中國IDC圈7月14日報(bao)道，發電機(ji)（俗稱電球）是將(jiang)機(ji)械能轉(zhuan)變(bian)成交流(liu)電能的(de)機(ji)器，是柴油(you)發電機(ji)組(zu)的(de)電能產生和輸(shu)出(chu)的(de)機(ji)器。

1 發(fa)電機的基(ji)本(ben)結構(gou)

19世紀(ji)英國科學家法拉(la)第通(tong)過實(shi)驗發現(xian)了電磁(ci)感應現(xian)象(xiang)；導體(ti)(ti)與磁(ci)場(chang)(chang)的磁(ci)力(li)線相對(dui)切割運動(dong)時，導體(ti)(ti)中會感應出電動(dong)勢。如(ru)果將這(zhe)根導體(ti)(ti)的兩端連接起來，則在這(zhe)個(ge)閉(bi)合導體(ti)(ti)與磁(ci)場(chang)(chang)相對(dui)切割運動(dong)時，導體(ti)(ti)中就會產生(sheng)感應電流(liu)。這(zhe)種現(xian)象(xiang)可以用多種實(shi)驗方式得(de)以驗證，見圖1所示的實(shi)驗。

原線(xian)(xian)圈(quan)(quan)(quan)A通以(yi)直(zhi)流(liu)電(dian)，則線(xian)(xian)圈(quan)(quan)(quan)因有電(dian)流(liu)流(liu)過而產(chan)(chan)生(sheng)直(zhi)流(liu)磁場(chang)。在副線(xian)(xian)圈(quan)(quan)(quan)B的兩端接上電(dian)流(liu)表(biao)(biao)G.當線(xian)(xian)圈(quan)(quan)(quan)A穿越線(xian)(xian)圈(quan)(quan)(quan)B的中(zhong)間向下運(yun)動時，電(dian)流(liu)表(biao)(biao)G的指(zhi)針(zhen)會(hui)隨(sui)之從(cong)中(zhong)心點擺(bai)向一邊。向上運(yun)動時，電(dian)流(liu)表(biao)(biao)G的指(zhi)針(zhen)會(hui)隨(sui)之擺(bai)向另一邊。這就(jiu)是說：由線(xian)(xian)圈(quan)(quan)(quan)A的直(zhi)流(liu)磁場(chang)的磁力線(xian)(xian)切割(ge)線(xian)(xian)圈(quan)(quan)(quan)B，或者說線(xian)(xian)圈(quan)(quan)(quan)B內的磁場(chang)從(cong)無(wu)到(dao)有或從(cong)小(xiao)到(dao)大(da)發生(sheng)變化(hua)時，它就(jiu)會(hui)產(chan)(chan)生(sheng)感應電(dian)動勢和感應電(dian)流(liu)。而且(qie)線(xian)(xian)圈(quan)(quan)(quan)B中(zhong)的感應電(dian)動勢和感應電(dian)流(liu)的方向還(huan)隨(sui)磁場(chang)方向的變化(hua)而變化(hua)。通過大(da)量的電(dian)磁感應實(shi)驗，科學家總結(jie)出了恒定磁場(chang)與金(jin)屬導體線(xian)(xian)圈(quan)(quan)(quan)相(xiang)對切割(ge)運(yun)動時線(xian)(xian)圈(quan)(quan)(quan)內的感應電(dian)動勢為：

式(shi)中(zhong)，N代表(biao)線(xian)圈(quan)B共有多少圈(quan)（也稱匝）。 / t是線(xian)圈(quan)B中(zhong)的一(yi)圈(quan)在(zai) t時間內磁通(tong)（表(biao)示磁場的強(qiang)弱）的變(bian)化量 。

可見線圈(quan)B中(zhong)(zhong)的感應電動(dong)勢e與線圈(quan)A穿(chuan)越(yue)其(qi)中(zhong)(zhong)間上下(xia)運動(dong)形(xing)成的磁通變化(hua)有關(guan)。而且與其(qi)運動(dong)的速度也有關(guan)，上下(xia)運動(dong)越(yue)快感應電動(dong)勢e越(yue)大。線圈(quan)繞(rao)的圈(quan)數N越(yue)多e也越(yue)大。

法拉第定律告(gao)訴我們：金屬線圈穿過磁場切(qie)割磁力(li)線，或者線圈不動而(er)磁場磁力(li)線掃過它，都會在金屬線圈的兩個(ge)端頭間產(chan)生電(dian)壓。發電(dian)機就是根據這個(ge)原理制造(zao)的。

