小xiao功gong率lv的de開kai關guan電dian源yuan適shi配pei器qi在zai進jin行xing傳chuan導dao幹gan擾rao測ce試shi時shi，由you於yu本ben身shen的de功gong率lv比bi較jiao小xiao，所suo接jie收shou到dao的de輻fu射she信xin號hao強qiang度du也ye比bi大da功gong率lv的de適shi配pei器qi弱ruo很hen多duo，因yin此ci在zai測ce試shi的de過guo程cheng中zhong工gong程cheng師shi需xu要yao全quan麵mian參can考kao傳chuan導dao幹gan擾rao的de幅fu值zhi大da小xiao
，在zai設she計ji時shi就jiu需xu要yao充chong分fen考kao慮lv到dao電dian磁ci幹gan擾rao所suo產chan生sheng的de影ying響xiang。下xia麵mian我wo們men將jiang會hui通tong過guo對dui小xiao功gong率lv電dian源yuan適shi配pei器qi通tong用yong機ji理li的de分fen析xi，進jin一yi步bu解jie釋shi電dian磁ci幹gan擾rao和he噪zao聲sheng的de產chan生sheng原yuan因yin。

 

目前我國所生產的小功率開關電源，其運行的基本原理按電路結構不同，可以細分為串並聯式和直流變換式，相關的框圖如下圖所示。

圖為開關電源適配器的原理框圖

 

由you上shang圖tu可ke以yi看kan出chu，市shi電dian經jing過guo一yi次ci整zheng流liu濾lv波bo後hou將jiang會hui變bian成cheng直zhi流liu電dian壓ya，並bing通tong過guo電dian路lu係xi統tong輸shu送song到dao開kai關guan逆ni變bian電dian路lu。逆ni變bian電dian路lu將jiang直zhi流liu變bian成cheng幾ji百bai赫he茲zi到dao幾ji千qian赫he茲zi的de高gao頻pin矩ju形xing波bo，高gao頻pin矩ju形xing波bo通tong過guo高gao頻pin變bian壓ya器qi耦ou合he到dao二er次ci線xian圈quan以yi得de到dao小xiao電dian壓ya交jiao流liu電dian， 此(ci)交(jiao)流(liu)電(dian)經(jing)過(guo)二(er)次(ci)整(zheng)流(liu)濾(lv)波(bo)後(hou)輸(shu)出(chu)以(yi)驅(qu)動(dong)負(fu)載(zai)。同(tong)時(shi)，該(gai)輸(shu)出(chu)經(jing)過(guo)誤(wu)差(cha)放(fang)大(da)電(dian)路(lu)采(cai)樣(yang)取(qu)得(de)的(de)輸(shu)出(chu)電(dian)壓(ya)值(zhi)又(you)回(hui)饋(kui)給(gei)脈(mai)衝(chong)控(kong)製(zhi)電(dian)路(lu)。脈(mai)衝(chong)控(kong)製(zhi)電(dian)路(lu)將(jiang)回(hui)饋(kui)的(de)電(dian)壓(ya)值(zhi)與(yu)基(ji)準(zhun)電(dian)壓(ya)值(zhi)比(bi)對(dui)後(hou)得(de)出(chu)一(yi)個(ge)脈(mai)衝(chong)占(zhan)空(kong)比(bi)的(de)相(xiang)應(ying)改(gai)變(bian)動(dong)作(zuo)
，在(zai)開(kai)關(guan)動(dong)作(zuo)過(guo)程(cheng)中(zhong)會(hui)產(chan)生(sheng)很(hen)強(qiang)的(de)噪(zao)聲(sheng)
，它(ta)們(men)通(tong)過(guo)電(dian)源(yuan)線(xian)以(yi)共(gong)模(mo)或(huo)者(zhe)差(cha)模(mo)方(fang)式(shi)向(xiang)外(wai)傳(chuan)導(dao)。這(zhe)也(ye)是(shi)目(mu)前(qian)大(da)部(bu)分(fen)小(xiao)型(xing)電(dian)源(yuan)適(shi)配(pei)器(qi)出(chu)現(xian)噪(zao)聲(sheng)問(wen)題(ti)的(de)最(zui)大(da)原(yuan)因(yin)所(suo)在(zai)。

 

 

除chu了le上shang文wen中zhong提ti及ji的de噪zao聲sheng產chan生sheng原yuan因yin之zhi外wai，開kai關guan電dian源yuan適shi配pei器qi也ye是shi一yi個ge非fei常chang敏min感gan的de器qi件jian，由you電dian網wang侵qin入ru的de外wai部bu噪zao聲sheng傳chuan遞di到dao內nei部bu電dian子zi電dian路lu過guo程cheng中zhong也ye會hui產chan生sheng幹gan擾rao。所suo以yi在zai設she計ji一yi款kuan開kai關guan電dian源yuan之zhi初chu就jiu應ying該gai考kao慮lv到dao電dian磁ci幹gan擾rao。