基于高壓陶瓷電容設計的開關電源優勢分析
來(lai)源：世(shi)紀電源網
摘要：序(xu)言(yan)現代電源(yuan)技術中，無論(lun)是線性(xing)電源(yuan)還是開關電源(yuan)，鋁電解電容都是必不可(ke)少的關鍵(jian)器件。然而(er)，在行業內(nei)常(chang)規的AC-DC電源(yuan)設(she)計(ji)中，鋁電解電容會(hui)給電源(yuan)帶來(lai)高低溫條(tiao)件下可(ke)靠性(xing)差、壽(shou)命短等問題。那么，有(you)沒有(you)一種既能(neng)(neng)替(ti)代傳(chuan)統鋁電解電容，又(you)能(neng)(neng)提高電源(yuan)可(ke)靠性(xing)和(he)...
序 言
現(xian)代電(dian)(dian)(dian)(dian)源(yuan)(yuan)技術中，無(wu)論(lun)是線性電(dian)(dian)(dian)(dian)源(yuan)(yuan)還是開關(guan)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，鋁(lv)(lv)電(dian)(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)(dian)容(rong)都(dou)是必不可(ke)(ke)少的關(guan)鍵器(qi)件。然而，在行業內常(chang)規的AC-DC電(dian)(dian)(dian)(dian)源(yuan)(yuan)設(she)計中，鋁(lv)(lv)電(dian)(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)(dian)容(rong)會給電(dian)(dian)(dian)(dian)源(yuan)(yuan)帶來高(gao)低溫條件下可(ke)(ke)靠(kao)(kao)性差、壽(shou)命短等問題。那(nei)么，有(you)沒有(you)一(yi)種既能替(ti)代傳統鋁(lv)(lv)電(dian)(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)(dian)容(rong)，又能提高(gao)電(dian)(dian)(dian)(dian)源(yuan)(yuan)可(ke)(ke)靠(kao)(kao)性和(he)壽(shou)命的器(qi)件呢？本文著重(zhong)從高(gao)壓陶瓷電(dian)(dian)(dian)(dian)容(rong)與(yu)傳統鋁(lv)(lv)電(dian)(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)(dian)容(rong)的優劣勢(shi)對比進(jin)行探(tan)討與(yu)分(fen)析。
一、鋁電解(jie)電容的設計缺陷
AC-DC電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源轉(zhuan)換器，要實(shi)(shi)現交(jiao)流(liu)(liu)到直流(liu)(liu)的(de)變換，首(shou)先需要將交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓經過整流(liu)(liu)濾波后形成(cheng)(cheng)一個(ge)穩定、平(ping)滑的(de)直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓給(gei)自(zi)身及外部器件(jian)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。而電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)由(you)于具有(you)單(dan)位體積(ji)內(nei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)量(liang)大(da)、額定容(rong)量(liang)大(da)（可實(shi)(shi)現法拉級）、價(jia)格低(di)廉等優點(dian)，常成(cheng)(cheng)為常規開關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源中整流(liu)(liu)濾波的(de)關鍵器件(jian)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)是由(you)鋁(lv)圓筒做負極，里面裝(zhuang)有(you)液體電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)質，插入一片彎曲的(de)鋁(lv)帶(dai)做正極制(zhi)成(cheng)(cheng)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)液在高溫和低(di)溫等極端條件(jian)下(xia)，非(fei)常容(rong)易漏液和干涸，從而使其(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)氣屬(shu)性發生變化，最(zui)終導(dao)致(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)失效。一旦鋁(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)失效，因其(qi)劇烈(lie)反應形成(cheng)(cheng)壓力，就會釋(shi)放出易燃(ran)、腐蝕(shi)性氣體，導(dao)致(zhi)(zhi)失效。