按照發(fa)(fa)電(dian)(dian)(dian)(dian)(dian)機(ji)的(de)(de)(de)基本結(jie)構(gou)，磁場固(gu)定（相(xiang)當(dang)于(yu)圖1中(zhong)(zhong)的(de)(de)(de)線(xian)圈(quan)A），金屬線(xian)圈(quan)繞(rao)組做成(cheng)可旋(xuan)轉(zhuan)的(de)(de)(de)以便(bian)切割磁力線(xian)（相(xiang)當(dang)于(yu)圖1中(zhong)(zhong)的(de)(de)(de)線(xian)圈(quan)B），電(dian)(dian)(dian)(dian)(dian)壓從這(zhe)個(ge)線(xian)圈(quan)繞(rao)組引出（稱為(wei)電(dian)(dian)(dian)(dian)(dian)樞(shu)繞(rao)組），這(zhe)種結(jie)構(gou)的(de)(de)(de)發(fa)(fa)電(dian)(dian)(dian)(dian)(dian)機(ji)叫做旋(xuan)轉(zhuan)電(dian)(dian)(dian)(dian)(dian)樞(shu)式(shi)發(fa)(fa)電(dian)(dian)(dian)(dian)(dian)機(ji)。因為(wei)電(dian)(dian)(dian)(dian)(dian)樞(shu)是旋(xuan)轉(zhuan)運動(dong)(dong)的(de)(de)(de)，電(dian)(dian)(dian)(dian)(dian)樞(shu)繞(rao)組的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)要(yao)靠活動(dong)(dong)接(jie)觸的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)刷(shua)和(he)滑(hua)環引出才能供(gong)給負荷。因此輸出電(dian)(dian)(dian)(dian)(dian)流(liu)和(he)電(dian)(dian)(dian)(dian)(dian)壓都不能太大，一般不超(chao)過500V，否則電(dian)(dian)(dian)(dian)(dian)刷(shua)和(he)滑(hua)環之間將產生很(hen)大的(de)(de)(de)火花。這(zhe)種結(jie)構(gou)形式(shi)的(de)(de)(de)發(fa)(fa)電(dian)(dian)(dian)(dian)(dian)機(ji)已很(hen)少(shao)采用。

常用的(de)(de)同步(bu)發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)的(de)(de)結構形式是輸(shu)出電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流(liu)的(de)(de)繞組(zu)（即電(dian)(dian)(dian)樞(shu)）是固(gu)定的(de)(de)（相(xiang)當(dang)于(yu)(yu)圖1中的(de)(de)線圈(quan)B），而產(chan)生磁(ci)力線的(de)(de)線圈(quan)繞組(zu)是旋轉的(de)(de)（相(xiang)當(dang)于(yu)(yu)圖1中的(de)(de)線圈(quan)A），其(qi)磁(ci)場(chang)自然也(ye)(ye)隨之旋轉，這種叫做旋轉磁(ci)場(chang)式發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)。發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)轉子(zi)部分只(zhi)產(chan)生直流(liu)磁(ci)場(chang)，而取消了滑環(huan)和電(dian)(dian)(dian)刷(shua)。定子(zi)部分有更多的(de)(de)空間嵌放電(dian)(dian)(dian)樞(shu)繞組(zu)和絕(jue)緣(yuan)材料，電(dian)(dian)(dian)樞(shu)產(chan)生的(de)(de)電(dian)(dian)(dian)流(liu)可(ke)以直接輸(shu)往負荷(he)，其(qi)機(ji)(ji)械(xie)強度和絕(jue)緣(yuan)性(xing)能都較好，可(ke)靠性(xing)也(ye)(ye)大為(wei)提高(gao)。所(suo)以又稱為(wei)無刷(shua)同步(bu)發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)。

2 同步發電(dian)機的特點

在(zai)(zai)同步發(fa)電(dian)(dian)機(ji)中，轉(zhuan)(zhuan)子上(shang)安裝產(chan)生(sheng)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)的(de)繞(rao)組，稱為(wei)勵(li)磁(ci)(ci)(ci)(ci)(ci)繞(rao)組（也稱轉(zhuan)(zhuan)子繞(rao)組）。通上(shang)直(zhi)流(liu)電(dian)(dian)后，勵(li)磁(ci)(ci)(ci)(ci)(ci)繞(rao)組在(zai)(zai)定(ding)子和(he)轉(zhuan)(zhuan)子之(zhi)(zhi)(zhi)間產(chan)生(sheng)直(zhi)流(liu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)。當柴油機(ji)帶動發(fa)電(dian)(dian)機(ji)的(de)轉(zhuan)(zhuan)子旋(xuan)轉(zhuan)(zhuan)時，這(zhe)個直(zhi)流(liu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)也隨(sui)(sui)著旋(xuan)轉(zhuan)(zhuan)起來。為(wei)此，稱它為(wei)主(zhu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)或(huo)轉(zhuan)(zhuan)子磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)。旋(xuan)轉(zhuan)(zhuan)的(de)主(zhu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)切割定(ding)子上(shang)安裝的(de)電(dian)(dian)樞(shu)繞(rao)組線圈(quan)，就會(hui)(hui)在(zai)(zai)線圈(quan)中產(chan)生(sheng)電(dian)(dian)壓(ya)和(he)電(dian)(dian)流(liu)，此電(dian)(dian)流(liu)在(zai)(zai)電(dian)(dian)樞(shu)繞(rao)組線圈(quan)中流(liu)動也會(hui)(hui)在(zai)(zai)定(ding)子和(he)轉(zhuan)(zhuan)子之(zhi)(zhi)(zhi)間產(chan)生(sheng)一(yi)個磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)，稱為(wei)定(ding)子磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)或(huo)電(dian)(dian)樞(shu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)。由于電(dian)(dian)樞(shu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)是(shi)主(zhu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)引起的(de)，所以它總(zong)是(shi)跟隨(sui)(sui)著主(zhu)磁(ci)(ci)(ci)(ci)(ci)場(chang)(chang)(chang)而轉(zhuan)(zhuan)動，彼此之(zhi)(zhi)(zhi)間以同一(yi)速度、同一(yi)方向(xiang)始(shi)終保持同步，所以稱為(wei)同步發(fa)電(dian)(dian)機(ji)。同步發(fa)電(dian)(dian)機(ji)的(de)內部結構如圖2所示。

