作為UPS關鍵部件的充電器與UPS的(de)(de)許多指標密切相關(guan)。文章提出(chu)了(le)(le)UPS充電器(qi)的(de)(de)設計要求(qiu)，將UPS按功率大(da)小劃分，分別為(wei)它們(men)選(xuan)擇了(le)(le)合(he)適的(de)(de)充電器(qi)拓撲，并分析(xi)了(le)(le)工作原理(li)，指出(chu)了(le)(le)存在的(de)(de)不足。

　　1 在線式(shi)UPS的組成

　　隨著電(dian)(dian)(dian)子技(ji)術的(de)(de)飛速發展，各種各樣的(de)(de)電(dian)(dian)(dian)器設(she)備(bei)(bei)越來(lai)越多，而這其中的(de)(de)大部(bu)分都是非線性(xing)負載，即(ji)它(ta)們從電(dian)(dian)(dian)網(wang)汲取的(de)(de)電(dian)(dian)(dian)流波形(xing)與(yu)電(dian)(dian)(dian)壓(ya)波形(xing)不一(yi)樣。這無疑給電(dian)(dian)(dian)網(wang)帶來(lai)了大量(liang)(liang)的(de)(de)諧波以及其他(ta)的(de)(de)公(gong)害，使(shi)供(gong)(gong)(gong)電(dian)(dian)(dian)的(de)(de)質量(liang)(liang)變得較差。另一(yi)方面，一(yi)些重要(yao)的(de)(de)用(yong)電(dian)(dian)(dian)部(bu)門(如機場、醫院、銀行)和一(yi)些重要(yao)的(de)(de)用(yong)電(dian)(dian)(dian)設(she)備(bei)(bei)(如計算(suan)機、通(tong)信設(she)備(bei)(bei))對供(gong)(gong)(gong)電(dian)(dian)(dian)質量(liang)(liang)的(de)(de)要(yao)求(qiu)越來(lai)越高，不僅要(yao)求(qiu)不停電(dian)(dian)(dian)，還(huan)要(yao)求(qiu)電(dian)(dian)(dian)壓(ya)、頻率(lv)、波形(xing)質量(liang)(liang)良好(hao)，避免受到電(dian)(dian)(dian)網(wang)的(de)(de)干擾(rao)，具(ju)備(bei)(bei)一(yi)個凈化的(de)(de)電(dian)(dian)(dian)源環境(jing)。這就使(shi)負載與(yu)電(dian)(dian)(dian)網(wang)供(gong)(gong)(gong)電(dian)(dian)(dian)質量(liang)(liang)之間的(de)(de)矛(mao)盾(dun)日(ri)益(yi)加劇。為解決這一(yi)矛(mao)盾(dun)，UPS供(gong)(gong)(gong)電(dian)(dian)(dian)系(xi)統迅(xun)猛發展并普及起來(lai)。

　　隨著計算機(ji)、各(ge)種辦公設(she)備(bei)、精密電(dian)(dian)(dian)(dian)(dian)子儀器(qi)的(de)普(pu)及(ji)，UPS得到了(le)廣泛的(de)應(ying)用。現在應(ying)用較多的(de)是在線式UPS，當市電(dian)(dian)(dian)(dian)(dian)正常時(shi)，電(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)壓(ya)一路經過整流模(mo)(mo)塊AC/DC、逆變模(mo)(mo)塊DC/AC，得到所需的(de)正弦(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)或準方波電(dian)(dian)(dian)(dian)(dian)壓(ya)供給(gei)(gei)負載(zai)，另(ling)一路通過充電(dian)(dian)(dian)(dian)(dian)模(mo)(mo)塊給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian);市電(dian)(dian)(dian)(dian)(dian)異常時(shi)，電(dian)(dian)(dian)(dian)(dian)池通過DC/DC模(mo)(mo)塊、DC/AC模(mo)(mo)塊，輸出正弦(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)或準方波電(dian)(dian)(dian)(dian)(dian)壓(ya)，給(gei)(gei)負載(zai)供電(dian)(dian)(dian)(dian)(dian);如果UPS異常，電(dian)(dian)(dian)(dian)(dian)網直(zhi)接通過旁(pang)路給(gei)(gei)負載(zai)供電(dian)(dian)(dian)(dian)(dian)。

