作為UPS關鍵部件的充電器與UPS的(de)許多指標密切相關。文章提出了UPS充電(dian)器的(de)設計要(yao)求，將UPS按功率(lv)大小劃分，分別為它們(men)選擇了合適(shi)的(de)充電(dian)器拓撲，并分析了工作原理，指出了存在(zai)的(de)不(bu)足。

　　1 在線式UPS的組成

　　隨著電(dian)(dian)子技術的(de)飛速發展，各種各樣(yang)的(de)電(dian)(dian)器設備(bei)越來(lai)(lai)越多(duo)，而這其中的(de)大部分(fen)都是非線性負載，即它們從電(dian)(dian)網汲取的(de)電(dian)(dian)流波形與電(dian)(dian)壓波形不(bu)一(yi)(yi)樣(yang)。這無疑(yi)給(gei)電(dian)(dian)網帶來(lai)(lai)了大量(liang)的(de)諧(xie)波以及其他的(de)公害，使(shi)供(gong)(gong)電(dian)(dian)的(de)質(zhi)量(liang)變得較差。另一(yi)(yi)方面，一(yi)(yi)些重要(yao)(yao)的(de)用(yong)電(dian)(dian)部門(如機(ji)場、醫(yi)院、銀行)和一(yi)(yi)些重要(yao)(yao)的(de)用(yong)電(dian)(dian)設備(bei)(如計算機(ji)、通信設備(bei))對供(gong)(gong)電(dian)(dian)質(zhi)量(liang)的(de)要(yao)(yao)求(qiu)越來(lai)(lai)越高(gao)，不(bu)僅(jin)要(yao)(yao)求(qiu)不(bu)停電(dian)(dian)，還要(yao)(yao)求(qiu)電(dian)(dian)壓、頻率、波形質(zhi)量(liang)良(liang)好，避免受到(dao)電(dian)(dian)網的(de)干(gan)擾，具備(bei)一(yi)(yi)個凈化的(de)電(dian)(dian)源環境。這就(jiu)使(shi)負載與電(dian)(dian)網供(gong)(gong)電(dian)(dian)質(zhi)量(liang)之間(jian)的(de)矛(mao)盾日益加劇。為解決這一(yi)(yi)矛(mao)盾，UPS供(gong)(gong)電(dian)(dian)系統(tong)迅猛發展并(bing)普及起來(lai)(lai)。

　　隨著(zhu)計算機、各種辦公設(she)備、精密電(dian)子儀(yi)器的普及，UPS得(de)到(dao)了(le)廣(guang)泛的應用(yong)。現在(zai)(zai)應用(yong)較多的是在(zai)(zai)線式UPS，當市電(dian)正常時，電(dian)網電(dian)壓(ya)(ya)一路(lu)經過整(zheng)流模塊(kuai)AC/DC、逆變(bian)模塊(kuai)DC/AC，得(de)到(dao)所需的正弦(xian)電(dian)壓(ya)(ya)或(huo)(huo)準方(fang)波(bo)電(dian)壓(ya)(ya)供給(gei)負載(zai)(zai)，另一路(lu)通(tong)過充(chong)電(dian)模塊(kuai)給(gei)電(dian)池(chi)充(chong)電(dian);市電(dian)異常時，電(dian)池(chi)通(tong)過DC/DC模塊(kuai)、DC/AC模塊(kuai)，輸出(chu)正弦(xian)電(dian)壓(ya)(ya)或(huo)(huo)準方(fang)波(bo)電(dian)壓(ya)(ya)，給(gei)負載(zai)(zai)供電(dian);如果UPS異常，電(dian)網直(zhi)接通(tong)過旁(pang)路(lu)給(gei)負載(zai)(zai)供電(dian)。

　　2 UPS充電器的設計要求

　　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。輸出功率(lv)也是充(chong)電(dian)(dian)器設(she)計(ji)需要(yao)考慮的(de)，當(dang)然功率(lv)也很(hen)重要(yao)。作為UPS重要(yao)部件之(zhi)一的(de)充(chong)電(dian)(dian)器，不得不考慮成本(ben)。歸納一下有如下設(she)計(ji)要(yao)求：

