Ib qho xwm txheej tshwm sim: Tus kws tsim qauv tsim cov hlaws ferrite rau hauv Circuit Court muaj teeb meem EMC, tsuas yog pom tias cov hlaws ua rau lub suab nrov tsis zoo.Qhov no yuav ua li cas?Yuav tsum tsis txhob ferrite hlaws tshem tawm suab nrov tsis ua qhov teeb meem loj dua?
Cov lus teb rau lo lus nug no yog yooj yim, tab sis tej zaum nws yuav tsis tau dav to taub tshwj tsis yog rau cov neeg siv feem ntau ntawm cov sij hawm daws teeb meem EMI.Tsuas muab, ferrite hlaws tsis yog ferrite hlaws, tsis ferrite hlaws, thiab lwm yam.Feem ntau ferrite hlaws dai manufacturers muab ib lub rooj uas teev lawv tus lej, impedance ntawm qee qhov zaus (feem ntau yog 100 MHz), DC tsis kam (DCR), qhov siab tshaj plaws ntsuas tam sim no thiab qee qhov loj me Cov Ntaub Ntawv (saib Table 1).Txhua yam yog yuav luag tus qauv.Dab tsi yog tsis qhia hauv cov ntaub ntawv daim ntawv yog cov ntaub ntawv cov ntaub ntawv thiab cov yam ntxwv ntawm kev ua haujlwm zaus.
Ferrite hlaws dai yog ib qho khoom siv passive uas tuaj yeem tshem tawm lub suab nrov ntawm lub voj voog nyob rau hauv daim ntawv ntawm tshav kub.Magnetic hlaws tsim impedance nyob rau hauv ib tug ntau zaus, yog li tshem tawm tag nrho los yog ib feem ntawm lub pliaj suab nrov zog nyob rau hauv no ntau zaus.Rau DC voltage daim ntaub ntawv ( xws li Vcc kab ntawm IC), nws yog ntshaw kom muaj tus nqi qis DC tiv thaiv kom tsis txhob muaj hluav taws xob loj hauv cov teeb liab uas yuav tsum tau muaj thiab / lossis qhov hluav taws xob lossis qhov tam sim no (I2 x DCR poob). Txawm li cas los xij, nws yog ntshaw kom muaj. siab impedance nyob rau hauv tej yam kev txiav txim ntau zaus.Yog li ntawd, lub impedance muaj feem xyuam rau cov khoom siv (permeability), qhov loj ntawm cov hlaws ferrite, tus naj npawb ntawm windings, thiab cov qauv winding.Obviously, nyob rau hauv ib tug muab vaj tse loj thiab cov khoom siv tshwj xeeb. , ntau windings, siab dua impedance, tab sis raws li lub cev ntev ntawm lub internal coil yog ntev, qhov no kuj yuav ua tau ib tug ntau dua DC resistance.Cov rated tam sim no ntawm cov khoom no yog inversely proportional rau nws DC kuj.
Ib qho tseem ceeb ntawm kev siv ferrite hlaws dai hauv EMI daim ntawv thov yog tias cov khoom siv yuav tsum nyob rau theem tsis kam.Nws txhais li cas?Yuav ua li cas, qhov no txhais tau hais tias "R" (AC resistance) yuav tsum ntau dua "XL" (inductive. Reactance).Ntawm zaus qhov twg XL> R (tsawg zaus), cov tivthaiv yog zoo li ib tug inductor tshaj ib tug resistor.Ntawm zaus ntawm R> XL, ib feem behaves raws li ib tug resistor, uas yog ib tug yuav tsum tau cov yam ntxwv ntawm ferrite hlaws dai. zaus uas "R" ua loj dua "XL" yog hu ua "crossover" zaus.Qhov no yog qhia nyob rau hauv daim duab 1, qhov crossover zaus yog 30 MHz hauv qhov piv txwv no thiab yog cim los ntawm ib tug liab xub.
