作為UPS關鍵部件的充電器與UPS的許多(duo)指標(biao)密(mi)切(qie)相關。文章提出(chu)了(le)(le)UPS充電器的設計(ji)要求，將UPS按功率大小(xiao)劃分(fen)，分(fen)別為(wei)它們選擇了(le)(le)合適的充電器拓撲，并分(fen)析了(le)(le)工作原理(li)，指出(chu)了(le)(le)存在的不足(zu)。

　　1 在線式UPS的組(zu)成

　　隨(sui)著電(dian)(dian)(dian)(dian)子技術的(de)飛速發展，各種各樣的(de)電(dian)(dian)(dian)(dian)器設備(bei)越(yue)(yue)來(lai)越(yue)(yue)多，而這(zhe)(zhe)其中的(de)大(da)部分都是(shi)非線性負載，即它們從電(dian)(dian)(dian)(dian)網(wang)汲取的(de)電(dian)(dian)(dian)(dian)流波形(xing)與(yu)電(dian)(dian)(dian)(dian)壓波形(xing)不(bu)一(yi)樣。這(zhe)(zhe)無疑給(gei)電(dian)(dian)(dian)(dian)網(wang)帶來(lai)了大(da)量的(de)諧波以及其他的(de)公害，使(shi)供(gong)電(dian)(dian)(dian)(dian)的(de)質(zhi)量變得較差(cha)。另(ling)一(yi)方面，一(yi)些重(zhong)要的(de)用電(dian)(dian)(dian)(dian)部門(如(ru)機場(chang)、醫院、銀(yin)行)和一(yi)些重(zhong)要的(de)用電(dian)(dian)(dian)(dian)設備(bei)(如(ru)計算(suan)機、通(tong)信設備(bei))對供(gong)電(dian)(dian)(dian)(dian)質(zhi)量的(de)要求越(yue)(yue)來(lai)越(yue)(yue)高，不(bu)僅要求不(bu)停(ting)電(dian)(dian)(dian)(dian)，還要求電(dian)(dian)(dian)(dian)壓、頻率(lv)、波形(xing)質(zhi)量良好，避免受到電(dian)(dian)(dian)(dian)網(wang)的(de)干擾(rao)，具備(bei)一(yi)個凈化的(de)電(dian)(dian)(dian)(dian)源環境(jing)。這(zhe)(zhe)就(jiu)使(shi)負載與(yu)電(dian)(dian)(dian)(dian)網(wang)供(gong)電(dian)(dian)(dian)(dian)質(zhi)量之間的(de)矛盾(dun)日益加劇。為解決這(zhe)(zhe)一(yi)矛盾(dun)，UPS供(gong)電(dian)(dian)(dian)(dian)系統迅猛發展并普及起來(lai)。

　　隨著(zhu)計算(suan)機、各種辦公設備、精密電(dian)(dian)子儀器的普及，UPS得到(dao)了(le)廣泛的應(ying)用(yong)。現在應(ying)用(yong)較多(duo)的是在線式UPS，當市(shi)電(dian)(dian)正常時，電(dian)(dian)網電(dian)(dian)壓一路經過整流(liu)模塊(kuai)(kuai)(kuai)AC/DC、逆(ni)變(bian)模塊(kuai)(kuai)(kuai)DC/AC，得到(dao)所需的正弦(xian)電(dian)(dian)壓或準方波(bo)電(dian)(dian)壓供給負載，另一路通過充電(dian)(dian)模塊(kuai)(kuai)(kuai)給電(dian)(dian)池充電(dian)(dian);市(shi)電(dian)(dian)異(yi)常時，電(dian)(dian)池通過DC/DC模塊(kuai)(kuai)(kuai)、DC/AC模塊(kuai)(kuai)(kuai)，輸出正弦(xian)電(dian)(dian)壓或準方波(bo)電(dian)(dian)壓，給負載供電(dian)(dian);如果UPS異(yi)常，電(dian)(dian)網直接通過旁路給負載供電(dian)(dian)。

