作為UPS關鍵部件的充電器與UPS的(de)許多指標(biao)密(mi)切相關。文(wen)章(zhang)提出了(le)(le)UPS充電器的(de)設(she)計要求(qiu)，將UPS按功率大小劃(hua)分，分別(bie)為它們選擇了(le)(le)合適(shi)的(de)充電器拓(tuo)撲(pu)，并分析了(le)(le)工作原理，指出了(le)(le)存在(zai)的(de)不足。

　　1 在線式(shi)UPS的組(zu)成

　　隨著電(dian)(dian)(dian)子(zi)技術(shu)的(de)(de)(de)飛速發(fa)展，各種各樣(yang)的(de)(de)(de)電(dian)(dian)(dian)器(qi)設(she)備(bei)越來(lai)(lai)越多，而這(zhe)其中(zhong)的(de)(de)(de)大部分(fen)都(dou)是(shi)非線性負(fu)載，即它們從電(dian)(dian)(dian)網(wang)汲取(qu)的(de)(de)(de)電(dian)(dian)(dian)流波形與電(dian)(dian)(dian)壓(ya)波形不(bu)一樣(yang)。這(zhe)無(wu)疑給電(dian)(dian)(dian)網(wang)帶來(lai)(lai)了大量(liang)的(de)(de)(de)諧波以及(ji)其他的(de)(de)(de)公害，使供(gong)(gong)電(dian)(dian)(dian)的(de)(de)(de)質量(liang)變得(de)較差。另一方面，一些(xie)重要的(de)(de)(de)用電(dian)(dian)(dian)部門(如機場、醫院、銀(yin)行(xing))和一些(xie)重要的(de)(de)(de)用電(dian)(dian)(dian)設(she)備(bei)(如計算機、通(tong)信設(she)備(bei))對供(gong)(gong)電(dian)(dian)(dian)質量(liang)的(de)(de)(de)要求越來(lai)(lai)越高，不(bu)僅要求不(bu)停(ting)電(dian)(dian)(dian)，還要求電(dian)(dian)(dian)壓(ya)、頻率、波形質量(liang)良好，避免受(shou)到電(dian)(dian)(dian)網(wang)的(de)(de)(de)干擾(rao)，具備(bei)一個(ge)凈(jing)化(hua)的(de)(de)(de)電(dian)(dian)(dian)源(yuan)環境(jing)。這(zhe)就使負(fu)載與電(dian)(dian)(dian)網(wang)供(gong)(gong)電(dian)(dian)(dian)質量(liang)之間的(de)(de)(de)矛(mao)盾日益加劇(ju)。為解(jie)決這(zhe)一矛(mao)盾，UPS供(gong)(gong)電(dian)(dian)(dian)系(xi)統迅猛發(fa)展并(bing)普及(ji)起來(lai)(lai)。

　　隨(sui)著計算機、各種辦公設備、精(jing)密電(dian)(dian)(dian)(dian)子儀器的(de)普(pu)及，UPS得到了廣泛的(de)應(ying)用。現在(zai)應(ying)用較(jiao)多(duo)的(de)是在(zai)線式UPS，當(dang)市電(dian)(dian)(dian)(dian)正(zheng)(zheng)常時(shi)，電(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)壓(ya)(ya)一(yi)路(lu)經過整(zheng)流模(mo)塊AC/DC、逆變模(mo)塊DC/AC，得到所需的(de)正(zheng)(zheng)弦(xian)電(dian)(dian)(dian)(dian)壓(ya)(ya)或準方(fang)波電(dian)(dian)(dian)(dian)壓(ya)(ya)供給(gei)負(fu)載(zai)(zai)，另一(yi)路(lu)通過充(chong)電(dian)(dian)(dian)(dian)模(mo)塊給(gei)電(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian);市電(dian)(dian)(dian)(dian)異常時(shi)，電(dian)(dian)(dian)(dian)池通過DC/DC模(mo)塊、DC/AC模(mo)塊，輸出正(zheng)(zheng)弦(xian)電(dian)(dian)(dian)(dian)壓(ya)(ya)或準方(fang)波電(dian)(dian)(dian)(dian)壓(ya)(ya)，給(gei)負(fu)載(zai)(zai)供電(dian)(dian)(dian)(dian);如(ru)果UPS異常，電(dian)(dian)(dian)(dian)網直接通過旁路(lu)給(gei)負(fu)載(zai)(zai)供電(dian)(dian)(dian)(dian)。

　　2 UPS充電器的設計(ji)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(shu)出功率也是充(chong)電(dian)器設(she)計需(xu)要考慮的，當然功率也很重(zhong)要。作為UPS重(zhong)要部件之一的充(chong)電(dian)器，不得不考慮成(cheng)本。歸納一下有(you)如下設(she)計要求：

　　(1) 要求輸入電壓(ya)寬泛;

　　(2) 充(chong)電器的THDI值小，且能承(cheng)受(shou)一定市電脈沖和浪涌(yong);

　　(3) 寬范圍(wei)可調節的輸出(chu)電(dian)壓，輸出(chu)電(dian)流波(bo)紋(wen)較小(xiao);

