Kev soj ntsuam ntawm Electromagnetic Compatibility Design Method for Switching Power Supply
Vim qhov zoo ntawm qhov me me thiab lub zog loj, kev hloov hluav taws xob yog siv dav hauv kev sib txuas lus, tswj, khoos phis tawj thiab lwm yam haujlwm. Txawm li cas los xij, vim muaj kev cuam tshuam electromagnetic, nws daim ntawv thov ntxiv tsuas yog txwv rau qee yam. Daim ntawv no yuav txheeb xyuas ntau yam kev cuam tshuam ntawm electromagnetic cuam tshuam ntawm kev hloov hluav taws xob, thiab ntawm lub hauv paus ntawm nws, nthuav tawm cov qauv tsim hluav taws xob sib xws ntawm kev hloov hluav taws xob.
Electromagnetic Interference Analysis ntawm Switching Power Supply
Cov qauv ntawm cov khoom siv hluav taws xob hloov pauv tau pom nyob rau hauv daim duab 1. Ua ntej, lub zog zaus AC yog rectified rau DC, thiab tom qab ntawd hloov mus rau siab zaus, thiab thaum kawg tso tawm los ntawm rectification thiab filtering Circuit Court kom tau txais qhov ruaj khov DC voltage. Kev tsim hluav taws xob tsis tsim nyog thiab kev teeb tsa, kev ua haujlwm tsis zoo, tsis zoo hauv av, thiab lwm yam yuav ua rau muaj kev cuam tshuam hauv electromagnetic. Nyob rau tib lub sijhawm, qhov xau inductance ntawm transformer thiab lub ncov tshwm sim los ntawm qhov rov qab rov qab tam sim no ntawm cov zis diode kuj tseem muaj peev xwm cuam tshuam qhov chaw muaj zog.
1 Internal qhov chaw ntawm kev cuam tshuam
● Hloov Circuit Court
Lub tshuab hluav taws xob hloov hluav taws xob feem ntau yog tsim los ntawm lub raj hloov pauv thiab lub tshuab hluav taws xob ntau zaus. Muaj ib qho kev faib tawm ntawm lub raj hloov pauv thiab nws lub dab dej kub, lub casing thiab cov khoom siv hluav taws xob sab hauv. Lub du/dt generated los ntawm nws muaj ib tug kuj loj mem tes, ib tug dav zaus band thiab nplua nuj harmonics. Hloov lub raj load yog thawj kauj ntawm lub siab zaus transformer, uas yog inductive load. Thaum lub qhov hluav taws xob hloov hluav taws xob uas tau qhib thaum xub thawj raug muab tua, qhov xau inductance ntawm high-frequency transformer generates counter electromotive force E=-Ldi / dt, thiab nws tus nqi yog proportional rau tus nqi hloov tam sim no ntawm lub collector. thiab proportional to the to to inductance, superimposed on the off Nyob rau ntawm qhov kev txiav tawm voltage, ib tug tig-off voltage ncov yog tsim, yog li tsim ib tug conduction cuam tshuam.
● Rectifier diodes rau rectifier circuits
Muaj qhov thim rov qab tam sim no thaum cov zis rectifier diode raug txiav tawm, thiab lub sijhawm nws rov qab mus rau xoom yog cuam tshuam nrog rau yam xws li junction capacitance. Nws yuav tsim ib qho kev hloov pauv loj tam sim no di / dt nyob rau hauv kev cuam tshuam ntawm transformer to inductance thiab lwm yam kev faib tawm, thiab tsim kom muaj kev cuam tshuam ntau zaus, qhov zaus tuaj yeem ncav cuag kaum tawm megahertz.
● Spurious tsis
Vim yog kev ua haujlwm ntawm ntau zaus, cov yam ntxwv ntawm cov khoom siv tsawg zaus hauv cov khoom siv hluav taws xob hloov pauv yuav hloov, ua rau lub suab nrov. Nyob rau hauv high zaus, cov kev tsis sib haum xeeb muaj kev cuam tshuam zoo rau cov yam ntxwv ntawm kev sib txuas ntawm cov channel, thiab cov kev faib tawm tau dhau los ua cov channel ntawm electromagnetic cuam tshuam.