　　2 UPS充電器的設計(ji)要(yao)求(qiu)

　　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。輸出功率(lv)也是(shi)充電(dian)器設計需(xu)要(yao)考慮的(de)(de)，當然功率(lv)也很重(zhong)要(yao)。作為UPS重(zhong)要(yao)部(bu)件(jian)之一的(de)(de)充電(dian)器，不(bu)得不(bu)考慮成本。歸納一下(xia)有如下(xia)設計要(yao)求：

　　(1) 要求輸入電壓(ya)寬(kuan)泛;

　　(2) 充(chong)電器的THDI值小(xiao)，且(qie)能承受一定市電脈沖和浪涌;

　　(3) 寬范圍可調節的輸(shu)(shu)出電(dian)壓(ya)，輸(shu)(shu)出電(dian)流波紋(wen)較小;

　　(4) 對輸入(ru)電(dian)壓和輸出負載(zai)有(you)良好響應;

　　(5) 達(da)到設計的功率要(yao)求;

　　(6) 效率(lv)較高;

　　(7) 成本較(jiao)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為例，一般選擇單端(duan)反擊拓撲(pu)結構作為充電(dian)器，變(bian)壓器原(yuan)副邊(bian)同名(ming)端(duan)相反，輸(shu)(shu)入從市電(dian)直接獲取，經過整流濾波(bo)器后得到(dao)正弦半波(bo)電(dian)壓，再(zai)變(bian)換為所需的輸(shu)(shu)出電(dian)壓，如(ru)果按照不連(lian)續模(mo)式(shi)設計，變(bian)壓器原(yuan)邊(bian)電(dian)感值較小(xiao)且輸(shu)(shu)出端(duan)無電(dian)抗元件，控制系統(tong)對輸(shu)(shu)入電(dian)壓和輸(shu)(shu)出負載的響應要很快(kuai)。

　　當(dang)VT1導通時，以輸入電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)正(zheng)半(ban)周(zhou)為(wei)(wei)(wei)例，輸入電(dian)(dian)(dian)流(liu)由L端經(jing)VD2、變壓(ya)(ya)(ya)(ya)器(qi)VR1原(yuan)邊(bian)VT1、R1和VD4回(hui)到N端，TR原(yuan)邊(bian)產生(sheng)上(shang)正(zheng)下(xia)(xia)負的(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，原(yuan)邊(bian)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)Ui(Ui為(wei)(wei)(wei)市(shi)電(dian)(dian)(dian)整流(liu)后的(de)半(ban)波(bo)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya))，副(fu)邊(bian)極(ji)性相應產生(sheng)下(xia)(xia)正(zheng)上(shang)負的(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，二極(ji)管VD5承受反向電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)而截(jie)止(zhi)，VD5承受電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)(Ns/Np)Ui+UB;VT1截(jie)止(zhi)時，為(wei)(wei)(wei)使磁(ci)芯工作點(dian)順利返回(hui)，變壓(ya)(ya)(ya)(ya)器(qi)原(yuan)邊(bian)產生(sheng)下(xia)(xia)負上(shang)正(zheng)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，則(ze)副(fu)邊(bian)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)上(shang)正(zheng)下(xia)(xia)負，副(fu)邊(bian)電(dian)(dian)(dian)流(liu)通過VD5向電(dian)(dian)(dian)池充電(dian)(dian)(dian)。原(yuan)邊(bian)相應電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)下(xia)(xia)正(zheng)上(shang)負，U1=-(Np/Ns)UB，則(ze)VT1承受電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)(Np/Ns)UB+U1。根(gen)據原(yuan)邊(bian)線圈的(de)伏秒平衡。

　　但是(shi)，變壓器帶來磁滯損(sun)(sun)耗和繞線損(sun)(sun)耗，另外輸出電(dian)流波(bo)(bo)(bo)紋較大(da)，整(zheng)體(ti)效率不高，VT1導通時輸出靠濾波(bo)(bo)(bo)電(dian)容C1維持(chi)，要用(yong)大(da)容量的濾波(bo)(bo)(bo)電(dian)容。

