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Mamiriro ezvinhu akajairika: Injiniya yekugadzira anoisa bhedhi yeferrite mudunhu rine matambudziko EMC, kungoona kuti bhedhi rinotoita ruzha rusingadiwi zvakanyanya. Izvi zvingave sei? Haafanire kuita ferrite bead kubvisa ruzha simba pasina kuita kuti dambudziko riwedzere?
Mhinduro kumubvunzo uyu iri nyore, asi inogona kusanzwisiswa zvakanyanya kunze kweavo vanopedza nguva yakawanda vachigadzirisa matambudziko eEMI.Zvichitaurwa, ferrite beads haisi ferrite beads, kwete ferrite beads, etc.Most ferrite bead vagadziri vanopa tafura inoronga nhamba yezvikamu zvavo, kupindira pane imwe nguva yakapiwa (kazhinji 100 MHz), DC resistance (DCR), yepamusoro yakayerwa ikozvino uye mamwe mativi Ruzivo (ona Tafura 1) .Zvese zvinenge zvakajairwa.Chii chisina kuratidzwa mu data sheet ndiyo ruzivo rwezvinhu uye inoenderana frequency performance performance.
Ferrite beads chinhu chisingaiti chinogona kubvisa simba remhere kubva kudunhu nenzira yekupisa.Magnetic beads inogadzira impedance muhuwandu hwehuwandu hwehuwandu, nokudaro kubvisa zvose kana chikamu chesimba risingadiwi reruzha mune iyi frequency range.For DC voltage applications. seVcc mutsara weIC), zvinodikanwa kuve neDC yakaderera kukosha kwekudzivirira kudzivirira kurasikirwa kukuru kwesimba muchiratidzo chinodiwa uye / kana voltage kana ikozvino sosi (I2 x DCR kurasikirwa) .Zvisinei, zvinodikanwa kuve nazvo. high impedance mune mamwe anotsanangurwa frequency ranges.Naizvozvo, iyo impedance inoenderana nechinhu chinoshandiswa (permeability), saizi yeferrite bead, huwandu hwemamhepo, uye chimiro chemhepo.Zviri pachena, mune yakapihwa saizi yeimba uye chaiyo zvinhu zvinoshandiswa. , iyo yakawanda mhepo inoputika, iyo yakakwirira iyo impedance, asi sezvo kureba kwemuviri wekoiri yemukati yakareba, izvi zvichabudisawo yakakwirira DC resistance.The rated current yechikamu ichi inversely proportional to its DC resistance.
Chimwe chezvinhu zvinokosha zvekushandisa ferrite beads muEMI applications ndeyekuti chikamu chinofanira kunge chiri muchikamu chekupikisa. reactance).Pamafrequencies apo XL> R (yakaderera frequency), chikamu chakanyanya kufanana neinductor pane resistor.Panguva yeR> XL, chikamu chinoita sechipikisa, chinova chimiro chinodiwa che ferrite bead.The frequency iyo "R" inova yakakura kupfuura "XL" inonzi "crossover" frequency.Izvi zvinoratidzwa muFigure 1, apo crossover frequency ndeye 30 MHz mumuenzaniso uyu uye inoratidzirwa nemuseve mutsvuku.
Imwe nzira yekutarisa iyi iri maererano nezvinoitwa chaizvo nechikamu panguva yayo inductance uye kupikisa phases.Sezvimwe nemamwe maapplication apo iyo impedance yeinductor haina kufananidzwa, chikamu chechiratidzo chinopinda chinoratidzwa kumashure kune chitubu.Izvi zvinogona kupa imwe dziviriro yemidziyo inonzwisisika kune rimwe divi re ferrite bead, asi zvakare inosuma "L" mukati medunhu, izvo zvinogona kukonzera resonance uye oscillation (kurira) . Naizvozvo, kana magineti mabedhi achiri inductive mune zvakasikwa, chikamu simba reruzha richaratidzwa uye chikamu chesimba reruzha chichapfuura, zvichienderana neiyo inductance uye impedance kukosha.
Kana ferrite bead iri muchikamu chayo chekudzivirira, chikamu chinoita sechipikisa, saka chinovhara simba remhere uye chinotora simba iroro kubva kudunhu, uye rinotora nenzira yekupisa.Kunyange zvazvo yakavakwa nenzira imwechete sevamwe inductors, vachishandisa. nzira imwe chete, mutsara wekugadzira uye teknolojia, michina, uye zvimwe zvezvinhu zvakafanana zvezvikamu, ferrite beads inoshandisa lossy ferrite zvinhu, nepo inductors inoshandisa yakaderera simbi Oxygen zvinhu.
