用戶(hu)在(zai)購買大功率UPS的(de)(de)時候，常(chang)常(chang)面臨在(zai)工(gong)頻(pin)機(ji)(ji)(ji)和高頻(pin)機(ji)(ji)(ji)之間進(jin)行(xing)選(xuan)(xuan)擇(ze)的(de)(de)困惑。就(jiu)UPS廠商(shang)(shang)(shang)方面而言，當(dang)然都認為是自(zi)己(ji)的(de)(de)好(hao)，“公(gong)說(shuo)(shuo)公(gong)有理(li)，婆說(shuo)(shuo)婆有理(li)”。提供(gong)工(gong)頻(pin)機(ji)(ji)(ji)的(de)(de)廠商(shang)(shang)(shang)說(shuo)(shuo)工(gong)頻(pin)機(ji)(ji)(ji)穩定(ding)性和可靠性高；提供(gong)高頻(pin)機(ji)(ji)(ji)的(de)(de)廠商(shang)(shang)(shang)會說(shuo)(shuo)高頻(pin)機(ji)(ji)(ji)節省空間，成本相對較低(di)等諸如此類(lei)的(de)(de)說(shuo)(shuo)法。其(qi)實，工(gong)頻(pin)機(ji)(ji)(ji)和高頻(pin)機(ji)(ji)(ji)到底孰(shu)優孰(shu)劣，很難一概(gai)而論，可以說(shuo)(shuo)各(ge)有利弊(bi)。用戶(hu)應當(dang)在(zai)全面認識(shi)這兩種UPS機(ji)(ji)(ji)型的(de)(de)基(ji)礎上，客觀審視自(zi)身的(de)(de)應用和需(xu)求，選(xuan)(xuan)擇(ze)適合自(zi)己(ji)需(xu)要的(de)(de)產品。

　　工頻機和高頻機的原理分析

　　工(gong)(gong)頻(pin)(pin)(pin)機和(he)高頻(pin)(pin)(pin)機是按UPS的設計電(dian)路(lu)(lu)工(gong)(gong)作頻(pin)(pin)(pin)率(lv)來區分的。工(gong)(gong)頻(pin)(pin)(pin)機是以傳統(tong)的模擬(ni)電(dian)路(lu)(lu)原理設計，由(you)晶閘(zha)管(SCR)整(zheng)(zheng)流器、IGBT逆變器、旁路(lu)(lu)和(he)工(gong)(gong)頻(pin)(pin)(pin)升壓(ya)(ya)隔離變壓(ya)(ya)器組成。因(yin)其(qi)整(zheng)(zheng)流器和(he)變壓(ya)(ya)器工(gong)(gong)作頻(pin)(pin)(pin)率(lv)均為(wei)工(gong)(gong)頻(pin)(pin)(pin)50Hz，顧名(ming)思義叫工(gong)(gong)頻(pin)(pin)(pin)UPS。高頻(pin)(pin)(pin)機通(tong)常由(you)IGBT高頻(pin)(pin)(pin)整(zheng)(zheng)流器、電(dian)池變換(huan)器、逆變器和(he)旁路(lu)(lu)組成。IGBT可以通(tong)過控制加在門極的驅(qu)動(dong)來控制其(qi)開通(tong)與關(guan)斷，IGBT整(zheng)(zheng)流器開關(guan)頻(pin)(pin)(pin)率(lv)通(tong)常在幾千(qian)赫到幾十千(qian)赫，甚(shen)至高達(da)上百千(qian)赫，遠遠高于工(gong)(gong)頻(pin)(pin)(pin)機，因(yin)此稱為(wei)高頻(pin)(pin)(pin)UPS。

