在進行電(dian)器電(dian)路(lu)模塊規劃或給新產(chan)品定型(xing)時，許(xu)多人(ren)不會(hui)去細(xi)心(xin)考慮配套(tao)開關(guan)電(dian)源的選擇，直到發(fa)現開關(guan)電(dian)源部分(fen)有了故障問題，才從頭處理(li)這個問題。

一、選擇(ze)開關電源的基(ji)本依據

電壓和電流規劃，這是兩個最(zui)容易承認的(de)目標，只需依(yi)據(ju)電路(lu)的(de)功耗計算(suan)出即(ji)可。也應考(kao)慮檢驗高、低供電電壓極值。

大多數固定電(dian)源(yuan)答應(ying)(ying)輸出(chu)電(dian)壓±10%的(de)規(gui)劃(hua)內改(gai)動，假設(she)這(zhe)還不能滿意電(dian)路(lu)要求，可(ke)選用(yong)輸出(chu)可(ke)調的(de)或(huo)答應(ying)(ying)**改(gai)動規(gui)劃(hua)的(de)電(dian)源(yuan)。

假設用該電(dian)源給組合式(shi)設備(bei)供(gong)(gong)電(dian)，則設備(bei)所需**的(de)電(dian)流的(de)75%到(dao)90%由一個電(dian)源供(gong)(gong)應，不夠(gou)部分可并接兩個或(huo)更(geng)多(duo)電(dian)源。

二(er)、開關電源的擴展和安全性

1、并聯或串聯作業

當一(yi)(yi)個(ge)(ge)電(dian)(dian)源不(bu)能滿意所需的電(dian)(dian)壓或電(dian)(dian)流規劃時，可將兩個(ge)(ge)或多個(ge)(ge)電(dian)(dian)源(或將同(tong)一(yi)(yi)電(dian)(dian)源的不(bu)同(tong)輸出(chu))并聯(lian)或串(chuan)聯(lian)起來(lai)運(yun)用。在(zai)這(zhe)種作業方(fang)式下，各電(dian)(dian)源模(mo)塊(kuai)間(jian)的穩壓和控(kong)(kong)制電(dian)(dian)路之間(jian)的聯(lian)絡仍然存(cun)在(zai)，只不(bu)過(guo)一(yi)(yi)個(ge)(ge)電(dian)(dian)源作為主控(kong)(kong)方(fang)另一(yi)(yi)個(ge)(ge)電(dian)(dian)源作為受控(kong)(kong)方(fang)運(yun)用。

2、過載保護

因為一(yi)個電(dian)源(yuan)要(yao)供應不同的(de)(de)電(dian)路(lu)運用(yong)，這(zhe)些電(dian)路(lu)的(de)(de)電(dian)流的(de)(de)流量可能是不知道的(de)(de)，為了防(fang)止對電(dian)源(yuan)的(de)(de)損壞，需設置保(bao)護電(dian)路(lu)的(de)(de)規(gui)劃。

簡直(zhi)一(yi)切的(de)電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)都(dou)具有以下特征：在(zai)(zai)超(chao)(chao)出(chu)輸出(chu)規劃時(shi)，要(yao)么(me)輸出(chu)保持(chi)在(zai)(zai)**輸出(chu)值，要(yao)么(me)就自行(xing)封閉(bi)電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)。某些程(cheng)控電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)除(chu)可(ke)(ke)用(yong)程(cheng)序設定輸出(chu)規劃外，還能(neng)主(zhu)動(dong)設置電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)安穩輸出(chu)的(de)類型。也就是說，當外電(dian)(dian)路(lu)需(xu)求的(de)電(dian)(dian)壓(ya)或電(dian)(dian)流(liu)超(chao)(chao)越設置極(ji)限時(shi)，電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)可(ke)(ke)主(zhu)動(dong)地(di)由恒(heng)(heng)壓(ya)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)變成(cheng)恒(heng)(heng)流(liu)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)或由值流(liu)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)變成(cheng)恒(heng)(heng)壓(ya)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)。為電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)加上保護二極(ji)管(guan)能(neng)夠防(fang)止誤接外接電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)的(de)極(ji)性構(gou)成(cheng)的(de)損壞。熱傳感器也可(ke)(ke)用(yong)于防(fang)止由于電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)繼續(xu)作(zuo)業在(zai)(zai)過載(zai)狀態或冷卻無效而(er)燒壞電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)(yuan)。

三(san)、開關電源內部潛在的構成(cheng)損害的根源

1、脈動與噪聲

志(zhi)向的直(zhi)流(liu)(liu)電(dian)(dian)源(yuan)應供(gong)應純真的直(zhi)流(liu)(liu)，然而總有一些煩擾(rao)存在，比如在開關(guan)電(dian)(dian)源(yuan)輸出(chu)端口(kou)疊(die)加的脈(mo)動電(dian)(dian)流(liu)(liu)和高頻振動。這兩種(zhong)煩擾(rao)再加上電(dian)(dian)源(yuan)自身發生的尖峰噪聲使電(dian)(dian)源(yuan)出(chu)現斷續和隨意的漂移。

