為(wei)實現市電(dian)供(gong)電(dian)與逆變器供(gong)電(dian)之(zhi)間(jian)的(de)自(zi)(zi)動(dong)切(qie)換，而EPS電(dian)源(yuan)按國家(jia)標(biao)準需是(shi)(shi)后備式的(de)，因(yin)此自(zi)(zi)動(dong)切(qie)換裝置(zhi)是(shi)(shi)EPS電(dian)源(yuan)中必不(bu)可少的(de)部件(jian)，也(ye)是(shi)(shi)影響EPS電(dian)源(yuan)在(zai)可靠性(xing)方面(mian)的(de)關鍵部件(jian)之(zhi)一，因(yin)此濟南啟創電(dian)氣有限公司專門就自(zi)(zi)動(dong)切(qie)換裝置(zhi)進行(xing)了下(xia)面(mian)的(de)分(fen)析(xi)解釋。
??????根據EPS電(dian)源的(de)輸出容量和負(fu)載(zai)要(yao)求不同(tong)，自動切(qie)(qie)換(huan)(huan)裝置可(ke)采用功率繼電(dian)器、交流接觸(chu)器、互投(tou)開關、固(gu)態開關（晶閘(zha)管）等(deng)構成。對EPS的(de)切(qie)(qie)換(huan)(huan)時(shi)間要(yao)求具有多樣性(xing)，比(bi)如，一(yi)般消(xiao)防(fang)應(ying)急照(zhao)明(ming)要(yao)求切(qie)(qie)換(huan)(huan)時(shi)間小于(yu)5s，但是高危險區域使用的(de)消(xiao)防(fang)應(ying)急照(zhao)明(ming)要(yao)求切(qie)(qie)換(huan)(huan)時(shi)間小于(yu)0.25s，為(wei)高壓氣體放電(dian)燈供電(dian)時(shi)不熄輝(hui)，則(ze)要(yao)求切(qie)(qie)換(huan)(huan)時(shi)間為(wei)數(shu)毫秒(miao)量級，而為(wei)風(feng)機、泵類、卷簾(lian)門、電(dian)梯等(deng)負(fu)載(zai)供電(dian)時(shi)，根據應(ying)用要(yao)求不同(tong)，切(qie)(qie)換(huan)(huan)時(shi)間也會在數(shu)毫秒(miao)等(deng)。
??????EPS電(dian)源(yuan)(yuan)與UPS電(dian)源(yuan)(yuan)不同之(zhi)處在(zai)于多數應用場合對切換(huan)(huan)時間(jian)沒(mei)有很苛(ke)刻(ke)要求，在(zai)切換(huan)(huan)時間(jian)的要求也并不是越短(duan)越好，在(zai)能滿足(zu)應用需求的大前提(ti)下，適當慢一點(dian)切換(huan)(huan)可(ke)(ke)在(zai)其他方(fang)面獲益，比如可(ke)(ke)以降低損耗，減小暫態沖(chong)擊，提(ti)高可(ke)(ke)靠性(xing)等等方(fang)面，避免負載可(ke)(ke)能由于瞬間(jian)的斷電(dian)而導致工作失常等。市電(dian)正(zheng)常時EPS電(dian)源(yuan)(yuan)的逆(ni)變器基本上(shang)都(dou)處于備(bei)用狀(zhuang)態，而且有冷(leng)備(bei)份(fen)與熱備(bei)份(fen)兩種(zhong)工作方(fang)式。
在(zai)冷備(bei)份(fen)時，逆變(bian)器(qi)只是控制部分(fen)處(chu)于(yu)工作(zuo)狀(zhuang)態(tai)，功(gong)率部分(fen)處(chu)于(yu)加(jia)電待機狀(zhuang)態(tai)，但(dan)不(bu)起動(dong)；熱備(bei)份(fen)時，整個逆變(bian)器(qi)處(chu)于(yu)正常運轉狀(zhuang)態(tai)，但(dan)不(bu)承(cheng)擔負載。當(dang)逆變(bian)器(qi)熱備(bei)份(fen)時，最短切(qie)換時間(jian)基本決定于(yu)所用切(qie)換裝置的動(dong)作(zuo)時間(jian)；