　　在(zai)工頻UPS電(dian)(dian)路(lu)中，主路(lu)三相(xiang)交流(liu)(liu)輸(shu)(shu)入經過(guo)換相(xiang)電(dian)(dian)感，接到三個SCR橋臂組成的(de)整流(liu)(liu)器(qi)之(zhi)(zhi)后變換成直流(liu)(liu)電(dian)(dian)壓(ya)(ya)，通(tong)過(guo)控制(zhi)整流(liu)(liu)橋SCR的(de)導(dao)(dao)通(tong)角來(lai)調節輸(shu)(shu)出直流(liu)(liu)電(dian)(dian)壓(ya)(ya)值。由于(yu)SCR屬(shu)于(yu)半(ban)控器(qi)件，控制(zhi)系(xi)統只能控制(zhi)開通(tong)點，一旦SCR導(dao)(dao)通(tong)之(zhi)(zhi)后，即(ji)使(shi)(shi)門極驅動撤消，也無(wu)法關(guan)斷，只有等到其電(dian)(dian)流(liu)(liu)為零之(zhi)(zhi)后才能自然關(guan)斷，所(suo)以(yi)其開通(tong)和(he)關(guan)斷均是(shi)基于(yu)一個工頻周期，不存在(zai)高頻的(de)開通(tong)和(he)關(guan)斷控制(zhi)。由于(yu)SCR整流(liu)(liu)器(qi)屬(shu)于(yu)降壓(ya)(ya)整流(liu)(liu)，所(suo)以(yi)直流(liu)(liu)母線電(dian)(dian)壓(ya)(ya)經逆(ni)變輸(shu)(shu)出的(de)交流(liu)(liu)電(dian)(dian)壓(ya)(ya)比輸(shu)(shu)入交流(liu)(liu)電(dian)(dian)壓(ya)(ya)低，要(yao)使(shi)(shi)輸(shu)(shu)出相(xiang)電(dian)(dian)壓(ya)(ya)能夠(gou)得到恒定的(de)220V電(dian)(dian)壓(ya)(ya)，就必(bi)須在(zai)逆(ni)變輸(shu)(shu)出增加(jia)升(sheng)壓(ya)(ya)隔離(li)變壓(ya)(ya)器(qi)。

　　相比而言，高(gao)(gao)頻(pin)(pin)UPS整(zheng)流屬于升(sheng)壓(ya)(ya)(ya)(ya)整(zheng)流，其輸(shu)出(chu)直流母(mu)線(xian)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)比輸(shu)入線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)的(de)(de)(de)峰值高(gao)(gao)，一般典型值為(wei)800V左右，如果電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)直接(jie)掛接(jie)母(mu)線(xian)，所(suo)需(xu)要(yao)的(de)(de)(de)標配電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)節(jie)數需(xu)要(yao)67節(jie)，這樣給實際應用帶來極大的(de)(de)(de)限制。因(yin)此一般高(gao)(gao)頻(pin)(pin)UPS會(hui)單(dan)獨配置一個電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)變(bian)換器，市(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)正常的(de)(de)(de)時(shi)候電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)變(bian)換器把(ba)(ba)800V的(de)(de)(de)母(mu)線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)降到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)；市(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)故障或超限時(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)變(bian)換器把(ba)(ba)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)升(sheng)高(gao)(gao)到800V的(de)(de)(de)母(mu)線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)。由(you)于高(gao)(gao)頻(pin)(pin)機(ji)母(mu)線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)800V左右，所(suo)以逆變(bian)器輸(shu)出(chu)相電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)可以直接(jie)達到220V，逆變(bian)器之(zhi)后就不再需(xu)要(yao)升(sheng)壓(ya)(ya)(ya)(ya)變(bian)壓(ya)(ya)(ya)(ya)器。因(yin)此，有無(wu)隔離變(bian)壓(ya)(ya)(ya)(ya)器是工頻(pin)(pin)機(ji)與(yu)高(gao)(gao)頻(pin)(pin)機(ji)在(zai)結構(gou)上(shang)的(de)(de)(de)主要(yao)區別。

　　UPS輸出隔離變壓器的作用

　　隔(ge)離變壓器是(shi)利用(yong)電磁(ci)感應原理，對配電或信號進(jin)行電氣(qi)隔(ge)離的(de)裝置。隔(ge)離變壓器在UPS中通(tong)常被設計在逆變器的(de)輸出端，可以(yi)起到增(zeng)加UPS性能改善負載端供電質量(liang)的(de)作用(yong)。通(tong)常，UPS的(de)輸出隔(ge)離變壓器有以(yi)下四(si)大優點:

　　降低零地電壓，優化UPS末端供電網絡

　　UPS的(de)(de)(de)逆變輸出(chu)安裝(zhuang)(zhuang)隔(ge)(ge)離變壓(ya)(ya)器可(ke)以(yi)隔(ge)(ge)離輸入和輸出(chu)之間的(de)(de)(de)電(dian)氣(qi)連接，從(cong)而有效地(di)(di)(di)(di)降(jiang)低(di)輸出(chu)的(de)(de)(de)零地(di)(di)(di)(di)電(dian)壓(ya)(ya)。由于(yu)隔(ge)(ge)離變壓(ya)(ya)器的(de)(de)(de)副(fu)邊繞組(zu)采用Y型接法，中性點(dian)接地(di)(di)(di)(di)后(hou)產(chan)生新的(de)(de)(de)零線，從(cong)而達到降(jiang)低(di)零地(di)(di)(di)(di)電(dian)壓(ya)(ya)的(de)(de)(de)目的(de)(de)(de)。事(shi)實上，HP、IBM、SUN的(de)(de)(de)小型機因(yin)為要保證精密的(de)(de)(de)計算(suan)能力與高可(ke)靠的(de)(de)(de)數(shu)據處(chu)理傳輸能力，都會對零地(di)(di)(di)(di)電(dian)壓(ya)(ya)有極(ji)高的(de)(de)(de)要求(qiu)，加裝(zhuang)(zhuang)隔(ge)(ge)離變壓(ya)(ya)器可(ke)以(yi)徹(che)底(di)解決因(yin)為零地(di)(di)(di)(di)電(dian)壓(ya)(ya)偏(pian)高所造成的(de)(de)(de)一些問題(ti)。

　　濾除負載端諧波，提高供電質量

　　隔離(li)變壓器(qi)本身具(ju)有電(dian)(dian)感特(te)性，輸出隔離(li)變壓器(qi)可(ke)以濾除負(fu)載端的大量(liang)低次(ci)諧(xie)波，減(jian)少高(gao)頻*，并可(ke)以使高(gao)次(ci)諧(xie)波大幅度(du)衰減(jian)。采用(yong)電(dian)(dian)源隔離(li)變壓器(qi)，可(ke)以有效地抑制竄入交流電(dian)(dian)源中的噪(zao)聲*，提高(gao)設(she)備的電(dian)(dian)磁兼(jian)容性。

　　增強過載短路保護能力，保護負載與UPS主機

　　由于其自(zi)身的(de)特(te)性，隔(ge)離變壓器是UPS中工作最為(wei)穩定的(de)器件。UPS在正常工作過程中，如果遇到大的(de)短路(lu)電(dian)流，變壓器會產(chan)生反(fan)向電(dian)動勢(shi)，延緩(huan)短路(lu)電(dian)流對負載(zai)以及逆變器的(de)沖(chong)擊破壞，具有保護負載(zai)與(yu)UPS主機的(de)作用(yong)。

　　“通交流阻直流”，UPS故障時保護負載

　　高額UPS的(de)AC/DC變換部分采用高頻化設(she)計，提高了UPS的(de)輸(shu)(shu)入功(gong)(gong)率因數(shu)(0.98以上)及輸(shu)(shu)入電(dian)壓范圍，DC/AC逆變部分高頻化減少了輸(shu)(shu)出(chu)濾(lv)波電(dian)感的(de)體積，功(gong)(gong)率密(mi)度大。由于無輸(shu)(shu)出(chu)隔離變壓器，一旦(dan)逆變器橋(qiao)臂的(de)IGBT被擊穿(chuan)短路，BUS母(mu)線直流高電(dian)壓將(jiang)加到負(fu)(fu)載上，危及負(fu)(fu)載的(de)安全(quan)。輸(shu)(shu)出(chu)隔離變壓器具有“通交流阻直流”的(de)能(neng)力(li)，可以解決此類問題，在UPS發生故(gu)障時(shi)能(neng)夠使負(fu)(fu)載安全(quan)運(yun)行。

　　工頻機和高頻機的性能對比

　　在可靠性方面，工頻機要優于高頻機

　　工頻(pin)(pin)機采(cai)用(yong)晶閘管(SCR)整(zheng)(zheng)流(liu)器(qi)，該技術經過半(ban)(ban)個(ge)多世紀的(de)發展(zhan)和革(ge)新，已經非(fei)常成熟(shu)，其抗電(dian)(dian)流(liu)沖擊(ji)能力非(fei)常強。由于SCR屬于半(ban)(ban)控器(qi)件，不會出(chu)現直(zhi)通(tong)、誤觸發等故障。相比(bi)而言，高(gao)頻(pin)(pin)機采(cai)用(yong)的(de)IGBT高(gao)頻(pin)(pin)整(zheng)(zheng)流(liu)器(qi)雖然開關頻(pin)(pin)率(lv)較(jiao)高(gao)，但是IGBT工作時有(you)嚴格(ge)的(de)電(dian)(dian)壓、電(dian)(dian)流(liu)工作區域(yu)，抗沖擊(ji)能力較(jiao)低(di)。因(yin)此在總體可靠(kao)性(xing)方面(mian)，IGBT整(zheng)(zheng)流(liu)器(qi)比(bi)SCR整(zheng)(zheng)流(liu)器(qi)低(di)。