圖(tu)中，同步發電(dian)(dian)(dian)機的(de)(de)定子部分（1）按(an)照120 的(de)(de)空間位置(zhi)分布了(le)三個(ge)同樣的(de)(de)繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)，這(zhe)就(jiu)(jiu)是(shi)定子繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)，發電(dian)(dian)(dian)機的(de)(de)輸出電(dian)(dian)(dian)壓由(you)它(ta)們通過發電(dian)(dian)(dian)機定子繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)（270）引出線(xian)接線(xian)端(duan)(duan)子給出，所以把它(ta)們也(ye)稱(cheng)(cheng)為(wei)電(dian)(dian)(dian)樞繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)。圖(tu)中同步發電(dian)(dian)(dian)機轉(zhuan)子（4）上(shang)面安裝著轉(zhuan)子繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)，它(ta)由(you)同一軸上(shang)的(de)(de)勵磁(ci)機電(dian)(dian)(dian)樞繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)（100）輸出的(de)(de)交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)，經旋轉(zhuan)整流(liu)(liu)(liu)(liu)器（78）整流(liu)(liu)(liu)(liu)后的(de)(de)直(zhi)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)供電(dian)(dian)(dian)，并形成(cheng)(cheng)主磁(ci)場。主磁(ci)場和(he)電(dian)(dian)(dian)樞磁(ci)場（共同形成(cheng)(cheng)一個(ge)合成(cheng)(cheng)磁(ci)場）的(de)(de)磁(ci)力(li)線(xian)剛掃入電(dian)(dian)(dian)樞繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)時，繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)兩端(duan)(duan)的(de)(de)電(dian)(dian)(dian)壓小，全部掃入時電(dian)(dian)(dian)壓最(zui)大(da)，快(kuai)掃過繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)時電(dian)(dian)(dian)壓也(ye)小。所以說，繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)兩端(duan)(duan)的(de)(de)電(dian)(dian)(dian)壓是(shi)交(jiao)流(liu)(liu)(liu)(liu)變(bian)化的(de)(de)，稱(cheng)(cheng)之為(wei)交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)壓。這(zhe)樣，同步發電(dian)(dian)(dian)機就(jiu)(jiu)可以產生彼此相(xiang)差120 的(de)(de)三相(xiang)交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)壓。如果按(an)順序將這(zhe)三個(ge)電(dian)(dian)(dian)樞繞(rao)(rao)(rao)(rao)(rao)組(zu)(zu)編號為(wei)A、B、C，則它(ta)們各(ge)自的(de)(de)輸出電(dian)(dian)(dian)壓瞬時值可表達成(cheng)(cheng)

uA=Umsin（2 f t+0 ）

uB=Umsin（2 f t-120 ）

uC=Umsin（2 f t+120 ）

式中，（1）0 、-120 、+120 叫做初相角(jiao)，它們是由同(tong)步發電(dian)機的(de)結構決定的(de)。

（2） f 是(shi)(shi)(shi)電壓(ya)的(de)(de)頻率。它(ta)(ta)(ta)表示單位(wei)時間內，同步發(fa)電機(ji)(ji)(ji)轉子(zi)(zi)磁(ci)(ci)場的(de)(de)磁(ci)(ci)力線(xian)切(qie)割電樞(shu)繞組的(de)(de)次(ci)數。f的(de)(de)大(da)小實際上是(shi)(shi)(shi)由發(fa)電機(ji)(ji)(ji)組的(de)(de)柴油發(fa)動機(ji)(ji)(ji)的(de)(de)轉速決(jue)定的(de)(de)，因為是(shi)(shi)(shi)它(ta)(ta)(ta)直接帶(dai)著發(fa)電機(ji)(ji)(ji)轉子(zi)(zi)一(yi)(yi)起(qi)旋(xuan)轉，轉速越(yue)快，則(ze) f 越(yue)高。反(fan)之亦(yi)然， f 越(yue)低。對于同一(yi)(yi)臺同步發(fa)電機(ji)(ji)(ji)而(er)言，顯(xian)然三個電壓(ya)的(de)(de)頻率 f 是(shi)(shi)(shi)一(yi)(yi)樣的(de)(de)。2 f 則(ze)是(shi)(shi)(shi)轉子(zi)(zi)磁(ci)(ci)場的(de)(de)磁(ci)(ci)力線(xian)切(qie)割電樞(shu)繞組的(de)(de)角頻率，用 表示。從三相(xiang)電壓(ya)的(de)(de)表達式(shi)可(ke)知：2 f t+ i（ i=0 、-120 、+120 ）是(shi)(shi)(shi)正弦量變(bian)化的(de)(de)核心，它(ta)(ta)(ta)反(fan)映(ying)了正弦量隨時間t變(bian)化的(de)(de)進程。