根據鋁電(dian)(dian)(dian)解電(dian)(dian)(dian)容的(de)物理(li)結構，可以用圖(tu) 1中(zhong)所(suo)示的(de)電(dian)(dian)(dian)路等(deng)效，其中(zhong)CAK代表兩電(dian)(dian)(dian)極間的(de)理(li)想電(dian)(dian)(dian)容量(liang)；Rp 是并聯電(dian)(dian)(dian)阻，代表了電(dian)(dian)(dian)容的(de)漏電(dian)(dian)(dian)流成分；Rl 代表了電(dian)(dian)(dian)容引出(chu)(chu)端及電(dian)(dian)(dian)極部分的(de)串(chuan)聯電(dian)(dian)(dian)阻成分；L 代表了引出(chu)(chu)線和連(lian)接處的(de)等(deng)效串(chuan)聯電(dian)(dian)(dian)感成分。
鋁(lv)電(dian)(dian)解(jie)電(dian)(dian)容(rong)的(de)(de)(de)性(xing)能主(zhu)(zhu)要依賴其中介質部(bu)分(fen)，即陽極(ji)金屬(shu)氧(yang)化膜(mo)(mo)部(bu)分(fen)。除(chu)受(shou)初始工藝的(de)(de)(de)影(ying)響(xiang)外，在工作過(guo)程中，電(dian)(dian)解(jie)液(ye)也會不斷修補并增厚該氧(yang)化膜(mo)(mo)，隨著(zhu)陽極(ji)金屬(shu)氧(yang)化膜(mo)(mo)的(de)(de)(de)不斷增厚，鋁(lv)電(dian)(dian)解(jie)電(dian)(dian)容(rong)等效電(dian)(dian)路(lu)模型中的(de)(de)(de)電(dian)(dian)容(rong)值C會不斷下降，等效串聯電(dian)(dian)阻ESR會不斷增大(da)，同時陰極(ji)反應(ying)產生(sheng)的(de)(de)(de)氫氣又加(jia)速了電(dian)(dian)解(jie)液(ye)的(de)(de)(de)揮發，這些便是引(yin)起(qi)鋁(lv)電(dian)(dian)解(jie)電(dian)(dian)容(rong)退化的(de)(de)(de)主(zhu)(zhu)要因素。
因(yin)而(er)，雖(sui)然電(dian)解電(dian)容有(you)著其他類型的電(dian)容無法替代(dai)的優(you)勢，但還(huan)是具(ju)有(you)內部損耗大(da)、靜電(dian)容量誤差大(da)、漏電(dian)流(liu)大(da)、高低溫特性(xing)差等(deng)(deng)缺陷。故采(cai)用電(dian)解電(dian)容設計(ji)的常規AC-DC電(dian)源模塊(kuai)在高低溫特性(xing)、可靠性(xing)、使用壽命等(deng)(deng)方面具(ju)有(you)明顯的劣勢。
那(nei)么，如果AC-DC電(dian)(dian)(dian)源設(she)計中(zhong)不使用電(dian)(dian)(dian)解電(dian)(dian)(dian)容，電(dian)(dian)(dian)源產品(pin)將(jiang)會怎樣呢？無(wu)電(dian)(dian)(dian)解電(dian)(dian)(dian)容的AC-DC電(dian)(dian)(dian)源模塊是否可避免(mian)上述(shu)致命缺陷(xian)？
日前，金升(sheng)陽(yang)通(tong)過采用(yong)高壓陶瓷電(dian)(dian)容的(de)填谷電(dian)(dian)路設計替代并優化(hua)電(dian)(dian)解(jie)(jie)電(dian)(dian)容的(de)基本功能，成功設計出(chu)滿(man)足性能要求(qiu)的(de)無電(dian)(dian)解(jie)(jie)電(dian)(dian)容AC-DC電(dian)(dian)源模(mo)塊(kuai)LN系列，解(jie)(jie)決了AC-DC電(dian)(dian)源因(yin)電(dian)(dian)解(jie)(jie)電(dian)(dian)容而帶來的(de)產品大體積、壽命(ming)短、高低溫(wen)性能差等問題。
二(er)、無(wu)電解電容產品的優勢
