Zosefera ma capacitor, ma inductors amtundu wamba, ndi mikanda ya maginito ndi ziwerengero zodziwika bwino m'mabwalo apangidwe a EMC, komanso ndi zida zitatu zamphamvu zochotsera kusokoneza kwamagetsi.
Paudindo wa atatuwa muderali, ndikukhulupirira kuti pali mainjiniya ambiri omwe sakumvetsetsa, nkhaniyo idapangidwa ndikuwunikira mwatsatanetsatane mfundo yochotsa atatu akuthwa kwambiri a EMC.
1.Sefa capacitor
Ngakhale resonance ya capacitor ndi yosafunika kuchokera pamalingaliro a kusefa phokoso lapamwamba kwambiri, resonance ya capacitor si nthawi zonse yovulaza.
Pamene mafupipafupi a phokoso ayenera kusefedwa atsimikiziridwa, mphamvu ya capacitor ikhoza kusinthidwa kotero kuti resonant point imangogwera pafupipafupi kusokoneza.
Muumisiri wothandiza, ma frequency a electromagnetic phokoso kuti asefe nthawi zambiri amakhala okwera mpaka mazana a MHz, kapena kupitilira 1GHz.Pamaphokoso apamwamba kwambiri amagetsi amagetsi otere, ndikofunikira kugwiritsa ntchito capacitor yodutsa-pakati kuti musefa bwino.
Chifukwa chomwe ma capacitor wamba sangathe kusefa maphokoso apamwamba kwambiri ndichifukwa chazifukwa ziwiri:
(1) Chifukwa chimodzi ndi chakuti inductance ya capacitor lead imayambitsa capacitor resonance, yomwe imapereka kulepheretsa kwakukulu kwa chizindikiro chapamwamba, ndikufooketsa mphamvu yodutsa chizindikiro chapamwamba;
(2) Chifukwa china ndi chakuti mphamvu ya parasitic pakati pa mawaya ogwirizanitsa chizindikiro chapamwamba kwambiri, kuchepetsa zotsatira zosefera.
Chifukwa chomwe capacitor yodutsa imatha kusefa phokoso lapamwamba kwambiri ndikuti kudzera pakatikati capacitor sikuti ilibe vuto kuti inductance yotsogolera imapangitsa kuti ma frequency a capacitor resonance akhale otsika kwambiri.
Ndipo kupyolera-core capacitor ikhoza kuikidwa mwachindunji pazitsulo zachitsulo, pogwiritsa ntchito zitsulo zachitsulo kuti zizitha kudzipatula kwambiri.Komabe, mukamagwiritsa ntchito kudzera-core capacitor, vuto lomwe muyenera kulabadira ndi vuto la kukhazikitsa.
Kufooka kwakukulu kwa capacitor yodutsa-pakati ndikuwopa kutentha kwambiri komanso kutentha kwamphamvu, komwe kumayambitsa zovuta kwambiri pakuwotcherera kudzera pa-core capacitor pagulu lachitsulo.
Ma capacitor ambiri amawonongeka pakuwotcherera.Makamaka pamene chiwerengero chachikulu cha ma capacitor apakati chiyenera kuikidwa pa gululo, malinga ngati pali zowonongeka, zimakhala zovuta kukonza, chifukwa pamene capacitor yowonongeka imachotsedwa, idzawononga ma capacitor ena oyandikana nawo.
2.Common mode inductance
Popeza mavuto omwe EMC amakumana nawo nthawi zambiri amakhala kusokoneza wamba, ma inductors wamba ndi amodzi mwazinthu zomwe zimagwiritsidwa ntchito kwambiri.
The wamba mumalowedwe inductor ndi wamba akafuna kusokoneza kupondereza chipangizo ndi ferrite monga pachimake, umene uli ndi coils awiri ofanana kukula ndi chiwerengero chomwecho cha mokhota symmetrically bala pa yemweyo ferrite mphete maginito pachimake kupanga anayi otsiriza chipangizo, amene ili ndi mphamvu yayikulu yopondereza ya siginecha wamba, komanso kutsitsa kwakung'ono kwa siginecha yosiyana.
Mfundo yake ndi yakuti pamene njira yodziwika bwino imayenda, maginito a maginito a maginito amapita patsogolo, motero amakhala ndi inductance yochuluka, yomwe imalepheretsa njira yodziwika bwino, ndipo pamene ma coil awiriwa akuyenda mosiyanasiyana, maginito flux. mu mphete ya maginito amaletsa wina ndi mzake, ndipo palibe pafupifupi inductance, kotero masiyanidwe amachitidwe panopa akhoza kudutsa popanda attenuation.