（3）Um是(shi)電(dian)(dian)壓(ya)的(de)(de)最(zui)大(da)值。它是(shi)由同步(bu)發電(dian)(dian)機的(de)(de)勵(li)磁系統(tong)勵(li)磁電(dian)(dian)流(liu)的(de)(de)大(da)小決定的(de)(de)，同步(bu)發電(dian)(dian)機的(de)(de)轉(zhuan)子(zi)磁場是(shi)由勵(li)磁電(dian)(dian)流(liu)流(liu)過轉(zhuan)子(zi)繞組產(chan)生(sheng)的(de)(de)，電(dian)(dian)流(liu)大(da)則轉(zhuan)子(zi)磁場強(qiang)，磁力線切割電(dian)(dian)樞繞組在繞組上產(chan)生(sheng)的(de)(de)感應電(dian)(dian)動勢就(jiu)大(da)。反(fan)之亦然，感應電(dian)(dian)動勢就(jiu)小。同步(bu)發電(dian)(dian)機只有一個勵(li)磁系統(tong)，因此三個繞組輸出電(dian)(dian)壓(ya)的(de)(de)最(zui)大(da)值Um都是(shi)一樣的(de)(de)。

根據設計，三個電(dian)樞繞組之間的電(dian)壓（稱為(wei)線電(dian)壓）為(wei)380～400V.由(you)于這種同步發(fa)(fa)電(dian)機在(zai)電(dian)氣性(xing)能和機械性(xing)能方面都具有優點，因而被柴油發(fa)(fa)電(dian)機組普遍采用(yong)。

3 轉子繞組的勵磁

所(suo)謂勵磁即是向同步發(fa)(fa)電(dian)(dian)機轉子繞組(zu)提(ti)供直流(liu)電(dian)(dian)，使其(qi)產生(sheng)直流(liu)磁場的(de)(de)過(guo)程。早期的(de)(de)發(fa)(fa)電(dian)(dian)機是采用單獨的(de)(de)勵磁機給轉子線圈(quan)提(ti)供直流(liu)電(dian)(dian)，系統龐大(da)而(er)復雜。隨著技術的(de)(de)進(jin)步，現(xian)代同步發(fa)(fa)電(dian)(dian)機都是將(jiang)發(fa)(fa)電(dian)(dian)機與(yu)勵磁機組(zu)裝在(zai)一起(qi)構成(cheng)一個(ge)完整的(de)(de)發(fa)(fa)電(dian)(dian)機。如圖2后半部(bu)分所(suo)示(shi)。

勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)其實就(jiu)是(shi)個小發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)，其工作(zuo)原理與同步發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)一樣。所不(bu)同的(de)是(shi)它(ta)的(de)定子(zi)(zi)線(xian)(xian)圈(quan)和(he)轉(zhuan)子(zi)(zi)線(xian)(xian)圈(quan)所起的(de)作(zuo)用與同步發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji) 主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)正好相反；圖2中勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)定子(zi)(zi)繞組(zu)(zu)(zu)（90）固定在(zai)主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)定子(zi)(zi)旁，勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)的(de)定子(zi)(zi)線(xian)(xian)圈(quan)通(tong)以直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)形(xing)成(cheng)直(zhi)(zhi)流(liu)(liu)磁(ci)(ci)(ci)(ci)(ci)場。而(er)(er)(er)安(an)裝在(zai)主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)軸上的(de)勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)的(de)轉(zhuan)子(zi)(zi)線(xian)(xian)圈(quan)，即圖2中勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)樞繞組(zu)(zu)(zu)（100）成(cheng)為(wei)輸出電(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)繞組(zu)(zu)(zu)。勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)的(de)轉(zhuan)子(zi)(zi)與定子(zi)(zi)內壁之間也(ye)是(shi)保(bao)持著較(jiao)小而(er)(er)(er)均勻的(de)間隙。勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)定子(zi)(zi)線(xian)(xian)圈(quan)的(de)直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)，是(shi)由主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)定子(zi)(zi)線(xian)(xian)圈(quan)即電(dian)(dian)(dian)(dian)(dian)(dian)樞的(de)部分輸出電(dian)(dian)(dian)(dian)(dian)(dian)壓經整(zheng)(zheng)流(liu)(liu)后而(er)(er)(er)得到的(de)。它(ta)使勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)定子(zi)(zi)線(xian)(xian)圈(quan)產(chan)生直(zhi)(zhi)流(liu)(liu)磁(ci)(ci)(ci)(ci)(ci)場，且該(gai)磁(ci)(ci)(ci)(ci)(ci)場是(shi)不(bu)動(dong)的(de)。工作(zuo)時，與主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)同軸安(an)裝的(de)勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)線(xian)(xian)圈(quan)在(zai)這個磁(ci)(ci)(ci)(ci)(ci)場內旋轉(zhuan)、切割磁(ci)(ci)(ci)(ci)(ci)力(li)線(xian)(xian)產(chan)生感應電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)勢。該(gai)電(dian)(dian)(dian)(dian)(dian)(dian)勢經圖2中同軸安(an)裝在(zai)勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)機(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)樞繞組(zu)(zu)(zu)旁邊的(de)旋轉(zhuan)整(zheng)(zheng)流(liu)(liu)器(qi)（78）變成(cheng)直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，再(zai)輸到主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)轉(zhuan)子(zi)(zi)繞組(zu)(zu)(zu)使其產(chan)生直(zhi)(zhi)流(liu)(liu)轉(zhuan)子(zi)(zi)磁(ci)(ci)(ci)(ci)(ci)場。從(cong)而(er)(er)(er)達到了對(dui)主(zhu)(zhu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)繞組(zu)(zu)(zu)勵(li)(li)磁(ci)(ci)(ci)(ci)(ci)的(de)要求。