而(er)當逆(ni)(ni)(ni)變(bian)器(qi)(qi)冷備(bei)份時(shi)，最短(duan)切換時(shi)間(jian)(jian)還要(yao)受逆(ni)(ni)(ni)變(bian)器(qi)(qi)其動時(shi)間(jian)(jian)的(de)制約。特別(bie)是容(rong)量(liang)(liang)較(jiao)大(da)的(de)EPS電源，如果起(qi)動過快，逆(ni)(ni)(ni)變(bian)變(bian)壓器(qi)(qi)和低通濾(lv)波器(qi)(qi)會產生很大(da)的(de)暫態沖擊(ji)，甚至可能損(sun)壞IGBT功率(lv)器(qi)(qi)件，因此(ci)逆(ni)(ni)(ni)變(bian)器(qi)(qi)一般(ban)都具備(bei)軟起(qi)動特性，且功率(lv)越大(da)，起(qi)動越慢，大(da)容(rong)量(liang)(liang)EPS逆(ni)(ni)(ni)變(bian)器(qi)(qi)的(de)起(qi)動時(shi)間(jian)(jian)可達(da)數秒之久。如果要(yao)求(qiu)更快的(de)切換時(shi)間(jian)(jian)，則只(zhi)能采取熱備(bei)份工作(zuo)方式，此(ci)時(shi)EPS的(de)待機(ji)(ji)損(sun)耗自(zi)然要(yao)增加(jia)許(xu)多，整機(ji)(ji)效率(lv)會較(jiao)低。
至于(yu)使用(yong)哪種切(qie)(qie)換(huan)(huan)裝置，這主要(yao)(yao)是依據對切(qie)(qie)換(huan)(huan)時(shi)(shi)間(jian)的(de)要(yao)(yao)求而定。如要(yao)(yao)求毫秒級的(de)切(qie)(qie)換(huan)(huan)時(shi)(shi)間(jian)，那(nei)么就只(zhi)能采(cai)用(yong)固態(tai)開關(guan)(guan)(guan)（晶閘(zha)管(guan)(guan)）切(qie)(qie)換(huan)(huan)，且逆變(bian)器要(yao)(yao)處于(yu)熱備狀態(tai)。與同容(rong)量(liang)的(de)機械(xie)切(qie)(qie)換(huan)(huan)開關(guan)(guan)(guan)相比，固態(tai)開關(guan)(guan)(guan)（晶閘(zha)管(guan)(guan)）切(qie)(qie)換(huan)(huan)的(de)造價要(yao)(yao)高得多，通態(tai)損耗(hao)也會相對比較多。在對切(qie)(qie)換(huan)(huan)時(shi)(shi)間(jian)沒有苛(ke)刻(ke)要(yao)(yao)求的(de)應用(yong)場合，一般采(cai)用(yong)機械(xie)切(qie)(qie)換(huan)(huan)開關(guan)(guan)(guan)進行(xing)切(qie)(qie)換(huan)(huan)，容(rong)量(liang)較小的(de)EPS電源一般采(cai)用(yong)功率繼(ji)電器，功率較大的(de)EPS通常采(cai)用(yong)互鎖的(de)交(jiao)流(liu)接觸(chu)器或自(zi)動互投(tou)開關(guan)(guan)(guan)。與交(jiao)流(liu)接觸(chu)器相比，自(zi)動互投(tou)開關(guan)(guan)(guan)動作較慢，但由于(yu)互投(tou)開關(guan)(guan)(guan)具有機械(xie)自(zi)保持(chi)特性，對于(yu)不頻繁的(de)切(qie)(qie)換(huan)(huan)而言，在長(chang)期運行(xing)的(de)可靠性方(fang)面更具優勢。
用固態開關（晶閘管）實(shi)現(xian)市(shi)電(dian)(dian)與(yu)逆變器(qi)輸出(chu)之(zhi)間的(de)快速切(qie)換(huan)(huan)技術雖在UPS電(dian)(dian)源中(zhong)應用多年，但也有(you)所(suo)不同，UPS用功率繼電(dian)(dian)器(qi)（或(huo)接觸器(qi)）與(yu)固態開關（晶閘管）組合成一個旁路（BYPASS）切(qie)換(huan)(huan)裝置的(de)，固態開關（晶閘管）主要是做瞬間過載旁路（BYPASS）切(qie)換(huan)(huan)，靠它瞬間使逆變器(qi)與(yu)電(dian)(dian)網(wang)有(you)個短暫的(de)并聯運行，從而獲得瞬間無切(qie)換(huan)(huan)時間的(de)供電(dian)(dian)（彌補(bu)了(le)功率繼電(dian)(dian)器(qi)或(huo)接觸器(qi)的(de)渡越時間）。