2 Sab nraud qhov chaw cuam tshuam
Kev cuam tshuam sab nraud tuaj yeem muab faib ua hluav taws xob cuam tshuam thiab kev cuam tshuam xob laim, thiab lub zog cuam tshuam muaj nyob hauv "hom hom" thiab "hom txawv". Nyob rau tib lub sijhawm, txij li AC daim phiaj hluav taws xob txuas ncaj qha mus rau tus choj rectifier thiab lub lim lim, hauv ib nrab lub voj voog, tsuas yog lub sijhawm siab tshaj plaws ntawm cov khoom siv hluav taws xob muaj cov khoom siv tam sim no, uas ua rau lub zog hluav taws xob tsawg heev ntawm lub zog. khoom (txog 0.6). Tsis tas li ntawd, qhov tam sim no muaj ntau cov khoom sib haum xeeb tam sim no, uas yuav ua rau muaj kev sib haum xeeb "kev ua qias tuaj" rau daim phiaj.
EMC Tsim Kev Hloov Hluav Taws Xob
Muaj peb yam tsim nyog rau kev cuam tshuam electromagnetic: cuam tshuam qhov chaw, kis nruab nrab, thiab cov khoom siv rhiab heev. Lub hom phiaj ntawm EMC tsim yog txhawm rau rhuav tshem ib qho ntawm peb qhov xwm txheej no. Rau qhov no, cov txheej txheem tseem ceeb tau txais yuav yog: kev ntsuas hluav taws xob, EMI lim, tiv thaiv, luam tawm Circuit Board los tiv thaiv kev cuam tshuam, thiab lwm yam.
1 Mos switching thev naus laus zis los txo kev hloov pauv thiab hloov suab nrov
Mos switching yog ib qho kev hloov pauv siab tshaj plaws raws li cov thev naus laus zis thev naus laus zis lossis siv thev naus laus zis tswj hauv xoom voltage / tam sim no lub xeev tsim los ntawm kev hloov nyuaj.
Txoj kev ua kom pom tseeb ntawm kev hloov pauv yog: ntxiv me me inductors, capacitors thiab lwm yam resonant Cheebtsam nyob rau hauv thawj Circuit Court, qhia resonance ua ntej thiab tom qab lub switching txheej txheem, thiab tshem tawm cov overlap ntawm voltage thiab tam sim no. Daim duab 2 qhia txog kev hloov pauv yooj yim uas siv cov cuab yeej hloov hluav taws xob.
Siv cov shielding los suppress radiated thiab induced cuam tshuam
Qhov cuam tshuam spectrum ntawm kev hloov fais fab mov yog concentrated nyob rau hauv lub zaus band hauv qab 30MHz, thiab txoj kab uas hla r<λ 2π="" is="" mainly="" an="" electromagnetic="" field="" of="" near-field="" nature,="" and="" it="" is="" a="" low-impedance="" field.="" materials="" with="" good="" electrical="" conductivity="" can="" be="" used="" to="" shield="" the="" electric="" field,="" while="" materials="" with="" high="" magnetic="" permeability="" can="" be="" used="" to="" shield="" the="" magnetic="" field.="" in="" addition,="" effective="" shielding="" measures="" should="" be="" taken="" for="" transformers,="" inductors,="" power="" devices,="" etc.="" the="" ventilation="" holes="" on="" the="" shielding="" shell="" are="" preferably="" circular,="" and="" the="" number="" of="" holes="" can="" be="" many="" if="" ventilation="" conditions="" are="" satisfied,="" and="" the="" size="" of="" each="" hole="" should="" be="" as="" small="" as="" possible.="" the="" seams="" are="" to="" be="" welded="" to="" ensure="" electromagnetic="" continuity.="" filtering="" measures="" should="" be="" taken="" at="" the="" lead-in="" and="" lead-out="" lines="" of="" the="" shielded="" enclosure.="" for="" electric="" field="" shielding,="" the="" shielding="" case="" must="" be="" grounded.="" for="" magnetic="" field="" shielding,="" the="" shielded="" case="" does="" not="" need="" to="" be="">