　　小功(gong)率UPS的(de)(de)充(chong)電(dian)(dian)器根據(ju)充(chong)電(dian)(dian)電(dian)(dian)流的(de)(de)打(da)消設計成模組和充(chong)電(dian)(dian)板(ban)，為滿足UPS緊湊化的(de)(de)要求，降低(di)成本(ben)，把(ba)充(chong)電(dian)(dian)器設計在功(gong)率板(ban)上將是一種選擇，輸入(ru)從母線電(dian)(dian)壓獲取。

　　DC/DC和(he)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)利用一(yi)(yi)個拓撲實現，即推挽正激電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，它在推挽電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的基(ji)礎上(shang)變更了(le)(le)(le)線阻N1、N2與開(kai)(kai)(kai)關(guan)管(guan)(guan)(guan)VT1、VT2的為(wei)之，增(zeng)加了(le)(le)(le)一(yi)(yi)個儲(chu)能電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C1。為(wei)了(le)(le)(le)形成(cheng)雙向(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，在高(gao)壓(ya)側增(zeng)加一(yi)(yi)個開(kai)(kai)(kai)關(guan)管(guan)(guan)(guan)VT4，低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)側增(zeng)加一(yi)(yi)個輔助充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)繞(rao)組和(he)開(kai)(kai)(kai)關(guan)管(guan)(guan)(guan)VT3，形成(cheng)正激充(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(gei)(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(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)徑如圖4所示。充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)，VT3一(yi)(yi)直打開(kai)(kai)(kai)，VT4進行PWM調(diao)制，繞(rao)組N5電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大(da)于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(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(chi)模式下的推挽正激電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，以VT1管(guan)(guan)(guan)和(he)N1支路(lu)為(wei)例(li)，當VT1管(guan)(guan)(guan)開(kai)(kai)(kai)通時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通過N1、VT1，在繞(rao)組N4感應(ying)(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C2充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian);VT1關(guan)閉(bi)瞬間，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通過N1、C1、VT2體內二極管(guan)(guan)(guan)續流(liu)(liu)，當VT2開(kai)(kai)(kai)通時(shi)(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)，在繞(rao)線N3感應(ying)(ying)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給(gei)(gei)C2充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，路(lu)徑見(jian)圖中I2。C1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)在VT1、VT2關(guan)斷時(shi)(shi)刻儲(chu)能，當相應(ying)(ying)對管(guan)(guan)(guan)開(kai)(kai)(kai)通時(shi)(shi)刻放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，由此提(ti)高(gao)了(le)(le)(le)效率，限制了(le)(le)(le)開(kai)(kai)(kai)關(guan)管(guan)(guan)(guan)關(guan)斷時(shi)(shi)漏極電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)過大(da)。這種拓撲尤其(qi)適合低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)場合，因此可以減少(shao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)節(jie)數，降低成(cheng)本。另外(wai)，提(ti)高(gao)了(le)(le)(le)變壓(ya)器(qi)的利用率，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)輸出(chu)端沒有接輸出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感，充(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(da)。

　　4 中功率(lv)UPS充(chong)電(dian)器拓撲選擇(ze)

　　一般UPS的(de)(de)(de)電(dian)(dian)池(chi)(chi)節(jie)數(shu)(shu)是固定的(de)(de)(de)，像1kVA的(de)(de)(de)UPS配(pei)(pei)備(bei)2或3節(jie)電(dian)(dian)池(chi)(chi)，3kVA的(de)(de)(de)UPS配(pei)(pei)備(bei)6或8節(jie)，10kVA配(pei)(pei)備(bei)16或20節(jie)，中(zhong)功率UPS所(suo)配(pei)(pei)備(bei)的(de)(de)(de)電(dian)(dian)池(chi)(chi)節(jie)數(shu)(shu)較多，時間長了，難(nan)免有(you)電(dian)(dian)池(chi)(chi)損(sun)壞，要求相對(dui)應的(de)(de)(de)充(chong)電(dian)(dian)器電(dian)(dian)壓能(neng)做出調整。某(mou)品牌(pai)10kVA UPS，電(dian)(dian)池(chi)(chi)在12-24節(jie)數(shu)(shu)范(fan)圍可調，對(dui)應充(chong)電(dian)(dian)器輸出電(dian)(dian)壓范(fan)圍為164-328V，單端反激(ji)拓撲(pu)輸出電(dian)(dian)壓幾(ji)乎(hu)不可能(neng)在此寬范(fan)圍可調，為此設計了BOOST-BUCK變換器。

