Daim ntawv thov ntawm Magnetic Beads nyob rau hauv EMC Tsim ntawm Switching Power Supply
Daim ntawv no qhia txog cov yam ntxwv ntawm cov hlaws ferrite, thiab raws li nws cov yam ntxwv, tshuaj xyuas thiab qhia txog nws daim ntawv thov tseem ceeb hauv EMC tsim ntawm kev hloov hluav taws xob, thiab muab cov kev sim thiab ntsuas cov txiaj ntsig hauv cov kab hluav taws xob lim.
EMC tau dhau los ua qhov teeb meem kub thiab nyuaj hauv kev tsim hluav taws xob niaj hnub no thiab tsim khoom. Qhov teeb meem EMC hauv kev siv tswv yim yog qhov nyuaj heev, thiab nws tsis tuaj yeem daws tau los ntawm kev cia siab rau kev paub theoretical. Nws nyob ntawm ntau qhov kev paub dhau los ntawm cov kws tshaj lij hluav taws xob. Yuav kom daws tau qhov teeb meem zoo dua ntawm EMC ntawm cov khoom siv hluav taws xob, nws yog ib qho tsim nyog yuav tsum tau xav txog cov teeb meem xws li kev cog lus hauv av, Circuit Court thiab PCB board tsim, cable tsim, thiab shielding tsim.
Daim ntawv no qhia txog cov hauv paus ntsiab lus thiab cov yam ntxwv ntawm cov hlaws sib nqus los piav qhia nws qhov tseem ceeb hauv kev hloov hluav taws xob EMC, txhawm rau muab cov khoom siv hluav taws xob hloov hluav taws xob nrog ntau thiab kev xaiv zoo dua thaum tsim cov khoom tshiab.
1 Ferrite EMI tiv thaiv Cheebtsam
Ferrite yog cov khoom siv ferrimagnetic nrog lub cubic lattice qauv. Nws cov txheej txheem tsim khoom thiab cov khoom siv kho tshuab zoo ib yam li cov ceramics, thiab nws cov xim yog grey-dub. Ib hom hlau nplaum feem ntau siv hauv EMI cov ntxaij lim dej yog cov khoom siv ferrite, thiab ntau lub tuam txhab muab cov ntaub ntawv ferrite tshwj xeeb uas siv rau EMI kev tawm tsam. Cov khoom no yog tus cwj pwm los ntawm kev poob loj heev. Rau ferrite siv los suppress electromagnetic cuam tshuam, qhov tseem ceeb tshaj plaws kev ua tau zoo tsis yog magnetic permeability μ thiab saturation magnetic flux ceev Bs. Qhov sib nqus permeability μ tuaj yeem qhia tau tias yog tus lej nyuaj, qhov tseeb yog qhov inductance, thiab qhov xav txog qhov nruab nrab yog qhov poob, uas nce nrog qhov ntau zaus. Yog li ntawd, nws sib npaug Circuit Court yog ib tug series Circuit Court tsim los ntawm ib tug inductor L thiab ib tug resistor R, ob qho tib si L thiab R yog functions ntawm zaus. Thaum cov hlau hla los ntawm cov tub ntxhais ferrite no, qhov tsim inductive impedance nce hauv daim ntawv raws li qhov zaus nce, tab sis cov txheej txheem sib txawv kiag li ntawm ntau zaus.
Hauv qhov tsawg zaus band, impedance yog tsim los ntawm inductive reactance ntawm inductor. Ntawm qhov tsawg zaus, R yog qhov me me, thiab qhov sib nqus permeability ntawm cov tub ntxhais sib nqus yog siab, yog li qhov inductance loj, thiab L ua lub luag haujlwm tseem ceeb, thiab kev cuam tshuam ntawm electromagnetic cuam tshuam thiab cuam tshuam; thiab nyob rau lub sijhawm no, qhov poob ntawm cov tub ntxhais sib nqus yog me me, thiab tag nrho cov cuab yeej yog ib qho inductor nrog qis qis thiab siab Q yam ntxwv.
Nyob rau hauv high-frequency band, lub impedance yog tsim los ntawm cov khoom tiv thaiv. Raws li qhov zaus nce, qhov sib nqus permeability ntawm cov tub ntxhais sib nqus tau txo qis, ua rau txo qis ntawm inductance ntawm inductor thiab txo qis ntawm inductive reactance tivthaiv. Txawm li cas los xij, nyob rau lub sijhawm no, qhov poob ntawm cov tub ntxhais sib nqus nce thiab cov khoom tiv thaiv kev tiv thaiv nce, uas ua rau muaj qhov nce ntawm tag nrho impedance. Thaum lub teeb liab ntau zaus dhau los ntawm ferrite, electromagnetic cuam tshuam yog absorbed thiab dissipated nyob rau hauv daim ntawv ntawm tshav kub zog.
