音頻噪聲的可能來源多種多樣。噪聲可以是設計缺陷（如振蕩輸出電壓）導致，或者由電容或變壓器等噪聲元件導致。在有些情況下，您所聽到的尖銳刺耳的噪鳴或嘶嘶聲可能就像風扇在異常頻率下出現的搖蕩，或者由於電源靠近外部EMI源（熒光燈或電源插排）所導致。

本ben文wen將jiang探tan討tao反fan激ji式shi電dian源yuan中zhong最zui常chang見jian的de噪zao聲sheng來lai源yuan，並bing介jie紹shao可ke能neng的de解jie決jue方fang案an。下xia文wen中zhong描miao述shu的de所suo有you操cao作zuo程cheng序xu都dou可ke以yi使shi用yong一yi個ge可ke程cheng控kong交jiao流liu電dian源yuan供gong應ying器qi或huo自zi耦ou變bian壓ya器qi和he一yi個ge電dian子zi負fu載zai來lai完wan成cheng。請qing記ji住zhu，在zai有you些xie情qing況kuang下xia，您nin的de電dian源yuan所suo產chan生sheng的de噪zao聲sheng水shui平ping可ke能neng非fei常chang低di，如ru果guo該gai電dian源yuan將jiang在zai密mi閉bi殼ke體ti內nei使shi用yong
，那na麼me音yin頻pin噪zao聲sheng就jiu不bu會hui構gou成cheng問wen題ti。

可能的噪聲源

反fan激ji式shi電dian源yuan中zhong最zui常chang見jian的de噪zao聲sheng源yuan是shi噪zao聲sheng元yuan件jian。這zhe種zhong噪zao聲sheng通tong常chang由you陶tao瓷ci電dian容rong或huo鐵tie氧yang體ti變bian壓ya器qi磁ci芯xin產chan生sheng。陶tao瓷ci電dian容rong中zhong的de噪zao聲sheng通tong常chang由you逆ni向xiang壓ya電dian效xiao應ying造zao成cheng。對dui介jie質zhi結jie構gou施shi加jia電dian壓ya後hou，會hui引yin發fa機ji械xie應ying力li或huo應ying變bian，造zao成cheng材cai料liao變bian形xing。當dang這zhe種zhong材cai料liao發fa生sheng變bian形xing時shi
，會hui排pai出chu周zhou圍wei的de空kong氣qi，從cong而er產chan生sheng噪zao聲sheng。

由於在發生較大的電壓擺動時會出現逆向壓電效應，因此設計師可以重點查找出現較高dV/dt擺幅的陶瓷電容。在典型的電源中，這些電容包括緩衝電容、箝(qian)位(wei)電(dian)容(rong)以(yi)及(ji)陶(tao)瓷(ci)輸(shu)出(chu)電(dian)容(rong)要(yao)想(xiang)快(kuai)速(su)確(que)定(ding)一(yi)個(ge)陶(tao)瓷(ci)電(dian)容(rong)是(shi)否(fou)在(zai)產(chan)生(sheng)噪(zao)聲(sheng)
，請(qing)用(yong)一(yi)個(ge)具(ju)有(you)相(xiang)同(tong)電(dian)容(rong)值(zhi)和(he)適(shi)當(dang)電(dian)壓(ya)額(e)定(ding)值(zhi)的(de)金(jin)屬(shu)膜(mo)電(dian)容(rong)將(jiang)其(qi)替(ti)換(huan)。如(ru)果(guo)噪(zao)聲(sheng)水(shui)平(ping)下(xia)降(jiang)，說(shuo)明(ming)您(nin)找(zhao)到(dao)了(le)電(dian)路(lu)中(zhong)的(de)噪(zao)聲(sheng)源(yuan)。

如(ru)果(guo)噪(zao)聲(sheng)源(yuan)是(shi)箝(qian)位(wei)電(dian)容(rong)，可(ke)以(yi)用(yong)一(yi)個(ge)金(jin)屬(shu)膜(mo)電(dian)容(rong)將(jiang)其(qi)徹(che)底(di)替(ti)換(huan)，或(huo)者(zhe)嚐(chang)試(shi)使(shi)用(yong)介(jie)質(zhi)材(cai)料(liao)不(bu)同(tong)的(de)陶(tao)瓷(ci)電(dian)容(rong)。另(ling)一(yi)個(ge)方(fang)法(fa)是(shi)，更(geng)換(huan)正(zheng)在(zai)使(shi)用(yong)的(de)箝(qian)位(wei)電(dian)容(rong)，例(li)如(ru)，將(jiang)其(qi)更(geng)換(huan)為(wei)穩(wen)壓(ya)管(guan)箝(qian)位(wei)電(dian)路(lu)。如(ru)果(guo)噪(zao)聲(sheng)問(wen)題(ti)源(yuan)自(zi)緩(huan)衝(chong)電(dian)容(rong)，可(ke)以(yi)用(yong)一(yi)個(ge)金(jin)屬(shu)膜(mo)電(dian)容(rong)將(jiang)其(qi)替(ti)換(huan)
，也(ye)可(ke)以(yi)提(ti)高(gao)串(chuan)聯(lian)電(dian)阻(zu)的(de)值(zhi)，以(yi)降(jiang)低(di)電(dian)容(rong)上(shang)的(de)dV/dt噪聲。您也可以改用其它介質的陶瓷電容，看噪聲能否降低。

