UPS（Uninterruptible Power System/Uninterruptible Power Supply），即(ji)不(bu)(bu)間(jian)斷電(dian)源，是將(jiang)蓄(xu)(xu)電(dian)池（多為鉛(qian)酸免維(wei)護蓄(xu)(xu)電(dian)池）與主(zhu)機(ji)相連接，通過主(zhu)機(ji)逆變器(qi)等(deng)模(mo)塊電(dian)路將(jiang)直流電(dian)轉換成市(shi)(shi)電(dian)的系(xi)統(tong)設(she)(she)備。主(zhu)要(yao)用于給(gei)單臺計算機(ji)、計算機(ji)網(wang)絡系(xi)統(tong)或其它(ta)電(dian)力電(dian)子(zi)設(she)(she)備如電(dian)磁閥、壓力變送(song)器(qi)等(deng)提(ti)供穩定、不(bu)(bu)間(jian)斷的電(dian)力供應。當(dang)市(shi)(shi)電(dian)輸入正常時，UPS 將(jiang)市電穩壓后(hou)供(gong)應給負載(zai)使(shi)用，此時的UPS就是一臺交流市電(dian)(dian)穩壓器，同時(shi)它還向機內電(dian)(dian)池充電(dian)(dian)；當市電(dian)(dian)中斷（事故停電(dian)(dian)）時(shi)， UPS 立即將電(dian)(dian)池的直流電(dian)(dian)能(neng)，通過逆(ni)變(bian)零(ling)切(qie)換轉(zhuan)換的方法向負載繼(ji)續供應(ying)220V交流電，使負載維持正(zheng)常工作(zuo)并保護負載軟、硬(ying)件不受損壞。UPS 設備通常對(dui)電(dian)壓(ya)(ya)過高或(huo)電(dian)壓(ya)(ya)過低都能(neng)提供保(bao)護。
UPS電(dian)源(yuan)系統由五部分(fen)組成：主路(lu)、旁路(lu)、電(dian)池等電(dian)源(yuan)輸(shu)入電(dian)路(lu)，進行AC/DC變換的(de)整流器（REC），進行(xing)DC/AC變換的逆變器（INV），逆變和旁路輸(shu)出切換(huan)電(dian)(dian)路以及(ji)蓄(xu)能(neng)(neng)電(dian)(dian)池。其系統的(de)(de)(de)(de)穩(wen)(wen)壓功(gong)(gong)能(neng)(neng)通常(chang)是由(you)整(zheng)流器(qi)(qi)(qi)完(wan)成(cheng)的(de)(de)(de)(de)，整(zheng)流器(qi)(qi)(qi)件采用可(ke)控硅或高頻(pin)開關(guan)整(zheng)流器(qi)(qi)(qi)，本(ben)身具有可(ke)根(gen)據外電(dian)(dian)的(de)(de)(de)(de)變化(hua)(hua)控制輸(shu)出幅度(du)的(de)(de)(de)(de)功(gong)(gong)能(neng)(neng)，從而當外電(dian)(dian)發生變化(hua)(hua)時（該(gai)變化(hua)(hua)應滿(man)足系統要求），輸(shu)出幅度(du)基(ji)本(ben)不(bu)變的(de)(de)(de)(de)整(zheng)流電(dian)(dian)壓。凈化(hua)(hua)功(gong)(gong)能(neng)(neng)由(you)儲(chu)能(neng)(neng)電(dian)(dian)池來(lai)完(wan)成(cheng)，由(you)于(yu)整(zheng)流器(qi)(qi)(qi)對(dui)瞬時脈(mo)沖(chong)干擾不(bu)能(neng)(neng)消除，整(zheng)流后的(de)(de)(de)(de)電(dian)(dian)壓仍存在干擾脈(mo)沖(chong)。儲(chu)能(neng)(neng)電(dian)(dian)池除可(ke)存儲(chu)直(zhi)(zhi)流直(zhi)(zhi)能(neng)(neng)的(de)(de)(de)(de)功(gong)(gong)能(neng)(neng)外，對(dui)整(zheng)流器(qi)(qi)(qi)來(lai)說就像接了一只大容器(qi)(qi)(qi)電(dian)(dian)容器(qi)(qi)(qi)，其等效電(dian)(dian)容量的(de)(de)(de)(de)大小(xiao)，與儲(chu)能(neng)(neng)電(dian)(dian)池容量大小(xiao)成(cheng)正比。由(you)于(yu)電(dian)(dian)容兩端的(de)(de)(de)(de)電(dian)(dian)壓是不(bu)能(neng)(neng)突變的(de)(de)(de)(de)，即(ji)利用了電(dian)(dian)容器(qi)(qi)(qi)對(dui)脈(mo)沖(chong)的(de)(de)(de)(de)平滑特性(xing)消除了脈(mo)沖(chong)干擾，起到了凈化(hua)(hua)功(gong)(gong)能(neng)(neng)，也稱對(dui)干擾的(de)(de)(de)(de)屏蔽。