異步(bu)電機(ji)和(he)同步(bu)電機(ji)的區別 異步(bu)電機(ji)和(he)同步(bu)電機(ji)哪個好

異步電動機（asynchronous motor）

異步電動機是由定子側接入三相交流電源，定子繞組流過的三相對稱電流產生三相磁動勢（定子旋轉磁動勢）并產生旋轉磁場。該旋轉磁場與轉子導體有相對切割運動,根據電磁感應(ying)原理,轉(zhuan)(zhuan)(zhuan)(zhuan)子導體產生感應電(dian)動(dong)勢并產生感應電(dian)流。根(gen)據電(dian)磁(ci)(ci)力定(ding)(ding)律，載流的(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)子導體在磁(ci)(ci)場(chang)(chang)中受到電(dian)磁(ci)(ci)力作用，形成電(dian)磁(ci)(ci)轉(zhuan)(zhuan)(zhuan)(zhuan)矩(ju)，驅(qu)動(dong)轉(zhuan)(zhuan)(zhuan)(zhuan)子旋(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)。異步(bu)電(dian)動(dong)機的(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)小于(yu)定(ding)(ding)子旋(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)(ci)場(chang)(chang)的(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)，有個轉(zhuan)(zhuan)(zhuan)(zhuan)差(cha)(cha)(cha)（轉(zhuan)(zhuan)(zhuan)(zhuan)差(cha)(cha)(cha)與(yu)定(ding)(ding)子所產生的(de)(de)(de)(de)旋(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)(ci)場(chang)(chang)的(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)的(de)(de)(de)(de)比值叫轉(zhuan)(zhuan)(zhuan)(zhuan)差(cha)(cha)(cha)率(lv)），從而叫做(zuo)異步(bu)電(dian)動(dong)機。因(yin)其轉(zhuan)(zhuan)(zhuan)(zhuan)子繞組電(dian)流是感應產生的(de)(de)(de)(de)，又稱感應電(dian)動(dong)機。

異步電動機的同步轉速，即旋轉磁場的轉速為：n=60f/p

其中：

n——異步電動(dong)機的同步轉速；

f——電源頻率(lv)；

p——磁(ci)極對數。

由上(shang)式可以看出，改變(bian)異步(bu)電動(dong)機的供電頻率就(jiu)可以改變(bian)其同步(bu)轉速(su)，從而實現調(diao)速(su)運行，即變(bian)頻調(diao)速(su)。

異步電動機按照轉子結構分為兩種形式:有(you)鼠籠式（鼠籠式異步電機(ji)）、繞線式異步電動機(ji)。

特點:

優點：結構簡(jian)單，制造方便(bian)，價格便(bian)宜，運行方便(bian)。

缺點(dian)：功率因數(shu)(shu)滯后，輕載功率因數(shu)(shu)低，調速性能稍(shao)差。

主(zhu)要做電(dian)動機用，一(yi)般(ban)不做發(fa)電(dian)機。

同步電動機是由定子側送入三相交流電，不同的只是在轉子側同時通一個直流電流，產生相對定子方向不變的磁場，這個磁場旋轉的速度和由定子產生的旋轉磁場的速度是相等的，所以稱為同步電動機。其轉子轉速n與磁(ci)極對數p、電源(yuan)頻率f之(zhi)間(jian)滿足(zu)n=60f/p。轉速n決定于電(dian)源頻率(lv)f，故電源頻率一定時，轉速不變(bian)，且(qie)與(yu)負載無關。具(ju)有運行穩(wen)定性高和過載能力大等(deng)特點。

