Hloov fais fab mov EMI tsim kev paub
1. EMI qhov chaw hloov hluav taws xob
EMI cuam tshuam qhov chaw ntawm lub zog hloov hluav taws xob feem ntau yog tshwm sim hauv lub hwj chim hloov raj, rectifier diode, high-frequency transformer, thiab lwm yam. ntaus, thiab hluav taws xob sab nraud.
(1) Fais fab hloov raj
Lub hwj chim hloov raj ua haujlwm nyob rau hauv lub xeev ntawm On-Off ceev lub voj voog hloov, thiab dv / dt thiab di / dt hloov sai heev. Yog li ntawd, lub hwj chim hloov raj tsis yog tsuas yog lub ntsiab cuam tshuam ntawm hluav taws xob teb coupling, tab sis kuj yog lub ntsiab cuam tshuam qhov chaw ntawm magnetic teb coupling.
(2) High zaus transformer
EMI qhov chaw ntawm lub high-frequency transformer yog concentrated nyob rau hauv lub di / dt ceev voj voog transformation coj mus rau lub to inductance, yog li ntawd lub high-frequency transformer yog ib qho tseem ceeb cuam tshuam qhov chaw ntawm magnetic teb coupling.
(3) Rectifier diode
EMI qhov chaw ntawm lub rectifier diode feem ntau yog tshwm sim hauv cov yam ntxwv rov qab los. Lub ntsiab lus tsis tu ncua ntawm qhov rov qab rov qab tam sim no yuav ua rau muaj qhov siab dv / dt nyob rau hauv inductance (lead inductance, stray inductance, thiab lwm yam), uas ua rau muaj zog electromagnetic cuam tshuam.
(4) PCB
Txhawm rau kom meej meej, PCB yog qhov txuas txuas rau cov kev cuam tshuam saum toj no, thiab qhov zoo ntawm PCB ncaj qha cuam tshuam rau kev tawm tsam ntawm EMI qhov chaw saum toj no.
2. EMI kis tau tus mob channel kev faib tawm ntawm kev hloov fais fab mov
(1) Kev xa tawm channel rau kev cuam tshuam
(1) Capacitive coupling
(2) Inductive coupling
(3) Resistive coupling
ib. Resistive conduction coupling generated los ntawm lub internal kuj ntawm cov pej xeem fais fab mov
b. Resistive conduction coupling generated los ntawm cov av impedance
c. Resistive conduction coupling generated los ntawm cov kab impedance
(2) Kev sib kis ntawm hluav taws xob cuam tshuam
(1) Hauv kev hloov pauv hluav taws xob, cov khoom siv thiab cov xov hlau uas tuaj yeem tsim cov hluav taws xob cuam tshuam tuaj yeem suav tias yog cov kav hlau txais xov, kom cov hluav taws xob dipole thiab sib nqus dipole txoj kev xav tuaj yeem siv rau kev tsom xam; diodes, capacitors, thiab fais fab hloov raj tuaj yeem suav tias yog Hluav Taws Xob dipoles, inductance coils tuaj yeem suav tias yog cov hlau nplaum dipoles;
(2) Thaum tsis muaj ntaub thaiv npog, kev sib kis ntawm cov hluav taws xob hluav taws xob uas tsim los ntawm hluav taws xob dipoles thiab sib nqus dipoles yog huab cua (uas tuaj yeem suav tias yog qhov chaw dawb);
(3) Thaum muaj lub cev tiv thaiv, xav txog qhov khoob thiab qhov ntawm lub cev tiv thaiv, thiab tshuaj xyuas thiab txheej txheem raws li tus qauv lej ntawm qhov xau.
3. cuaj qhov kev ntsuas loj rau EMI kev tawm tsam ntawm kev hloov hluav taws xob
Hauv kev hloov pauv hluav taws xob, kev hloov pauv tam sim ntawm qhov hluav taws xob thiab tam sim no, uas yog siab dv / dt thiab di / dt, yog qhov ua rau EMI. EMC tsim kev ntsuas kev paub txog kev hloov pauv hluav taws xob yog feem ntau raws li ob lub ntsiab lus hauv qab no:
(1) Txo qhov kev cuam tshuam los ntawm cov khoom siv hluav taws xob nws tus kheej, siv cov txheej txheem ntawm kev cuam tshuam los yog tsim cov khoom siv thiab cov circuits uas muaj kev cuam tshuam tsawg dua, thiab ua qhov tsim nyog;
(2) Tshem tawm EMI ntawm cov khoom siv hluav taws xob thiab txhim kho EMS ntawm cov khoom siv hluav taws xob los ntawm kev siv hauv av, lim, thaiv thiab lwm yam thev naus laus zis.
