Kev tshuaj xyuas ntawm EMI tswj thev naus laus zis ntawm kev hloov fais fab mov
Nyob rau hauv daim ntawv no, lub mechanism ntawm EMI nyob rau hauv switching fais fab mov yog soj ntsuam nyob rau hauv kom meej, thiab ib tug series ntawm EMI suppression lub tswv yim tau muab tso rau pem hauv ntej, yog li zoo txhim kho cov electromagnetic compatibility ntawm switching fais fab mov.
Hloov fais fab mov yog ib yam khoom siv hluav taws xob hluav taws xob uas siv cov khoom siv hluav taws xob semiconductor thiab sib xyaw ua ke lub zog hloov tshuab, hluav taws xob hluav taws xob tshuab hluav taws xob thiab kev tswj tsis siv neeg. Vim tias nws qhov zoo ntawm kev siv hluav taws xob tsawg, kev ua haujlwm siab, ntim me me, lub teeb yuag, kev ua haujlwm ruaj khov, kev nyab xeeb thiab kev ntseeg tau, thiab qhov dav dav voltage stabilizing ntau yam, nws yog dav siv hauv cov computers, kev sib txuas lus, cov cuab yeej hluav taws xob, kev tswj tsis siv neeg, lub teb chaws tiv thaiv thiab cov khoom siv hauv tsev. Txawm li cas los xij, cov khoom siv hluav taws xob hloov pauv muaj cov lus teb tsis zoo thiab muaj feem cuam tshuam rau electromagnetic cuam tshuam (EMD), thiab EMI teeb liab nyob ntawm ntau zaus thiab muaj qee qhov amplitude. Cov teeb liab EMI no ua rau cov khoom siv hluav taws xob tsis zoo los ntawm kev siv hluav taws xob thiab hluav taws xob, thiab ua rau muaj kev cuam tshuam rau cov khoom siv sib txuas lus thiab cov cuab yeej hluav taws xob, yog li txwv kev siv cov khoom siv hluav taws xob hloov mus rau qee qhov.
1 switching fais fab mov ua rau electromagnetic cuam tshuam
Electromagneticlnterference (EMI) yog ib hom kev puas tsuaj ntawm cov khoom siv hluav taws xob lossis cov khoom siv hluav taws xob uas tshwm sim los ntawm kev xav tsis zoo ntawm electromagnetic cuam tshuam. Nws muaj peb lub ntsiab lus tseem ceeb: cuam tshuam qhov chaw, uas yog, cov cuab yeej tsim hluav taws xob cuam tshuam lub zog; Coupling channel, uas yog, cov channel lossis nruab nrab rau kev cuam tshuam electromagnetic; Cov khoom siv rhiab heev, uas yog, cov khoom siv, cov khoom siv, subsystems lossis cov tshuab puas los ntawm electromagnetic cuam tshuam. Raws li qhov no, cov kev ntsuas tseem ceeb los tswj kev cuam tshuam ntawm electromagnetic cuam tshuam yog: tshem tawm cov kev cuam tshuam los ntawm kev cuam tshuam, txiav tawm txoj hauv kev ntawm kev puas tsuaj, txo cov lus teb ntawm cov khoom siv rhiab rau kev cuam tshuam lossis nce qib electromagnetic rhiab heev.
Raws li lub hauv paus ntsiab lus ntawm kev hloov hluav taws xob hloov hluav taws xob, nws paub tias kev hloov hluav taws xob ua ntej rectifies lub zog zaus hloov tam sim no mus rau hauv qhov tam sim no ncaj qha, tom qab ntawd hloov mus rau hauv siab zaus hloov tam sim no, thiab thaum kawg tso tawm nws los ntawm kev hloov kho thiab lim kom tau txais cov hluav taws xob ncaj qha tam sim no. . Hauv Circuit Court, lub zog triode thiab diode feem ntau ua haujlwm hauv lub xeev hloov, thiab ua haujlwm hauv microsecond xaj; Thaum triode thiab diode qhib thiab tawm, tam sim no hloov pauv zoo heev thaum lub sij hawm nce thiab poob, uas yog ib qho yooj yim los tsim cov xov tooj cua zaus zog thiab tsim cov kev cuam tshuam. 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 tseem yuav tsim muaj peev xwm cuam tshuam electromagnetic.