關鍵是(shi)(shi)(shi)(shi)要(yao)(yao)實現逆變器(qi)的(de)(de)鎖相運(yun)行和對(dui)市(shi)(shi)電(dian)(dian)(dian)即(ji)時(shi)(shi)電(dian)(dian)(dian)壓的(de)(de)快速檢(jian)測(ce)與跟蹤(zong)。它并(bing)不(bu)是(shi)(shi)(shi)(shi)真真的(de)(de)斷(duan)電(dian)(dian)(dian)切(qie)(qie)換(huan)(huan)，因(yin)這種方式(shi)均為“在線(xian)式(shi)”UPS所用，真真的(de)(de)斷(duan)電(dian)(dian)(dian)切(qie)(qie)換(huan)(huan)工(gong)作(zuo)時(shi)(shi)固(gu)態(tai)開(kai)關（晶閘(zha)管）是(shi)(shi)(shi)(shi)不(bu)參于工(gong)作(zuo)的(de)(de)。當其用于EPS電(dian)(dian)(dian)源時(shi)(shi)才真正(zheng)是(shi)(shi)(shi)(shi)固(gu)態(tai)開(kai)關（晶閘(zha)管）的(de)(de)參與斷(duan)電(dian)(dian)(dian)切(qie)(qie)換(huan)(huan)，EPS電(dian)(dian)(dian)源均為后備式(shi)是(shi)(shi)(shi)(shi)不(bu)設旁路(lu)接(jie)觸器(qi)的(de)(de)。就是(shi)(shi)(shi)(shi)處于在市(shi)(shi)電(dian)(dian)(dian)正(zheng)常(chang)、逆變器(qi)也(ye)正(zheng)常(chang)運(yun)轉的(de)(de)情況下，即(ji)使是(shi)(shi)(shi)(shi)進(jin)行不(bu)間斷(duan)的(de)(de)切(qie)(qie)換(huan)(huan)，在技術上也(ye)是(shi)(shi)(shi)(shi)可以做到的(de)(de)，但(dan)實際情況是(shi)(shi)(shi)(shi)，切(qie)(qie)換(huan)(huan)需要(yao)(yao)在市(shi)(shi)電(dian)(dian)(dian)突然發(fa)生(sheng)中(zhong)斷(duan)或故(gu)(gu)障時(shi)(shi)進(jin)行，因(yin)市(shi)(shi)電(dian)(dian)(dian)中(zhong)斷(duan)或故(gu)(gu)障的(de)(de)發(fa)生(sheng)時(shi)(shi)刻是(shi)(shi)(shi)(shi)隨(sui)機的(de)(de)和非預知的(de)(de)，檢(jian)測(ce)確認市(shi)(shi)電(dian)(dian)(dian)故(gu)(gu)障需要(yao)(yao)時(shi)(shi)間，此時(shi)(shi)的(de)(de)切(qie)(qie)換(huan)(huan)時(shi)(shi)間不(bu)可能小于檢(jian)測(ce)、確認市(shi)(shi)電(dian)(dian)(dian)故(gu)(gu)障需要(yao)(yao)的(de)(de)時(shi)(shi)間。
為(wei)防(fang)止(zhi)各種(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)源干擾導致誤動作(zuo)，檢(jian)測時(shi)(shi)(shi)間(jian)不(bu)能(neng)(neng)(neng)太(tai)短。實(shi)踐證(zheng)明，當(dang)檢(jian)測時(shi)(shi)(shi)間(jian)小(xiao)于2ms時(shi)(shi)(shi)，檢(jian)測可(ke)靠(kao)性(xing)會(hui)明顯下降。因此小(xiao)于2ms的(de)(de)(de)切(qie)(qie)換(huan)時(shi)(shi)(shi)間(jian)是不(bu)可(ke)取。