換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)是(shi)起整(zheng)流(liu)(liu)作(zuo)用，其(qi)作(zuo)用是(shi)使(shi)電(dian)(dian)(dian)(dian)樞繞組(zu)(zu)(zu)中的(de)電(dian)(dian)(dian)(dian)流(liu)(liu)方(fang)(fang)向(xiang)(xiang)(xiang)是(shi)交變(bian)的(de)，以(yi)保證電(dian)(dian)(dian)(dian)磁(ci)(ci)轉(zhuan)(zhuan)矩方(fang)(fang)向(xiang)(xiang)(xiang)始終不(bu)(bu)變(bian).在發(fa)電(dian)(dian)(dian)(dian)機(ji)中，換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)能(neng)使(shi)元件中的(de)交變(bian)電(dian)(dian)(dian)(dian)勢變(bian)為電(dian)(dian)(dian)(dian)刷(shua)(shua)間直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)勢。當(dang)線圈(quan)(quan)通(tong)(tong)過(guo)電(dian)(dian)(dian)(dian)流(liu)(liu)后，會(hui)(hui)在永磁(ci)(ci)鐵的(de)作(zuo)用下(xia)，通(tong)(tong)過(guo)吸引(yin)和(he)排斥力轉(zhuan)(zhuan)動(dong)(dong)，當(dang)它(ta)轉(zhuan)(zhuan)到(dao)和(he)磁(ci)(ci)鐵平(ping)衡(heng)時，原(yuan)來通(tong)(tong)著電(dian)(dian)(dian)(dian)的(de)線較(jiao)對(dui)應(ying)(ying)換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)上的(de)觸片(pian)(pian)就(jiu)(jiu)與電(dian)(dian)(dian)(dian)刷(shua)(shua)分(fen)離(li)開，而電(dian)(dian)(dian)(dian)刷(shua)(shua)連(lian)接到(dao)符合產(chan)生推(tui)動(dong)(dong)力的(de)那(nei)組(zu)(zu)(zu)線圈(quan)(quan)對(dui)應(ying)(ying)的(de)觸片(pian)(pian)上，這(zhe)(zhe)樣不(bu)(bu)停的(de)重(zhong)復下(xia)去(qu)，直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)就(jiu)(jiu)轉(zhuan)(zhuan)起來了。如(ru)果(guo)(guo)沒有換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)的(de)作(zuo)用，那(nei)電(dian)(dian)(dian)(dian)機(ji)只能(neng)轉(zhuan)(zhuan)不(bu)(bu)到(dao)半圈(quan)(quan)就(jiu)(jiu)會(hui)(hui)卡(ka)死。如(ru)果(guo)(guo)不(bu)(bu)安裝換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)，那(nei)么就(jiu)(jiu)無法(fa)換(huan)(huan)向(xiang)(xiang)(xiang)，那(nei)么電(dian)(dian)(dian)(dian)流(liu)(liu)一(yi)直(zhi)是(shi)通(tong)(tong)過(guo)一(yi)個繞組(zu)(zu)(zu)流(liu)(liu)過(guo)，而繞組(zu)(zu)(zu)到(dao)達(da)過(guo)零點位(wei)置（就(jiu)(jiu)是(shi)磁(ci)(ci)場的(de)位(wei)置）后就(jiu)(jiu)不(bu)(bu)會(hui)(hui)再轉(zhuan)(zhuan)下(xia)去(qu)，根本(ben)無法(fa)轉(zhuan)(zhuan)動(dong)(dong)。這(zhe)(zhe)個時候一(yi)直(zhi)通(tong)(tong)電(dian)(dian)(dian)(dian)，由(you)(you)于電(dian)(dian)(dian)(dian)阻很小，就(jiu)(jiu)會(hui)(hui)燒(shao)毀轉(zhuan)(zhuan)子。換(huan)(huan)向(xiang)(xiang)(xiang)器(qi)(qi)的(de)每一(yi)組(zu)(zu)(zu)繞組(zu)(zu)(zu)至少有1對(dui)接觸片(pian)(pian)，如(ru)果(guo)(guo)是(shi)多(duo)繞組(zu)(zu)(zu)電(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)可能(neng)多(duo)個繞組(zu)(zu)(zu)公用一(yi)個接觸片(pian)(pian)也是(shi)可以(yi)的(de)。由(you)(you)于轉(zhuan)(zhuan)子不(bu)(bu)斷(duan)(duan)(duan)運動(dong)(dong)而碳(tan)(tan)刷(shua)(shua)不(bu)(bu)動(dong)(dong)，這(zhe)(zhe)樣當(dang)轉(zhuan)(zhuan)子的(de)某一(yi)組(zu)(zu)(zu)線圈(quan)(quan)現在和(he)碳(tan)(tan)刷(shua)(shua)連(lian)接形(xing)成回路，由(you)(you)于通(tong)(tong)電(dian)(dian)(dian)(dian)導體周圍存在磁(ci)(ci)場，那(nei)么就(jiu)(jiu)會(hui)(hui)繼續轉(zhuan)(zhuan)動(dong)(dong)，轉(zhuan)(zhuan)動(dong)(dong)后這(zhe)(zhe)一(yi)組(zu)(zu)(zu)就(jiu)(jiu)會(hui)(hui)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)，然(ran)后下(xia)一(yi)組(zu)(zu)(zu)就(jiu)(jiu)會(hui)(hui)通(tong)(tong)電(dian)(dian)(dian)(dian)，這(zhe)(zhe)樣不(bu)(bu)斷(duan)(duan)(duan)下(xia)去(qu)就(jiu)(jiu)可維持運轉(zhuan)(zhuan)。