異步電機和(he)同步電機的區別(bie) 異步電機和(he)同步電機哪個(ge)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)子導體產(chan)生感(gan)應電(dian)(dian)動(dong)(dong)(dong)(dong)勢(shi)并產(chan)生感(gan)應電(dian)(dian)流。根據電(dian)(dian)磁(ci)力定律，載流的(de)(de)(de)轉(zhuan)子導體在磁(ci)場中受到電(dian)(dian)磁(ci)力作用，形成電(dian)(dian)磁(ci)轉(zhuan)矩，驅動(dong)(dong)(dong)(dong)轉(zhuan)子旋轉(zhuan)。異(yi)步(bu)電(dian)(dian)動(dong)(dong)(dong)(dong)機的(de)(de)(de)轉(zhuan)速小于定子旋轉(zhuan)磁(ci)場的(de)(de)(de)轉(zhuan)速，有個轉(zhuan)差(cha)（轉(zhuan)差(cha)與定子所產(chan)生的(de)(de)(de)旋轉(zhuan)磁(ci)場的(de)(de)(de)轉(zhuan)速的(de)(de)(de)比值叫轉(zhuan)差(cha)率），從而叫做異(yi)步(bu)電(dian)(dian)動(dong)(dong)(dong)(dong)機。因其轉(zhuan)子繞(rao)組電(dian)(dian)流是感(gan)應產(chan)生的(de)(de)(de)，又稱感(gan)應電(dian)(dian)動(dong)(dong)(dong)(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——異步電動機的同步轉速；

f——電源頻率(lv)；

p——磁極對數。

由上(shang)式可以看出，改(gai)變(bian)異(yi)步電(dian)動機(ji)的(de)供電(dian)頻率(lv)就可以改(gai)變(bian)其(qi)同步轉速，從而(er)實現調速運(yun)行，即(ji)變(bian)頻調速。

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

特點:

優點：結(jie)構簡單，制造方便(bian)(bian)，價格便(bian)(bian)宜，運(yun)行方便(bian)(bian)。

缺(que)點：功率因(yin)數滯后(hou)，輕載(zai)功率因(yin)數低，調速性(xing)能稍差。

主要(yao)做電(dian)動(dong)機用，一般不做發電(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與磁極對數(shu)p、電(dian)源(yuan)頻率f之間(jian)滿足(zu)n=60f/p。轉(zhuan)速(su)n決(jue)定于電源頻(pin)率f，故電(dian)源頻率一定(ding)時，轉速不(bu)變，且(qie)與負載無關(guan)。具有運行穩定(ding)性高和過載能力大等特點(dian)。

過去的(de)(de)(de)電(dian)(dian)力拖動(dong)(dong)中(zhong)，很少(shao)采(cai)用同(tong)(tong)步(bu)(bu)電(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)，同(tong)(tong)步(bu)(bu)電(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)主要作(zuo)(zuo)為發(fa)電(dian)(dian)機(ji)(ji)(ji)使(shi)(shi)用，其主要原因(yin)是同(tong)(tong)步(bu)(bu)電(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)不能在(zai)電(dian)(dian)網電(dian)(dian)壓下(xia)自行(xing)起動(dong)(dong)，靜止(zhi)的(de)(de)(de)轉子(zi)磁極在(zai)旋轉磁場的(de)(de)(de)作(zuo)(zuo)用下(xia)，平均轉矩為零。但是近年來，隨(sui)著電(dian)(dian)力電(dian)(dian)子(zi)技(ji)術的(de)(de)(de)發(fa)展，解決了同(tong)(tong)步(bu)(bu)電(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)起動(dong)(dong)和調速(su)的(de)(de)(de)問題(ti)，使(shi)(shi)同(tong)(tong)步(bu)(bu)電(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)在(zai)電(dian)(dian)力拖動(dong)(dong)中(zhong)作(zuo)(zuo)為原動(dong)(dong)機(ji)(ji)(ji)出(chu)現(xian)。

同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)和(he)異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)區(qu)別在(zai)(zai)于：從供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)方(fang)面說(shuo)，異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)只(zhi)是(shi)在(zai)(zai)定(ding)子(zi)(zi)側加上(shang)(shang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓（也有轉子(zi)(zi)上(shang)(shang)加電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)），而(er)同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)要在(zai)(zai)定(ding)子(zi)(zi)和(he)轉子(zi)(zi)上(shang)(shang)都加上(shang)(shang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓。也就(jiu)是(shi)說(shuo)異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)是(shi)單(dan)邊勵(li)磁，同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)是(shi)雙邊勵(li)磁。同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)就(jiu)是(shi)靠勵(li)磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流運(yun)行的(de)，如果沒(mei)有勵(li)磁，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)就(jiu)是(shi)異步(bu)(bu)(bu)的(de)。從轉速(su)方(fang)面說(shuo)，異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)轉速(su)只(zhi)與負(fu)荷大小有關(guan)（當然有一(yi)定(ding)的(de)范圍），而(er)同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)轉速(su)只(zhi)與定(ding)子(zi)(zi)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)頻率(lv)有關(guan)。從結構(gou)(gou)上(shang)(shang)說(shuo)，同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)與異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)轉子(zi)(zi)的(de)構(gou)(gou)造(zao)也不一(yi)樣(yang)。異步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)轉子(zi)(zi)是(shi)有夕(xi)鋼片和(he)鋁條（或夕(xi)鋼片和(he)線(xian)圈組(zu)成），而(er)同(tong)步(bu)(bu)(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)一(yi)般由(you)數塊磁鋼和(he)線(xian)圈組(zu)成（也有隱極式的(de)不太一(yi)樣(yang)）。