　　2 UPS充電器(qi)的設計要求

　　UPS的市電輸入電壓范圍較寬，以輸出220V的UPS為例，輸入電壓為110-270V,充電器從市電取得這個范圍的輸入電壓，輸出還要達到一定的功率。充電器接入UPS后，會加大輸入電流的諧波失真，THDI升高，對THDI要求較高的UPS，有必要再充電器中加入功率因數校正環節，使輸入電流失真變小，輸入市電有高壓脈沖和浪涌，脈沖持續幾毫秒，高達七八百伏，浪涌是微妙級但高達4000V，他們會給充電器帶來瞬間高達幾百安培的電流沖擊，這對充電器是很大的考驗。中功率ULPS的電池節數不固定，從幾節到幾十節可變，充電器輸出電壓從幾十伏到幾百伏可變，輸出電壓如此寬泛，在設定的每個輸出電壓處，要求對輸入電壓和輸出負載的變化都有良好的響應，輸出電流(充電電流)紋波也要比較小，這樣輸出端不再需要耐高壓和高紋波電流的濾波電容。單端反激拓撲有隔離變壓器和輸出整流二極管，降低了效率，因此它難以應用于中大功率的充電器。輸出(chu)功率也是充電器(qi)設(she)計需要考(kao)慮的(de)，當然功率也很重要。作為UPS重要部件之一(yi)的(de)充電器(qi)，不得(de)不考(kao)慮成本。歸納一(yi)下(xia)有如(ru)下(xia)設(she)計要求：

　　(1) 要(yao)求輸(shu)入(ru)電壓(ya)寬泛(fan);

　　(2) 充電器的THDI值小，且能承受一定市電脈沖和浪涌;

　　(3) 寬范圍可調節的輸出電壓，輸出電流波紋(wen)較(jiao)小;

　　(4) 對輸入電壓和輸出負(fu)載有良好(hao)響應;

　　(5) 達(da)到設計(ji)的功率(lv)要求;

　　(6) 效率較高;

　　(7) 成(cheng)本較低。

　　3 小功率UPS充電器拓撲的選擇

　　以某公司的1～3kVA功率等(deng)級的UPS為例，一般選擇(ze)單端反(fan)擊拓撲結構作(zuo)為充電(dian)(dian)器，變(bian)壓器原副邊(bian)同名端相反(fan)，輸入(ru)從市電(dian)(dian)直(zhi)接獲取，經過(guo)整流(liu)濾(lv)波器后得到正弦(xian)半波電(dian)(dian)壓，再變(bian)換為所需的輸出(chu)電(dian)(dian)壓，如(ru)果按照不連續模式(shi)設計，變(bian)壓器原邊(bian)電(dian)(dian)感(gan)值(zhi)較小且輸出(chu)端無(wu)電(dian)(dian)抗元件，控制系統對輸入(ru)電(dian)(dian)壓和輸出(chu)負載的響(xiang)應要很(hen)快。

　　當(dang)VT1導通時，以輸(shu)入電(dian)(dian)(dian)壓(ya)(ya)(ya)正(zheng)(zheng)半(ban)周為(wei)例，輸(shu)入電(dian)(dian)(dian)流由L端經VD2、變壓(ya)(ya)(ya)器(qi)(qi)VR1原(yuan)邊(bian)(bian)VT1、R1和VD4回到N端，TR原(yuan)邊(bian)(bian)產生上(shang)正(zheng)(zheng)下(xia)負(fu)(fu)的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)，原(yuan)邊(bian)(bian)電(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)Ui(Ui為(wei)市電(dian)(dian)(dian)整流后(hou)的(de)(de)半(ban)波(bo)電(dian)(dian)(dian)壓(ya)(ya)(ya))，副(fu)(fu)邊(bian)(bian)極性相(xiang)(xiang)應產生下(xia)正(zheng)(zheng)上(shang)負(fu)(fu)的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)，二極管VD5承(cheng)(cheng)受(shou)反向電(dian)(dian)(dian)壓(ya)(ya)(ya)而截(jie)止(zhi)，VD5承(cheng)(cheng)受(shou)電(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)(Ns/Np)Ui+UB;VT1截(jie)止(zhi)時，為(wei)使磁芯工作點順(shun)利(li)返回，變壓(ya)(ya)(ya)器(qi)(qi)原(yuan)邊(bian)(bian)產生下(xia)負(fu)(fu)上(shang)正(zheng)(zheng)電(dian)(dian)(dian)壓(ya)(ya)(ya)，則副(fu)(fu)邊(bian)(bian)電(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)上(shang)正(zheng)(zheng)下(xia)負(fu)(fu)，副(fu)(fu)邊(bian)(bian)電(dian)(dian)(dian)流通過VD5向電(dian)(dian)(dian)池充電(dian)(dian)(dian)。原(yuan)邊(bian)(bian)相(xiang)(xiang)應電(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)下(xia)正(zheng)(zheng)上(shang)負(fu)(fu)，U1=-(Np/Ns)UB，則VT1承(cheng)(cheng)受(shou)電(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)(Np/Ns)UB+U1。根據原(yuan)邊(bian)(bian)線(xian)圈的(de)(de)伏秒平衡。