Choncho, wamba mode inductor akhoza bwino kupondereza wamba mode kusokoneza siginecha mu mzere bwino, koma alibe mphamvu pa kufala yachibadwa ya masiyanidwe mode chizindikiro.
Common mode inductors ayenera kukwaniritsa zofunika izi akapangidwa:
(1) Mawaya omwe amabala pa coil pachimake ayenera kutsekedwa kuti atsimikizire kuti palibe kusweka kwafupipafupi pakati pa kutembenuka kwa koyilo pansi pa kuphulika kwadzidzidzi;
(2) Pamene koyiloyo ikudutsa mumsewu waukulu wamakono, maginito sayenera kudzaza;
(3) The maginito pachimake mu koyilo ayenera insulated ku koyilo kuteteza kusweka pakati pa awiri pansi zochita za overvoltage yomweyo;
(4) The koyilo ayenera bala limodzi wosanjikiza monga momwe angathere, kuti kuchepetsa parasitic capacitance wa koyilo ndi kumapangitsanso luso koyilo kupatsira chosakhalitsa overvoltage.
Nthawi zonse, poyang'anira kusankha kwa frequency band yomwe ikufunika kusefa, kukulira kwamtundu wamba, kumakhala bwinoko, chifukwa chake tiyenera kuyang'ana deta ya chipangizocho posankha inductor wamba, makamaka malinga ndi Impedans pafupipafupi curve.
Kuphatikiza apo, posankha, tcherani khutu ku kukhudzidwa kwa njira yosiyanitsira mawonekedwe pazizindikiro, makamaka poyang'ana pamayendedwe osiyanitsa, makamaka kulabadira madoko othamanga kwambiri.
3.Maginito mkanda
Mu mankhwala digito dera EMC kapangidwe ndondomeko, ife nthawi zambiri ntchito maginito mikanda, ferrite chuma ndi chitsulo-magnesium aloyi kapena chitsulo faifi tambala aloyi, zinthu zimenezi ali mkulu maginito permeability, iye akhoza kukhala inductor pakati koyilo yokhotakhota mu nkhani ya mkulu pafupipafupi komanso kukana kwakukulu kunapanga capacitance osachepera.
Zida za ferrite nthawi zambiri zimagwiritsidwa ntchito pama frequency apamwamba, chifukwa pamayendedwe otsika mawonekedwe awo akulu a inductance amapangitsa kutayika pamzere kukhala kochepa kwambiri.Pama frequency apamwamba, amakhala makamaka ma reactance komanso kusintha pafupipafupi.Pakugwiritsa ntchito, zida za ferrite zimagwiritsidwa ntchito ngati ma frequency attenuators pama radio frequency circuit.
M'malo mwake, ferrite ndi yofanana bwino ndi kufanana kwa kukana ndi kutulutsa, kukana kumafupikitsidwa ndi inductor pafupipafupi otsika, ndipo inductor impedance imakhala yokwera kwambiri pafupipafupi, kotero kuti pano zonse zimadutsa kukana.
Ferrite ndi chipangizo chowonongera chomwe mphamvu zothamanga kwambiri zimasinthidwa kukhala mphamvu ya kutentha, yomwe imatsimikiziridwa ndi mawonekedwe ake okana magetsi.Mikanda ya maginito ya Ferrite ili ndi mawonekedwe abwinoko osefa pafupipafupi kuposa ma inductors wamba.
Ferrite imalimbana ndi ma frequency apamwamba, ofanana ndi inductor yokhala ndi chinthu chotsika kwambiri, kotero imatha kukhalabe ndi vuto lalikulu pama frequency angapo, potero imakulitsa luso la kusefa kwafupipafupi.
Mu band yotsika pafupipafupi, impedance imapangidwa ndi inductance.Pafupipafupi, R ndi yaying'ono kwambiri, ndipo mphamvu ya maginito ya pachimake ndiyokwera kwambiri, kotero kuti inductance ndi yaikulu.L imagwira ntchito yayikulu, ndipo kusokoneza kwamagetsi kumaponderezedwa ndi kusinkhasinkha.Ndipo panthawiyi, kutayika kwa maginito pachimake kumakhala kochepa, chipangizo chonsecho ndi chotayika chochepa, makhalidwe apamwamba a Q a inductor, inductor iyi ndiyosavuta kuchititsa resonance, kotero mu gulu lochepa lafupipafupi, nthawi zina pangakhale kusokoneza kwakukulu. pambuyo ntchito ferrite maginito mikanda.
