顧名思義，開關(guan)電源就是利用電子(zi)開關器(qi)件（如晶體管(guan)(guan)、場效應管(guan)(guan)、可(ke)控(kong)硅閘(zha)流管(guan)(guan)等(deng)），通(tong)過(guo)控(kong)制(zhi)電路，使(shi)電子(zi)開關器(qi)件不停地“接通(tong)”和“關斷”，讓電子(zi)開關器(qi)件對輸入電壓進行脈(mo)沖調制(zhi)，從而實現DC/AC、DC/DC電壓變換，以(yi)及輸出電壓可(ke)調和自(zi)動穩(wen)壓。

工(gong)作(zuo)模式
　　開關(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源一般有(you)三(san)種工(gong)(gong)作(zuo)模(mo)(mo)式(shi)(shi)(shi)(shi)：頻率、脈沖(chong)寬(kuan)度固定(ding)模(mo)(mo)式(shi)(shi)(shi)(shi)，頻率固定(ding)、脈沖(chong)寬(kuan)度可變(bian)模(mo)(mo)式(shi)(shi)(shi)(shi)，頻率、脈沖(chong)寬(kuan)度可變(bian)模(mo)(mo)式(shi)(shi)(shi)(shi)。前一種工(gong)(gong)作(zuo)模(mo)(mo)式(shi)(shi)(shi)(shi)多用于(yu)(yu)(yu)(yu)DC/AC逆變(bian)電(dian)(dian)(dian)(dian)(dian)源，或DC/DC電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)變(bian)換；后(hou)兩(liang)種工(gong)(gong)作(zuo)模(mo)(mo)式(shi)(shi)(shi)(shi)多用于(yu)(yu)(yu)(yu)開關(guan)(guan)穩(wen)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)源。另外，開關(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源輸出電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)也有(you)三(san)種工(gong)(gong)作(zuo)方式(shi)(shi)(shi)(shi)：直(zhi)接輸出電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)方式(shi)(shi)(shi)(shi)、平(ping)均值輸出電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)方式(shi)(shi)(shi)(shi)、幅值輸出電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)方式(shi)(shi)(shi)(shi)。同(tong)樣，前一種工(gong)(gong)作(zuo)方式(shi)(shi)(shi)(shi)多用于(yu)(yu)(yu)(yu)DC/AC逆變(bian)電(dian)(dian)(dian)(dian)(dian)源，或DC/DC電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)變(bian)換；后(hou)兩(liang)種工(gong)(gong)作(zuo)方式(shi)(shi)(shi)(shi)多用于(yu)(yu)(yu)(yu)開關(guan)(guan)穩(wen)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)源。
　　根據開(kai)關(guan)(guan)(guan)器(qi)件在(zai)電(dian)路(lu)中(zhong)連接的方式(shi)(shi)(shi)，開(kai)關(guan)(guan)(guan)電(dian)源(yuan)，大體上可(ke)分(fen)為：串聯式(shi)(shi)(shi)開(kai)關(guan)(guan)(guan)電(dian)源(yuan)、并聯式(shi)(shi)(shi)開(kai)關(guan)(guan)(guan)電(dian)源(yuan)、變壓(ya)(ya)器(qi)式(shi)(shi)(shi)開(kai)關(guan)(guan)(guan)電(dian)源(yuan)等(deng)三大類(lei)。其中(zhong)，變壓(ya)(ya)器(qi)式(shi)(shi)(shi)開(kai)關(guan)(guan)(guan)電(dian)源(yuan)（后面簡(jian)稱變壓(ya)(ya)器(qi)開(kai)關(guan)(guan)(guan)電(dian)源(yuan)）還(huan)可(ke)以(yi)進(jin)一步分(fen)成：推挽式(shi)(shi)(shi)、半(ban)橋式(shi)(shi)(shi)、全橋式(shi)(shi)(shi)等(deng)多種；根據變壓(ya)(ya)器(qi)的激勵和(he)輸出電(dian)壓(ya)(ya)的相位，又(you)可(ke)以(yi)分(fen)成：正激式(shi)(shi)(shi)、反激式(shi)(shi)(shi)、單激式(shi)(shi)(shi)和(he)雙(shuang)激式(shi)(shi)(shi)等(deng)多種；如果從用途上來分(fen)，還(huan)可(ke)以(yi)分(fen)成更多種類(lei)。
主要特點(dian)
　　1、體(ti)(ti)積(ji)小、重量輕：由于沒有(you)工頻變壓器，所以體(ti)(ti)積(ji)和(he)重量只有(you)線(xian)性電源的20～30%。
　　2、功(gong)耗(hao)小、效率高(gao)(gao)：功(gong)率晶體管(guan)工作在開關狀態，所以(yi)晶體管(guan)上的功(gong)耗(hao)小，轉 化效率高(gao)(gao)，一般為60～70%，而線性電電源只有30～40%。