　　(1) 要求輸(shu)入電壓寬(kuan)泛;

　　(2) 充(chong)電(dian)器(qi)的THDI值小，且能(neng)承受一定市(shi)電(dian)脈沖和(he)浪涌;

　　(3) 寬范圍可(ke)調節的輸出(chu)電壓，輸出(chu)電流(liu)波紋(wen)較小;

　　(4) 對(dui)輸(shu)入電壓和(he)輸(shu)出負載有良(liang)好響應;

　　(5) 達到設計的(de)功率要求;

　　(6) 效率較高;

　　(7) 成(cheng)本(ben)較低。

　　3 小功率UPS充電器拓撲的選擇

　　以某公司的(de)(de)1～3kVA功率等級的(de)(de)UPS為(wei)例(li)，一(yi)般選擇單端(duan)反擊拓撲結構作為(wei)充(chong)電(dian)(dian)(dian)(dian)器，變壓(ya)器原(yuan)副邊同名端(duan)相反，輸(shu)入(ru)從市電(dian)(dian)(dian)(dian)直(zhi)接(jie)獲(huo)取，經過整(zheng)流(liu)濾波器后得到正弦半波電(dian)(dian)(dian)(dian)壓(ya)，再變換為(wei)所(suo)需的(de)(de)輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)，如果按照不連(lian)續模(mo)式設(she)計(ji)，變壓(ya)器原(yuan)邊電(dian)(dian)(dian)(dian)感值較小(xiao)且輸(shu)出端(duan)無電(dian)(dian)(dian)(dian)抗元(yuan)件，控制系統(tong)對(dui)輸(shu)入(ru)電(dian)(dian)(dian)(dian)壓(ya)和輸(shu)出負載的(de)(de)響應要很快。

　　當VT1導通時，以(yi)輸(shu)入電(dian)(dian)(dian)壓(ya)正(zheng)(zheng)半周為例，輸(shu)入電(dian)(dian)(dian)流由L端經VD2、變壓(ya)器VR1原邊(bian)(bian)(bian)VT1、R1和(he)VD4回到N端，TR原邊(bian)(bian)(bian)產生(sheng)(sheng)上(shang)(shang)(shang)正(zheng)(zheng)下(xia)(xia)負的(de)(de)(de)電(dian)(dian)(dian)壓(ya)，原邊(bian)(bian)(bian)電(dian)(dian)(dian)壓(ya)為Ui(Ui為市電(dian)(dian)(dian)整流后的(de)(de)(de)半波(bo)電(dian)(dian)(dian)壓(ya))，副邊(bian)(bian)(bian)極性相應(ying)產生(sheng)(sheng)下(xia)(xia)正(zheng)(zheng)上(shang)(shang)(shang)負的(de)(de)(de)電(dian)(dian)(dian)壓(ya)，二(er)極管(guan)VD5承(cheng)(cheng)受反(fan)向電(dian)(dian)(dian)壓(ya)而截止，VD5承(cheng)(cheng)受電(dian)(dian)(dian)壓(ya)為(Ns/Np)Ui+UB;VT1截止時，為使磁芯工作點順(shun)利返回，變壓(ya)器原邊(bian)(bian)(bian)產生(sheng)(sheng)下(xia)(xia)負上(shang)(shang)(shang)正(zheng)(zheng)電(dian)(dian)(dian)壓(ya)，則副邊(bian)(bian)(bian)電(dian)(dian)(dian)壓(ya)為上(shang)(shang)(shang)正(zheng)(zheng)下(xia)(xia)負，副邊(bian)(bian)(bian)電(dian)(dian)(dian)流通過VD5向電(dian)(dian)(dian)池充電(dian)(dian)(dian)。原邊(bian)(bian)(bian)相應(ying)電(dian)(dian)(dian)壓(ya)為下(xia)(xia)正(zheng)(zheng)上(shang)(shang)(shang)負，U1=-(Np/Ns)UB，則VT1承(cheng)(cheng)受電(dian)(dian)(dian)壓(ya)為(Np/Ns)UB+U1。根據(ju)原邊(bian)(bian)(bian)線圈的(de)(de)(de)伏秒平衡。