Lwm txoj hauv kev los saib qhov no yog nyob rau hauv cov nqe lus ntawm qhov kev tivthaiv ua tau zoo thaum lub sij hawm nws inductance thiab kuj theem.Raws li nrog rau lwm yam kev siv uas lub impedance ntawm inductor tsis sib haum, ib feem ntawm cov teeb liab tuaj yog reflected rov qab mus rau qhov chaw.Qhov no tau. muab qee qhov kev tiv thaiv rau cov khoom siv rhiab nyob rau sab nraud ntawm cov hlaws ferrite, tab sis nws kuj qhia "L" rau hauv Circuit Court, uas tuaj yeem ua rau resonance thiab oscillation (ringing). ntawm lub suab nrov lub zog yuav cuam tshuam thiab ib feem ntawm lub suab nrov yuav dhau mus, nyob ntawm qhov inductance thiab impedance qhov tseem ceeb.
Thaum cov hlaws ferrite nyob rau hauv nws cov theem resistive, cov tivthaiv coj zoo li ib tug resistor, yog li nws thaiv lub suab nrov zog thiab absorbs lub zog ntawm Circuit Court, thiab absorbs nws nyob rau hauv daim ntawv ntawm tshav kub.Txawm hais tias tsim nyob rau hauv tib txoj kev raws li ib co inductors, siv. tib cov txheej txheem, cov kab ntau lawm thiab tshuab, tshuab, thiab qee cov khoom siv tib yam, ferrite hlaws siv lossy ferrite cov ntaub ntawv, thaum inductors siv tsis tshua muaj hlau Oxygen khoom.Qhov no yog qhia nyob rau hauv lub nkhaus hauv daim duab 2.
Daim duab qhia tau hais tias [μ''], uas qhia txog tus cwj pwm ntawm cov khoom siv losses ferrite hlaws.
Qhov tseeb hais tias qhov impedance yog muab rau ntawm 100 MHz kuj yog ib feem ntawm qhov teeb meem xaiv.Ntau zaus ntawm EMI, qhov impedance ntawm qhov zaus no tsis cuam tshuam thiab tsis meej pem.Tus nqi ntawm qhov "taw tes" tsis qhia seb qhov impedance nce, txo. , ua tiaj tus, thiab cov impedance ncav cuag nws cov nqi siab tshaj ntawm qhov zaus no, thiab seb cov khoom puas tseem nyob rau hauv nws theem inductance lossis tau hloov mus rau hauv nws cov theem tsis kam.Qhov tseeb, ntau tus neeg siv khoom ferrite hlaws siv ntau yam khoom siv rau tib lub ferrite hlaws, lossis yam tsawg kawg nkaus raws li qhia hauv daim ntawv teev cov ntaub ntawv.Saib daim duab 3.Tag nrho 5 nkhaus nyob rau hauv daim duab no yog rau txawv 120 ohm ferrite hlaws dai.
Tom qab ntawd, qhov uas tus neeg siv yuav tsum tau txais yog qhov impedance nkhaus uas qhia cov yam ntxwv zaus ntawm ferrite hlaws.Ib qho piv txwv ntawm ib qho kev nkhaus nkhaus yog qhia hauv daim duab 4.
Daim duab 4 qhia txog qhov tseeb tseem ceeb heev.Qhov no yog tsim los ua 50 ohm ferrite hlaws nrog zaus ntawm 100 MHz, tab sis nws cov zaus crossover yog li 500 MHz, thiab nws ua tiav ntau tshaj 300 ohms ntawm 1 thiab 2.5 GHz.Dua, tsuas yog saib ntawm daim ntawv teev cov ntaub ntawv yuav tsis qhia rau tus neeg siv paub qhov no thiab tej zaum yuav yuam kev.
Raws li pom nyob rau hauv daim duab, cov khoom ntawm cov ntaub ntawv sib txawv.Nws muaj ntau yam sib txawv ntawm ferrite siv los ua ferrite hlaws.Qee cov ntaub ntawv yog siab poob, broadband, siab zaus, tsis tshua muaj insertion poob thiab lwm yam.Daim duab 5 qhia txog kev sib koom ua ke los ntawm daim ntawv thov zaus thiab impedance.