　　前級采(cai)(cai)用BOOST結構，把(ba)市電(dian)(dian)升到400V，市電(dian)(dian)經(jing)(jing)整(zheng)流(liu)(liu)橋后得到直流(liu)(liu)脈(mo)動(dong)電(dian)(dian)壓(ya)，VT1導通(tong)時(shi)(shi)，L1上電(dian)(dian)流(liu)(liu)增加，并(bing)儲存能量(liang)，VD5承受反向電(dian)(dian)壓(ya)而(er)截止(zhi)，濾波電(dian)(dian)容C2給負載提(ti)供能量(liang);VT1截止(zhi)時(shi)(shi)，市電(dian)(dian)通(tong)過L1和VD5對電(dian)(dian)池充(chong)電(dian)(dian)，并(bing)給負載提(ti)供能量(liang)，輸(shu)入和輸(shu)出(chu)關(guan)(guan)系見式(shi)(shi)。后級采(cai)(cai)用BUCK結構，它把(ba)輸(shu)入端400V降到所需的充(chong)電(dian)(dian)電(dian)(dian)壓(ya)，VT2導通(tong)時(shi)(shi)，VD5承受反向電(dian)(dian)壓(ya)截止(zhi)，輸(shu)入經(jing)(jing)過L2給電(dian)(dian)容C2充(chong)電(dian)(dian)，并(bing)提(ti)供能量(liang)給負載，VT2截止(zhi)時(shi)(shi)，電(dian)(dian)感電(dian)(dian)流(liu)(liu)經(jing)(jing)過VD6續流(liu)(liu)，L2和C2共同負載提(ti)供能量(liang)，輸(shu)入輸(shu)出(chu)關(guan)(guan)系見式(shi)(shi)，聯立式(shi)(shi)和式(shi)(shi)可得充(chong)電(dian)(dian)器輸(shu)入輸(shu)出(chu)關(guan)(guan)系，見式(shi)(shi)，D1不變(bian)，D2可變(bian)。

　　結束語

　　小功(gong)(gong)(gong)率(lv)(lv)UPS不要求(qiu)寬范圍的輸(shu)出電(dian)壓(ya)，希望對輸(shu)入(ru)電(dian)壓(ya)和(he)輸(shu)出負載有良好相應，單端反激拓撲(pu)能(neng)滿足此要求(qiu)，盡管其輸(shu)出功(gong)(gong)(gong)率(lv)(lv)和(he)效率(lv)(lv)不高;推挽正激拓撲(pu)同時實現了充電(dian)器和(he)DC/DC的功(gong)(gong)(gong)能(neng)，減低了整機(ji)成本;中功(gong)(gong)(gong)率(lv)(lv)UPS則(ze)希望充電(dian)器輸(shu)出電(dian)壓(ya)可調(diao)，BOOST-BUCK和(he)BOOST-半(ban)橋都是(shi)明智(zhi)的選擇;大功(gong)(gong)(gong)率(lv)(lv)UPS采用模(mo)塊(kuai)化(hua)結構(gou)，對THDI和(he)輸(shu)入(ru)功(gong)(gong)(gong)率(lv)(lv)因數等指(zhi)標要求(qiu)很高，輸(shu)入(ru)取自母線(xian)電(dian)壓(ya)的BUCK變換器拓撲(pu)簡單實用，當(dang)然，BOOST一半(ban)橋在縮減模(mo)塊(kuai)體積方(fang)面表(biao)現突(tu)出。