Ferrite suppression Cheebtsam yog dav siv nyob rau hauv cov ntawv luam Circuit Court boards, fais fab kab thiab cov ntaub ntawv kab. Yog hais tias ib tug ferrite suppression caij ntxiv rau qhov kawg ntawm lub hwj chim kab ntawm lub rooj tsavxwm luam ntawv, high-frequency cuam tshuam yuav raug lim tawm. Ferrite magnetic rings los yog magnetic hlaws dai tshwj xeeb yog siv los tiv thaiv kev cuam tshuam ntau zaus thiab cuam tshuam ntawm cov kab teeb liab thiab cov kab hluav taws xob. Nws kuj muaj peev xwm nqus tau electrostatic tawm mem tes cuam tshuam.
2. Lub hauv paus ntsiab lus thiab cov yam ntxwv ntawm cov hlaws sib nqus Thaum cov tam sim no ntws los ntawm cov hlau hauv nws lub hauv paus qhov, nws yuav yog ib qho kev sib nqus khiav hauv cov hlaws sib nqus. Ferrites rau EMI tswj yuav tsum tau tsim xws li tias feem ntau ntawm cov hlau nplaum flux yog dissipated li cua sov hauv cov khoom. Qhov tshwm sim no tuaj yeem ua qauv los ntawm kev sib xyaw ua ke ntawm inductor thiab resistor. raws li pom hauv daim duab 2
Tus lej tus nqi ntawm ob lub ntsiab lus yog proportional rau qhov ntev ntawm cov hlaws sib nqus, thiab qhov ntev ntawm cov hlaws sib nqus muaj qhov cuam tshuam loj heev rau kev tawm tsam. Qhov ntev ntawm qhov ntev ntawm cov hlaws sib nqus, qhov zoo dua qhov kev tawm tsam. Txij li thaum lub teeb liab lub zog yog magnetically ua ke nrog cov hlaws sib nqus, qhov reactance thiab tsis kam ntawm inductor nce nrog qhov nce ntawm zaus. Qhov ua tau zoo ntawm cov hlau nplaum sib txuas yog nyob ntawm qhov sib nqus permeability ntawm cov hlaws cov khoom txheeb ze rau huab cua. Feem ntau qhov poob ntawm cov khoom siv ferrite uas ua rau cov hlaws tuaj yeem qhia tau tias muaj ntau yam los ntawm nws cov permeability txheeb ze rau huab cua.
Cov ntaub ntawv sib nqus feem ntau siv qhov piv no los qhia lub kaum sab xis poob. Lub kaum sab xis loj yog xav tau rau EMI cov khoom tiv thaiv, uas txhais tau hais tias feem ntau ntawm kev cuam tshuam yuav ploj mus thiab tsis cuam tshuam. Ntau yam khoom siv ferrite muaj niaj hnub no muab cov neeg tsim qauv nrog ntau yam kev xaiv rau kev siv cov hlaws ferrite hauv ntau daim ntawv thov.
3 Kev siv cov hlaws sib nqus
3.1 Spike suppressor
Qhov loj tshaj qhov tsis zoo ntawm kev hloov hluav taws xob yog qhov yooj yim los tsim cov suab nrov thiab cuam tshuam, uas yog qhov teeb meem tseem ceeb uas tau cuam tshuam kev hloov hluav taws xob rau lub sijhawm ntev. Lub suab nrov ntawm cov khoom siv hluav taws xob hloov pauv feem ntau yog tshwm sim los ntawm kev hloov pauv ceev-voltage hloov pauv thiab mem tes luv luv tam sim no ntawm lub hwj chim hloov lub raj thiab lub switching rectifier diode. Yog li ntawd, siv cov khoom siv tau zoo los txwv lawv kom tsawg kawg yog ib txoj hauv kev tseem ceeb ntawm kev tawm suab nrov. Tsis yog-linear saturated inductance feem ntau yog siv los txhawm rau thim rov qab rov qab tam sim no ncov, lub sijhawm no lub xeev ua haujlwm ntawm cov tub ntxhais hlau yog los ntawm -Bs rau ntxiv rau Bs. Raws li qhov sib xws ntawm lub siab sib nqus permeability thiab saturable ultra-me me inductance caij-sib nqus hlaws ntawm lub freewheeling diode ntawm lub zog hloov hluav taws xob, ib qho kev siv hluav taws xob siv los txhawm rau txhawm rau lub ncov tam sim no tsim thaum lub zog hloov pauv hloov tau tsim.