過去的電(dian)(dian)(dian)(dian)力(li)拖動(dong)(dong)(dong)中(zhong)，很少采用(yong)(yong)同步電(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機，同步電(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機主要(yao)作為(wei)(wei)發電(dian)(dian)(dian)(dian)機使用(yong)(yong)，其主要(yao)原因是(shi)同步電(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機不能在電(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)壓下(xia)自行起動(dong)(dong)(dong)，靜(jing)止(zhi)的轉子磁極在旋轉磁場(chang)的作用(yong)(yong)下(xia)，平均轉矩(ju)為(wei)(wei)零。但是(shi)近年(nian)來(lai)，隨(sui)著電(dian)(dian)(dian)(dian)力(li)電(dian)(dian)(dian)(dian)子技術的發展，解(jie)決了同步電(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機起動(dong)(dong)(dong)和調速的問題，使同步電(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機在電(dian)(dian)(dian)(dian)力(li)拖動(dong)(dong)(dong)中(zhong)作為(wei)(wei)原動(dong)(dong)(dong)機出現。

同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)和(he)(he)(he)(he)異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)區別在于：從(cong)供電(dian)(dian)(dian)方面(mian)說，異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)只(zhi)是(shi)(shi)在定(ding)(ding)子(zi)(zi)(zi)(zi)側加上(shang)(shang)電(dian)(dian)(dian)壓(ya)（也有轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)上(shang)(shang)加電(dian)(dian)(dian)壓(ya)的(de)），而同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)要在定(ding)(ding)子(zi)(zi)(zi)(zi)和(he)(he)(he)(he)轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)上(shang)(shang)都加上(shang)(shang)電(dian)(dian)(dian)壓(ya)。也就是(shi)(shi)說異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)是(shi)(shi)單邊(bian)勵磁(ci)，同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)是(shi)(shi)雙邊(bian)勵磁(ci)。同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)就是(shi)(shi)靠(kao)勵磁(ci)電(dian)(dian)(dian)流運行的(de)，如(ru)果(guo)沒有勵磁(ci)，電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)就是(shi)(shi)異(yi)(yi)步(bu)(bu)的(de)。從(cong)轉(zhuan)(zhuan)速(su)方面(mian)說，異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)轉(zhuan)(zhuan)速(su)只(zhi)與負荷大小有關（當(dang)然有一(yi)定(ding)(ding)的(de)范圍），而同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)轉(zhuan)(zhuan)速(su)只(zhi)與定(ding)(ding)子(zi)(zi)(zi)(zi)供電(dian)(dian)(dian)的(de)頻率有關。從(cong)結(jie)構上(shang)(shang)說，同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)與異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)的(de)構造也不一(yi)樣(yang)。異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)是(shi)(shi)有夕鋼片和(he)(he)(he)(he)鋁條(tiao)（或(huo)夕鋼片和(he)(he)(he)(he)線(xian)圈(quan)組成），而同(tong)步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)一(yi)般(ban)由數塊磁(ci)鋼和(he)(he)(he)(he)線(xian)圈(quan)組成（也有隱極(ji)式(shi)的(de)不太一(yi)樣(yang)）。

結構

同步(bu)電(dian)機(ji)和(he)異步(bu)電(dian)機(ji)的定(ding)子繞組(zu)是相(xiang)同的，主要(yao)區別在于轉(zhuan)(zhuan)子的結(jie)構(gou)。同步(bu)電(dian)機(ji)的轉(zhuan)(zhuan)子上有直流勵(li)磁繞組(zu)，所以需要(yao)外加勵(li)磁電(dian)源，通過滑環引入(ru)電(dian)流；而異步(bu)電(dian)機(ji)的轉(zhuan)(zhuan)子是短(duan)路的繞組(zu)，靠(kao)電(dian)磁感應產生電(dian)流。相(xiang)比之(zhi)下，同步(bu)電(dian)機(ji)較復(fu)雜，造價高。