Hloov cov khoom siv hluav taws xob feem ntau ua haujlwm ntawm qhov zaus siab, thiab qhov zaus siab dua 02 kHz, yog li nws qhov kev faib tawm tsis tuaj yeem tsis quav ntsej. Ntawm qhov tod tes, cov ntawv rwb thaiv tsev ntawm lub dab dej kub thiab cov khoom siv hluav taws xob hloov hluav taws xob muaj qhov chaw sib txuas loj thiab cov ntawv rwb thaiv tsev nyias nyias, yog li qhov kev faib tawm ntawm lawv tsis tuaj yeem raug ignored ntawm ntau zaus, thiab high-frequency tam sim no. ntws mus rau lub dab dej kub los ntawm kev faib capacitance thiab tom qab ntawd mus rau hauv av chassis, ua rau muaj kev cuam tshuam ntau hom; Ntawm qhov tod tes, muaj ib qho kev faib tawm ntawm cov theem pib ntawm cov mem tes transformer, uas tuaj yeem ncaj qha fuse qhov hluav taws xob ntawm thawj winding mus rau theem nrab winding thiab tsim cov hom kev cuam tshuam ntawm ob txoj kab hluav taws xob nrog DC tso zis ntawm theem nrab. winding.
Yog li, cov kev cuam tshuam hauv kev hloov hluav taws xob yog qhov tseem ceeb hauv cov khoom xws li hloov cov raj, diodes thiab high-frequency transformers, nrog rau AC input thiab rectification output circuits.
2 Kev ntsuas los tiv thaiv electromagnetic cuam tshuam ntawm kev hloov fais fab mov
Feem ntau, EMI tswj kev hloov hluav taws xob feem ntau yog siv cov cuab yeej lim dej, tiv thaiv kev siv thev naus laus zis, sealing thev naus laus zis thiab thev naus laus zis hauv av. EMI cuam tshuam tuaj yeem muab faib ua kev cuam tshuam kev cuam tshuam thiab hluav taws xob cuam tshuam raws li txoj kev sib kis. Hloov fais fab mov feem ntau cuam tshuam, thiab nws qhov ntau zaus yog qhov dav tshaj plaws, txog 10kHz-30MHz. Cov kev tiv thaiv tiv thaiv kev cuam tshuam kev cuam tshuam yog qhov pib daws teeb meem hauv peb qhov zaus: 10kHz-150kHz, 150kHz-10MHz thiab siab dua. Ib txwm cuam tshuam feem ntau yog nyob rau hauv thaj tsam ntawm 10kHz txog 150kHz, uas feem ntau daws tau los ntawm cov lim dej dav dav LC. Cov hom kev cuam tshuam feem ntau yog nyob rau hauv thaj tsam ntawm 150kHz-10 MHz, uas feem ntau yog daws los ntawm hom kev tsis pom zoo lim. Cov kev tiv thaiv rau cov zaus band siab tshaj 10MHz yog los txhim kho cov duab ntawm lub lim thiab siv electromagnetic shielding ntsuas.
2.1 siv AC input EMI lim.