Cov yam ntxwv ua haujlwm ntawm Spike Suppressors
(1) Tus nqi pib thiab qhov siab tshaj plaws inductance yog qhov siab heev, thiab qhov tsis yog linearity ntawm qhov seem inductance tus nqi tom qab saturation yog unobvious heev. Tom qab txuas rau hauv series rau hauv Circuit Court, qhov tam sim no nce thiab qhia tau hais tias siab impedance tam sim ntawd, uas yuav siv tau raws li ib tug thiaj li hu ua instantaneous impedance caij.
(2) Nws yog qhov tsim nyog rau kev tiv thaiv cov teeb liab tam sim no siab tshaj plaws nyob rau hauv semiconductor Circuit Court, cuam tshuam rau hluav taws xob hluav taws xob thiab lub suab nrov, thiab nws tuaj yeem tiv thaiv cov khoom siv hluav taws xob los ntawm kev puas tsuaj.
(3) Qhov seem inductance yog qhov tsawg heev, thiab qhov poob tsawg heev thaum lub voj voog ruaj khov.
(4) Nws txawv kiag li ntawm kev ua haujlwm ntawm cov khoom ferrite.
(5) Raws li ntev raws li kev sib nqus saturation yog zam, nws tuaj yeem siv los ua ib qho ultra-me me, high-inductance inductance keeb.
(6) Nws tuaj yeem siv los ua qhov ua tau zoo saturable hlau core nrog tsawg poob los tswj thiab tsim oscillation.
Spike suppressor xav tau cov khoom siv hlau kom muaj qhov sib nqus permeability ntau dua kom tau txais qhov inductance loj dua; Thaum lub siab square ratio tuaj yeem saturate cov tub ntxhais hlau, qhov inductance yuav tsum poob mus rau xoom sai; lub zog quab yuam me me thiab qhov siab zaus poob qis, txwv tsis pub cov cua kub dissipation ntawm cov tub ntxhais hlau yuav tsis ua haujlwm ib txwm.
Lub hom phiaj ntawm tus spike suppressor yog tsuas yog los txo cov teeb liab ncov tam sim no; txo cov suab nrov los ntawm cov teeb liab ncov tam sim no; tiv thaiv kev puas tsuaj ntawm kev hloov pauv transistor; txo qhov hloov pauv ntawm qhov hloov pauv transistor; them rov qab cov yam ntxwv ntawm lub diode; tiv thaiv high-frequency mem tes tam sim no shock excitation. Siv raws li cov kab lim ultra-me me, thiab lwm yam.
3.2 Daim ntawv thov hauv lim a) Cov txiaj ntsig tsis muaj cov hlaws sib nqus b) Cov txiaj ntsig nrog cov hlaws sib nqus c) Cov txiaj ntsig nrog L kab thiab cov hlaws sib nqus d) Cov txiaj ntsig nrog N kab thiab cov hlaws sib nqus
Cov lim dej zoo tib yam yog tsim los ntawm cov khoom tsis muaj zog. Nws txoj haujlwm nyob rau hauv Circuit Court yog los cuam tshuam qhov nres nres zaus rov qab mus rau lub teeb liab qhov chaw, yog li hom lim no kuj hu ua lub lim dej. Thaum lub lim dej tsis sib haum nrog qhov impedance ntawm lub teeb liab qhov chaw, ib feem ntawm lub zog yuav cuam tshuam rov qab mus rau lub teeb liab, uas ua rau muaj kev cuam tshuam ntau ntxiv. Txhawm rau daws qhov tsis zoo no, ferrite sib nqus nplhaib lossis lub tes tsho sib nqus cov hlaws tuaj yeem siv rau ntawm cov kab nkag ntawm lub lim, thiab eddy tam sim no poob ntawm cov teeb liab siab zaus los ntawm lub nplhaib ferrite lossis cov hlaws sib nqus tuaj yeem siv los hloov qhov siab. -frequency tivthaiv rau hauv tshav kub poob. Yog li ntawd, lub nplhaib sib nqus thiab cov hlaws sib nqus tau nqus cov khoom siv ntau zaus, yog li lawv qee zaum hu ua cov lim dej nqus.