Lwm qhov teeb meem tshwm sim yog tias cov neeg tsim hluav taws xob hauv Circuit Court qee zaum txwv rau kev xaiv cov hlaws ferrite hauv lawv cov ntaub ntawv pov thawj pom zoo.Yog tias lub tuam txhab tsuas muaj ob peb ferrite hlaws dai uas tau pom zoo siv rau hauv lwm cov khoom thiab pom tau tias txaus siab, muaj ntau yam, Nws tsis yog qhov tsim nyog los ntsuas thiab pom zoo rau lwm cov ntaub ntawv thiab ib feem ntawm tus lej.Nyob rau yav dhau los, qhov no tau rov ua rau qee qhov ua rau muaj kev cuam tshuam loj heev ntawm qhov teeb meem EMI suab nrov uas tau piav qhia saum toj no.Cov txheej txheem yav dhau los yuav siv tau rau qhov project tom ntej, lossis nws tej zaum yuav tsis muaj txiaj ntsig.Koj tsis tuaj yeem ua raws li EMI kev daws teeb meem ntawm qhov project dhau los, tshwj xeeb tshaj yog thaum qhov zaus ntawm cov teeb liab yuav tsum tau hloov lossis qhov zaus ntawm cov khoom siv hluav taws xob xws li cov khoom siv moos hloov.
Yog tias koj saib ob lub impedance nkhaus hauv daim duab 6, koj tuaj yeem sib piv cov khoom siv los ntawm ob qhov zoo sib xws.
Rau ob lub ntsiab lus no, qhov impedance ntawm 100 MHz yog 120 ohms.Rau ib feem ntawm sab laug, siv cov khoom siv "B", qhov siab tshaj plaws impedance yog li 150 ohms, thiab nws tau paub txog ntawm 400 MHz.Rau qhov ntawm sab xis. , siv cov khoom "D", qhov siab tshaj plaws impedance yog 700 ohms, uas yog ua tiav ntawm kwv yees li 700 MHz.Tab sis qhov sib txawv loj tshaj plaws yog qhov crossover zaus.Lub ultra-siab poob "B" cov ntaub ntawv hloov pauv ntawm 6 MHz (R> XL) , thaum cov khoom siv ntau zaus "D" tseem inductive nyob ib ncig ntawm 400 MHz.Qhov twg yog qhov raug siv?Nws nyob ntawm txhua daim ntawv thov.
Daim duab 7 qhia tag nrho cov teeb meem tshwm sim thaum cov hlaws ferrite tsis ncaj ncees lawm raug xaiv los tua EMI.Cov teeb liab tsis pom zoo qhia 474.5 mV undershoot ntawm 3.5V, 1 usS mem tes.
Nyob rau hauv qhov tshwm sim ntawm kev siv cov khoom siv high-lossis (center plot), qhov undershoot ntawm kev ntsuas nce vim qhov ntau dua crossover zaus ntawm qhov.Lub teeb liab undershoot nce los ntawm 474.5 mV mus rau 749.8 mV.Cov khoom siv Super High Loss muaj a tsawg crossover zaus thiab kev ua haujlwm zoo. Nws yuav yog cov khoom siv zoo siv hauv daim ntawv thov no (daim duab ntawm sab xis).Lub undershoot siv qhov no yog txo rau 156.3 mV.
Raws li qhov ncaj qha tam sim no los ntawm cov hlaws dai nce, cov khoom tseem ceeb pib saturate.Rau inductors, qhov no yog hu ua saturation tam sim no thiab tau teev tseg raws li qhov feem pua poob hauv tus nqi inductance.Rau ferrite hlaws dai, thaum lub sij hawm yog nyob rau hauv lub saturation theem. Cov nyhuv ntawm saturation yog tshwm sim los ntawm qhov txo qis hauv impedance tus nqi nrog zaus.Qhov kev poob hauv impedance txo qhov ua tau zoo ntawm cov hlaws ferrite thiab lawv lub peev xwm los tshem tawm EMI (AC) suab nrov.Daim duab 8 qhia txog cov txheej txheem ntawm DC bias curves rau ferrite hlaws.
Nyob rau hauv daim duab no, cov hlaws ferrite raug ntsuas ntawm 100 ohms ntawm 100 MHz.Qhov no yog qhov raug ntsuas impedance thaum qhov tsis muaj DC tam sim no.Txawm li cas los xij, nws tuaj yeem pom tias ib zaug DC tam sim no raug siv (piv txwv li, rau IC VCC. input), qhov zoo impedance poob sharply. Hauv qhov nkhaus saum toj no, rau 1.0 A tam sim no, qhov zoo impedance hloov ntawm 100 ohms mus rau 20 ohms.100 MHz.Tej zaum tsis yog qhov tseem ceeb, tab sis ib yam dab tsi uas tus tsim engineer yuav tsum tau xyuam xim rau. Ib yam li ntawd, los ntawm kev siv cov ntaub ntawv hluav taws xob nkaus xwb. ntawm cov khoom nyob rau hauv tus neeg muag khoom cov ntaub ntawv, tus neeg siv yuav tsis paub txog qhov no DC bias tshwm sim.