　　(4) 對輸入電(dian)壓和輸出負載有良好響應;

　　(5) 達到設計的功率要求;

　　(6) 效率較高(gao);

　　(7) 成本較低。

　　3 小功率UPS充電器拓撲的選擇

　　以某公司的1～3kVA功率等級的UPS為(wei)(wei)例(li)，一般選擇單端反擊(ji)拓撲結構作為(wei)(wei)充電器(qi)，變(bian)壓(ya)(ya)器(qi)原副邊同(tong)名(ming)端相反，輸(shu)入從(cong)市電直接獲(huo)取，經過(guo)整流濾(lv)波器(qi)后得到正弦半(ban)波電壓(ya)(ya)，再變(bian)換為(wei)(wei)所需的輸(shu)出(chu)電壓(ya)(ya)，如果按照(zhao)不連(lian)續模(mo)式設計，變(bian)壓(ya)(ya)器(qi)原邊電感值較小(xiao)且輸(shu)出(chu)端無電抗元件，控制系統對輸(shu)入電壓(ya)(ya)和輸(shu)出(chu)負載的響應要很快。

　　當VT1導(dao)通(tong)時，以輸(shu)入(ru)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)正(zheng)(zheng)半周(zhou)為例，輸(shu)入(ru)電(dian)(dian)(dian)(dian)流(liu)由L端經VD2、變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)VR1原(yuan)(yuan)邊(bian)VT1、R1和VD4回(hui)到N端，TR原(yuan)(yuan)邊(bian)產生上正(zheng)(zheng)下負(fu)的電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，原(yuan)(yuan)邊(bian)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為Ui(Ui為市電(dian)(dian)(dian)(dian)整流(liu)后(hou)的半波電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya))，副邊(bian)極(ji)性相應(ying)產生下正(zheng)(zheng)上負(fu)的電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，二極(ji)管VD5承(cheng)受(shou)反向(xiang)(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)而截止(zhi)，VD5承(cheng)受(shou)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為(Ns/Np)Ui+UB;VT1截止(zhi)時，為使(shi)磁芯工作點順利返(fan)回(hui)，變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)原(yuan)(yuan)邊(bian)產生下負(fu)上正(zheng)(zheng)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，則副邊(bian)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為上正(zheng)(zheng)下負(fu)，副邊(bian)電(dian)(dian)(dian)(dian)流(liu)通(tong)過VD5向(xiang)(xiang)電(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)。原(yuan)(yuan)邊(bian)相應(ying)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為下正(zheng)(zheng)上負(fu)，U1=-(Np/Ns)UB，則VT1承(cheng)受(shou)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為(Np/Ns)UB+U1。根據原(yuan)(yuan)邊(bian)線圈(quan)的伏秒平衡。

　　但是(shi)，變壓器(qi)帶來磁(ci)滯損耗和(he)繞線損耗，另外輸出電流波(bo)(bo)紋較大，整體效率(lv)不高，VT1導通時輸出靠濾(lv)波(bo)(bo)電容C1維持，要用大容量的(de)濾(lv)波(bo)(bo)電容。

　　小功率UPS的充電器根據充電電流的打消設(she)計成模組和充電板，為滿足UPS緊(jin)湊化(hua)的要求(qiu)，降(jiang)低成本，把充電器設(she)計在功率板上將是(shi)一種選擇，輸入(ru)從母(mu)線電壓獲取。

　　DC/DC和(he)(he)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器利用(yong)一個(ge)(ge)拓撲實現，即推挽(wan)(wan)正激電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，它在(zai)推挽(wan)(wan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的基礎上變(bian)(bian)更(geng)了(le)(le)(le)線阻(zu)N1、N2與開(kai)關(guan)(guan)(guan)(guan)管(guan)VT1、VT2的為(wei)之，增(zeng)加(jia)了(le)(le)(le)一個(ge)(ge)儲能(neng)(neng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C1。為(wei)了(le)(le)(le)形成雙向電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，在(zai)高壓(ya)側增(zeng)加(jia)一個(ge)(ge)開(kai)關(guan)(guan)(guan)(guan)管(guan)VT4，低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)側增(zeng)加(jia)一個(ge)(ge)輔助充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)繞組(zu)和(he)(he)開(kai)關(guan)(guan)(guan)(guan)管(guan)VT3，形成正激充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)I1路(lu)徑(jing)如(ru)圖4所示(shi)。充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)，VT3一直打(da)開(kai)，VT4進行PWM調制，繞組(zu)N5電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian);對于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池模式下的推挽(wan)(wan)正激電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，以VT1管(guan)和(he)(he)N1支路(lu)為(wei)例(li)，當VT1管(guan)開(kai)通(tong)(tong)時(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)(tong)過N1、VT1，在(zai)繞組(zu)N4感應(ying)(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C2充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian);VT1關(guan)(guan)(guan)(guan)閉瞬間(jian)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)(tong)過N1、C1、VT2體內(nei)二極管(guan)續流(liu)(liu)，當VT2開(kai)通(tong)(tong)時(shi)，C1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)功過N1、VT2放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，在(zai)繞線N3感應(ying)(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給C2充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，路(lu)徑(jing)見(jian)圖中I2。C1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)VT1、VT2關(guan)(guan)(guan)(guan)斷時(shi)刻儲能(neng)(neng)，當相應(ying)(ying)對管(guan)開(kai)通(tong)(tong)時(shi)刻放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，由此提高了(le)(le)(le)效(xiao)率，限制了(le)(le)(le)開(kai)關(guan)(guan)(guan)(guan)管(guan)關(guan)(guan)(guan)(guan)斷時(shi)漏極電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)過大。這種拓撲尤其適合(he)(he)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)場(chang)合(he)(he)，因此可以減少電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池節數(shu)，降低成本。另外，提高了(le)(le)(le)變(bian)(bian)壓(ya)器的利用(yong)率，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器輸出(chu)端沒有接(jie)輸出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)波紋過大。

