三相(xiang)(xiang)異(yi)步(bu)電(dian)(dian)(dian)機(ji)(Triple-phase asynchronous motor)是(shi)靠同(tong)時接入380V三相(xiang)(xiang)交流電(dian)(dian)(dian)源(相(xiang)(xiang)位差(cha)120度(du))供電(dian)(dian)(dian)的(de)(de)一類電(dian)(dian)(dian)動機(ji),由(you)于三相(xiang)(xiang)異(yi)步(bu)電(dian)(dian)(dian)機(ji)的(de)(de)轉(zhuan)(zhuan)子與定子旋(xuan)轉(zhuan)(zhuan)磁場以相(xiang)(xiang)同(tong)的(de)(de)方向、不(bu)同(tong)的(de)(de)轉(zhuan)(zhuan)速成(cheng)旋(xuan)轉(zhuan)(zhuan),存在(zai)轉(zhuan)(zhuan)差(cha)率,所以叫三相(xiang)(xiang)異(yi)步(bu)電(dian)(dian)(dian)機(ji)。
當電(dian)(dian)動機(ji)的三(san)相定(ding)子繞組(zu) 通(tong)入三(san)相對稱交流(liu)(liu)電(dian)(dian)后,將產(chan)生(sheng)一個旋(xuan)(xuan)轉(zhuan)(zhuan)磁(ci)(ci)場,該旋(xuan)(xuan)轉(zhuan)(zhuan)磁(ci)(ci)場切(qie)割轉(zhuan)(zhuan)子繞組(zu),從而在轉(zhuan)(zhuan)子繞組(zu)中產(chan)生(sheng)感應(ying)電(dian)(dian)流(liu)(liu)(轉(zhuan)(zhuan)子繞組(zu)是(shi)閉合通(tong)路),載流(liu)(liu)的轉(zhuan)(zhuan)子導體在定(ding)子旋(xuan)(xuan)轉(zhuan)(zhuan)磁(ci)(ci)場作(zuo)用下將產(chan)生(sheng)電(dian)(dian)磁(ci)(ci)力(li),從而在電(dian)(dian)機(ji)轉(zhuan)(zhuan)軸上形(xing)成電(dian)(dian)磁(ci)(ci)轉(zhuan)(zhuan)矩,驅動電(dian)(dian)動機(ji)旋(xuan)(xuan)轉(zhuan)(zhuan),并且(qie)電(dian)(dian)機(ji)旋(xuan)(xuan)轉(zhuan)(zhuan)方向與旋(xuan)(xuan)轉(zhuan)(zhuan)磁(ci)(ci)場方向相同(tong).
當導體(ti)在磁(ci)(ci)場(chang)內(nei)(nei)切割磁(ci)(ci)力線時,在導體(ti)內(nei)(nei)產生(sheng)感(gan)(gan)應電(dian)流,"感(gan)(gan)應電(dian)機"的名稱由此而來。感(gan)(gan)應電(dian)流和磁(ci)(ci)場(chang)的聯合作(zuo)用向電(dian)機轉子(zi)施(shi)加驅動力。
我們讓閉(bi)合線圈ABCD在(zai)磁(ci)場B內圍繞軸xy旋轉。如果(guo)沿順時針方向轉動(dong)(dong)磁(ci)場,閉(bi)合線圈經(jing)受(shou)可變(bian)磁(ci)通量,產生(sheng)感(gan)(gan)應(ying)(ying)電(dian)動(dong)(dong)勢,該電(dian)動(dong)(dong)勢會(hui)產生(sheng)感(gan)(gan)應(ying)(ying)電(dian)流(liu)(法拉(la)第定律)。根據楞次定律,電(dian)流(liu)的方向為:感(gan)(gan)應(ying)(ying)電(dian)流(liu)產生(sheng)的效果(guo)總是(shi)要阻礙(ai)引起感(gan)(gan)應(ying)(ying)電(dian)流(liu)的原因(yin)。因(yin)此,每(mei)個導體(ti)承受(shou)相對(dui)于感(gan)(gan)應(ying)(ying)磁(ci)場的運動(dong)(dong)方向相反的洛侖茲(zi)力F。
確定(ding)每個導(dao)體力(li)F方(fang)(fang)向(xiang)(xiang)的(de)一(yi)個簡單的(de)方(fang)(fang)法(fa)是采用右手三手指(zhi)定(ding)則(磁場對(dui)電(dian)流作(zuo)用將(jiang)拇指(zhi)置(zhi)于感(gan)(gan)應(ying)(ying)磁場的(de)方(fang)(fang)向(xiang)(xiang),食指(zhi)為力(li)的(de)方(fang)(fang)向(xiang)(xiang)。將(jiang)中指(zhi)置(zhi)于感(gan)(gan)應(ying)(ying)電(dian)流的(de)方(fang)(fang)向(xiang)(xiang)。這(zhe)樣一(yi)來,閉合線圈承受一(yi)定(ding)的(de)轉(zhuan)矩,從而(er)沿與(yu)感(gan)(gan)應(ying)(ying)子磁場相(xiang)同方(fang)(fang)向(xiang)(xiang)旋轉(zhuan),該磁場稱(cheng)為旋轉(zhuan)磁場。閉合線圈旋轉(zhuan)所產生的(de)電(dian)動(dong)轉(zhuan)矩平衡了負載轉(zhuan)矩。