Zoo li high-frequency RF inductors, winding kev taw qhia ntawm lub puab kauj nyob rau hauv lub ferrite hlaws dai muaj ib tug zoo ntxim rau cov zaus cov yam ntxwv ntawm cov hlaws.Winding kev taw qhia tsis tsuas yog cuam tshuam rau kev sib raug zoo ntawm impedance thiab zaus theem, tab sis kuj hloov lub zaus teb. Hauv daim duab 9, ob lub 1000 ohm ferrite hlaws tau pom nrog tib lub tsev loj thiab cov khoom siv tib yam, tab sis nrog ob qhov sib txawv winding configurations.
Cov coils ntawm sab laug yog qhov txhab ntawm lub dav hlau ntsug thiab stacked nyob rau hauv kab rov tav kev taw qhia, uas ua rau impedance siab dua thiab ntau zaus teb dua ib feem ntawm sab xis qhov txhab nyob rau hauv lub dav hlau kab rov tav thiab stacked nyob rau hauv txoj kev ntsug.Qhov no yog ib nrab vim mus rau qis capacitive reactance (XC) cuam tshuam nrog qhov txo qis parasitic capacitance nruab nrab ntawm qhov kawg davhlau ya nyob twg thiab sab hauv coil.A qis dua XC yuav tsim ntau dua tus kheej resonance zaus, thiab tom qab ntawd tso cai rau lub impedance ntawm ferrite hlaws mus txuas ntxiv mus txog thaum nws. ncav cuag tus kheej-resonance zaus ntau dua, uas yog siab dua tus qauv qauv ntawm cov hlaws ferrite Tus nqi impedance.Cov nkhaus ntawm ob lub 1000 ohm ferrite hlaws dai saum toj no tau qhia hauv daim duab 10.
Txhawm rau qhia ntxiv txog qhov cuam tshuam ntawm kev xaiv cov hlaws ferrite raug thiab tsis raug, peb siv lub rooj sib tw sim yooj yim thiab lub rooj sib tw sim los ua kom pom cov ntsiab lus feem ntau tau tham saum toj no.Hauv daim duab 11, pawg thawj coj saib xyuas qhia cov haujlwm ntawm peb cov hlaws ferrite thiab cov ntsiab lus kuaj. "A", "B" thiab "C", uas nyob ntawm qhov deb ntawm lub transmitter tso zis (TX) ntaus ntawv.
Lub teeb liab kev ncaj ncees yog ntsuas ntawm qhov tso zis ntawm cov hlaws ferrite hauv txhua qhov ntawm peb txoj haujlwm, thiab rov ua dua nrog ob lub ferrite hlaws ua los ntawm cov khoom sib txawv.Cov khoom siv thawj zaug, cov khoom siv tsawg zaus "S", tau sim ntawm cov ntsiab lus. "A", "B" thiab "C".Tom ntej no, cov khoom siv zaus ntau dua "D" tau siv. Cov ntsiab lus taw tes rau-taw tes uas siv ob lub hlaws ferrite no tau pom hauv daim duab 12.
Lub teeb liab "los ntawm" unfiltered yog tso tawm nyob rau hauv nruab nrab kab, uas qhia ib co overshoot thiab undershoot nyob rau hauv lub nce thiab ntog npoo, ntsig txog.Nws yuav pom tau hais tias siv cov khoom raug rau cov saum toj no xeem tej yam kev mob, qhov tsawg zaus lossy khoom qhia zoo overshoot. thiab undershoot teeb liab txhim kho ntawm qhov nce thiab poob npoo.Cov txiaj ntsig tau pom nyob rau hauv kab sab saud ntawm daim duab 12.Qhov tshwm sim ntawm kev siv cov khoom siv ntau zaus tuaj yeem ua rau lub suab nrov nrov, uas ua kom nrov nrov rau txhua qib thiab ua rau lub sijhawm tsis ruaj khov.Cov kev sim no yog qhia rau kab hauv qab.