Cais hais lus, cuaj qhov kev ntsuas loj yog:
(1) Txo dv / dt thiab di / dt (txo nws cov nqi siab tshaj, qeeb nws txoj kab nqes)
(2) Tsim nyog thov ntawm varistors kom txo qhov hluav taws xob surge
(3) Damping network suppresses overshoot
(4) Diodes nrog cov yam ntxwv zoo rov qab yog siv los txo qis EMI zaus
(5) Kev kho lub zog zoo, thiab lwm yam kev kho kom haum xeeb
(6) Siv lub tshuab lim fais fab uas tsim nyog
(7) Kev kho av tsim nyog
(8) Kev tiv thaiv kev tiv thaiv zoo
(9) Tsim nyog PCB tsim
4. Kev tswj cov dej xau inductance ntawm lub siab zaus transformer
Cov xau inductance ntawm high-frequency transformer yog ib qho ntawm cov laj thawj tseem ceeb rau kev tig-tawm siab kawg ntawm lub hwj chim hloov raj. Yog li ntawd, kev tswj cov dej xau inductance dhau los ua qhov teeb meem tseem ceeb los daws qhov EMI tshwm sim los ntawm lub tshuab hluav taws xob ntau zaus.
Muaj ob lub ntsiab lus nkag rau kev txo cov xau inductance ntawm high-frequency transformers: hluav taws xob tsim thiab txheej txheem tsim!
(1) Xaiv qhov tsim nyog cov tub ntxhais sib nqus kom txo qis inductance. Lub to taub inductance yog proportional rau lub square ntawm tus naj npawb ntawm lem nyob rau hauv thawj sab, txo tus naj npawb ntawm lem yuav ho txo qhov to inductance.
(2) Txo cov txheej rwb thaiv tsev ntawm cov windings. Tam sim no muaj ib txheej insulating hu ua "kub zaj duab xis" nrog ib tug tuab ntawm 20-100um thiab ib tug pulse breakdown voltage ntawm ob peb txhiab volts.
(3) Ua kom cov coupling ntawm windings thiab txo qhov to inductance.
5. Kev tiv thaiv ntawm high-frequency transformers
Txhawm rau tiv thaiv kom tsis txhob muaj qhov sib nqus sib nqus ntawm lub tshuab hluav taws xob ntau zaus los ntawm kev cuam tshuam nrog cov kab hluav taws xob nyob ib puag ncig, cov ntaub thaiv npog tuaj yeem siv los tiv thaiv cov hlau nplaum tawm ntawm lub tshuab hluav taws xob high-frequency. Cov ntaub thaiv npog feem ntau yog ua los ntawm cov ntawv ci tooj liab, qhov txhab nyob ib puag ncig sab nraud ntawm transformer, thiab hauv av. Cov ntaub thaiv npog yog lub nplhaib luv luv uas cuam tshuam rau qhov chaw xau, yog li tiv thaiv cov pa tawm ntawm cov pa tawm hauv qhov ntau dua.
Rau high-frequency transformers, txheeb ze hloov chaw yuav tshwm sim ntawm cov hlau nplaum cores thiab nruab nrab ntawm cov windings, uas yuav ua rau lub suab nrov (howling, vibration) nyob rau hauv lub lag luam ntawm high-frequency transformer. Txhawm rau tiv thaiv cov suab nrov no, lub transformer yuav tsum tau hardened:
(1) Siv epoxy resin los khi peb qhov chaw sib nqus ntawm cov tub ntxhais sib nqus (xws li EE, EI magnetic core) txhawm rau txhawm rau tsim cov kev sib txawv ntawm cov txheeb ze;
(2) Siv "iav hlaws dai" (iav hlaws dai) cov kua nplaum los txuas cov tub ntxhais sib nqus, cov nyhuv zoo dua.