Mufananidzo wacho unoratidza [μ''], inoratidza maitiro ezvakarasika ferrite bead zvinhu.
Ichokwadi chokuti iyo impedance inopiwa pa 100 MHz zvakare chikamu chechinetso chekusarudza.Muzviitiko zvakawanda zveEMI, iyo impedance pane iyi frequency haina basa uye inotsausa.Kukosha kwe "point" iyi hakuratidzi kana impedance inowedzera, inoderera. , inova yakati sandara, uye iyo impedance inosvika pakukosha kwayo panguva iyi, uye kana zvinhu zvichiri muchikamu chayo chekudzivirira kana kuti chachinja kuva chikamu chayo chekudzivisa.Kutaura zvazviri, vatengesi vakawanda ve ferrite bead vanoshandisa zvinhu zvakawanda zvechimwechete ferrite bead, kana zvishoma sezvinoratidzwa mubepa re data.Ona Mufananidzo 3.Ma curves mashanu ari pamufananidzo uyu ndeemhando dzakasiyana 120 ohm ferrite bead.
Zvadaro, zvinofanirwa kuwanikwa nemushandisi ndeye impedance curve inoratidza frequency maitiro eiyo ferrite bead.
Mufananidzo 4 unoratidza chokwadi chakakosha.Ichi chikamu chakasarudzwa se 50 ohm ferrite bead ine frequency ye 100 MHz, asi iyo crossover frequency inenge 500 MHz, uye inobudirira kupfuura 300 ohms pakati pe 1 ne 2.5 GHz. Zvakare, chete kutarisa pabepa re data hakuite kuti mushandisi azive izvi uye zvinogona kunge zvichirasisa.
Sezvinoratidzwa mumufananidzo, maitiro ezvigadzirwa zvinosiyana.Kune zvakawanda zvakasiyana-siyana zveferrite zvinoshandiswa kugadzira ferrite beads.Zvimwe zvinhu zvakakura kurasikirwa, Broadband, high frequency, low kuisa kurasikirwa uye zvichingodaro.Mufananidzo 5 unoratidza general grouping by application frequency uye impedance.
Rimwe dambudziko rinowanzoitika nderokuti vagadziri vebhodhi redunhu dzimwe nguva vanongogumira pakusarudzwa kwemabheji eferrite mune yavo yakatenderwa chikamu dhatabhesi.Kana kambani ine mabhesi mashoma eferrite akabvumidzwa kushandiswa mune zvimwe zvigadzirwa uye anoonekwa seanogutsa, muzviitiko zvakawanda, hazvidikanwi kuongorora uye kubvumidza zvimwe zvinhu uye chikamu nhamba.Munguva ichangopfuura, izvi zvagara zvichitungamirira kune mamwe maitiro akaipisisa epakutanga EMI dambudziko reruzha rinotsanangurwa pamusoro apa.Nzira yaimboshanda inogona kushanda kune purojekiti inotevera, kana kuti iyo inogona kunge isingashande.Haugone kungotevedzera EMI mhinduro yeprojekti yapfuura, kunyanya kana kuwanda kwechiratidzo chinodiwa kuchichinja kana kuwanda kwezvinogona kuita zvinopenya zvikamu zvakadai sewachi inochinja.
Kana iwe ukatarisa iwo maviri impedance curves muFigure 6, unogona kuenzanisa mhedzisiro yezvinhu zvezvikamu zviviri zvakafanana zvakasarudzwa.
Pamusoro pezvikamu zviviri izvi, iyo impedance pa 100 MHz ndeye 120 ohms. Kune chikamu kuruboshwe, uchishandisa "B" zvinhu, iyo impedance yakakura inenge 150 ohms, uye inowanikwa pa400 MHz. , uchishandisa "D" zvinhu, iyo yakanyanya impedance ndeye 700 ohms, iyo inowanikwa paanenge 700 MHz. , nepo iyo yakanyanya frequency "D" zvinhu zvichiramba zviri inductive pa400 MHz. Ndeipi chikamu chiri chakakodzera chekushandisa? Zvinoenderana nega yega application.
Mufananidzo 7 unoratidza matambudziko ose anowanzoitika kana mabhero asina kunaka akasarudzwa kudzvanyirira EMI.Chiratidzo chisina kusefa chinoratidza 474.5 mV undershoot pane 3.5V, 1 uS pulse.