4 輸出電壓的調控

調控的目的就是(shi)實現在同(tong)步發(fa)電(dian)機額(e)定范圍內的負荷(he)，無論(lun)其性質及大小如何變化都能穩住輸(shu)出電(dian)壓(ya)。調控的技術(shu)方式隨(sui)著發(fa)電(dian)機額(e)定功率的不(bu)同(tong)、每個時期技術(shu)發(fa)展程度(du)的不(bu)同(tong)，有簡潔(jie)及完善的許多類型。

但總的理念都是(shi)：實(shi)(shi)時(shi)(shi)從(cong)主(zhu)發電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)電(dian)(dian)(dian)(dian)樞取(qu)得電(dian)(dian)(dian)(dian)壓(ya)(ya)和電(dian)(dian)(dian)(dian)流(liu)，經自動(dong)電(dian)(dian)(dian)(dian)壓(ya)(ya)調(diao)節器整流(liu)和負(fu)反饋調(diao)理后供給勵(li)磁機(ji)(ji)(ji)的定子(zi)(zi)線圈(quan)，使其產生變化規(gui)律與主(zhu)發電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)(ya)變化規(gui)律相反的直流(liu)電(dian)(dian)(dian)(dian)磁場(chang)。這(zhe)個磁場(chang)也(ye)必然使勵(li)磁機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)電(dian)(dian)(dian)(dian)樞的輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)(ya)以及旋轉(zhuan)整流(liu)器供給主(zhu)發電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)線圈(quan)的直流(liu)電(dian)(dian)(dian)(dian)流(liu)按同樣的規(gui)律而變化。從(cong)而起(qi)到(dao)實(shi)(shi)時(shi)(shi)調(diao)節主(zhu)發電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)轉(zhuan)子(zi)(zi)磁場(chang)大(da)小，使主(zhu)發電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)在額定負(fu)荷范(fan)圍內保持良好(hao)輸(shu)出特(te)性的作用(yong)。

一種電壓調控裝置的自動控制邏輯如圖3所示。

對(dui)發電(dian)機輸(shu)出電(dian)壓(ya)(ya)的調控過程，自動電(dian)壓(ya)(ya)調節器(qi)起著重要作用(yong)。可用(yong)圖4的流程表示。

可(ke)見，通過勵(li)磁(ci)(ci)機實時調控主發電機轉子繞(rao)組(zu)磁(ci)(ci)場的(de)大小(xiao)，就可(ke)以(yi)穩住輸出電壓(ya)。這其(qi)中起重要作(zuo)用的(de)是(shi)具有負(fu)反饋功能的(de)自(zi)動電壓(ya)調節器。通常也稱其(qi)為恒壓(ya)勵(li)磁(ci)(ci)裝置(zhi)(zhi)。圖2中（198）指的(de)就是(shi)這個裝置(zhi)(zhi)。

5 自動電壓調節器

在柴油發電(dian)(dian)(dian)機(ji)(ji)組的額(e)(e)定(ding)負(fu)荷(he)范圍之內，無(wu)論負(fu)荷(he)是電(dian)(dian)(dian)阻(zu)、電(dian)(dian)(dian)容、電(dian)(dian)(dian)感性或兼而(er)有之，也無(wu)論它們的大小怎樣(yang)變化，對柴油機(ji)(ji)的主(zhu)(zhu)要要求是穩住轉速（通常柴油發動(dong)機(ji)(ji)的額(e)(e)定(ding)轉速為(wei)每分(fen)鐘1500轉）。而(er)對同步發電(dian)(dian)(dian)機(ji)(ji)的主(zhu)(zhu)要要求則(ze)是穩住輸(shu)出電(dian)(dian)(dian)壓。為(wei)此，一般都采用以先進(jin)電(dian)(dian)(dian)子裝置為(wei)核心的自動(dong)電(dian)(dian)(dian)壓調控系統(tong)。