2、安穩度

當(dang)線電(dian)壓(ya)或(huo)負(fu)載電(dian)流(liu)改動肘(zhou)，直流(liu)電(dian)源的(de)輸出電(dian)壓(ya)也會有所高(gao)低(di)。穩壓(ya)程度由穩壓(ya)電(dian)路的(de)參數抉擇，參數是(shi)指濾(lv)波電(dian)容(rong)的(de)容(rong)量和能量開(kai)釋的(de)速率。

假設給電源供(gong)電的(de)(de)一(yi)個相對安(an)穩(wen)的(de)(de)電源，那么只需基本的(de)(de)負載穩(wen)壓(ya)(ya)。安(an)穩(wen)度的(de)(de)大小一(yi)般定義為(wei)空載或滿載時輸出電壓(ya)(ya)的(de)(de)百分比，或電壓(ya)(ya)的(de)(de)改動值。

3、內部阻抗

相(xiang)(xiang)對較大的電源內阻對負(fu)載(zai)(zai)來講有兩點(dian)倒(dao)霉(mei)，首(shou)先是(shi)倒(dao)霉(mei)于負(fu)載(zai)(zai)穩壓電路作業，更為倒(dao)霉(mei)的是(shi)負(fu)載(zai)(zai)電流的任何改動都會導致(zhi)直流電源輸(shu)出(chu)的高(gao)低，這種(zhong)高(gao)低對檢(jian)驗效(xiao)果的影(ying)響(xiang)同脈沖與噪聲對檢(jian)驗效(xiao)果構成的影(ying)響(xiang)完全相(xiang)(xiang)同。

4、開關電源(yuan)瞬態(tai)呼應(ying)或恢(hui)復

電(dian)(dian)(dian)源(yuan)瞬(shun)態(tai)呼應(ying)和恢(hui)(hui)(hui)復(fu)時(shi)(shi)(shi)間的大(da)小標(biao)明(ming)輸(shu)(shu)出(chu)(chu)負(fu)(fu)載(zai)(zai)遽(ju)然改(gai)(gai)動(dong)(dong)(dong)時(shi)(shi)(shi)，電(dian)(dian)(dian)源(yuan)穩壓(ya)電(dian)(dian)(dian)路恢(hui)(hui)(hui)復(fu)正常電(dian)(dian)(dian)壓(ya)能力的大(da)小。有兩種(zhong)參(can)數(shu)(shu)來標(biao)定(ding)電(dian)(dian)(dian)源(yuan)瞬(shun)態(tai)呼應(ying)和恢(hui)(hui)(hui)復(fu)：一(yi)是(shi)當負(fu)(fu)載(zai)(zai)遽(ju)然發(fa)生改(gai)(gai)動(dong)(dong)(dong)時(shi)(shi)(shi)輸(shu)(shu)出(chu)(chu)的違(wei)反值；二是(shi)輸(shu)(shu)出(chu)(chu)恢(hui)(hui)(hui)復(fu)到(dao)(dao)原本值所(suo)用(yong)(yong)(yong)的時(shi)(shi)(shi)間。為(wei)共同起見，一(yi)般在負(fu)(fu)載(zai)(zai)改(gai)(gai)動(dong)(dong)(dong)10%時(shi)(shi)(shi)，用(yong)(yong)(yong)輸(shu)(shu)出(chu)(chu)違(wei)反峰(feng)值電(dian)(dian)(dian)壓(ya)的毫優(you)數(shu)(shu)標(biao)定(ding)輸(shu)(shu)出(chu)(chu)違(wei)反量，用(yong)(yong)(yong)輸(shu)(shu)出(chu)(chu)恢(hui)(hui)(hui)復(fu)到(dao)(dao)正常值所(suo)用(yong)(yong)(yong)毫伏數(shu)(shu)標(biao)定(ding)恢(hui)(hui)(hui)復(fu)時(shi)(shi)(shi)間。還有一(yi)些生產廠(chang)商(shang)，用(yong)(yong)(yong)**的負(fu)(fu)載(zai)(zai)電(dian)(dian)(dian)流改(gai)(gai)動(dong)(dong)(dong)測定(ding)恢(hui)(hui)(hui)復(fu)時(shi)(shi)(shi)間。比如(ru)用(yong)(yong)(yong)輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)流改(gai)(gai)動(dong)(dong)(dong)的50%到(dao)(dao)****時(shi)(shi)(shi)所(suo)用(yong)(yong)(yong)的恢(hui)(hui)(hui)復(fu)正常值的時(shi)(shi)(shi)間。