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。

 

 

chuleshangwenzhongtijidezaoshengchanshengyuanyinzhiwai，kaiguandianyuanshipeiqiyeshiyigefeichangmingandeqijian，youdianwangqinrudewaibuzaoshengchuandidaoneibudianzidianluguochengzhongyehuichanshengganrao。suoyizaishejiyikuankaiguandianyuanzhichujiuyinggaikaolvdaodianciganrao。