izindaba

Ama-capacitor angenye yezingxenye ezisetshenziswa kakhulu kumabhodi wesekethe. Njengoba isibalo semishini kagesi (kusuka kumakhalekhukhwini ukuya ezimotweni) siqhubeka nokwanda, kanjalo nesidingo sama-capacitor. Umqedazwe we-Covid 19 uphazamise uchungechunge lokuhlinzekwa kwezingxenye zomhlaba wonke kusuka kuma-semiconductors kuya ezingxenyeni ze-passive, futhi ama-capacitor abelokhu eshoda1.
Izingxoxo ngesihloko sama-capacitor zingaguqulwa kalula zibe yincwadi noma isichazamazwi. Okokuqala, kunezinhlobo ezahlukene ze-capacitor, njenge-electrolytic capacitors, ifilimu capacitors, i-ceramic capacitors njalonjalo. Khona-ke, ohlotsheni olufanayo, kukhona izinto ezihlukene ze-dielectric. Kukhona futhi izigaba ezahlukene. Ngokuqondene nesakhiwo somzimba, kunezinhlobo ezimbili ze-terminal kanye ne-threminal capacitor. Kukhona futhi uhlobo lwe-X2Y capacitor, okuyipheya lama-Y capacitor ahlanganiswe kwelinye. Kuthiwani ngama-supercapacitor? Iqiniso liwukuthi, uma uhlala phansi futhi uqala ukufunda imihlahlandlela yokukhetha i-capacitor evela kubakhiqizi abakhulu, ungasebenzisa kalula usuku!
Njengoba lesi sihloko sikhuluma ngezinto eziyisisekelo, ngizosebenzisa indlela ehlukile njengenjwayelo. Njengoba kushiwo ngaphambili, iziqondiso zokukhetha i-capacitor zingatholakala kalula kumawebhusayithi abahlinzeki 3 no-4, futhi onjiniyela bezindawo ngokuvamile bangaphendula imibuzo eminingi mayelana nama-capacitor. Kulesi sihloko, ngeke ngiphinde lokho ongakuthola ku-intanethi, kodwa ngizobonisa indlela yokukhetha nokusebenzisa ama-capacitors ngezibonelo ezingokoqobo. Ezinye izici ezaziwa kancane zokukhethwa kwe-capacitor, njengokucekelwa phansi kwe-capacitance, nazo zizombozwa. Ngemuva kokufunda lesi sihloko, kufanele ube nokuqonda okuhle kokusetshenziswa kwama-capacitor.
Eminyakeni edlule, lapho ngisebenza enkampanini eyenza izinto zikagesi, sasinombuzo wenhlolokhono kanjiniyela we-power electronics. Kumdwebo wohlelo lomkhiqizo okhona, sizobuza abangaba amakhandidethi ukuthi “Uyini umsebenzi we-DC link electrolytic capacitor?” kanye nokuthi "Uyini umsebenzi we-ceramic capacitor eseduze ne-chip?" Sithemba ukuthi impendulo efanele i-DC bus capacitor Isetshenziselwa ukugcinwa kwamandla, ama-capacitor e-ceramic asetshenziselwa ukuhlunga.
Impendulo “elungile” esiyifunayo empeleni ibonisa ukuthi wonke umuntu oseqenjini lokuklama ubheka ama-capacitor ngokombono wesekethe olula, hhayi ngokombono wethiyori yensimu. Iphuzu lokubuka lethiyori yesifunda alilungile. Kumafrikhwensi aphansi (kusuka ku-kHz embalwa ukuya kuma-MHz ambalwa), ithiyori yesifunda ingachaza inkinga kahle. Lokhu kungenxa yokuthi kumaza aphansi, isignali ikakhulukazi ikumodi yokuhlukanisa. Ngokusebenzisa ithiyori yesifunda, singabona i-capacitor eboniswe kuMdwebo 1, lapho ukumelana kochungechunge olulinganayo (ESR) kanye ne-equivalent series inductance (ESL) kwenza ukuvinjelwa kwe-capacitor kushintshe ngemvamisa.