頻(pin)率(lv)(lv)的(de)(de)(de)(de)穩(wen)(wen)定則由(you)變換(huan)器(qi)(qi)(qi)來(lai)完(wan)成(cheng)，頻(pin)率(lv)(lv)穩(wen)(wen)定度(du)取決于(yu)變換(huan)器(qi)(qi)(qi)的(de)(de)(de)(de)振蕩頻(pin)率(lv)(lv)的(de)(de)(de)(de)穩(wen)(wen)定程度(du)。為方便UPS電源系統的日(ri)常操作(zuo)與(yu)維護，設(she)計了系統工(gong)作(zuo)開關，主機自檢故(gu)障后的自動(dong)旁路(lu)開關，檢修旁路(lu)開關等開關控制。
在電網電壓工作正常時，給負載供電如圖所示，而且，同(tong)時給(gei)儲能電池充電；當突發(fa)停電時，UPS電(dian)(dian)源(yuan)開始工作，由(you)儲能電(dian)(dian)池供給負(fu)(fu)載(zai)(zai)所需電(dian)(dian)源(yuan)，維(wei)持(chi)正(zheng)常的生(sheng)產(chan)(chan)（如粗黑→所示）；當由(you)于(yu)生(sheng)產(chan)(chan)需要，負(fu)(fu)載(zai)(zai)嚴重過載(zai)(zai)時(shi)，由(you)電(dian)(dian)網電(dian)(dian)壓(ya)經整(zheng)流直接給負(fu)(fu)載(zai)(zai)供電(dian)(dian)（如虛線所示）。
當市電正常為380/220VAC時，直(zhi)流主(zhu)回路有(you)直(zhi)流電壓，供給DC-AC交流逆變器，輸出穩定的(de)220V或380V交流電(dian)(dian)(dian)(dian)(dian)(dian)壓，同時(shi)(shi)市電(dian)(dian)(dian)(dian)(dian)(dian)經整流后(hou)對電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)。當(dang)(dang)(dang)任何時(shi)(shi)候(hou)市電(dian)(dian)(dian)(dian)(dian)(dian)欠壓或突然掉電(dian)(dian)(dian)(dian)(dian)(dian)，則由電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組通過隔離二極(ji)管開關向(xiang)直流回路(lu)饋送電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)。從電(dian)(dian)(dian)(dian)(dian)(dian)網供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)到(dao)(dao)(dao)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)沒有(you)切(qie)換時(shi)(shi)間。當(dang)(dang)(dang)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)能(neng)(neng)量即將(jiang)耗盡時(shi)(shi)，不間斷(duan)電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)發出(chu)聲光報警，并在電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)放電(dian)(dian)(dian)(dian)(dian)(dian)下限點停(ting)止(zhi)逆變器工作，長(chang)鳴告警。不間斷(duan)電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)還有(you)過載保護(hu)功能(neng)(neng)，當(dang)(dang)(dang)發生(sheng)超(chao)載時(shi)(shi)，跳(tiao)到(dao)(dao)(dao)旁路(lu)狀態(tai)，并在負(fu)載正(zheng)常時(shi)(shi)自動返回。當(dang)(dang)(dang)發生(sheng)嚴重超(chao)載時(shi)(shi)，不間斷(duan)電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)立(li)即停(ting)止(zhi)逆變器輸出(chu)并跳(tiao)到(dao)(dao)(dao)旁路(lu)狀態(tai)，此時(shi)(shi)前(qian)面(mian)輸入空(kong)氣(qi)開關也可能(neng)(neng)跳(tiao)閘。消除故(gu)障后(hou)，只要合上開關，重新開機即開始恢復工作。