管理變壓器磁芯噪聲

lingyifangmian，bianyaqicixinchanshengdezaoshengtongchangyoucizhishensuozaocheng，taleisiyunixiangyadianxiaoying。dangshoudaocichangyingxiangshi
，xuduotiecicailiaodouhuigaibianxingzhuang。suizhebianyaqicixinzhongcichangdebianhua，cileicailiaohuishicixinfashengwulizhendong。dangzhendongpinlvdadaobianyaqidejixiegongzhenpinlvshi，zhendongjiuhuibeifangda
，bingzaochenggengdadeyinpinzaosheng。zaijiaoliudianqishebei（如使用60Hz外加磁場的變壓器）中，最大長度變化每周期出現兩次，從而產生熟悉的120Hz噪聲。

ruguonindeshejichuxianzhezhongwenti，zaikaishipaizhayuanyinzhiqianshouxianyaoquebaotabushiyoushejibudangyinqi。shouxian

，querensuotigongdeshurudianyaheshuchufuzaifuheshejiguige。ruguodianyuandegongzuodianyadiyuzhidingdezuidishurudianya，huogaoyuzhidingdeshuchufuzai
，namebufenjiaoliuzhouqijianghuishiquwenya，zheyanghuizaochengcixinzhongdecitongliangzengdabingchanshengzaosheng。

ruguoshurudianyahefuzaichuyuguigefanweizhinei

，jiexialaijianyanshurudarongliangdianrongdezhishifouzhengque。ruguoshurudianrongxiangduiyuyingyongeryanguoxiao，zhiliuzongxiandianyajiangzaijiaoliushuaxinzhouqizhijiandafujiangdi，zaochengbufenshurudejiaoliuzhouqishiquwenya。

變壓器中包含多種可活動元件
，如線圈、隔(ge)離(li)膠(jiao)帶(dai)和(he)骨(gu)架(jia)
，它(ta)們(men)使(shi)變(bian)壓(ya)器(qi)成(cheng)為(wei)了(le)常(chang)見(jian)的(de)噪(zao)聲(sheng)源(yuan)。線(xian)圈(quan)中(zhong)電(dian)流(liu)可(ke)產(chan)生(sheng)電(dian)磁(ci)場(chang)，電(dian)磁(ci)場(chang)會(hui)產(chan)生(sheng)令(ling)許(xu)多(duo)變(bian)壓(ya)器(qi)元(yuan)件(jian)出(chu)現(xian)機(ji)械(xie)振(zhen)動(dong)的(de)力(li)。減(jian)小(xiao)變(bian)壓(ya)器(qi)元(yuan)件(jian)物(wu)理(li)移(yi)動(dong)的(de)最(zui)有(you)效(xiao)方(fang)法(fa)是(shi)使(shi)用(yong)粘(zhan)合(he)材(cai)料(liao)或(huo)塗(tu)漆(qi)。例(li)如(ru)，用(yong)清(qing)漆(qi)浸(jin)漬(zi)磁(ci)芯(xin)是(shi)一(yi)種(zhong)廣(guang)泛(fan)使(shi)用(yong)的(de)方(fang)法(fa)，用(yong)來(lai)防(fang)止(zhi)磁(ci)芯(xin)隨(sui)骨(gu)架(jia)進(jin)行(xing)振(zhen)動(dong)。雖(sui)然(ran)供(gong)應(ying)商(shang)提(ti)供(gong)了(le)眾(zhong)多(duo)塗(tu)漆(qi)技(ji)術(shu)，但(dan)我(wo)們(men)推(tui)薦(jian)使(shi)用(yong)清(qing)漆(qi)浸(jin)漬(zi)技(ji)術(shu)，而(er)不(bu)是(shi)真(zhen)空(kong)浸(jin)漬(zi)
，這(zhe)是(shi)因(yin)為(wei)真(zhen)空(kong)浸(jin)漬(zi)會(hui)大(da)幅(fu)提(ti)高(gao)繞(rao)組(zu)電(dian)容(rong)，從(cong)而(er)降(jiang)低(di)效(xiao)率(lv)並(bing)使(shi)EMI增大。