Lo modeli uchaza ngokugcwele ukusebenza kwesifunda lapho isifunda sishintshwa kancane. Nokho, njengoba imvamisa ikhula, izinto ziba nzima nakakhulu. Kwesinye isikhathi, ingxenye iqala ukukhombisa ukungahambisani nomugqa. Lapho imvamisa ikhuphuka, imodeli ye-LCR elula inemikhawulo yayo.
Namuhla, uma ngibuzwa umbuzo ofanayo we-interview, bengizogqoka izibuko zami zokubuka ithiyori yasensimini futhi ngithi zombili izinhlobo ze-capacitor zingamadivayisi okugcina amandla. Umehluko wukuthi ama-electrolytic capacitors angagcina amandla amaningi kunama-ceramic capacitors. Kodwa mayelana nokudluliswa kwamandla, ama-capacitor e-ceramic angadlulisela amandla ngokushesha. Lokhu kuchaza ukuthi kungani ama-capacitor e-ceramic adinga ukubekwa eduze kwe-chip, ngoba i-chip ine-frequency yokushintsha ephezulu kanye nesivinini sokushintsha uma kuqhathaniswa nesifunda samandla esikhulu.
Kulo mbono, singavele sichaze amazinga amabili okusebenza ama-capacitor. Enye iwukuthi angakanani amandla i-capacitor engawagcina, kanti enye ukuthi la mandla angadluliswa ngokushesha kangakanani. Kokubili kuncike endleleni yokukhiqiza ye-capacitor, impahla ye-dielectric, uxhumano ne-capacitor, njalonjalo.
Uma inkinobho kusekethe ivaliwe (bheka Umfanekiso 2), ibonisa ukuthi umthwalo udinga amandla avela emthonjeni wamandla. Isivinini lapho le swishi ivala ngaso sinquma ukuphuthuma kwesidingo samandla. Njengoba amandla ehamba ngesivinini sokukhanya (uhhafu wejubane lokukhanya ezintweni ze-FR4), kuthatha isikhathi ukudlulisa amandla. Ngaphezu kwalokho, kukhona ukungahambisani kahle komthombo kanye nolayini wokudlulisela kanye nomthwalo. Lokhu kusho ukuthi amandla awasoze adluliswa ohambweni olulodwa, kodwa ohambweni oluningi lokujikeleza5, yingakho uma iswishi ishintshwa ngokushesha, sizobona ukubambezeleka nokukhala ekushintsheni kwe-waveform.
Umfanekiso 2: Kuthatha isikhathi ukuthi amandla andise emkhathini; ukungahambisani kahle kwe-impedance kubangela uhambo oluningi lokuya nokubuya lokudluliswa kwamandla.
Iqiniso lokuthi ukulethwa kwamandla kuthatha isikhathi kanye nohambo oluningi lokubuya lisitshela ukuthi sidinga ukuhambisa amandla eduze ngangokunokwenzeka kumthwalo, futhi sidinga ukuthola indlela yokuwaletha ngokushesha. Eyokuqala ivame ukufezwa ngokunciphisa ibanga lomzimba phakathi komthwalo, ukushintshwa kanye ne-capacitor. Lokhu kokugcina kufinyelelwa ngokuqoqa iqembu lama-capacitor ane-impedance encane kakhulu.
I-Field theory iphinde ichaze ukuthi yini ebangela umsindo wemodi evamile. Ngamafuphi, umsindo wemodi evamile ukhiqizwa lapho isidingo samandla somthwalo singahlangatshezwana nayo ngesikhathi sokushintsha. Ngakho-ke, amandla agcinwe esikhaleni phakathi komthwalo kanye nama-conductor aseduze azonikezwa ukusekela isidingo sesinyathelo. Isikhala phakathi komthwalo kanye namakhondaktha aseduze yilokho esikubiza ngokuthi i-parasitic/mutual capacitance (bheka Umfanekiso 2).