Mumugumisiro wekushandisa yakakwira-kurasikirwa mhando zvinhu (center plot), iyo undershoot yechiyero inowedzera nekuda kwepamusoro crossover frequency yechikamu.Chiratidzo chepasi pasi chakawedzera kubva ku474.5 mV kusvika 749.8 mV. Iyo Super High Loss zvinhu ine a low crossover frequency uye kuita kwakanaka.Chichava chinhu chakakodzera chekushandisa muchikumbiro ichi (mufananidzo uri kurudyi). The undershoot uchishandisa chikamu ichi inoderedzwa kusvika 156.3 mV.
Sezvo iyo yakananga ikozvino kuburikidza nemabheji inowedzera, iyo yakakosha zvinhu inotanga kuzara.Kune inductors, izvi zvinonzi saturation ikozvino uye inotsanangurwa senge muzana inodonha mu inductance kukosha. Mhedzisiro yekuzara inoratidzwa mukuderera kwekukosha kwe impedance ne frequency.Iyi inodonha mu impedance inoderedza kushanda kwe ferrite beads uye kukwanisa kwavo kubvisa EMI (AC) ruzha.
Mumufananidzo uyu, ferrite bead inotaridzirwa pa 100 ohms pa 100 MHz. Iyi ndiyo inowanzopimwa impedance kana chikamu chacho chisina DC ikozvino.Zvisinei, zvinogona kuonekwa kuti kana DC ikozvino inoshandiswa (somuenzaniso, yeIC VCC input), iyo impedance inoshanda inodonha zvakanyanya.Muchikamu chepamusoro, kune 1.0 A ikozvino, iyo impedance inobudirira inoshanduka kubva ku100 ohms kusvika ku20 ohms. 100 MHz. Pamwe haisi kunyanya kutsoropodza, asi chimwe chinhu icho mugadziri wekugadzira anofanira kuterera. yechikamu chiri mupepa re data remupi, mushandisi haazoziva nezve DC inorerekera chiitiko.
Kufanana nepamusoro-frequency RF inductors, kutungamira kwemukati coil mu ferrite bead ine simba guru pane frequency maitiro eiyo bead.Winding direction haingokanganisa hukama pakati pe impedance uye frequency level, asi zvakare inoshandura frequency mhinduro. Mumufananidzo 9, maviri 1000 ohm ferrite beads anoratidzwa ane saizi yeimba yakafanana uye zvinhu zvakafanana, asi aine maviri akasiyana mamhepo masisitimu.
Makoiri echikamu chekuruboshwe anokuvadzwa mundege yakatwasuka uye akaturikidzana munzira yakachinjika, iyo inoburitsa yakakwira impedance uye yakakwirira frequency mhinduro pane chikamu chekurudyi ronda mundege yakachinjika uye yakaturikidzana munzira yakatwasuka.Izvi zvakakonzerwa kusvika kune yakaderera capacitive reactance (XC) yakabatana neyakaderedzwa parasitic capacitance pakati pekupedzisira terminal uye mukati coil.A yakaderera XC ichaburitsa yakakwira self-resonance frequency, uye yozobvumira iyo impedance ye ferrite bead kuti irambe ichiwedzera kusvika iyo. inosvika pakakwirira self-resonance frequency, iyo yakakwirira kudarika chiyero chechimiro cheferrite bead The impedance value.Makona epamusoro maviri 1000 ohm ferrite beads anoratidzwa muMufananidzo 10.
Kuenderera mberi nekuratidza mhedzisiro yekusarudzwa kwakaringana uye kwakashata ferrite bead, takashandisa chiyero chakareruka chekuyedza uye test board kuratidza zvakawanda zvemukati zvakurukurwa pamusoro. "A", "B" uye "C", ayo ari chinhambwe kubva kune inoburitsa inoburitsa (TX) mudziyo.
Chiratidzo chekutendeseka chinoyerwa padivi rekubuda kwemaferrite beads mune imwe neimwe yezvinzvimbo zvitatu, uye inodzokororwa nemhando mbiri dzeferrite dzakagadzirwa nezvinhu zvakasiyana-siyana.Iyo yekutanga zvinhu, yakaderera-frequency kurasikirwa "S" zvinhu, yakaedzwa panzvimbo. "A", "B" uye "C" .Next, yakakwira frequency "D" zvinhu zvakashandiswa.Mibairo yekunongedza-ku-point uchishandisa mabhidhi maviri aya eferrite anoratidzwa muMufananidzo 12.
