異步(bu)電(dian)機(ji)和同步(bu)電(dian)機(ji)的區別 異步(bu)電(dian)機(ji)和同步(bu)電(dian)機(ji)哪個(ge)好(hao)

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(gen)據電磁感應原理,轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)導(dao)體產(chan)(chan)生(sheng)感(gan)應電動(dong)勢并產(chan)(chan)生(sheng)感(gan)應電流(liu)。根據電磁(ci)力定(ding)律(lv)，載流(liu)的轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)導(dao)體在磁(ci)場(chang)中受到電磁(ci)力作用，形成電磁(ci)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)矩，驅動(dong)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)旋(xuan)(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)。異(yi)(yi)步電動(dong)機(ji)的轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)小于定(ding)子(zi)旋(xuan)(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)場(chang)的轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)，有個轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)差(cha)（轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)差(cha)與定(ding)子(zi)所(suo)產(chan)(chan)生(sheng)的旋(xuan)(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)場(chang)的轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)的比值叫轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)差(cha)率(lv)），從而叫做異(yi)(yi)步電動(dong)機(ji)。因其轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)繞組電流(liu)是感(gan)應產(chan)(chan)生(sheng)的，又稱(cheng)感(gan)應電動(dong)機(ji)。

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(tong)步轉速；

f——電源(yuan)頻率；

p——磁極對數。

由(you)上式可以(yi)看出，改變(bian)(bian)異步電(dian)動機的供電(dian)頻率(lv)就可以(yi)改變(bian)(bian)其同步轉(zhuan)速，從而(er)實現調(diao)速運(yun)行(xing)，即變(bian)(bian)頻調(diao)速。

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

特點:

優點：結構簡(jian)單，制(zhi)造方便，價格便宜，運(yun)行方便。

缺(que)點：功率因數滯后，輕載功率因數低，調速(su)性能(neng)稍差。

主要(yao)做電動(dong)機用，一般(ban)不做發電機。

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p、電源頻率(lv)f之間滿足n=60f/p。轉速n決定于(yu)電源頻率f，故電源頻率一定時，轉速不變，且(qie)與(yu)負載無關。具有運行(xing)穩定性高(gao)和過載能(neng)力大等特點。

過去(qu)的(de)電(dian)(dian)力(li)拖(tuo)動(dong)(dong)(dong)中，很少(shao)采用同(tong)(tong)步(bu)電(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)，同(tong)(tong)步(bu)電(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)主要作為(wei)(wei)發電(dian)(dian)機(ji)(ji)(ji)使(shi)用，其主要原因(yin)是同(tong)(tong)步(bu)電(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)不能在電(dian)(dian)網電(dian)(dian)壓下自行起動(dong)(dong)(dong)，靜止的(de)轉(zhuan)(zhuan)子磁極在旋轉(zhuan)(zhuan)磁場的(de)作用下，平(ping)均轉(zhuan)(zhuan)矩為(wei)(wei)零(ling)。但是近年來，隨著電(dian)(dian)力(li)電(dian)(dian)子技術的(de)發展，解決了同(tong)(tong)步(bu)電(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)起動(dong)(dong)(dong)和(he)調速的(de)問題，使(shi)同(tong)(tong)步(bu)電(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)在電(dian)(dian)力(li)拖(tuo)動(dong)(dong)(dong)中作為(wei)(wei)原動(dong)(dong)(dong)機(ji)(ji)(ji)出現。

同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)和(he)異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)的(de)(de)(de)(de)(de)區別在于(yu)：從供(gong)電(dian)(dian)(dian)方(fang)面(mian)說，異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)只(zhi)是(shi)(shi)在定(ding)子(zi)(zi)側(ce)加(jia)(jia)上電(dian)(dian)(dian)壓(ya)（也(ye)有(you)轉(zhuan)子(zi)(zi)上加(jia)(jia)電(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)(de)），而(er)同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)要在定(ding)子(zi)(zi)和(he)轉(zhuan)子(zi)(zi)上都(dou)加(jia)(jia)上電(dian)(dian)(dian)壓(ya)。也(ye)就(jiu)是(shi)(shi)說異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)是(shi)(shi)單邊勵磁(ci)，同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)是(shi)(shi)雙邊勵磁(ci)。同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)就(jiu)是(shi)(shi)靠勵磁(ci)電(dian)(dian)(dian)流運行的(de)(de)(de)(de)(de)，如果沒有(you)勵磁(ci)，電(dian)(dian)(dian)機(ji)就(jiu)是(shi)(shi)異步(bu)(bu)(bu)(bu)(bu)(bu)的(de)(de)(de)(de)(de)。從轉(zhuan)速(su)方(fang)面(mian)說，異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)的(de)(de)(de)(de)(de)轉(zhuan)速(su)只(zhi)與負荷大小有(you)關（當然(ran)有(you)一(yi)定(ding)的(de)(de)(de)(de)(de)范圍），而(er)同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)的(de)(de)(de)(de)(de)轉(zhuan)速(su)只(zhi)與定(ding)子(zi)(zi)供(gong)電(dian)(dian)(dian)的(de)(de)(de)(de)(de)頻率有(you)關。從結構(gou)上說，同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)與異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)轉(zhuan)子(zi)(zi)的(de)(de)(de)(de)(de)構(gou)造也(ye)不一(yi)樣(yang)。異步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)的(de)(de)(de)(de)(de)轉(zhuan)子(zi)(zi)是(shi)(shi)有(you)夕(xi)鋼(gang)片(pian)和(he)鋁條(tiao)（或夕(xi)鋼(gang)片(pian)和(he)線圈組成），而(er)同(tong)(tong)步(bu)(bu)(bu)(bu)(bu)(bu)電(dian)(dian)(dian)機(ji)一(yi)般由數塊磁(ci)鋼(gang)和(he)線圈組成（也(ye)有(you)隱(yin)極式(shi)的(de)(de)(de)(de)(de)不太一(yi)樣(yang)）。