現(xian)代交(jiao)流同步發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)常用(yong)自動電(dian)(dian)(dian)壓調(diao)節器(qi)（AVR）這種(zhong)電(dian)(dian)(dian)子部件(jian)，調(diao)節勵磁機(ji)(ji)(ji)定子磁場(chang)(chang)的(de)強弱(ruo)。進而(er)達到穩住輸出(chu)(chu)電(dian)(dian)(dian)壓的(de)目的(de)。雖然AVR的(de)種(zhong)類很多，但性能大(da)同小(xiao)異。都(dou)是實(shi)時(shi)(shi)采樣主發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)輸出(chu)(chu)電(dian)(dian)(dian)壓值(zhi)(zhi)與預先設定的(de)值(zhi)(zhi)相比較，用(yong)比較的(de)結(jie)果去(qu)調(diao)節脈(mo)沖(chong)寬度調(diao)制器(qi)（PWM）。輸出(chu)(chu)電(dian)(dian)(dian)壓值(zhi)(zhi)高則(ze)(ze)調(diao)制器(qi)輸出(chu)(chu)脈(mo)沖(chong)寬度窄，反之則(ze)(ze)寬。然后再用(yong)這些脈(mo)沖(chong)去(qu)調(diao)控(kong)大(da)功率(lv)半導體開關器(qi)件(jian)，控(kong)制送入勵磁機(ji)(ji)(ji)定子線圈(quan)的(de)電(dian)(dian)(dian)流的(de)時(shi)(shi)間(jian)及大(da)小(xiao)。從而(er)使(shi)它的(de)磁場(chang)(chang)強弱(ruo)隨著主發(fa)(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)輸出(chu)(chu)電(dian)(dian)(dian)壓的(de)變化(hua)而(er)相反變化(hua)。即輸出(chu)(chu)電(dian)(dian)(dian)壓升高則(ze)(ze)勵磁機(ji)(ji)(ji)定子磁場(chang)(chang)減小(xiao)，輸出(chu)(chu)電(dian)(dian)(dian)壓降低(di)則(ze)(ze)勵磁機(ji)(ji)(ji)定子磁場(chang)(chang)增強，從而(er)達到負反饋調(diao)控(kong)的(de)目的(de)。

常用(yong)的一種(zhong)AVR類型如圖5所示(shi)。

采樣(yang)取自主發(fa)(fa)電(dian)(dian)(dian)機輸(shu)出(chu)(chu)的部分(fen)電(dian)(dian)(dian)壓(ya)(ya)(ya)，從（8）、（9）兩(liang)端進入電(dian)(dian)(dian)壓(ya)(ya)(ya)測量單元(yuan)。經降壓(ya)(ya)(ya)、分(fen)壓(ya)(ya)(ya)、整(zheng)流濾波后(hou)，得(de)到與發(fa)(fa)電(dian)(dian)(dian)機輸(shu)出(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)(ya)成正比的直(zhi)流電(dian)(dian)(dian)壓(ya)(ya)(ya)。它被(bei)R4、R5、PR1分(fen)壓(ya)(ya)(ya)后(hou)獲得(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)UA，并送(song)(song)入脈(mo)寬調(diao)制(zhi)器(qi)(qi)。出(chu)(chu)廠前或(huo)者發(fa)(fa)電(dian)(dian)(dian)機帶載正常(chang)工(gong)作時，調(diao)節RHR外接(jie)電(dian)(dian)(dian)壓(ya)(ya)(ya)微調(diao)電(dian)(dian)(dian)位(wei)器(qi)(qi)使UA確定一(yi)個值(zhi)作為基(ji)準。測量單元(yuan)輸(shu)出(chu)(chu)的電(dian)(dian)(dian)壓(ya)(ya)(ya)Uc則送(song)(song)入低頻保護(hu)單元(yuan)。

脈沖(chong)(chong)寬度調制(zhi)(zhi)器(qi)（PWM）的(de)(de)(de)(de)(de)輸出(chu)(chu)調寬脈沖(chong)(chong)UB控(kong)制(zhi)(zhi)調制(zhi)(zhi)管VT3.若由電壓測(ce)量單元送來的(de)(de)(de)(de)(de)UA比基準電壓大，表(biao)明主發電機輸出(chu)(chu)電壓升(sheng)高，則大的(de)(de)(de)(de)(de)UA就(jiu)會使(shi)脈沖(chong)(chong)寬度調制(zhi)(zhi)器(qi)輸出(chu)(chu)的(de)(de)(de)(de)(de)脈沖(chong)(chong)電壓UB的(de)(de)(de)(de)(de)寬度變(bian)窄。窄的(de)(de)(de)(de)(de)脈沖(chong)(chong)就(jiu)會使(shi)VT3導通(tong)時(shi)間短，通(tong)過的(de)(de)(de)(de)(de)電流(liu)小(xiao)。反之，主發電機輸出(chu)(chu)電壓降低(di)，UA變(bian)小(xiao)，則脈沖(chong)(chong)寬度調制(zhi)(zhi)器(qi)輸出(chu)(chu)UB的(de)(de)(de)(de)(de)寬度隨(sui)之變(bian)寬，從而使(shi)VT3導通(tong)時(shi)間變(bian)長(chang)，通(tong)過的(de)(de)(de)(de)(de)電流(liu)增多。