Sisebenzisa izibonelo ezilandelayo ukuze sibonise indlela yokusebenzisa ama-electrolytic capacitor, ama-multilayer ceramic capacitor (MLCC), nama-filimi capacitor. Kokubili ithiyori yesekethe neyensimu isetshenziselwa ukuchaza ukusebenza kwama-capacitor akhethiwe.
Ama-electrolytic capacitor asetshenziswa kakhulu kusixhumanisi se-DC njengomthombo wamandla oyinhloko. Ukukhetha i-electrolytic capacitor ngokuvamile kuncike ku:
Ngokusebenza kwe-EMC, izici ezibaluleke kakhulu zama-capacitor ziyi-impedance nezici zemvamisa. Ukukhishwa kwe-low-frequency okwenziwa njalo kuncike ekusebenzeni kwe-DC link capacitor.
I-impedance yesixhumanisi se-DC ayincikile kuphela ku-ESR ne-ESL ye-capacitor, kodwa futhi endaweni ye-loop eshisayo, njengoba kuboniswe kuMfanekiso 3. Indawo enkulu ye-thermal loop isho ukuthi ukudluliswa kwamandla kuthatha isikhathi eside, ngakho ukusebenza izothinteka.
I-converter eyehlayo ye-DC-DC yakhelwe ukufakazela lokhu. Isethaphu yokuhlolwa kwe-EMC yokuthobelana ngaphambilini eboniswe kuMfanekiso 4 yenza iskena sokukhishwa esikhiqiziwe phakathi kuka-150kHz no-108MHz.
Kubalulekile ukuqinisekisa ukuthi ama-capacitor asetshenziswe kulolu cwaningo lwecala wonke avela kumkhiqizi ofanayo ukuze agweme ukuhluka kwezici ze-impedance. Lapho u-soldering i-capacitor ku-PCB, qiniseka ukuthi awekho umkhondo omude, njengoba lokhu kuzokwandisa i-ESL ye-capacitor. Umfanekiso 5 ubonisa ukucushwa okuthathu.
Imiphumela eyenziwe yalokhu kumiswa kokuthathu ikhonjisiwe kuMfanekiso 6. Kuyabonakala ukuthi, uma kuqhathaniswa ne-capacitor eyodwa engu-680 µF, ama-capacitor amabili angu-330 µF azuza ukusebenza kokunciphisa umsindo okungu-6 dB phezu kwebanga elibanzi lefrikhwensi.
Kusukela kumbono wesifunda, kungashiwo ukuthi ngokuxhuma ama-capacitor amabili ngokufana, kokubili i-ESL ne-ESR ihhafu. Ngokombono wethiyori yenkundla, akukho mthombo owodwa kuphela wamandla, kodwa imithombo emibili yamandla inikezwa emthwalweni ofanayo, kwehlisa ngempumelelo isikhathi sonke sokudluliswa kwamandla. Nokho, kumafrikhwensi aphezulu, umehluko phakathi kwama-capacitor amabili angu-330 µF kanye ne-680 µF capacitor eyodwa uzoncipha. Lokhu kungenxa yokuthi umsindo wemvamisa ephezulu ukhombisa impendulo enganele yamandla. Uma sisondeza i-capacitor engu-330 µF eduze neswishi, sinciphisa isikhathi sokudlulisa amandla, okwandisa ngempumelelo impendulo yesinyathelo se-capacitor.