　　但是，變(bian)壓器帶來磁滯損(sun)耗和繞線損(sun)耗，另外輸出(chu)電(dian)(dian)流(liu)波紋較大(da)，整體(ti)效率不高，VT1導通時(shi)輸出(chu)靠濾波電(dian)(dian)容C1維持，要用大(da)容量的(de)濾波電(dian)(dian)容。

　　小(xiao)功率UPS的充(chong)電(dian)(dian)(dian)器根據(ju)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流的打消設計(ji)成(cheng)模組和充(chong)電(dian)(dian)(dian)板(ban)，為滿足UPS緊(jin)湊化的要求，降低成(cheng)本，把(ba)充(chong)電(dian)(dian)(dian)器設計(ji)在功率板(ban)上將是一種選(xuan)擇，輸入從(cong)母線電(dian)(dian)(dian)壓獲(huo)取。

　　DC/DC和(he)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)利用一個(ge)拓撲(pu)(pu)實(shi)現(xian)，即推挽(wan)(wan)(wan)正激(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，它在推挽(wan)(wan)(wan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)基礎(chu)上(shang)變(bian)更了(le)線阻N1、N2與開(kai)關(guan)管VT1、VT2的(de)為之，增(zeng)加(jia)了(le)一個(ge)儲能電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C1。為了(le)形成(cheng)雙向電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，在高壓(ya)側(ce)增(zeng)加(jia)一個(ge)開(kai)關(guan)管VT4，低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)側(ce)增(zeng)加(jia)一個(ge)輔助充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)繞(rao)組(zu)和(he)開(kai)關(guan)管VT3，形成(cheng)正激(ji)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)I1路(lu)徑(jing)如圖4所(suo)示。充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)，VT3一直打(da)開(kai)，VT4進行PWM調制(zhi)，繞(rao)組(zu)N5電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian);對(dui)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池模(mo)式下的(de)推挽(wan)(wan)(wan)正激(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，以VT1管和(he)N1支路(lu)為例(li)，當(dang)VT1管開(kai)通(tong)(tong)(tong)時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)(tong)(tong)過(guo)(guo)(guo)N1、VT1，在繞(rao)組(zu)N4感(gan)應(ying)出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C2充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian);VT1關(guan)閉瞬(shun)間，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通(tong)(tong)(tong)過(guo)(guo)(guo)N1、C1、VT2體(ti)內二極管續流(liu)(liu)，當(dang)VT2開(kai)通(tong)(tong)(tong)時(shi)(shi)，C1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)功過(guo)(guo)(guo)N1、VT2放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，在繞(rao)線N3感(gan)應(ying)出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)給C2充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，路(lu)徑(jing)見圖中I2。C1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)在VT1、VT2關(guan)斷(duan)時(shi)(shi)刻儲能，當(dang)相應(ying)對(dui)管開(kai)通(tong)(tong)(tong)時(shi)(shi)刻放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，由此提高了(le)效率，限制(zhi)了(le)開(kai)關(guan)管關(guan)斷(duan)時(shi)(shi)漏極電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)過(guo)(guo)(guo)大。這種拓撲(pu)(pu)尤(you)其適(shi)合低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)場合，因此可以減(jian)少電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池節(jie)數，降低成(cheng)本。另外，提高了(le)變(bian)壓(ya)器(qi)的(de)利用率，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)輸出端沒有接輸出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感(gan)，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)波紋過(guo)(guo)(guo)大。