Feem ntau, muaj ob txoj hauv kev xa cov cuam tshuam tam sim no ntawm tus neeg xyuas pib: hom hom thiab hom sib txawv. Common-mode interference yog qhov cuam tshuam ntawm cov khoom nqa khoom thiab lub ntiaj teb: kev cuam tshuam muaj tib qhov loj thiab kev taw qhia, thiab muaj nyob nruab nrab ntawm txhua lub ntiaj teb ntawm cov khoom siv hluav taws xob lossis nruab nrab ntawm cov kab nruab nrab thiab lub ntiaj teb. Nws yog tsim los ntawm du / dt, thiab di / dt kuj tsim qee hom kev cuam tshuam. Qhov sib txawv hom kev cuam tshuam yog qhov cuam tshuam ntawm cov khoom thauj khoom: qhov cuam tshuam yog sib npaug ntawm qhov loj thiab qhov sib txawv ntawm cov kev taw qhia, thiab muaj nyob nruab nrab ntawm cov kab theem thiab cov kab nruab nrab ntawm cov khoom siv hluav taws xob thiab cov kab theem thiab cov kab theem. Thaum qhov cuam tshuam tam sim no kis ntawm tus neeg xyuas pib, nws tuaj yeem tshwm sim hauv ob qho tib si hom thiab hom sib txawv. Txawm li cas los xij, kev cuam tshuam ntau hom tam sim no tsuas tuaj yeem cuam tshuam nrog cov txiaj ntsig zoo tom qab nws dhau los ua qhov sib txawv-hom cuam tshuam tam sim no.
Muaj ob hom kev cuam tshuam saum toj no hauv AC lub zog xa hluav taws xob, feem ntau tsis tshua muaj kev sib txawv ntawm hom cuam tshuam thiab ntau zaus hom kev cuam tshuam. Feem ntau, qhov amplitude ntawm txawv hom kev cuam tshuam yog me me, zaus tsawg, thiab cuam tshuam los ntawm me me; Common-mode cuam tshuam muaj qhov loj amplitude thiab siab zaus, thiab nws tseem tuaj yeem tsim hluav taws xob los ntawm cov xov hlau, uas ua rau muaj kev cuam tshuam loj heev. Yog tias tsim nyog EMI lim siv rau ntawm qhov kawg ntawm cov khoom siv AC, electromagnetic cuam tshuam tuaj yeem cuam tshuam zoo. Lub hauv paus ntsiab lus ntawm lub hwj chim kab EMI lim yog qhia nyob rau hauv daim duab 1, nyob rau hauv uas cov sib txawv hom capacitors C1 thiab C2 yog siv rau luv luv-circuit qhov txawv hom cuam tshuam tam sim no, thaum lub intermediate kab grounding capacitors C3 thiab C4 yog siv rau luv luv- Circuit Court hom cuam tshuam tam sim no. Common-hom choke coil yog tsim los ntawm ob lub coils nrog sib npaug thickness thiab qhov txhab ntawm ib tug sib nqus core nyob rau hauv tib txoj kev. Yog tias qhov sib nqus sib nqus ntawm ob lub coils ze heev, qhov to ntawm inductance yuav tsawg heev, uas tsis zoo nyob rau hauv ntau zaus ntawm cov kab hluav taws xob.
Hom reactance yuav dhau los ua me me; Thaum cov khoom thauj tam sim no ntws los ntawm kev sib nqus hom choke, cov kab hlau nplaum uas tsim los ntawm cov coils txuas nrog hauv cov kab ntawm theem kab yog qhov sib txawv rau cov tsim los ntawm cov coils txuas nrog hauv cov kab ntawm cov kab nruab nrab, thiab lawv tshem tawm ib leeg hauv cov magnetic tub ntxhais. Yog li ntawd, txawm nyob rau hauv cov ntaub ntawv ntawm loj load tam sim no, lub magnetic core yuav tsis saturated. Rau cov hom kev cuam tshuam tam sim no, cov hlau nplaum uas tsim los ntawm ob lub coils yog nyob rau hauv tib txoj kev, uas yuav nthuav tawm cov inductance loj, yog li ua lub luag haujlwm hauv attenuating qhov kev cuam tshuam cov teeb liab. Ntawm no, hom hom choke coil yuav tsum tau ua los ntawm ferrite magnetic khoom nrog siab permeability thiab zoo zaus yam ntxwv.