Cov ferrite sib txawv ntawm cov khoom sib txawv muaj qhov sib txawv ntawm qhov kev pom zoo tshaj plaws. Feem ntau, qhov siab dua qhov permeability, qhov tsawg zaus suppressed. Tsis tas li ntawd, qhov loj dua qhov ntim ntawm cov ferrite, qhov zoo dua qhov cuam tshuam. Thaum lub ntim tas mus li, qhov ntev thiab nyias cov duab muaj kev tiv thaiv zoo dua li qhov luv thiab tuab, thiab qhov me me ntawm sab hauv txoj kab uas hla, qhov zoo dua qhov cuam tshuam. Txawm li cas los xij, nyob rau hauv cov ntaub ntawv ntawm DC los yog AC bias tam sim no, tseem muaj teeb meem ntawm ferrite saturation. Qhov loj dua ntawm qhov kev sib tshuam ntawm qhov kev tawm tsam, qhov tsawg dua nws yuav saturated, thiab ntau dua qhov kev tsis ncaj ncees tam sim no nws tuaj yeem tiv taus.
Raws li cov ntsiab lus saum toj no thiab cov yam ntxwv ntawm cov hlaws sib nqus, nws yog siv rau lub lim ntawm kev hloov hluav taws xob, thiab cov nyhuv yog pom tseeb. Los ntawm cov txiaj ntsig kev sim, nws tuaj yeem pom tias daim ntawv thov ntawm cov hlaws sib nqus yog qhov sib txawv heev. Nws tuaj yeem pom los ntawm kev sim cov txiaj ntsig tau hais tias vim muaj kev cuam tshuam ntawm kev hloov hluav taws xob hloov hluav taws xob, kev teeb tsa kev teeb tsa, thiab lub zog, qee zaum nws muaj kev cuam tshuam zoo rau kev cuam tshuam ntawm kev sib txawv, qee zaum nws muaj kev cuam tshuam zoo rau kev cuam tshuam ntau hom, thiab qee zaum nws tsis muaj kev cuam tshuam rau kev cuam tshuam tab sis ua rau muaj suab nrov cuam tshuam.
Thaum EMI absorbing magnetic nplhaib / magnetic hlaws suppresses txawv-hom cuam tshuam, tam sim no tus nqi dhau los ntawm nws yog proportional rau nws ntim, thiab qhov tsis sib xws ntawm ob ua rau saturation, uas txo cov kev ua tau zoo ntawm cov khoom; Thaum suppressing hom-mode cuam tshuam, ob lub xov hlau (zoo thiab tsis zoo) ntawm cov khoom siv hluav taws xob dhau los ntawm lub nplhaib sib nqus tib lub sijhawm, thiab cov teeb liab zoo yog lub teeb liab sib txawv. Lwm txoj hauv kev zoo dua hauv kev siv lub nplhaib sib nqus yog ua kom cov hlau dhau los ntawm lub nplhaib sib nqus rov ua dua ob peb zaug kom nce qhov inductance. Raws li nws txoj cai tswj hwm kev cuam tshuam ntawm electromagnetic cuam tshuam, nws cov nyhuv inhibition tuaj yeem siv tau.
Ferrite suppression Cheebtsam yuav tsum tau ntsia ze rau qhov chaw ntawm kev cuam tshuam. Rau qhov input / output Circuit Court, nws yuav tsum nyob ze li sai tau rau lub inlet thiab qhov hluav taws xob ntawm cov ntaub thaiv npog. Rau cov lim dej nqus tau tsim los ntawm ferrite sib nqus nplhaib thiab cov hlaws sib nqus, ntxiv rau kev xaiv cov khoom tsis zoo nrog cov hlau nplaum permeability siab, yuav tsum tau them nyiaj rau nws cov sijhawm thov. Lawv tsis kam mus rau high-frequency Cheebtsam nyob rau hauv cov kab yog hais txog kaum mus rau pua pua ntawm Ω, yog li nws lub luag hauj lwm nyob rau hauv high-impedance circuits yog tsis pom tseeb. Ntawm qhov tsis sib xws, nws yuav ua tau zoo heev hauv cov hluav taws xob tsis tshua muaj hluav taws xob (xws li hluav taws xob faib hluav taws xob, hluav taws xob lossis hluav taws xob zaus hluav taws xob).