用途

同步電機大多用在大型發電機的場合。而異步電機則幾乎全用在電動機場合。同步電機可以通過勵磁靈活調節輸入側的電壓和電流相位，即功率因數；異步電機的功率因數不可調，一般在0.75-0.85之間，因此在一(yi)些大的工(gong)(gong)廠，異步電(dian)(dian)(dian)機(ji)(ji)應用(yong)較多時(shi)，可附加一(yi)臺(tai)同步電(dian)(dian)(dian)機(ji)(ji)做調相機(ji)(ji)用(yong)，用(yong)來調節工(gong)(gong)廠與電(dian)(dian)(dian)網接口處的功率因數。但是，由于同步電(dian)(dian)(dian)機(ji)(ji)造價(jia)高，維護工(gong)(gong)作量大，現在一(yi)般(ban)都(dou)采用(yong)電(dian)(dian)(dian)容補(bu)償功率因數。

另外，一些早(zao)期采用晶閘管的(de)變頻(pin)器，由于器件沒(mei)有自關(guan)斷能力，需要依靠負載換流，這時需要用到(dao)同步電(dian)機。

同步電機效率較異步電機稍高，在2000KW以(yi)上的電(dian)動(dong)機(ji)選型時，一般(ban)要考慮是(shi)否選用同步電(dian)機(ji)。但(dan)是(shi)，同步機(ji)因為有勵磁繞組和滑環，需要操作工人有較高(gao)的水平來控制勵磁，另(ling)外(wai)，比(bi)起異步電(dian)機(ji)的免維(wei)護來，維(wei)護工作量較大；所以(yi)，現(xian)在2500KW以下的電動機，現在大多選(xuan)擇異步電機。在功(gong)率較(jiao)小(xiao)時(shi)，效率的差別已經變得微(wei)不足道了。

在應用變頻器時

應用(yong)(yong)變頻器(qi)時，需(xu)要將電(dian)(dian)機(ji)(ji)和(he)電(dian)(dian)網斷開，將變頻器(qi)接(jie)入。接(jie)入變頻器(qi)后，電(dian)(dian)網側的(de)功率與電(dian)(dian)機(ji)(ji)無關，只與變頻器(qi)有關。因此，除非用(yong)(yong)戶原來已(yi)經有同步電(dian)(dian)機(ji)(ji)，否則應該(gai)選用(yong)(yong)異步電(dian)(dian)機(ji)(ji)，因為變頻器(qi)和(he)電(dian)(dian)機(ji)(ji)的(de)造(zao)價都便宜。當然，如果選用(yong)(yong)早期(qi)的(de)負載換流型變頻器(qi)，則電(dian)(dian)機(ji)(ji)必須選用(yong)(yong)同步電(dian)(dian)機(ji)(ji)，這是變頻器(qi)對電(dian)(dian)機(ji)(ji)的(de)要求。

簡單的說：同步和異步電機均屬交流動力電機,是靠50周交流(liu)電(dian)網供電(dian)而轉動.異步(bu)電機是(shi)定子送入(ru)交(jiao)流電,產生旋轉(zhuan)磁場(chang),而轉子受感(gan)應而產生磁場,這(zhe)樣兩磁場(chang)作用,使得轉(zhuan)(zhuan)(zhuan)子(zi)跟著定子(zi)的旋轉(zhuan)(zhuan)(zhuan)磁(ci)場而轉(zhuan)(zhuan)(zhuan)動(dong).其(qi)中轉子(zi)比定子(zi)旋轉磁場(chang)慢(man),有個轉差(cha),不同步(bu)所以稱為異步(bu)機.而同步電(dian)(dian)機定(ding)子(zi)同異(yi)步電(dian)(dian)機,其轉子是(shi)人(ren)為加(jia)入直流電形(xing)成不變磁場(chang),這樣轉子(zi)就跟著(zhu)定子(zi)旋轉磁場一起轉而(er)同步(bu),始稱同步電(dian)機.異步電(dian)機簡單,成(cheng)本低.易于(yu)安裝,使用和維護.所以受到(dao)廣泛(fan)使用.缺點效(xiao)率(lv)低,功率因數低(di)對電網不(bu)利.而同步(bu)電機效率高是容(rong)性負(fu)載(zai),可(ke)改(gai)善電網功(gong)率(lv)因數.多用工礦大(da)型沒備。