　　但是，變壓器帶來磁(ci)滯(zhi)損(sun)(sun)耗和繞線損(sun)(sun)耗，另(ling)外輸(shu)出電流波紋較大，整體(ti)效(xiao)率不(bu)高，VT1導通時輸(shu)出靠濾波電容C1維持，要用大容量(liang)的(de)濾波電容。

　　小功率(lv)UPS的(de)充(chong)(chong)(chong)電器根據(ju)充(chong)(chong)(chong)電電流的(de)打消設計成(cheng)模組和充(chong)(chong)(chong)電板，為滿足UPS緊(jin)湊化(hua)的(de)要求，降(jiang)低成(cheng)本，把充(chong)(chong)(chong)電器設計在功率(lv)板上將是一種(zhong)選擇(ze)，輸入從母線電壓獲(huo)取(qu)。

　　DC/DC和(he)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)器利用一(yi)個拓撲實現，即推挽正(zheng)激電(dian)(dian)(dian)(dian)(dian)路(lu)，它在(zai)(zai)推挽電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)基礎(chu)上變(bian)更了線阻N1、N2與(yu)開(kai)關(guan)(guan)(guan)管(guan)VT1、VT2的(de)為之，增(zeng)加(jia)了一(yi)個儲(chu)能(neng)電(dian)(dian)(dian)(dian)(dian)容(rong)C1。為了形成雙向電(dian)(dian)(dian)(dian)(dian)路(lu)，在(zai)(zai)高(gao)壓側增(zeng)加(jia)一(yi)個開(kai)關(guan)(guan)(guan)管(guan)VT4，低(di)(di)電(dian)(dian)(dian)(dian)(dian)壓側增(zeng)加(jia)一(yi)個輔助(zhu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)繞組(zu)(zu)和(he)開(kai)關(guan)(guan)(guan)管(guan)VT3，形成正(zheng)激充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路(lu)，給電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。電(dian)(dian)(dian)(dian)(dian)路(lu)I1路(lu)徑如圖4所(suo)示。充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)時，VT3一(yi)直打開(kai)，VT4進(jin)行(xing)PWM調(diao)制，繞組(zu)(zu)N5電(dian)(dian)(dian)(dian)(dian)壓大(da)于電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓，給電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian);對(dui)于電(dian)(dian)(dian)(dian)(dian)池(chi)模(mo)式下的(de)推挽正(zheng)激電(dian)(dian)(dian)(dian)(dian)路(lu)，以VT1管(guan)和(he)N1支路(lu)為例，當VT1管(guan)開(kai)通(tong)時，電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)過(guo)(guo)N1、VT1，在(zai)(zai)繞組(zu)(zu)N4感(gan)(gan)應(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)壓給電(dian)(dian)(dian)(dian)(dian)容(rong)C2充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian);VT1關(guan)(guan)(guan)閉瞬間，電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)過(guo)(guo)N1、C1、VT2體內二極管(guan)續流(liu)(liu)，當VT2開(kai)通(tong)時，C1電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)功過(guo)(guo)N1、VT2放電(dian)(dian)(dian)(dian)(dian)，在(zai)(zai)繞線N3感(gan)(gan)應(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)壓給C2充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，路(lu)徑見圖中I2。C1電(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)(zai)VT1、VT2關(guan)(guan)(guan)斷時刻(ke)儲(chu)能(neng)，當相(xiang)應(ying)對(dui)管(guan)開(kai)通(tong)時刻(ke)放電(dian)(dian)(dian)(dian)(dian)，由(you)此(ci)提高(gao)了效率，限(xian)制了開(kai)關(guan)(guan)(guan)管(guan)關(guan)(guan)(guan)斷時漏(lou)極電(dian)(dian)(dian)(dian)(dian)壓過(guo)(guo)大(da)。這種拓撲尤其適合(he)(he)低(di)(di)電(dian)(dian)(dian)(dian)(dian)壓大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)場合(he)(he)，因此(ci)可以減少電(dian)(dian)(dian)(dian)(dian)池(chi)節數(shu)，降低(di)(di)成本。另(ling)外，提高(gao)了變(bian)壓器的(de)利用率，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)時充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)器輸(shu)出(chu)端沒有接輸(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)波(bo)紋過(guo)(guo)大(da)。

