直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)是(shi)(shi)(shi)指能(neng)(neng)(neng)(neng)將直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)轉(zhuan)(zhuan)(zhuan)(zhuan)換(huan)(huan)成(cheng)機(ji)(ji)(ji)械(xie)(xie)能(neng)(neng)(neng)(neng)（直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)(ji)(ji)）或(huo)將機(ji)(ji)(ji)械(xie)(xie)能(neng)(neng)(neng)(neng)轉(zhuan)(zhuan)(zhuan)(zhuan)換(huan)(huan)成(cheng)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)（直(zhi)(zhi)(zhi)流(liu)(liu)(liu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)）的(de)旋轉(zhuan)(zhuan)(zhuan)(zhuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)。它(ta)是(shi)(shi)(shi)能(neng)(neng)(neng)(neng)實現直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)和機(ji)(ji)(ji)械(xie)(xie)能(neng)(neng)(neng)(neng)互相轉(zhuan)(zhuan)(zhuan)(zhuan)換(huan)(huan)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)。當它(ta)作電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)(ji)(ji)運行(xing)時是(shi)(shi)(shi)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)(ji)(ji)，將電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)轉(zhuan)(zhuan)(zhuan)(zhuan)換(huan)(huan)為機(ji)(ji)(ji)械(xie)(xie)能(neng)(neng)(neng)(neng)；作發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)運行(xing)時是(shi)(shi)(shi)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)，將機(ji)(ji)(ji)械(xie)(xie)能(neng)(neng)(neng)(neng)轉(zhuan)(zhuan)(zhuan)(zhuan)換(huan)(huan)為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)(neng)(neng)(neng)。直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)結構(gou)(gou)應(ying)由定(ding)子(zi)和轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)兩大部分(fen)組(zu)成(cheng)。直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)運行(xing)時靜止不(bu)動的(de)部分(fen)稱為定(ding)子(zi)，定(ding)子(zi)的(de)主(zhu)要(yao)作用(yong)是(shi)(shi)(shi)產生(sheng)磁場，由機(ji)(ji)(ji)座、主(zhu)磁極、換(huan)(huan)向極、端蓋、軸承和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)刷裝置等組(zu)成(cheng)。直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)按照結構(gou)(gou)分(fen)為他勵(li)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)、并勵(li)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)、、串勵(li)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)、復勵(li)直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)；直(zhi)(zhi)(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)按照使用(yong)需求通常(chang)需要(yao)搭載減(jian)(jian)速(su)齒輪箱、行(xing)星齒輪箱、圓(yuan)柱齒輪箱、平行(xing)齒輪箱等，這種產品(pin)稱為直(zhi)(zhi)(zhi)流(liu)(liu)(liu)減(jian)(jian)速(su)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)；直(zhi)(zhi)(zhi)流(liu)(liu)(liu)減(jian)(jian)速(su)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)廣(guang)泛應(ying)用(yong)于(yu)機(ji)(ji)(ji)械(xie)(xie)設備(bei)(bei)產品(pin)、機(ji)(ji)(ji)器人、船(chuan)舶工業(ye)、通訊設備(bei)(bei)、汽車傳動等領域。

“交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)”是用于(yu)實現(xian)機(ji)(ji)(ji)(ji)(ji)械能和(he)交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)能相互轉換(huan)(huan)的(de)(de)(de)機(ji)(ji)(ji)(ji)(ji)械。由于(yu)交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)力系統(tong)的(de)(de)(de)巨大(da)發展，交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)已成為最常用的(de)(de)(de)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)。交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)與直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)相比(bi)，由于(yu)沒有(you)換(huan)(huan)向器（見直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)換(huan)(huan)向），因此結構(gou)簡(jian)單(dan)，制造(zao)方便，比(bi)較(jiao)牢(lao)固(gu)，容易做成高轉速、高電(dian)(dian)(dian)壓、大(da)電(dian)(dian)(dian)流(liu)(liu)(liu)、大(da)容量(liang)的(de)(de)(de)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)。交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)功率(lv)的(de)(de)(de)覆(fu)蓋(gai)范圍很(hen)大(da)，從幾(ji)瓦(wa)(wa)到幾(ji)十(shi)萬千瓦(wa)(wa)、甚至上百萬千瓦(wa)(wa)。交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)按(an)(an)其(qi)功能通(tong)常分(fen)為交(jiao)(jiao)流(liu)(liu)(liu)發電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)、交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)和(he)同步(bu)(bu)調相機(ji)(ji)(ji)(ji)(ji)幾(ji)大(da)類。由于(yu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)工作(zuo)狀(zhuang)態(tai)的(de)(de)(de)可逆性，同一臺電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)既可作(zuo)發電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)又(you)可作(zuo)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)。把(ba)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)分(fen)為發電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)與電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)并(bing)不很(hen)確切，只是有(you)些電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)主要作(zuo)發電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)運行，有(you)些電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)主要作(zuo)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)運行。交(jiao)(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)按(an)(an)品種分(fen)有(you)同步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)、異步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)兩大(da)類。同步(bu)(bu)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)轉子的(de)(de)(de)轉速ns與(yu)旋轉磁場的轉速(su)相同，稱為同步轉速(su)。ns與所接交流電的(de)頻(pin)率(lv)（f）、電機的磁極對數（P）之間有(you)嚴格的關(guan)系。