軟ruan啟qi動dong器qi采cai用yong三san相xiang反fan並bing聯lian晶jing閘zha管guan作zuo為wei調tiao壓ya器qi,用yong這zhe種zhong電dian路lu如ru三san相xiang全quan控kong橋qiao式shi整zheng流liu電dian路lu,使shi用yong軟ruan啟qi動dong器qi啟qi動dong電dian動dong機ji時shi,晶jing閘zha管guan的de輸shu出chu電dian壓ya逐zhu漸jian增zeng加jia,電dian動機逐漸加速,直到晶閘管全導通,電動機工作在額定電壓的機械特性上,實現平滑啟動,降低啟動電流,避免啟動過流跳閘。將其接入電源和電動機定子之間。