Xyoo 1895, German Overtone tsim lub ntiaj teb thawj zaugDC fais laum.Lub plhaub yog ua los ntawm cov hlau cam khwb cia thiab tuaj yeem laum 4 hli qhov ntawm cov phaj hlau.Tom qab ntawd, peb-theem fais fab zaus (50Hz) hluav taws xob xyaum tau tshwm sim, tab sis lub cev muaj zog ua tsis tau zoo tshaj 3000r / min.Xyoo 1914, cov cuab yeej hluav taws xob uas tau tsav los ntawm ib-theem series motors tau tshwm sim, thiab lub zog ceev tau mus txog ntau dua 10000r / min.Xyoo 1927, qhov nruab nrab zaus hluav taws xob cov cuab yeej nrog lub zog zaus ntawm 150 txog 200 Hz tau tshwm sim.Nws tsis tsuas yog muaj qhov zoo ntawm kev kub ceev ntawm ib-theem series lub cev muaj zog, tab sis kuj muaj qhov zoo ntawm qhov yooj yim thiab txhim khu kev qha peb-theem fais fab zaus lub cev muaj zog.Txawm li cas los xij, nws yuav tsum tau muab nrog cov zaus nruab nrab tam sim no., Kev siv yog txwv.