UPS按工作原理分成后備式、在線(xian)式與在線(xian)互動(dong)式三大類。
其中，我們最常用的是后備式UPS，它具(ju)備了(le)自動穩壓、斷電(dian)保護等UPS最基(ji)礎也最重要(yao)的功能，雖然一(yi)般(ban)有10ms左右(you)的轉換(huan)時間，但(dan)由于結構簡單而具有價格便宜，可靠性高(gao)等優點，因(yin)此廣泛應用(yong)于微(wei)機(ji)、外設、POS機等領域。
后備式UPS電(dian)源(yuan)又分為后備式正弦波輸出(chu)UPS電源和后備式(shi)方波(bo)輸(shu)出(chu)UPS電源(yuan)。
后備式正弦波輸出UPS電源：單機輸出可(ke)做到0.25KW~2KW，當市電(dian)在170V~264V間變(bian)化時，向用戶(hu)提供經調壓器(qi)處理的市(shi)電；當市(shi)電超出170V~264V范圍時，才(cai)由UPS提供高質量(liang)的正(zheng)弦(xian)波電源。
后備式方波輸出UPS電源：與后備式正弦波輸出UPS電源不同(tong)的只是為(wei)用(yong)戶(hu)提供(gong)50Hz方波電源。
在線式UPS結構較復雜，但性能完善，能解(jie)決所有電源問題，如四通PS系列，其顯著特點是能夠持續零(ling)中(zhong)斷地輸出(chu)純(chun)凈正弦波交流電，能夠解決(jue)尖峰(feng)、浪涌(yong)、頻(pin)率漂移(yi)等全部的電源問(wen)題；由于(yu)需要較(jiao)大的投資，通常應用在關(guan)鍵(jian)設備與網絡中(zhong)心等對電力要求苛(ke)刻的環境中(zhong)。
在線互動式UPS，同后備式相比較，在線(xian)互(hu)動式具有濾波功能(neng)，抗(kang)市電(dian)干擾能(neng)力很(hen)強，轉換時間小于(yu)4ms，逆變(bian)輸出為模擬正弦波，所(suo)以能配備服務器、路由器等網絡設備，或者(zhe)用(yong)在(zai)電力(li)環(huan)境較惡劣的地區(qu)。
不間斷電源的主要優點，在于它的不間斷供電能力。在市電交流輸入正常時，UPS把交(jiao)流(liu)(liu)電整流(liu)(liu)成直流(liu)(liu)電，然后(hou)再把直流(liu)(liu)電逆變成穩定無雜質的交(jiao)流(liu)(liu)電，給后(hou)級負載使用。一旦(dan)市電交(jiao)流(liu)(liu)輸入(ru)異(yi)常(chang)，比如欠(qian)壓了(le)(le)或者停電了(le)(le)又或者頻(pin)率異(yi)常(chang)了(le)(le)，那(nei)么UPS會啟用(yong)備(bei)用(yong)能源-蓄電池，UPS的(de)整流電(dian)路會關(guan)斷，相應(ying)的(de)，會把(ba)蓄電(dian)池的(de)直流電(dian)逆變(bian)成(cheng)穩定無雜質的(de)交(jiao)流電(dian)，繼續給后級負(fu)載(zai)使用(yong)。這就是UPS不間斷供(gong)電能(neng)力的由來。
當然，UPS的不間斷供電時(shi)間不是(shi)無(wu)限(xian)的，這(zhe)個時(shi)間受制于蓄(xu)電池自身儲存(cun)能量的大(da)小(xiao) 。如果發生交流停電，那么在UPS的(de)蓄電(dian)池供電(dian)的(de)寶貴時間內，您需要(yao)做(zuo)的(de)就(jiu)是趕(gan)緊(jin)恢(hui)復(fu)交流(liu)電(dian)，比(bi)如啟用(yong)備用(yong)交流(liu)電(dian)回(hui)路(lu)、啟用(yong)油機發電(dian)，實在(zai)不行(xing)，就(jiu)只能緊(jin)急(ji)存盤，保存勞動成果，等待交流(liu)電(dian)恢(hui)復(fu)正常后再(zai)繼續。
不間斷電源現已廣泛應用于：礦山、航天、工業、通訊、國防、醫院、計算機業務終端、網絡服務器、網絡設備、數據存儲設備、UPS不間斷電源、應急照(zhao)明(ming)系(xi)統(tong)(tong)、鐵路、航(hang)運、交通(tong)、電廠、變(bian)電站(zhan)、核電站(zhan)、消防(fang)安全(quan)報警(jing)系(xi)統(tong)(tong)、無(wu)線通(tong)訊系(xi)統(tong)(tong)、程控交換(huan)機、移動通(tong)訊、太陽能(neng)儲(chu)存能(neng)量轉換(huan)設(she)備(bei)、控制設(she)備(bei)及其緊急保護系(xi)統(tong)(tong)、個人計算機等領域。