Chiratidzo che "kuburikidza" chisina kucheneswa chinoratidzwa mumutsara wepakati, chinoratidza kumwe kupfura uye undershoot pamicheto inokwira uye inodonha, zvichienderana. uye undershoot chiratidzo chekuvandudzwa pamicheto inokwira uye inodonha.Izvi zvinoguma zvinoratidzwa mumutsara wepamusoro weMufananidzo 12. Mugumisiro wekushandisa zvinhu zvakakwirira-frequency zvinogona kukonzera kurira, iyo inosimudzira nhanho imwe neimwe uye inowedzera nguva yekusagadzikana.Izvi migumisiro yekuedza ndiyo inoratidzwa pamutsara wepasi.
Paunenge uchitarisa kuvandudzwa kweEMI nekuwanda muchikamu chepamusoro chakakurudzirwa (Mufananidzo 12) mune yakachinjika scan inoratidzwa muFigure 13, zvinogona kuoneka kuti kune ese mafrequency, chikamu ichi chinoderedza zvakanyanya EMI spikes uye chinoderedza huwandu hwese ruzha pa30. kusvika kunosvika Muchikamu che350 MHz, chiyero chinogamuchirwa chiri pasi pe EMI muganhu wakasimbiswa nemutsara mutsvuku.Uyu ndiwo muyero wakajairika wemidziyo yeKirasi B (FCC Chikamu 15 muUnited States). Iyo "S" inoshandiswa mumabhedhi eferrite inonyanya kushandiswa kune aya ma frequency epasi. Zvinogona kuonekwa kuti kana frequency yadarika 350 MHz, iyo "S" zvinhu zvine mhedzisiro shoma pane yekutanga, isina kusefa EMI ruzha mwero, asi inoderedza spike huru pa750 MHz ne6 dB. funga nezve kushandiswa kwepamusoro frequency ferrite zvinhu izvo zvakanyanya impedance yakakwira mune spectrum.
Ehe, kurira kwese (sezvinoratidzwa muzasi curve yeFigure 12) kazhinji kunogona kudziviswa nekuita kwechokwadi kuyedzwa kwekuita uye / kana simulation software, asi zvinotarisirwa kuti chinyorwa ichi chichabvumira vaverengi kunzvenga zvikanganiso zvakawanda zvinowanzoitika uye kuderedza kudiwa kwekuita. sarudza yakarurama ferrite bead Nguva, uye kupa mamwe "akadzidza" pokutangira apo ferrite beads zvinodiwa kubatsira kugadzirisa EMI matambudziko.
Pakupedzisira, zviri nani kubvumidza mutsara kana mutsara we ferrite bead, kwete nhamba yechikamu chimwe chete, kune dzimwe sarudzo uye dhizaini kuchinjika.Inofanira kucherechedzwa kuti vatengesi vakasiyana vanoshandisa zvinhu zvakasiyana, uye frequency kuita kwemupi wega wega kunofanirwa kuongororwa. , kunyanya kana kutenga kwakawanda kuchiitwa purojekiti imwechete.Zviri nyore kuita izvi nguva yekutanga, asi kana zvikamu zvapinda muchikamu chechikamu pasi penhamba yekutonga, zvinogona kushandiswa chero kupi zvako.Chinhu chakakosha ndechekuti kuwanda kwekuita kwezvikamu kubva kune vatengesi vakasiyana kwakafanana zvakanyanya kubvisa mukana wemamwe maapplication mune ramangwana Dambudziko rakaitika.Nzira yakanaka ndeyekuwana data yakafanana kubva kune vakasiyana vatengesi, uye kanenge uine impedance curve. Izvi zvakare zvichave nechokwadi chekuti mabheji chaiwo eferrite anoshandiswa kugadzirisa dambudziko rako reEMI.
Chris Burket anga achishanda kuTDK kubvira 1995 uye iye zvino inyanzvi yekushandiswa kwepamusoro, inotsigira nhamba huru yezvikamu zvepasi.Burket yakanyora uye yakaburitsa mapepa ehunyanzvi mumaforamu mazhinji.Burket yakawana matatu eUS patents pane optical/mechanical switches uye capacitor.
MuKuteerera ndiko kunobva nhau, ruzivo, dzidzo uye kurudziro yemagetsi nemagetsi einjiniya nyanzvi.
Aerospace Automotive Communications Consumer Electronics Dzidzo Simba neSimba Indasitiri Ruzivo rweTekinoroji Kurapa Mauto neNyika Dziviriro.