Umphumela usitshela isifundo esibaluleke kakhulu. Ukwandisa amandla e-capacitor eyodwa ngokuvamile ngeke kusekele isidingo sesinyathelo samandla engeziwe. Uma kungenzeka, sebenzisa izingxenye ezincane ze-capacitive. Kunezizathu eziningi ezinhle zalokhu. Okokuqala yizindleko. Ngokuvamile, ngosayizi wephakheji ofanayo, izindleko ze-capacitor zikhuphuka kakhulu ngevelu ye-capacitance. Ukusebenzisa i-capacitor eyodwa kungase kubize kakhulu kunokusebenzisa ama-capacitor ambalwa amancane. Isizathu sesibili ubukhulu. Isici esikhawulelayo ekwakhiweni komkhiqizo ngokuvamile ukuphakama kwezingxenye. Kuma-capacitor amakhulu, ukuphakama kuvame ukuba kukhulu kakhulu, okungafanelekile ukuklama umkhiqizo. Isizathu sesithathu ukusebenza kwe-EMC esikubonile ocwaningweni lwecala.
Esinye isici okufanele icatshangelwe lapho usebenzisa i-electrolytic capacitor ukuthi uma uxhuma ama-capacitor amabili ochungechungeni ukuze wabelane nge-voltage, uzodinga i-bancing resistor 6.
Njengoba kushiwo ngaphambili, ama-capacitor e-ceramic angamadivayisi amancane anganikeza amandla ngokushesha. Ngivame ukubuzwa umbuzo othi "Ngidinga i-capacitor engakanani?" Impendulo yalo mbuzo iwukuthi kuma-capacitors e-ceramic, inani le-capacitance akufanele libe elibaluleke kangako. Ukucatshangelwa okubalulekile lapha ukunquma ukuthi isivinini sokudluliswa kwamandla sanele kusiphi imvamisa kuhlelo lwakho lokusebenza. Uma ukukhishwa okwenziwe kwehluleka ku-100 MHz, khona-ke i-capacitor ene-impedance encane kakhulu ku-100 MHz izoba yisinqumo esihle.
Lokhu okunye ukungaqondi kahle kwe-MLCC. Ngibone onjiniyela bechitha amandla amaningi bekhetha ama-capacitor e-ceramic ane-ESR ne-ESL ephansi kakhulu ngaphambi kokuxhuma ama-capacitor endaweni eyireferensi ye-RF ngemikhondo emide. Kuhle ukusho ukuthi i-ESL ye-MLCC imvamisa iphansi kakhulu kune-inductance yokuxhuma ebhodini. I-Connection inductance iseyipharamitha ebaluleke kakhulu ethinta i-impedance ephezulu ye-ceramic capacitors7.
Umfanekiso wesi-7 ukhombisa isibonelo esibi. Amathrekhi amade (amayintshi angu-0.5 ubude) angenisa okungenani i-10nH inductance. Umphumela wokulingisa ubonisa ukuthi i-impedance ye-capacitor iba phezulu kakhulu kunalokho okulindelekile endaweni yemvamisa (50 MHz).
Enye yezinkinga nge-MLCCs ukuthi ijwayele ukuhambisana nesakhiwo se-inductive ebhodini. Lokhu kungabonakala esibonelweni esiboniswe kuMfanekiso 8, lapho ukusetshenziswa kwe-10 µF MLCC kwethula i-resonance cishe ku-300 kHz.
Unganciphisa i-resonance ngokukhetha ingxenye ene-ESR enkulu noma ngokumane ubeke i-resistor encane yenani (efana no-1 ohm) ochungechungeni nge-capacitor. Lolu hlobo lwendlela lusebenzisa izingxenye ezilahlekile ukucindezela uhlelo. Enye indlela ukusebenzisa elinye inani le-capacitance ukuhambisa i-resonance endaweni ephansi noma ephakeme ye-resonance.
Ama-capacitor amafilimu asetshenziswa ezinhlelweni eziningi. Zingama-capacitor ongawakhetha kuziguquli zamandla aphezulu e-DC-DC futhi asetshenziswa njengezihlungi zokucindezela ze-EMI kuzo zonke izintambo zamandla (AC ne-DC) kanye nokulungiselelwa kokuhlunga kwemodi evamile. Sithatha i-X capacitor njengesibonelo ukuze sibonise amanye amaphuzu ayinhloko okusebenzisa ama-film capacitor.