結構

同(tong)步(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機和異步(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機的(de)定子(zi)(zi)繞(rao)組(zu)是相同(tong)的(de)，主要(yao)區別在(zai)于轉子(zi)(zi)的(de)結(jie)構(gou)。同(tong)步(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機的(de)轉子(zi)(zi)上有直流(liu)勵磁繞(rao)組(zu)，所以需要(yao)外加(jia)勵磁電(dian)(dian)(dian)源，通過(guo)滑環引入電(dian)(dian)(dian)流(liu)；而(er)異步(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機的(de)轉子(zi)(zi)是短路的(de)繞(rao)組(zu)，靠電(dian)(dian)(dian)磁感應產生(sheng)電(dian)(dian)(dian)流(liu)。相比(bi)之下，同(tong)步(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機較(jiao)復雜，造價高(gao)。

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(zhi)間，因此在一些大的工(gong)廠(chang)，異步(bu)電(dian)(dian)機(ji)(ji)應用(yong)較多時，可附加一臺同步(bu)電(dian)(dian)機(ji)(ji)做調相機(ji)(ji)用(yong)，用(yong)來調節工(gong)廠(chang)與電(dian)(dian)網接口處的功率(lv)因數(shu)。但是，由于同步(bu)電(dian)(dian)機(ji)(ji)造價高(gao)，維(wei)護工(gong)作量大，現在一般都采用(yong)電(dian)(dian)容(rong)補償功率(lv)因數(shu)。

另外(wai)，一(yi)些(xie)早期采(cai)用晶閘管的(de)變頻器(qi)，由(you)于(yu)器(qi)件沒有自關斷(duan)能(neng)力，需要(yao)依靠(kao)負載(zai)換流，這時需要(yao)用到同步電機(ji)。

同步電機效率較異步電機稍高，在2000KW以(yi)(yi)上的電動機選型時，一(yi)般要(yao)(yao)考慮(lv)是否選用同步(bu)(bu)電機。但(dan)是，同步(bu)(bu)機因(yin)為(wei)有勵磁(ci)繞(rao)組(zu)和滑環(huan)，需(xu)要(yao)(yao)操作工人有較高(gao)的水平來(lai)控制勵磁(ci)，另外，比(bi)起異步(bu)(bu)電機的免(mian)維護(hu)來(lai)，維護(hu)工作量較大；所以(yi)(yi)，現在2500KW以下的電動機，現在大多選擇異步電機。在功率(lv)較小時(shi)，效(xiao)率(lv)的差別已經變得(de)微不(bu)足道了(le)。

在應用變頻器時

應用(yong)變頻(pin)(pin)(pin)(pin)器時，需要將(jiang)電(dian)(dian)機(ji)(ji)和(he)電(dian)(dian)網斷(duan)開，將(jiang)變頻(pin)(pin)(pin)(pin)器接(jie)入(ru)。接(jie)入(ru)變頻(pin)(pin)(pin)(pin)器后，電(dian)(dian)網側(ce)的功率與電(dian)(dian)機(ji)(ji)無(wu)關(guan)，只與變頻(pin)(pin)(pin)(pin)器有(you)關(guan)。因(yin)此，除非用(yong)戶原(yuan)來已經有(you)同(tong)步電(dian)(dian)機(ji)(ji)，否(fou)則應該選用(yong)異步電(dian)(dian)機(ji)(ji)，因(yin)為變頻(pin)(pin)(pin)(pin)器和(he)電(dian)(dian)機(ji)(ji)的造(zao)價都(dou)便宜。當然，如(ru)果選用(yong)早(zao)期的負載換(huan)流型變頻(pin)(pin)(pin)(pin)器，則電(dian)(dian)機(ji)(ji)必須(xu)選用(yong)同(tong)步電(dian)(dian)機(ji)(ji)，這是變頻(pin)(pin)(pin)(pin)器對電(dian)(dian)機(ji)(ji)的要求。

簡單的說：同步和異步電機均屬交流動力電機,是(shi)靠(kao)50周交流電網供電而轉動.異步(bu)電(dian)機是定子送入交(jiao)流(liu)電(dian),產生(sheng)旋轉磁場,而轉子(zi)受感應而產生磁(ci)場,這樣兩磁場作用,使得轉(zhuan)子(zi)跟著(zhu)定子(zi)的旋轉(zhuan)磁(ci)場而轉(zhuan)動(dong).其中轉子比定子旋轉磁(ci)場(chang)慢,有個轉差,不同步所以稱為異(yi)步機(ji).而同(tong)步電(dian)機定子(zi)同(tong)異(yi)步電(dian)機,其轉子是人為加入(ru)直流電形成不(bu)變磁場(chang),這樣轉(zhuan)子(zi)就跟著定(ding)子(zi)旋轉(zhuan)磁場(chang)一起轉(zhuan)而同步,始(shi)稱(cheng)同步電(dian)機.異步電(dian)機(ji)簡單,成(cheng)本低.易于安裝,使(shi)用和維護.所以受到廣泛使用(yong).缺點(dian)效率(lv)低,功(gong)率因數低對電網不利.而同步電機效(xiao)率高是容性負(fu)載,可改善電(dian)網功率(lv)因(yin)數.多用工礦大(da)型沒備(bei)。