　　4 中功率UPS充電器(qi)拓撲(pu)選擇

　　一般UPS的電(dian)(dian)池(chi)節數是固(gu)定的，像1kVA的UPS配(pei)備2或3節電(dian)(dian)池(chi)，3kVA的UPS配(pei)備6或8節，10kVA配(pei)備16或20節，中功率UPS所配(pei)備的電(dian)(dian)池(chi)節數較多，時間(jian)長(chang)了(le)，難免有電(dian)(dian)池(chi)損壞，要求相對應的充電(dian)(dian)器(qi)(qi)電(dian)(dian)壓能做出(chu)調(diao)整。某品牌(pai)10kVA UPS，電(dian)(dian)池(chi)在12-24節數范(fan)圍可(ke)調(diao)，對應充電(dian)(dian)器(qi)(qi)輸(shu)出(chu)電(dian)(dian)壓范(fan)圍為(wei)164-328V，單端反激拓(tuo)撲輸(shu)出(chu)電(dian)(dian)壓幾乎(hu)不可(ke)能在此寬范(fan)圍可(ke)調(diao)，為(wei)此設計了(le)BOOST-BUCK變換器(qi)(qi)。

　　前級采(cai)用BOOST結(jie)構，把(ba)市電(dian)(dian)(dian)(dian)(dian)升到400V，市電(dian)(dian)(dian)(dian)(dian)經(jing)整流(liu)橋后得到直流(liu)脈動電(dian)(dian)(dian)(dian)(dian)壓，VT1導通時(shi)，L1上電(dian)(dian)(dian)(dian)(dian)流(liu)增加，并儲存能量(liang)(liang)，VD5承受反向(xiang)電(dian)(dian)(dian)(dian)(dian)壓而截(jie)止，濾波(bo)電(dian)(dian)(dian)(dian)(dian)容C2給(gei)(gei)負(fu)載提(ti)供(gong)能量(liang)(liang);VT1截(jie)止時(shi)，市電(dian)(dian)(dian)(dian)(dian)通過(guo)L1和(he)VD5對電(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)，并給(gei)(gei)負(fu)載提(ti)供(gong)能量(liang)(liang)，輸入(ru)(ru)和(he)輸出(chu)關系見式。后級采(cai)用BUCK結(jie)構，它把(ba)輸入(ru)(ru)端400V降到所需的充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓，VT2導通時(shi)，VD5承受反向(xiang)電(dian)(dian)(dian)(dian)(dian)壓截(jie)止，輸入(ru)(ru)經(jing)過(guo)L2給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)容C2充電(dian)(dian)(dian)(dian)(dian)，并提(ti)供(gong)能量(liang)(liang)給(gei)(gei)負(fu)載，VT2截(jie)止時(shi)，電(dian)(dian)(dian)(dian)(dian)感(gan)電(dian)(dian)(dian)(dian)(dian)流(liu)經(jing)過(guo)VD6續流(liu)，L2和(he)C2共同負(fu)載提(ti)供(gong)能量(liang)(liang)，輸入(ru)(ru)輸出(chu)關系見式，聯立式和(he)式可(ke)得充電(dian)(dian)(dian)(dian)(dian)器輸入(ru)(ru)輸出(chu)關系，見式，D1不變，D2可(ke)變。

　　結束語

　　小功率(lv)UPS不要(yao)求寬范圍的(de)輸(shu)(shu)出電(dian)(dian)壓(ya)，希望對(dui)輸(shu)(shu)入電(dian)(dian)壓(ya)和(he)輸(shu)(shu)出負(fu)載有良(liang)好(hao)相應(ying)，單端反激拓撲能滿足(zu)此要(yao)求，盡(jin)管其輸(shu)(shu)出功率(lv)和(he)效率(lv)不高(gao);推(tui)挽正激拓撲同時實現(xian)了(le)充電(dian)(dian)器和(he)DC/DC的(de)功能，減低了(le)整機成本(ben);中功率(lv)UPS則希望充電(dian)(dian)器輸(shu)(shu)出電(dian)(dian)壓(ya)可(ke)調，BOOST-BUCK和(he)BOOST-半橋(qiao)都(dou)是明(ming)智的(de)選擇(ze);大功率(lv)UPS采用模(mo)(mo)塊化結構，對(dui)THDI和(he)輸(shu)(shu)入功率(lv)因數等指標要(yao)求很高(gao)，輸(shu)(shu)入取自母(mu)線電(dian)(dian)壓(ya)的(de)BUCK變換器拓撲簡單實用，當然，BOOST一半橋(qiao)在縮減模(mo)(mo)塊體(ti)積方面表現(xian)突(tu)出。