勵(li)(li)磁(ci)(ci)機(ji)(ji)的(de)定(ding)(ding)子(zi)(zi)(zi)線(xian)圈一(yi)端(duan)(duan)接在(zai)端(duan)(duan)子(zi)(zi)(zi)X1上(shang)，另(ling)一(yi)端(duan)(duan)接在(zai)XX1端(duan)(duan)子(zi)(zi)(zi)上(shang)。由主發電(dian)(dian)(dian)機(ji)(ji)電(dian)(dian)(dian)樞繞組(zu)取樣的(de)XA、XB、Xc三相電(dian)(dian)(dian)壓（一(yi)般為36～45V），經過(guo)三個(ge)二極管(guan)VD10、VD11、VD12整流(liu)后，其直流(liu)電(dian)(dian)(dian)流(liu)從X1端(duan)(duan)流(liu)入勵(li)(li)磁(ci)(ci)機(ji)(ji)的(de)定(ding)(ding)子(zi)(zi)(zi)線(xian)圈，由XX1流(liu)出(chu)，再經過(guo)調制管(guan)VT3和XN端(duan)(duan)子(zi)(zi)(zi)流(liu)回(hui)主發電(dian)(dian)(dian)機(ji)(ji)電(dian)(dian)(dian)樞繞組(zu)，形成一(yi)個(ge)勵(li)(li)磁(ci)(ci)機(ji)(ji)定(ding)(ding)子(zi)(zi)(zi)線(xian)圈的(de)勵(li)(li)磁(ci)(ci)電(dian)(dian)(dian)流(liu)通路(lu)。VT3是這(zhe)個(ge)通路(lu)上(shang)的(de)開關，它導通時(shi)(shi)間長，則定(ding)(ding)子(zi)(zi)(zi)線(xian)圈流(liu)過(guo)的(de)電(dian)(dian)(dian)流(liu)大，勵(li)(li)磁(ci)(ci)機(ji)(ji)定(ding)(ding)子(zi)(zi)(zi)磁(ci)(ci)場強度變(bian)大。VT3導通時(shi)(shi)間短，定(ding)(ding)子(zi)(zi)(zi)線(xian)圈電(dian)(dian)(dian)流(liu)少(shao)，定(ding)(ding)子(zi)(zi)(zi)磁(ci)(ci)場強度小。

AVR就是這(zhe)樣調(diao)控(kong)主發(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)的(de)電(dian)(dian)(dian)壓(ya)(ya)的(de)。主發(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)由于負荷原因(yin)輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)升高(gao)，電(dian)(dian)(dian)壓(ya)(ya)測量(liang)單(dan)元輸(shu)出(chu)(chu)(chu)的(de)UA隨著升高(gao)，受(shou)UA控(kong)制(zhi)的(de)脈寬調(diao)制(zhi)器輸(shu)出(chu)(chu)(chu)脈沖電(dian)(dian)(dian)壓(ya)(ya)UB寬度變(bian)(bian)窄，開關管VT3導通時間短，勵磁(ci)機(ji)(ji)(ji)(ji)定(ding)子(zi)繞組因(yin)電(dian)(dian)(dian)流(liu)少磁(ci)場(chang)減弱(ruo)，勵磁(ci)機(ji)(ji)(ji)(ji)轉(zhuan)(zhuan)(zhuan)子(zi)電(dian)(dian)(dian)樞電(dian)(dian)(dian)壓(ya)(ya)及旋(xuan)轉(zhuan)(zhuan)(zhuan)整(zheng)流(liu)器輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)流(liu)隨之(zhi)減小(xiao)，導致(zhi)供給主發(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)轉(zhuan)(zhuan)(zhuan)子(zi)繞組的(de)勵磁(ci)電(dian)(dian)(dian)流(liu)變(bian)(bian)小(xiao)，則主發(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)因(yin)其(qi)轉(zhuan)(zhuan)(zhuan)子(zi)磁(ci)場(chang)的(de)減小(xiao)而使輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)降低。反(fan)之(zhi)，AVR的(de)負反(fan)饋調(diao)控(kong)功能就會使主發(fa)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)的(de)輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)升高(gao)。

在(zai)主(zhu)發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)因負(fu)(fu)荷(he)超出(chu)(chu)額定(ding)(ding)值而輸(shu)(shu)(shu)出(chu)(chu)極(ji)大電(dian)(dian)流時，柴油發(fa)(fa)(fa)(fa)動機(ji)也需(xu)隨(sui)之輸(shu)(shu)(shu)出(chu)(chu)巨大的(de)動力導致其(qi)轉(zhuan)速低(di)(di)(di)(di)于額定(ding)(ding)值。低(di)(di)(di)(di)頻保(bao)護(hu)單元(yuan)(yuan)的(de)作(zuo)用(yong)就是在(zai)這(zhe)種(zhong)情況下(xia)限制(zhi)(zhi)勵磁機(ji)定(ding)(ding)子線圈里電(dian)(dian)流的(de)超額增大。它以電(dian)(dian)阻和(he)電(dian)(dian)容構(gou)成的(de)充放(fang)電(dian)(dian)支路預(yu)先(xian)設(she)定(ding)(ding)一個低(di)(di)(di)(di)頻保(bao)護(hu)點，當主(zhu)發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)負(fu)(fu)荷(he)正常時，從電(dian)(dian)壓測量單元(yuan)(yuan)來的(de)Uc小(xiao)于低(di)(di)(di)(di)頻保(bao)護(hu)點，則低(di)(di)(di)(di)頻保(bao)護(hu)單元(yuan)(yuan)輸(shu)(shu)(shu)出(chu)(chu)的(de)電(dian)(dian)壓UD高(gao)，二極(ji)管VD8被截止，UD到不了脈寬(kuan)調(diao)制(zhi)(zhi)器，起(qi)不了作(zuo)用(yong)。若主(zhu)發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)超載則UD變(bian)(bian)低(di)(di)(di)(di)，VD8導通(tong)，UD和(he)UA就可同時作(zuo)用(yong)于脈寬(kuan)調(diao)制(zhi)(zhi)器，使其(qi)輸(shu)(shu)(shu)出(chu)(chu)的(de)UB隨(sui)UD的(de)下(xia)降而變(bian)(bian)窄，調(diao)制(zhi)(zhi)管VT3導通(tong)時間隨(sui)之變(bian)(bian)短，勵磁電(dian)(dian)流減小(xiao)，勵磁機(ji)定(ding)(ding)子磁場(chang)變(bian)(bian)弱(ruo)。從而導致主(zhu)發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)轉(zhuan)子磁場(chang)減小(xiao)。發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)輸(shu)(shu)(shu)出(chu)(chu)電(dian)(dian)壓下(xia)降、電(dian)(dian)流減小(xiao)。低(di)(di)(di)(di)頻保(bao)護(hu)單元(yuan)(yuan)起(qi)到了保(bao)護(hu)勵磁機(ji)和(he)主(zhu)發(fa)(fa)(fa)(fa)電(dian)(dian)機(ji)的(de)作(zuo)用(yong)。