在EPS電(dian)(dian)(dian)(dian)(dian)(dian)源所應(ying)(ying)用(yong)(yong)各類(lei)(lei)負載里，對切(qie)(qie)換(huan)時(shi)(shi)(shi)間(jian)要(yao)求(qiu)最苛刻的(de)(de)(de)應(ying)(ying)當(dang)是高(gao)壓氣(qi)體(ti)放電(dian)(dian)(dian)(dian)(dian)(dian)燈。雖(sui)然這(zhe)種(zhong)(zhong)燈具不(bu)允許用(yong)(yong)于消防(fang)應(ying)(ying)急照明，但由(you)于其(qi)具有(you)(you)高(gao)強度、高(gao)效率的(de)(de)(de)性(xing)能(neng)(neng)(neng)特點，在很多大(da)型場館中(zhong)(zhong)都有(you)(you)應(ying)(ying)用(yong)(yong)。但有(you)(you)這(zhe)么一個問題(ti)，那就是這(zhe)種(zhong)(zhong)燈具一旦熄(xi)輝(hui)(hui)，需要(yao)冷(leng)卻(que)后方能(neng)(neng)(neng)重新啟(qi)動，為(wei)保(bao)證(zheng)照明不(bu)發生中(zhong)(zhong)斷(duan)，EPS電(dian)(dian)(dian)(dian)(dian)(dian)源必須具備快速切(qie)(qie)換(huan)能(neng)(neng)(neng)力。根據對多種(zhong)(zhong)高(gao)壓氣(qi)體(ti)放電(dian)(dian)(dian)(dian)(dian)(dian)燈產(chan)品的(de)(de)(de)測試，如果不(bu)采取適當(dang)的(de)(de)(de)續流措施，5ms的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)力中(zhong)(zhong)斷(duan)就有(you)(you)可(ke)能(neng)(neng)(neng)導致熄(xi)輝(hui)(hui)，個別(bie)產(chan)品甚(shen)至3ms電(dian)(dian)(dian)(dian)(dian)(dian)力中(zhong)(zhong)斷(duan)就會(hui)熄(xi)輝(hui)(hui)。而對于某些電(dian)(dian)(dian)(dian)(dian)(dian)梯(ti)類(lei)(lei)負載，毫秒級的(de)(de)(de)切(qie)(qie)換(huan)顯然是沒有(you)(you)必要(yao)的(de)(de)(de)，但切(qie)(qie)換(huan)時(shi)(shi)(shi)的(de)(de)(de)瞬間(jian)中(zhong)(zhong)斷(duan)電(dian)(dian)(dian)(dian)(dian)(dian)源同樣有(you)(you)可(ke)能(neng)(neng)(neng)導致電(dian)(dian)(dian)(dian)(dian)(dian)梯(ti)控制系統進入保(bao)護狀(zhuang)態(tai)。此種(zhong)(zhong)情況(kuang)需要(yao)通過EPS電(dian)(dian)(dian)(dian)(dian)(dian)源控制系統的(de)(de)(de)延時(shi)(shi)(shi)適當(dang)增加切(qie)(qie)換(huan)時(shi)(shi)(shi)間(jian)，才(cai)能(neng)(neng)(neng)保(bao)證(zheng)電(dian)(dian)(dian)(dian)(dian)(dian)梯(ti)在應(ying)(ying)急供電(dian)(dian)(dian)(dian)(dian)(dian)后繼續正常(chang)運(yun)行(xing)。在有(you)(you)些應(ying)(ying)用(yong)(yong)場合，為(wei)了實(shi)現零切(qie)(qie)換(huan)，要(yao)求(qiu)將EPS設計(ji)成(cheng)在線運(yun)行(xing)方式，那么這(zhe)時(shi)(shi)(shi)EPS電(dian)(dian)(dian)(dian)(dian)(dian)源實(shi)際就已經變成(cheng)一臺專用(yong)(yong)的(de)(de)(de)UPS，逆變器是長帶負荷(he)工作(zuo)的(de)(de)(de)。
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