Mu gulu lapamwamba la frequency, impedance imapangidwa ndi zigawo zotsutsa.Pamene mafupipafupi akuwonjezeka, kutsekemera kwa maginito kumachepa, zomwe zimapangitsa kuchepa kwa inductance ya inductor ndi kuchepa kwa gawo la inductive reactance.
Komabe, panthawiyi, kutayika kwa maginito kumawonjezeka, chigawo chotsutsa chikuwonjezeka, zomwe zimapangitsa kuti chiwonjezeko chiwonjezeke, ndipo pamene chizindikiro chapamwamba chikudutsa pa ferrite, kusokoneza kwa electromagnetic kumatengedwa ndikusandulika kukhala mawonekedwe. wa kutaya kutentha.
Zida zopondereza za ferrite zimagwiritsidwa ntchito kwambiri m'mabokosi osindikizira, mizere yamagetsi ndi mizere ya data.Mwachitsanzo, chinthu chopondereza cha ferrite chimawonjezedwa kumapeto kwa chingwe champhamvu cha bolodi losindikizidwa kuti zisefe kusokoneza kwanthawi yayitali.
Ferrite maginito mphete kapena maginito mkanda umagwiritsidwa ntchito makamaka kupondereza kusokonezedwa kwafupipafupi komanso kusokoneza kwambiri pa mizere yama siginecha ndi mizere yamagetsi, komanso imatha kuyamwa kusokonezeka kwa ma electrostatic discharge pulse.Kugwiritsa ntchito chip maginito mikanda kapena chip inductors makamaka zimatengera ntchito yothandiza.
Ma chip inductors amagwiritsidwa ntchito m'mabwalo a resonant.Pamene phokoso la EMI losafunika liyenera kuthetsedwa, kugwiritsa ntchito mikanda ya chip magnetic ndiye chisankho chabwino kwambiri.
Kugwiritsa ntchito chip maginito mikanda ndi chip inductors
Chip inductors:Mafupipafupi a wailesi (RF) ndi mauthenga opanda zingwe, zipangizo zamakono zamakono, zowunikira radar, zamagetsi zamagetsi, mafoni a m'manja, ma pager, zipangizo zomvera, zothandizira digito (PDAs), makina oyendetsa kutali opanda waya, ndi ma modules otsika kwambiri a magetsi.
Chip maginito mikanda:Mabwalo opanga mawotchi, kusefa pakati pa ma analogi ndi ma digito, zolumikizira za I/O / zotulutsa (monga ma serial ports, madoko ofananira, makiyibodi, mbewa, matelefoni akutali, maukonde amderalo), mabwalo a RF ndi zida zomveka zomwe zimatha kusokoneza, kusefa kwa ma frequency apamwamba omwe amasokoneza mabwalo amagetsi, makompyuta, osindikiza, zojambulira mavidiyo (VCRS), kupondereza kwa EMI pama TV ndi mafoni.
Chigawo cha maginito bead ndi ohms, chifukwa chigawo cha maginito bead ndi mwadzina molingana ndi impedance yomwe imapanga pafupipafupi, ndipo unit of impedance ndi ohms.
Dongosolo la maginito la DATASHEET lidzapereka mafupipafupi ndi mawonekedwe opindika, nthawi zambiri 100MHz monga muyezo, mwachitsanzo, ma frequency a 100MHz pomwe kutsekeka kwa mkanda wa maginito kumakhala kofanana ndi 1000 ohms.
Kwa ma frequency band omwe tikufuna kusefa, tiyenera kusankha chokulirapo champhamvu cha maginito, chabwinoko, nthawi zambiri kusankha 600 ohm impedance kapena kupitilira apo.
Kuphatikiza apo, posankha mikanda ya maginito, ndikofunikira kulabadira kusinthasintha kwa mikanda ya maginito, yomwe nthawi zambiri imayenera kuchepetsedwa ndi 80%, ndipo mphamvu ya DC impedance pakugwa kwamagetsi iyenera kuganiziridwa ikagwiritsidwa ntchito pamagetsi.
Nthawi yotumiza: Jul-24-2023