　　4 中功率UPS充電器拓(tuo)撲選擇(ze)

　　一般UPS的(de)電(dian)(dian)池節(jie)(jie)數(shu)是固定的(de)，像1kVA的(de)UPS配(pei)備2或3節(jie)(jie)電(dian)(dian)池，3kVA的(de)UPS配(pei)備6或8節(jie)(jie)，10kVA配(pei)備16或20節(jie)(jie)，中功率UPS所配(pei)備的(de)電(dian)(dian)池節(jie)(jie)數(shu)較多(duo)，時間長了(le)，難免有電(dian)(dian)池損壞，要求(qiu)相對應(ying)的(de)充電(dian)(dian)器電(dian)(dian)壓(ya)能做出調整。某品牌10kVA UPS，電(dian)(dian)池在12-24節(jie)(jie)數(shu)范(fan)圍(wei)(wei)可(ke)調，對應(ying)充電(dian)(dian)器輸(shu)出電(dian)(dian)壓(ya)范(fan)圍(wei)(wei)為164-328V，單端反激拓撲輸(shu)出電(dian)(dian)壓(ya)幾乎不可(ke)能在此寬范(fan)圍(wei)(wei)可(ke)調，為此設計了(le)BOOST-BUCK變換器。

　　前級采(cai)用(yong)BOOST結構，把(ba)市電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)升到400V，市電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)經整流(liu)橋后得(de)到直流(liu)脈動電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，VT1導(dao)通(tong)時(shi)，L1上電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)增加，并儲存能量，VD5承受反向(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)而(er)截(jie)止(zhi)，濾波電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C2給(gei)負載(zai)提(ti)(ti)供(gong)能量;VT1截(jie)止(zhi)時(shi)，市電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)通(tong)過L1和VD5對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并給(gei)負載(zai)提(ti)(ti)供(gong)能量，輸(shu)(shu)入(ru)和輸(shu)(shu)出(chu)關(guan)系見(jian)式(shi)。后級采(cai)用(yong)BUCK結構，它把(ba)輸(shu)(shu)入(ru)端400V降到所(suo)需的充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，VT2導(dao)通(tong)時(shi)，VD5承受反向(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)截(jie)止(zhi)，輸(shu)(shu)入(ru)經過L2給(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C2充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并提(ti)(ti)供(gong)能量給(gei)負載(zai)，VT2截(jie)止(zhi)時(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)經過VD6續流(liu)，L2和C2共(gong)同負載(zai)提(ti)(ti)供(gong)能量，輸(shu)(shu)入(ru)輸(shu)(shu)出(chu)關(guan)系見(jian)式(shi)，聯立式(shi)和式(shi)可得(de)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器輸(shu)(shu)入(ru)輸(shu)(shu)出(chu)關(guan)系，見(jian)式(shi)，D1不(bu)變，D2可變。

　　結束語

　　小功(gong)(gong)率(lv)(lv)UPS不要(yao)求(qiu)寬范圍(wei)的(de)輸(shu)(shu)出(chu)電(dian)(dian)壓(ya)，希(xi)望(wang)對輸(shu)(shu)入電(dian)(dian)壓(ya)和(he)(he)輸(shu)(shu)出(chu)負載(zai)有良好相應，單端(duan)反激拓(tuo)撲(pu)能滿足此要(yao)求(qiu)，盡管其輸(shu)(shu)出(chu)功(gong)(gong)率(lv)(lv)和(he)(he)效率(lv)(lv)不高;推(tui)挽正(zheng)激拓(tuo)撲(pu)同時實(shi)現(xian)了充電(dian)(dian)器(qi)(qi)和(he)(he)DC/DC的(de)功(gong)(gong)能，減低(di)了整機(ji)成本(ben);中功(gong)(gong)率(lv)(lv)UPS則希(xi)望(wang)充電(dian)(dian)器(qi)(qi)輸(shu)(shu)出(chu)電(dian)(dian)壓(ya)可調，BOOST-BUCK和(he)(he)BOOST-半橋都(dou)是明智的(de)選擇;大功(gong)(gong)率(lv)(lv)UPS采(cai)用模塊化結構，對THDI和(he)(he)輸(shu)(shu)入功(gong)(gong)率(lv)(lv)因數等指標要(yao)求(qiu)很高，輸(shu)(shu)入取(qu)自母線電(dian)(dian)壓(ya)的(de)BUCK變換器(qi)(qi)拓(tuo)撲(pu)簡單實(shi)用，當然，BOOST一(yi)半橋在縮(suo)減模塊體積方面表(biao)現(xian)突出(chu)。