結構

同(tong)步電(dian)(dian)(dian)(dian)機和異步電(dian)(dian)(dian)(dian)機的(de)定子繞(rao)組是相同(tong)的(de)，主要(yao)區別在于轉子的(de)結(jie)構。同(tong)步電(dian)(dian)(dian)(dian)機的(de)轉子上(shang)有直流勵磁繞(rao)組，所以需(xu)要(yao)外(wai)加勵磁電(dian)(dian)(dian)(dian)源，通過(guo)滑環引入電(dian)(dian)(dian)(dian)流；而(er)異步電(dian)(dian)(dian)(dian)機的(de)轉子是短路的(de)繞(rao)組，靠電(dian)(dian)(dian)(dian)磁感應(ying)產生電(dian)(dian)(dian)(dian)流。相比之下，同(tong)步電(dian)(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(yi)些大(da)的(de)工廠，異步電(dian)機應用(yong)較多時(shi)，可附加一(yi)臺同(tong)步電(dian)機做調相機用(yong)，用(yong)來調節工廠與電(dian)網接口處的(de)功(gong)率因數。但是，由于同(tong)步電(dian)機造價高，維護(hu)工作量大(da)，現在一(yi)般(ban)都采(cai)用(yong)電(dian)容補償功(gong)率因數。

另外，一些早期采(cai)用晶閘管(guan)的變頻器(qi)，由(you)于器(qi)件(jian)沒有自關斷能力(li)，需要依靠負載換流，這時需要用到同步電機(ji)。

同步電機效率較異步電機稍高，在2000KW以上的(de)電動機(ji)(ji)選型(xing)時，一般(ban)要考(kao)慮是否選用同步(bu)電機(ji)(ji)。但是，同步(bu)機(ji)(ji)因(yin)為有(you)勵磁繞(rao)組和(he)滑環，需要操作(zuo)工人(ren)有(you)較高的(de)水(shui)平(ping)來控制勵磁，另外，比(bi)起異(yi)步(bu)電機(ji)(ji)的(de)免維(wei)(wei)護來，維(wei)(wei)護工作(zuo)量較大；所以，現在2500KW以下的電動(dong)機(ji)，現在大多選擇異步(bu)電機(ji)。在功率(lv)較小(xiao)時(shi)，效(xiao)率(lv)的差別已(yi)經(jing)變(bian)得微不(bu)足道了。

在應用變頻器時

應用變(bian)(bian)頻器(qi)(qi)(qi)時(shi)，需要將(jiang)電(dian)機(ji)和(he)電(dian)網(wang)斷開，將(jiang)變(bian)(bian)頻器(qi)(qi)(qi)接(jie)入。接(jie)入變(bian)(bian)頻器(qi)(qi)(qi)后，電(dian)網(wang)側的(de)(de)功(gong)率與(yu)電(dian)機(ji)無關(guan)，只與(yu)變(bian)(bian)頻器(qi)(qi)(qi)有(you)關(guan)。因此，除非用戶原來已經有(you)同(tong)步電(dian)機(ji)，否則應該(gai)選用異步電(dian)機(ji)，因為變(bian)(bian)頻器(qi)(qi)(qi)和(he)電(dian)機(ji)的(de)(de)造價都(dou)便宜。當然，如果選用早期的(de)(de)負(fu)載換流(liu)型變(bian)(bian)頻器(qi)(qi)(qi)，則電(dian)機(ji)必(bi)須選用同(tong)步電(dian)機(ji)，這是變(bian)(bian)頻器(qi)(qi)(qi)對電(dian)機(ji)的(de)(de)要求。

簡單的說：同步和異步電機均屬交流動力電機,是(shi)靠50周交(jiao)流電網供電而(er)轉動.異(yi)步電機是定子送(song)入交(jiao)流(liu)電,產生旋轉磁(ci)場,而(er)(er)轉子受感應而(er)(er)產生磁場,這樣兩磁場作用,使得轉子跟著定子的旋(xuan)轉磁場而轉動.其中轉子(zi)比定子(zi)旋轉磁場慢,有個轉差,不同步所以稱為(wei)異步機.而(er)同步(bu)電機(ji)定子同異步(bu)電機(ji),其轉(zhuan)子(zi)是(shi)人為加入直流電形成不變(bian)磁場,這(zhe)樣(yang)轉(zhuan)子就跟著定子旋轉(zhuan)磁場一起轉(zhuan)而(er)同步,始稱同步(bu)電(dian)機.異步電(dian)機簡單,成本低(di).易于安(an)裝,使用和維護.所以(yi)受到廣泛使用.缺點效率(lv)低,功率因數低對(dui)電(dian)網不利.而同步電機(ji)效率高(gao)是容(rong)性負載(zai),可改(gai)善電網功率(lv)因(yin)數(shu).多(duo)用(yong)工礦大型沒備。