　　在環境適應性方面，高頻機要優于工頻機

　　高(gao)頻機是以微處(chu)理器作為處(chu)理控制中(zhong)心，將繁雜的(de)硬(ying)件(jian)模擬電路燒錄于(yu)微處(chu)理器中(zhong)，以軟件(jian)程序(xu)的(de)方(fang)式(shi)來控制UPS的(de)運行。因此，體積、重量等方(fang)面都有明顯的(de)降低，噪音也較(jiao)小，對空(kong)間、環境影響小，因此比較(jiao)適(shi)合于(yu)對可(ke)靠性要求(qiu)不太苛刻的(de)辦公場所(suo)。正因為如(ru)此，許多廠家的(de)中(zhong)小功率UPS普遍(bian)推出了高(gao)頻機。

　　在負載對零地電壓的要求方面，工頻機要優于高頻機

　　大功(gong)率(lv)三(san)相高(gao)頻機零(ling)(ling)(ling)線會引入整(zheng)流(liu)(liu)器并作為正負母線的中性點(dian)，這種結(jie)構就不(bu)可(ke)避免(mian)地(di)造成整(zheng)流(liu)(liu)器和(he)逆變(bian)器高(gao)頻諧波耦合在(zai)(zai)零(ling)(ling)(ling)線上(shang)，抬升零(ling)(ling)(ling)地(di)電(dian)(dian)(dian)壓，造成負載端零(ling)(ling)(ling)地(di)電(dian)(dian)(dian)壓抬高(gao)，很難滿足IBM、HP等服務(wu)器廠(chang)家對(dui)零(ling)(ling)(ling)地(di)電(dian)(dian)(dian)壓小于1V的場地(di)需求。另外，在(zai)(zai)市(shi)電(dian)(dian)(dian)和(he)發電(dian)(dian)(dian)機切換時(shi)，高(gao)頻機往往因(yin)零(ling)(ling)(ling)線缺失而必須轉旁路工(gong)(gong)作，在(zai)(zai)特定工(gong)(gong)況下可(ke)能造成負載閃斷的重大故障(zhang)。工(gong)(gong)頻機因(yin)整(zheng)流(liu)(liu)器不(bu)需要零(ling)(ling)(ling)線參與工(gong)(gong)作，在(zai)(zai)零(ling)(ling)(ling)線斷開時(shi)，UPS可(ke)以保持正常供電(dian)(dian)(dian)。

　　結束語

　　從(cong)(cong)結(jie)構上(shang)講(jiang)(jiang)，工頻(pin)機UPS和(he)高頻(pin)機UPS的(de)差(cha)異主要(yao)(yao)(yao)(yao)表(biao)現在(zai)隔離(li)變壓(ya)器(qi)上(shang)，而工頻(pin)機對隔離(li)變壓(ya)器(qi)的(de)使(shi)用(yong)，在(zai)很大程(cheng)度上(shang)提升了UPS的(de)可靠(kao)性(xing)。從(cong)(cong)綜合性(xing)能方面來講(jiang)(jiang)，工頻(pin)機和(he)高頻(pin)機則各有優(you)劣，至(zhi)少在(zai)當(dang)(dang)前，不(bu)存在(zai)誰取代誰的(de)問題。用(yong)戶(hu)在(zai)選(xuan)購設(she)備(bei)的(de)時候應(ying)(ying)當(dang)(dang)立(li)足于自身的(de)實際需要(yao)(yao)(yao)(yao)，而不(bu)是(shi)盲目跟從(cong)(cong)。比如(ru)，用(yong)戶(hu)要(yao)(yao)(yao)(yao)建設(she)中大型的(de)數據中心，那么對可靠(kao)性(xing)和(he)穩定性(xing)的(de)要(yao)(yao)(yao)(yao)求(qiu)就應(ying)(ying)當(dang)(dang)放在(zai)第一位，大功(gong)率(lv)的(de)工頻(pin)機UPS就應(ying)(ying)當(dang)(dang)是(shi)首選(xuan)；如(ru)果是(shi)一般的(de)辦公(gong)場(chang)所應(ying)(ying)用(yong)，或者主要(yao)(yao)(yao)(yao)考慮(lv)到(dao)設(she)備(bei)對空(kong)間的(de)占用(yong)，則可以采用(yong)高頻(pin)機UPS。