Uma kwenzeka isigameko sokuhlinzwa, kusiza ukukhawulela ukucindezela kwamandla kagesi aphezulu kulayini, ngakho-ke kuvame ukusetshenziswa ne-transient voltage suppressor (TVS) noma i-metal oxide varistor (MOV).
Kungenzeka ukuthi usukwazi konke lokhu, kodwa bewazi ukuthi inani le-capacitance ye-X capacitor lingancishiswa kakhulu ngeminyaka yokusetshenziswa? Lokhu kuyiqiniso ikakhulukazi uma i-capacitor isetshenziswa endaweni enomswakama. Ngibonile inani le-capacitance ye-X capacitor lehla kuphela laya kumaphesenti ambalwa yenani elilinganiselwe phakathi nonyaka noma emibili, ngakho uhlelo olwaklanywa ekuqaleni nge-X capacitor empeleni lwalahlekelwa yikho konke ukuvikela okungenzeka ukuthi i-front-end capacitor ingaba nayo.
Pho, kwenzekani? Umoya onomswakama ungase uvuze ku-capacitor, phezulu kocingo naphakathi kwebhokisi nenhlanganisela ye-epoxy potting. I-metalization ye-aluminium ingase ifakwe oxidized. I-Alumina iyisivikeli esihle sikagesi, ngaleyo ndlela inciphisa amandla. Le yinkinga wonke ama-filimi capacitor azohlangana nayo. Indaba engikhuluma ngayo ukushuba kwefilimu. Imikhiqizo ye-capacitor ehlonishwayo isebenzisa amafilimu aminyene, okuholela kuma-capacitor amakhulu kunezinye izinhlobo. Ifilimu ezacile yenza i-capacitor ingabi namandla okulayisha ngokweqile (i-voltage, yamanje, noma izinga lokushisa), futhi mancane amathuba okuthi izipholise.
Uma i-X capacitor ingaxhumekile unomphela kumandla kagesi, awudingi ukukhathazeka. Isibonelo, ngomkhiqizo onomshini oqinile phakathi kwamandla kagesi kanye ne-capacitor, ubukhulu bungase bubaluleke kakhulu kunokuphila, bese ungakhetha i-capacitor encane.
Kodwa-ke, uma i-capacitor ixhunywe unomphela kumthombo wamandla, kufanele ithembeke kakhulu. I-oxidation yama-capacitor ayinakugwenywa. Uma impahla ye-capacitor epoxy ingeyekhwalithi enhle futhi i-capacitor ayivami ukuvezwa emazingeni okushisa aphezulu, ukwehla kwenani kufanele kube kuncane.
Kulesi sihloko, okokuqala wethule umbono wethiyori yensimu yama-capacitor. Izibonelo ezisebenzayo nemiphumela yokulingisa ibonisa indlela yokukhetha nokusebenzisa izinhlobo ezivame kakhulu ze-capacitor. Sethemba ukuthi lolu lwazi lungakusiza uqonde indima yama-capacitor ekwakhiweni kwe-elekthronikhi ne-EMC ngokugcwele.
UDkt. Min Zhang ungumsunguli kanye nomeluleki omkhulu we-EMC we-Mach One Design Ltd, inkampani yobunjiniyela ezinze e-UK egxile ekuxhumaneni ne-EMC, ukuxazulula izinkinga nokuqeqeshwa. Ulwazi lwakhe olujulile kuma-electronics wamandla, i-digital electronics, motors kanye nokwakhiwa kwemikhiqizo kuye kwazuzisa izinkampani emhlabeni jikelele.
I-In Compliance ingumthombo oyinhloko wezindaba, ulwazi, imfundo kanye nogqozi lwabachwepheshe bezobunjiniyela bakagesi kanye nobuchwepheshe.
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