(fang)法附近,選用迫使B+輸出高的(de)思(si)路(lu)(lu)(留心:改(gai)變作(zuo)業點(dian)不(bu)能構成B+過高擴展(zhan)缺點(dian))。

總之,在(zai)電(dian)(dian)源的修(xiu)補中,當電(dian)(dian)壓(ya)不穩(wen)時(shi)可(ke)選用(yong)逆向思維,電(dian)(dian)壓(ya)高(gao)時(shi)使之變低(di),電(dian)(dian)壓(ya)低(di)時(shi)使之變高(gao),必(bi)要(yao)時(shi)可(ke)選用(yong)人(ren)為改(gai)變作業(ye)點(dian)電(dian)(dian)壓(ya)。以利于查找缺點(dian)點(dian),在(zai)于修(xiu)補人(ren)員活絡把握。


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