與電解電容(rong)相(xiang)比，陶(tao)瓷(ci)電容(rong)具有(you)極低(di)的ESR和ESL，能(neng)降低(di)因寄生參數(shu)而引(yin)起的損壞風險；同(tong)時(shi)，因陶(tao)瓷(ci)電容(rong)的電解質在(zai)高低(di)溫等極限條件下不易揮發、凝固，容(rong)量相(xiang)對穩(wen)定，能(neng)長時(shi)間保持電容(rong)的電氣特性，從而極大地提(ti)高了電源產品(pin)的高低(di)溫性能(neng)和長期使用的可(ke)靠(kao)性。
1）高效、環保
LN系(xi)列(lie)采用填谷電(dian)路進(jin)行(xing)設計，利用高(gao)壓陶(tao)瓷電(dian)容(rong)完美替代鋁電(dian)解(jie)電(dian)容(rong)，增加(jia)了整流管(guan)的(de)(de)(de)導通角，使(shi)輸入電(dian)流波(bo)形從尖(jian)峰脈沖變得(de)更接近正(zheng)弦波(bo)，從而大幅(fu)度提高(gao)電(dian)源(yuan)的(de)(de)(de)功率因素（如表1所示），提高(gao)電(dian)源(yuan)的(de)(de)(de)轉換(huan)效率，更加(jia)利于環(huan)保節能，顯著(zhu)降低總(zong)諧波(bo)失真。如圖1所示：
以下所有(you)表中舊方案為采用電(dian)解(jie)電(dian)容的(de)產品，新(xin)方案為采用填(tian)谷電(dian)路無電(dian)解(jie)電(dian)容的(de)新(xin)產品
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2）產品壽(shou)命的提(ti)升
電源(yuan)本身是一個(ge)功(gong)率(lv)器(qi)(qi)件，在(zai)正常工作時功(gong)率(lv)損(sun)耗通過熱的形式散(san)發(fa)到(dao)外部(bu)(bu)(bu)，其內部(bu)(bu)(bu)的變壓器(qi)(qi)、開關器(qi)(qi)件、整流(liu)二(er)極管等都是發(fa)熱器(qi)(qi)件。除(chu)內部(bu)(bu)(bu)因素外，大部(bu)(bu)(bu)分(fen)電源(yuan)需應(ying)用在(zai)較高的環境溫度中(zhong)，這些都會導致電解液(ye)的揮(hui)發(fa)，降低電解電容的使(shi)用壽命(ming)。
陶(tao)瓷電(dian)容(rong)(rong)采(cai)用特性最穩定(ding)的(de)陶(tao)瓷材(cai)料作為(wei)介質(zhi)，特別(bie)是一類陶(tao)瓷電(dian)容(rong)(rong)（NOP) 能實現-55℃~+125℃的(de)工(gong)作環境(jing)溫(wen)度(du)，容(rong)(rong)量變(bian)化不超過(guo)±30ppm/℃。電(dian)容(rong)(rong)溫(wen)度(du)變(bian)化時，容(rong)(rong)值很(hen)穩定(ding)，即具有溫(wen)度(du)補償功能，適用于要求容(rong)(rong)值在溫(wen)度(du)變(bian)化范(fan)圍(wei)內穩定(ding)和高Q值的(de)線路以(yi)及各種諧振線路中；二/三類陶(tao)瓷（X7R）實現-55℃~+125℃的(de)工(gong)作溫(wen)度(du)范(fan)圍(wei)內，容(rong)(rong)量最大的(de)變(bian)化為(wei) ±15%。
從(cong)高(gao)壓(ya)陶瓷電容(rong)的介(jie)質與鋁電解電容(rong)的電解液介(jie)質本身(shen)的特性可以(yi)看出，陶瓷電容(rong)能夠(gou)承(cheng)受更嚴(yan)格(ge)的環(huan)境要求，對電源(yuan)產(chan)品(pin)的壽命、可靠(kao)性的設計(ji)都有著重要的意義，能夠(gou)很大程度地提高(gao)電源(yuan)產(chan)品(pin)的使用壽命以(yi)及可靠(kao)性。
金升(sheng)陽無電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)LN系列(lie)通(tong)過采用(yong)填谷電(dian)(dian)(dian)路，利用(yong)高壓(ya)陶(tao)瓷電(dian)(dian)(dian)容(rong)成功替代(dai)鋁(lv)電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)，能(neng)夠有效避(bi)免(mian)電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)因(yin)內部電(dian)(dian)(dian)解液(ye)導(dao)致(zhi)的(de)高低溫性(xing)能(neng)差問(wen)題(ti)；避(bi)免(mian)因(yin)電(dian)(dian)(dian)解液(ye)的(de)揮發導(dao)致(zhi)電(dian)(dian)(dian)容(rong)容(rong)值下(xia)降、電(dian)(dian)(dian)源產品壽命降低問(wen)題(ti)；甚至可以避(bi)免(mian)因(yin)電(dian)(dian)(dian)解液(ye)的(de)劇(ju)烈噴發或者漏液(ye)引起的(de)安全問(wen)題(ti)。