　　4 中(zhong)功率UPS充(chong)電器(qi)拓撲選擇

　　一般(ban)UPS的(de)電(dian)池(chi)節數是固定(ding)的(de)，像1kVA的(de)UPS配(pei)備2或3節電(dian)池(chi)，3kVA的(de)UPS配(pei)備6或8節，10kVA配(pei)備16或20節，中(zhong)功率(lv)UPS所(suo)配(pei)備的(de)電(dian)池(chi)節數較多，時間(jian)長了，難免有電(dian)池(chi)損壞，要求相對應的(de)充電(dian)器(qi)電(dian)壓能(neng)做出調(diao)整。某品(pin)牌10kVA UPS，電(dian)池(chi)在12-24節數范圍可(ke)(ke)調(diao)，對應充電(dian)器(qi)輸出電(dian)壓范圍為164-328V，單端反激拓撲(pu)輸出電(dian)壓幾(ji)乎不可(ke)(ke)能(neng)在此(ci)寬范圍可(ke)(ke)調(diao)，為此(ci)設計了BOOST-BUCK變換(huan)器(qi)。

　　前級(ji)采用BOOST結構，把市(shi)電(dian)升到(dao)400V，市(shi)電(dian)經整流(liu)(liu)橋后(hou)得(de)到(dao)直流(liu)(liu)脈動電(dian)壓(ya)，VT1導通時(shi)(shi)，L1上電(dian)流(liu)(liu)增(zeng)加(jia)，并(bing)儲(chu)存(cun)能(neng)量，VD5承受(shou)反向(xiang)電(dian)壓(ya)而(er)截(jie)止(zhi)，濾波(bo)電(dian)容C2給(gei)負(fu)(fu)載提(ti)供(gong)能(neng)量;VT1截(jie)止(zhi)時(shi)(shi)，市(shi)電(dian)通過L1和VD5對電(dian)池充電(dian)，并(bing)給(gei)負(fu)(fu)載提(ti)供(gong)能(neng)量，輸入和輸出(chu)(chu)(chu)關系(xi)(xi)見式。后(hou)級(ji)采用BUCK結構，它把輸入端400V降(jiang)到(dao)所(suo)需的充電(dian)電(dian)壓(ya)，VT2導通時(shi)(shi)，VD5承受(shou)反向(xiang)電(dian)壓(ya)截(jie)止(zhi)，輸入經過L2給(gei)電(dian)容C2充電(dian)，并(bing)提(ti)供(gong)能(neng)量給(gei)負(fu)(fu)載，VT2截(jie)止(zhi)時(shi)(shi)，電(dian)感電(dian)流(liu)(liu)經過VD6續流(liu)(liu)，L2和C2共(gong)同負(fu)(fu)載提(ti)供(gong)能(neng)量，輸入輸出(chu)(chu)(chu)關系(xi)(xi)見式，聯立(li)式和式可得(de)充電(dian)器輸入輸出(chu)(chu)(chu)關系(xi)(xi)，見式，D1不變，D2可變。

　　結束語

　　小功(gong)率(lv)(lv)UPS不要求寬范(fan)圍的(de)輸出電壓，希(xi)(xi)望(wang)對(dui)輸入電壓和輸出負載有良好相應(ying)，單端反激(ji)拓(tuo)撲能滿足此要求，盡管其輸出功(gong)率(lv)(lv)和效(xiao)率(lv)(lv)不高(gao);推(tui)挽正激(ji)拓(tuo)撲同時實現了充電器(qi)和DC/DC的(de)功(gong)能，減低了整機成本(ben);中(zhong)功(gong)率(lv)(lv)UPS則希(xi)(xi)望(wang)充電器(qi)輸出電壓可調，BOOST-BUCK和BOOST-半(ban)橋(qiao)都是明智的(de)選(xuan)擇;大功(gong)率(lv)(lv)UPS采用模塊化結構，對(dui)THDI和輸入功(gong)率(lv)(lv)因數等指標要求很高(gao)，輸入取自(zi)母線(xian)電壓的(de)BUCK變換器(qi)拓(tuo)撲簡單實用，當然，BOOST一半(ban)橋(qiao)在縮(suo)減模塊體積方(fang)面表現突出。