Thaum saib kev txhim kho ntawm EMI nrog zaus nyob rau hauv qhov pom zoo sab saud (Daim duab 12) nyob rau hauv kab rov tav scan qhia nyob rau hauv daim duab 13, nws yuav pom tau hais tias rau tag nrho cov zaus, qhov no ho txo EMI spikes thiab txo cov suab nrov tag nrho ntawm 30. mus txog kwv yees li ntawm 350 MHz, qhov kev lees paub tau nyob deb ntawm EMI txwv qhov tseem ceeb los ntawm kab liab. Qhov no yog cov txheej txheem kev cai dav dav rau cov cuab yeej B (FCC Part 15 hauv Tebchaws Meskas).Cov khoom siv "S" siv hauv cov hlaws ferrite tshwj xeeb yog siv rau cov zaus qis dua no. Cov khoom siv "S" muaj qhov cuam tshuam tsis zoo rau qhov qub, tsis muaj suab nrov EMI, tab sis nws txo qis qhov loj ntawm 750 MHz los ntawm kwv yees li 6 dB.Yog tias qhov tseem ceeb ntawm EMI teeb meem suab nrov siab dua 350 MHz, koj yuav tsum tau xav txog kev siv cov khoom siv ntau dua ferrite uas nws qhov siab tshaj plaws impedance siab dua hauv spectrum.
Tau kawg, txhua lub suab nrov (raws li qhia hauv qab nkhaus ntawm daim duab 12) feem ntau tuaj yeem zam los ntawm kev sim ua haujlwm tiag tiag thiab / lossis simulation software, tab sis nws cia siab tias tsab xov xwm no yuav tso cai rau cov neeg nyeem hla dhau ntau qhov yuam kev thiab txo qhov xav tau. xaiv qhov tseeb ferrite hlaws Sijhawm, thiab muab qhov pib "kev kawm" ntau dua thaum cov hlaws ferrite xav tau los pab daws cov teeb meem EMI.
Thaum kawg, nws yog qhov zoo tshaj rau kev pom zoo rau cov kab los yog cov hlaws ferrite, tsis yog ib feem ntawm tus lej xwb, rau kev xaiv ntau dua thiab tsim kev yooj yim.Nws yuav tsum tau muab sau tseg tias cov neeg siv khoom sib txawv siv cov ntaub ntawv sib txawv, thiab qhov ua tau zoo ntawm txhua tus neeg muag khoom yuav tsum tau tshuaj xyuas. , tshwj xeeb tshaj yog thaum ntau qhov kev yuav khoom tau ua rau tib qhov project.Nws yog qhov yooj yim me ntsis ua qhov no thawj zaug, tab sis thaum cov khoom nkag mus rau hauv cov khoom siv hauv qab tus lej tswj, lawv tuaj yeem siv txhua qhov chaw. Qhov tseem ceeb tshaj plaws yog tias qhov kev ua tau zoo ntawm cov khoom siv los ntawm cov chaw muag khoom sib txawv yog qhov zoo sib xws rau kev tshem tawm qhov muaj peev xwm ntawm lwm yam kev siv yav tom ntej Qhov teeb meem tshwm sim.Qhov zoo tshaj plaws yog kom tau txais cov ntaub ntawv zoo sib xws los ntawm cov neeg muag khoom sib txawv, thiab tsawg kawg muaj qhov nkhaus impedance. Qhov no tseem yuav xyuas kom meej tias cov hlaws ferrite raug siv los daws koj qhov teeb meem EMI.
Chris Burket tau ua haujlwm ntawm TDK txij li xyoo 1995 thiab tam sim no yog tus kws tshaj lij daim ntawv thov kev lag luam, txhawb nqa ntau cov khoom siv tsis zoo.Nws tau koom tes nrog cov khoom tsim, kev muag khoom thiab kev lag luam.Mr. Burket tau sau thiab luam tawm cov ntaub ntawv thev naus laus zis hauv ntau lub rooj sib tham. Burket tau txais peb daim ntawv pov thawj Asmeskas ntawm optical / mechanical switches thiab capacitors.
Hauv Kev Ua Raws Cai yog qhov tseem ceeb ntawm cov xov xwm, cov ntaub ntawv, kev kawm thiab kev tshoov siab rau cov kws tshaj lij hluav taws xob thiab hluav taws xob engineering.
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Post lub sij hawm: Jan-05-2022