3）穩定(ding)的高(gao)低溫特性
目前，大(da)多(duo)數(shu)常(chang)規(gui)(gui)電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容(rong)的(de)(de)額(e)定(ding)工作(zuo)溫(wen)度為105℃，但(dan)因電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容(rong)在高(gao)(gao)溫(wen)條(tiao)件(jian)下(xia)電(dian)(dian)(dian)解(jie)液易揮發，電(dian)(dian)(dian)源(yuan)本身發熱較大(da)等(deng)原因，常(chang)規(gui)(gui)采用(yong)電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容(rong)的(de)(de)AC-DC電(dian)(dian)(dian)源(yuan)只能工作(zuo)在70℃的(de)(de)環境(jing)條(tiao)件(jian)下(xia)。要提高(gao)(gao)電(dian)(dian)(dian)源(yuan)的(de)(de)工作(zuo)環境(jing)溫(wen)度，必須采用(yong)價(jia)格更昂貴、體積更大(da)的(de)(de)電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容(rong)，或者以降(jiang)額(e)的(de)(de)方式實現高(gao)(gao)低溫(wen)條(tiao)件(jian)下(xia)的(de)(de)應用(yong)，下(xia)面(mian)以金升(sheng)陽常(chang)規(gui)(gui)AC-DC電(dian)(dian)(dian)源(yuan)產品在高(gao)(gao)低溫(wen)環境(jing)下(xia)的(de)(de)降(jiang)額(e)要求如圖3：
金(jin)升(sheng)陽LN系列能在成本、體積變化不大的情況下實現(xian)高溫工作，能滿足-40℃到70℃條件下無任何降額要求，可(ke)應用(yong)在環(huan)境溫度(du)較(jiao)(jiao)高/較(jiao)(jiao)低，且(qie)對電(dian)源產品的可(ke)靠性(xing)、使用(yong)壽命較(jiao)(jiao)高的場合(he)，如路燈控制、LED等行業。
4）高EMC特性
金升陽(yang)無電解電容LN系列(lie)產(chan)品(pin)，充分考(kao)慮到(dao)不(bu)同應用(yong)場合、不(bu)同的(de)設(she)計要求，對(dui)產(chan)品(pin)的(de)EMC性能(neng)進行了全(quan)面(mian)的(de)升級(ji)優化。在模塊內部(bu)通過PCB設(she)計、采用(yong)多級(ji)EMC濾波等方式實現在無任何外圍(wei)防護器件的(de)情況下EMI滿足CLSS B，防浪涌能(neng)力達4級(ji)。
三、總結
金升陽無電(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)容AC-DC電(dian)(dian)(dian)源模塊(kuai)LN系列的成功(gong)開發(fa)證明AC-DC電(dian)(dian)(dian)源設計(ji)中也可不使用(yong)(yong)電(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)容。通過采用(yong)(yong)高壓(ya)陶瓷(ci)電(dian)(dian)(dian)容的填谷電(dian)(dian)(dian)路設計(ji)替(ti)代并優化電(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)容的基本(ben)(ben)功(gong)能(neng)(neng)，能(neng)(neng)夠完美解(jie)(jie)決電(dian)(dian)(dian)源模塊(kuai)因電(dian)(dian)(dian)解(jie)(jie)電(dian)(dian)(dian)容本(ben)(ben)身固(gu)有缺陷而產生的高低(di)溫性能(neng)(neng)差(cha)、可靠(kao)性差(cha)、使用(yong)(yong)壽命(ming)短等問(wen)題。
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