如果您的設計需要使用長磁芯型變壓器
，則可以采用的另一個策略是使用標準磁芯長度。長磁芯產品（如EEL型變壓器和EERL型變壓器）都dou具ju有you極ji低di的de機ji械xie諧xie振zhen頻pin率lv。這zhe種zhong低di諧xie振zhen頻pin率lv容rong易yi增zeng大da音yin頻pin噪zao聲sheng。采cai用yong諧xie振zhen頻pin率lv較jiao高gao的de標biao準zhun磁ci芯xin長chang度du可ke以yi緩huan解jie該gai問wen題ti。但dan務wu必bi要yao注zhu意yi，如ru果guo改gai用yong較jiao短duan的de標biao準zhun磁ci芯xin，則ze必bi須xu使shi用yong更geng大da的de磁ci芯xin尺chi寸cun，才cai能neng提ti供gong足zu夠gou的de繞rao組zu窗chuang口kou麵mian積ji。


ruguozaoshengwenticunzaiyutaocishuchudianrong，keyichangshixuduobutongdecelvelaijiejue。qizhongyigefangfashi
，changshihuanyongdianjiedianronghuohuanyongqitajiezhicailiaodedianrong。huozhe
，keyiyongduogebingliantaocidianronglaitihuanwentidianrong。meigedianrongchicundejianxiaojiangshiqibiaomianjixiangyingjianxiao
，congergaibiandianrongdejixiegongzhen。
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處理脈衝束流

脈mai衝chong束shu流liu是shi另ling一yi個ge潛qian在zai的de噪zao聲sheng源yuan。當dang設she計ji中zhong的de傳chuan導dao電dian流liu脈mai衝chong聚ju集ji在zai一yi起qi，然ran後hou出chu現xian更geng多duo數shu量liang的de跳tiao脈mai衝chong時shi，就jiu會hui出chu現xian脈mai衝chong束shu流liu現xian象xiang。脈mai衝chong聚ju集ji會hui在zai開kai關guan模mo式shi中zhong產chan生sheng頻pin率lv分fen量liang，它ta們men通tong常chang都dou在zai聽ting覺jiao範fan圍wei內nei。脈mai衝chong束shu流liu在zai采cai用yong開kai/關控製模式的電源中最為常見。

為確定您的設計中是否存在這種現象，請斷開MOSFET漏極走線，然後插入一個電流環

，以監測漏極電流的開關模式。

電dian源yuan在zai正zheng常chang負fu載zai下xia工gong作zuo時shi，使shi用yong一yi個ge電dian流liu探tan針zhen和he一yi個ge示shi波bo器qi抓zhua取qu在zai一yi個ge寬kuan時shi間jian量liang程cheng內nei的de一yi組zu漏lou極ji開kai關guan脈mai衝chong。下xia圖tu對dui顯xian示shi脈mai衝chong束shu流liu的de波bo形xing與yu具ju有you正zheng常chang開kai關guan模mo式shi的de波bo形xing進jin行xing了le比bi較jiao。如ru果guo看kan到dao類lei似si於yu左zuo圖tu的de脈mai衝chong–一行出現大量脈衝，接著是兩個或更多跳脈衝，就說明您的設計可能存在這種問題。

tongchang，maichongshuliuxianxiangbiaoshifankuidianluguoman，daozhikongzhiqixiangyingzhihou。zhenduanciwentishi，keyixianquerenfankuidianluzhongdesuoyouyuanjianzhishifoudouyushejizhongzhidingdezhixiangfu。yigekeyichangshidejiejuefanganshi，zaishejizhongcaiyongD型光耦器。D型xing光guang耦ou器qi具ju有you比bi標biao準zhun光guang耦ou器qi更geng高gao的de增zeng益yi。另ling一yi個ge策ce略lve是shi

，添tian加jia一yi個ge反fan饋kui環huan路lu加jia速su電dian路lu，以yi縮suo短duan響xiang應ying時shi間jian。該gai電dian路lu將jiang能neng確que保bao光guang耦ou晶jing體ti管guan始shi終zhong在zai有you源yuan區qu工gong作zuo，這zhe樣yang可ke以yi防fang止zhi它ta發fa生sheng飽bao和he，並bing提ti高gao響xiang應ying速su度du。



結論

雖然反激式電源中的音頻噪聲源多種多樣，但最常見的“罪魁禍首”往(wang)往(wang)是(shi)陶(tao)瓷(ci)電(dian)容(rong)或(huo)鐵(tie)氧(yang)體(ti)變(bian)壓(ya)器(qi)磁(ci)芯(xin)。如(ru)果(guo)您(nin)測(ce)試(shi)發(fa)現(xian)電(dian)源(yuan)中(zhong)存(cun)在(zai)明(ming)顯(xian)的(de)噪(zao)聲(sheng)，則(ze)可(ke)以(yi)試(shi)用(yong)本(ben)文(wen)所(suo)介(jie)紹(shao)的(de)應(ying)對(dui)策(ce)略(lve)。在(zai)多(duo)數(shu)情(qing)況(kuang)下(xia)，您(nin)都(dou)可(ke)以(yi)快(kuai)速(su)找(zhao)到(dao)故(gu)障(zhang)元(yuan)件(jian)並(bing)解(jie)決(jue)噪(zao)聲(sheng)問(wen)題(ti)。

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