顧(gu)名思(si)義，開關電源就是利用電子開關(guan)(guan)器件(jian)（如(ru)晶體管、場效應管、可(ke)控硅閘流管等），通過控制電路，使電子開關(guan)(guan)器件(jian)不停地“接通”和(he)“關(guan)(guan)斷”，讓電子開關(guan)(guan)器件(jian)對輸入電壓(ya)進(jin)行脈沖調(diao)制，從(cong)而實現DC/AC、DC/DC電壓(ya)變換，以(yi)及輸出電壓(ya)可(ke)調(diao)和(he)自動穩壓(ya)。

工(gong)作模式
　　開(kai)關(guan)電(dian)(dian)源(yuan)一般有三種工(gong)(gong)作模(mo)(mo)式：頻率(lv)、脈(mo)沖寬度(du)(du)固(gu)定模(mo)(mo)式，頻率(lv)固(gu)定、脈(mo)沖寬度(du)(du)可變(bian)模(mo)(mo)式，頻率(lv)、脈(mo)沖寬度(du)(du)可變(bian)模(mo)(mo)式。前一種工(gong)(gong)作模(mo)(mo)式多(duo)(duo)用(yong)于DC/AC逆變(bian)電(dian)(dian)源(yuan)，或DC/DC電(dian)(dian)壓(ya)變(bian)換；后(hou)兩(liang)種工(gong)(gong)作模(mo)(mo)式多(duo)(duo)用(yong)于開(kai)關(guan)穩壓(ya)電(dian)(dian)源(yuan)。另外，開(kai)關(guan)電(dian)(dian)源(yuan)輸(shu)出(chu)電(dian)(dian)壓(ya)也有三種工(gong)(gong)作方(fang)(fang)式：直接輸(shu)出(chu)電(dian)(dian)壓(ya)方(fang)(fang)式、平均值輸(shu)出(chu)電(dian)(dian)壓(ya)方(fang)(fang)式、幅值輸(shu)出(chu)電(dian)(dian)壓(ya)方(fang)(fang)式。同(tong)樣，前一種工(gong)(gong)作方(fang)(fang)式多(duo)(duo)用(yong)于DC/AC逆變(bian)電(dian)(dian)源(yuan)，或DC/DC電(dian)(dian)壓(ya)變(bian)換；后(hou)兩(liang)種工(gong)(gong)作方(fang)(fang)式多(duo)(duo)用(yong)于開(kai)關(guan)穩壓(ya)電(dian)(dian)源(yuan)。
　　根(gen)據開(kai)關(guan)(guan)器(qi)(qi)件在電(dian)(dian)路(lu)中連(lian)接的方式(shi)(shi)，開(kai)關(guan)(guan)電(dian)(dian)源(yuan)，大體上可分(fen)為：串(chuan)聯(lian)式(shi)(shi)開(kai)關(guan)(guan)電(dian)(dian)源(yuan)、并(bing)聯(lian)式(shi)(shi)開(kai)關(guan)(guan)電(dian)(dian)源(yuan)、變壓(ya)器(qi)(qi)式(shi)(shi)開(kai)關(guan)(guan)電(dian)(dian)源(yuan)等三大類。其中，變壓(ya)器(qi)(qi)式(shi)(shi)開(kai)關(guan)(guan)電(dian)(dian)源(yuan)（后(hou)面簡稱(cheng)變壓(ya)器(qi)(qi)開(kai)關(guan)(guan)電(dian)(dian)源(yuan)）還可以進一(yi)步分(fen)成：推挽式(shi)(shi)、半橋(qiao)式(shi)(shi)、全橋(qiao)式(shi)(shi)等多種(zhong)；根(gen)據變壓(ya)器(qi)(qi)的激(ji)勵和輸出電(dian)(dian)壓(ya)的相位，又可以分(fen)成：正激(ji)式(shi)(shi)、反激(ji)式(shi)(shi)、單激(ji)式(shi)(shi)和雙激(ji)式(shi)(shi)等多種(zhong)；如果從用途(tu)上來分(fen)，還可以分(fen)成更多種(zhong)類。
主(zhu)要特點
　　1、體積(ji)小、重(zhong)量輕：由(you)于沒有工(gong)頻變壓器，所以體積(ji)和重(zhong)量只(zhi)有線性(xing)電源的(de)20～30%。
　　2、功(gong)(gong)耗小、效率(lv)高：功(gong)(gong)率(lv)晶體管工作(zuo)在開關狀態(tai)，所(suo)以晶體管上的功(gong)(gong)耗小，轉(zhuan) 化效率(lv)高，一般為60～70%，而(er)線性電電源只有(you)30～40%。