異(yi)(yi)步(bu)(bu)變(bian)頻(pin)調速(su)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)是由普(pu)通(tong)異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)派生(sheng)而(er)來(lai)，由于要(yao)適(shi)應(ying)變(bian)頻(pin)器(qi)輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)特性，電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)在(zai)轉(zhuan)(zhuan)(zhuan)子槽型，絕緣工藝，電(dian)(dian)(dian)(dian)(dian)磁(ci)設計校(xiao)核等作了(le)(le)很大的(de)(de)(de)改動(dong)，特別是電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)通(tong)風散熱，它(ta)在(zai)一般情(qing)況下(xia)附加了(le)(le)一個獨立式強迫冷卻風機(ji)(ji)(ji)，以適(shi)應(ying)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)在(zai)低速(su)運行時的(de)(de)(de)高(gao)效(xiao)散熱和(he)降低電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)在(zai)高(gao)速(su)運行時的(de)(de)(de)風摩耗。變(bian)頻(pin)器(qi)的(de)(de)(de)輸(shu)(shu)(shu)出一般顯示電(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)輸(shu)(shu)(shu)出頻(pin)率，轉(zhuan)(zhuan)(zhuan)速(su)輸(shu)(shu)(shu)出顯示為電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)極數和(he)電(dian)(dian)(dian)(dian)(dian)源輸(shu)(shu)(shu)出頻(pin)率的(de)(de)(de)計算值(zhi)，與異(yi)(yi)步(bu)(bu)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)實(shi)際轉(zhuan)(zhuan)(zhuan)速(su)有很大區別，使用(yong)一般異(yi)(yi)步(bu)(bu)變(bian)頻(pin)。

電(dian)動(dong)機(ji)(ji)(ji)時，由于異(yi)步(bu)電(dian)機(ji)(ji)(ji)的轉差率是(shi)由電(dian)機(ji)(ji)(ji)的制造工藝決(jue)定，故其離散性很大，并(bing)且負(fu)載(zai)的變化直接影響電(dian)機(ji)(ji)(ji)的轉速(su)(su)，要精確控制電(dian)機(ji)(ji)(ji)的轉速(su)(su)只能采用光電(dian)編碼器進行閉(bi)環控制，當單機(ji)(ji)(ji)控制時轉速(su)(su)的精度由編碼器的脈沖數決(jue)定，當多機(ji)(ji)(ji)控制時，多臺電(dian)機(ji)(ji)(ji)的轉速(su)(su)就無法嚴格同步(bu)。這是(shi)異(yi)步(bu)電(dian)機(ji)(ji)(ji)先天(tian)所決(jue)定的。

同步(bu)變頻(pin)(pin)(pin)調(diao)速(su)(su)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)轉子內鑲有永磁(ci)(ci)體(ti)，當電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)瞬間起動(dong)完畢后(hou)，電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)轉入正常運行(xing)，定子旋轉磁(ci)(ci)場帶動(dong)鑲有永磁(ci)(ci)體(ti)的(de)(de)(de)轉子進(jin)行(xing)同步(bu)運行(xing)，此時(shi)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)轉速(su)(su)根(gen)據(ju)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)極數和電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)輸入電(dian)(dian)(dian)(dian)(dian)(dian)源頻(pin)(pin)(pin)率形成(cheng)嚴(yan)格的(de)(de)(de)對應(ying)關(guan)(guan)系(xi)，轉速(su)(su)不受負載和其他(ta)因數影響。同樣(yang)同步(bu)變頻(pin)(pin)(pin)調(diao)速(su)(su)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)也附加(jia)了(le)一(yi)個獨立式強迫冷卻風機(ji)(ji)(ji)(ji)(ji)，以適(shi)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)在低速(su)(su)運行(xing)時(shi)的(de)(de)(de)高(gao)效(xiao)散熱(re)和降低電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)在高(gao)速(su)(su)運行(xing)時(shi)的(de)(de)(de)風摩耗。由于電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)轉速(su)(su)和電(dian)(dian)(dian)(dian)(dian)(dian)源頻(pin)(pin)(pin)率的(de)(de)(de)嚴(yan)格對應(ying)關(guan)(guan)系(xi)，使得(de)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)轉速(su)(su)精(jing)度主要(yao)就取(qu)決于變頻(pin)(pin)(pin)器(qi)輸出電(dian)(dian)(dian)(dian)(dian)(dian)源頻(pin)(pin)(pin)率的(de)(de)(de)精(jing)度，控(kong)制(zhi)系(xi)統簡單，對一(yi)臺變頻(pin)(pin)(pin)器(qi)控(kong)制(zhi)多臺電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)實現多臺電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)轉速(su)(su)一(yi)致，也不需要(yao)昂貴(gui)的(de)(de)(de)光學(xue)編碼(ma)器(qi)進(jin)行(xing)閉環控(kong)制(zhi)。