6 同步發(fa)電(dian)機(ji)常(chang)用技(ji)術參數

理解同步發電機(ji)的(de)(de)技術參數，對管好用(yong)好柴油發電機(ji)組是十分必要的(de)(de)。常用(yong)的(de)(de)參數有：

額定電(dian)壓(ya)(ya)UH 同步發(fa)電(dian)機正(zheng)常工作時，定子(zi)內(nei)的三相電(dian)樞(shu)繞組每(mei)組線端(duan)（每(mei)組的電(dian)壓(ya)(ya)輸(shu)出端(duan)）之間(jian)的線電(dian)壓(ya)(ya)。單(dan)位是V或kV.一(yi)般UH值(zhi)為400V（線電(dian)壓(ya)(ya)）或230V（相電(dian)壓(ya)(ya)）。

額定(ding)電流IH 帶額定(ding)負荷正常工作(zuo)時，流過定(ding)子(zi)繞組(zu)的(de)線電流，單位是A或者kA.

額(e)(e)定功率因(yin)數cos H 同步發電(dian)機帶額(e)(e)定負荷正常工作(zuo)時，其每相定子繞組內的(de)電(dian)壓(ya)與電(dian)流(liu)之間相角差 H的(de)余弦函數值(zhi)。一般這個值(zhi)是根據電(dian)力系統(tong)的(de)需要情況設計(ji)而定的(de)。通(tong)常為0.8（滯后(hou)）。

額(e)定(ding)(ding)(ding)容量SH 在(zai)額(e)定(ding)(ding)(ding)負(fu)荷及(ji)額(e)定(ding)(ding)(ding)功(gong)率(lv)(lv)(lv)因數情況下正(zheng)常運行時，同(tong)步(bu)發(fa)電(dian)(dian)機輸出的(de)視在(zai)功(gong)率(lv)(lv)(lv)。單位(wei)是(shi)(shi)kVA.有時也用有功(gong)功(gong)率(lv)(lv)(lv)PH表示，其單位(wei)為(wei)kW.兩(liang)者之間的(de)關系是(shi)(shi)PH=SHcos H.額(e)定(ding)(ding)(ding)容量是(shi)(shi)同(tong)步(bu)發(fa)電(dian)(dian)機的(de)重要(yao)參(can)數之一(yi)，它表明該機的(de)發(fa)電(dian)(dian)能力。

額定頻(pin)率(lv)fH 額定運行時，同(tong)步發電機輸出(chu)電壓每秒鐘內交變(bian)的次數。單位是Hz.我國(guo)制定的工(gong)業頻(pin)率(lv)為50Hz.

效率(lv) 同步發電機輸(shu)出的(de)有(you)(you)功(gong)(gong)(gong)功(gong)(gong)(gong)率(lv)與輸(shu)入(ru)的(de)有(you)(you)功(gong)(gong)(gong)功(gong)(gong)(gong)率(lv)（柴油發動機對它做的(de)有(you)(you)功(gong)(gong)(gong)功(gong)(gong)(gong)率(lv)）的(de)比(bi)值。它是表征同步發電機運(yun)行經濟性的(de)重要參數，越(yue)高越(yue)好。

文章編輯：CobiNet(寧波)，本公(gong)司(si)專注于(yu)電(dian)(dian)訊配件(jian),銅纜綜(zong)合布線(xian)系列領(ling)域(yu)產品研(yan)發生產超五類(lei)，六(liu)類(lei),七類(lei)屏蔽(bi)網(wang)線(xian)/屏蔽(bi)模塊及(ji)相關模塊配件(jian),歡迎(ying)來電(dian)(dian)咨(zi)詢0574 88168918,網(wang)址aliance.cn

我們是萬兆屏蔽模塊，10G屏蔽模塊，屏蔽線生產廠家。