變(bian)頻(pin)(pin)電(dian)(dian)源(yuan)(yuan)是將市電(dian)(dian)中的(de)(de)交(jiao)流電(dian)(dian)經過AC→DC→AC變(bian)換， 輸(shu)(shu)出為(wei)純(chun)凈(jing)的(de)(de)正弦(xian)波(bo)，輸(shu)(shu)出頻(pin)(pin)率(lv)(lv)和電(dian)(dian)壓(ya)(ya) 一定(ding)范圍內(nei)可調(diao)。它有別于(yu)用(yong)(yong)于(yu)電(dian)(dian)機調(diao)速用(yong)(yong)的(de)(de)變(bian)頻(pin)(pin)調(diao)速控制器(qi)(qi)(qi)，也有別于(yu)普通交(jiao)流穩壓(ya)(ya)電(dian)(dian)源(yuan)(yuan)。理想(xiang)的(de)(de)交(jiao)流電(dian)(dian)源(yuan)(yuan)的(de)(de)特點(dian)是頻(pin)(pin)率(lv)(lv)穩定(ding)、電(dian)(dian)壓(ya)(ya)穩定(ding)、內(nei)阻等于(yu)零(ling)、電(dian)(dian)壓(ya)(ya)波(bo)形為(wei)純(chun)正弦(xian)波(bo)(無失(shi)真)。變(bian)頻(pin)(pin)電(dian)(dian)源(yuan)(yuan)十分接近于(yu)理想(xiang)交(jiao)流電(dian)(dian)源(yuan)(yuan)，因此，先進(jin)發達國家越(yue)來(lai)越(yue)多(duo)地將變(bian)頻(pin)(pin)電(dian)(dian)源(yuan)(yuan)用(yong)(yong)作標準(zhun)供(gong)電(dian)(dian)電(dian)(dian)源(yuan)(yuan)，以(yi)便(bian)為(wei)用(yong)(yong)電(dian)(dian)器(qi)(qi)(qi)提供(gong)最(zui)優良(liang)的(de)(de)供(gong)電(dian)(dian)環境，便(bian)于(yu)客觀考(kao)核用(yong)(yong)電(dian)(dian)器(qi)(qi)(qi)的(de)(de)技術(shu)性(xing)能。 變(bian)頻(pin)(pin)電(dian)(dian)源(yuan)(yuan)主(zhu)要有二大(da)種類:線性(xing)放大(da)型(xing)和SPWM開關型(xing)。
