Ripple ɗin wutar lantarki ba makawa. Maƙasudin mu na ƙarshe shine mu rage yawan abin da ake fitarwa zuwa matakin da zai yuwu. Mafi mahimmancin mafita don cimma wannan manufar ita ce guje wa haɓakar ripple. Da farko Kuma sanadin.
Tare da sauyawa na SWITCH, na yanzu a cikin inductance L shima yana jujjuyawa sama da ƙasa a ingantacciyar ƙimar abin fitarwa na yanzu. Saboda haka, za a kuma sami ripple ɗin da ke daidai da mitar Sauyawa a ƙarshen fitarwa. Gabaɗaya, ripples na riber suna nufin wannan, wanda ke da alaƙa da ƙarfin ƙarfin fitarwa da ESR. Mitar wannan ripple iri ɗaya ne da wutar lantarki mai sauyawa, tare da kewayon dubun zuwa ɗaruruwan kHz.
Bugu da kari, Switch gabaɗaya yana amfani da transistor bipolar ko MOSFETs. Ko wanne ne, za a yi tashe da raguwa lokacin da aka kunna kuma ya mutu. A wannan lokacin, ba za a sami hayaniya a cikin da'irar da ke daidai da lokacin ƙaruwa kamar lokacin raguwar Sauyawa ba, ko ƴan lokuta kaɗan, kuma yawanci dubun MHz ne. Hakazalika, diode D yana dawowa baya. Da'irar da'irar ita ce jerin ƙarfin juriya da inductor, wanda zai haifar da resonance, kuma mitar amo shine dubun MHz. Wadannan surutu guda biyu ana kiran su da babbar murya, kuma girman girman ya fi girma fiye da ripple.
Idan mai canza AC/DC ne, ban da ripple biyu na sama (amo), akwai kuma hayaniyar AC. Mitar ita ce mitar shigar da wutar lantarki ta AC, kusan 50-60Hz. Hakanan akwai amo mai haɗin gwiwa, saboda na'urar wutar lantarki da yawa masu sauya wutar lantarki suna amfani da harsashi azaman radiator, wanda ke samar da ƙarfin daidai.
Ma'auni na sauya wutar lantarki
Abubuwan buƙatu na asali:
Haɗin kai tare da oscilloscope AC
Iyakar bandwidth 20MHz
Cire wayar ƙasa na binciken
1.AC hada biyu ne don cire superposition DC ƙarfin lantarki da kuma samun daidai waveform.
2. Bude iyakar bandwidth na 20MHz shine don hana tsangwama na amo mai girma da kuma hana kuskure. Saboda girman girman abun da ke cikin mitoci mai girma, ya kamata a cire lokacin da aka auna shi.
3. Cire shirin ƙasa na binciken oscilloscope, kuma yi amfani da ma'aunin ƙasa don rage tsangwama. Yawancin sassan ba su da zoben ƙasa. Amma la'akari da wannan batu lokacin yanke hukunci ko ya cancanta.
Wani batu shine amfani da tashar tashar 50Ω. Dangane da bayanin oscilloscope, ƙirar 50Ω shine don cire ɓangaren DC kuma auna daidai ɓangaren AC. Koyaya, akwai 'yan oscilloscopes masu irin waɗannan bincike na musamman. A yawancin lokuta, ana amfani da amfani da bincike daga 100kΩ zuwa 10MΩ, wanda ba shi da tabbas na ɗan lokaci.
Abin da ke sama shine ainihin matakan kiyayewa yayin auna ma'aunin juyawa. Idan binciken oscilloscope ba a bayyana kai tsaye zuwa wurin fitarwa ba, ya kamata a auna shi ta layukan murɗaɗɗen ko 50Ω igiyoyin coaxial.
Lokacin auna hayaniyar mitoci mai girma, cikakken rukunin oscilloscope gabaɗaya ɗaruruwan mega zuwa matakin GHz ne. Wasu iri daya ne da na sama. Wataƙila kamfanoni daban-daban suna da hanyoyin gwaji daban-daban. A cikin bincike na ƙarshe, dole ne ku san sakamakon gwajin ku.
Game da oscilloscope:
Wasu oscilloscope na dijital ba za su iya auna ripples daidai ba saboda tsangwama da zurfin ajiya. A wannan lokacin, ya kamata a maye gurbin oscilloscope. Wani lokaci ko da yake tsohuwar simintin oscilloscope bandwidth dubun mega ne kawai, aikin ya fi oscilloscope na dijital kyau.
Hana tabarbarewar wutar lantarki
Don sauya ripples, bisa ka'ida kuma a zahiri akwai. Akwai hanyoyi guda uku don murkushe shi ko rage shi:
1. Ƙara inductance da fitarwa capacitor tacewa
Dangane da tsarin samar da wutar lantarki, girman canjin halin yanzu da ƙimar inductance na inductive inductance ya zama daidai gwargwado, kuma abubuwan da ake fitarwa da na'urorin da ake fitarwa sun yi daidai da daidaituwa. Don haka, haɓaka ƙarfin lantarki da fitarwa na iya rage ɗimbin yawa.
Hoton da ke sama shine tsarin kalaman na yanzu a cikin inductor mai sauya wutar lantarki L. Ripple current △ i ana iya lissafta shi daga wannan dabara:
Ana iya ganin cewa haɓaka ƙimar L ko haɓaka mitar sauyawa na iya rage sauye-sauye na yanzu a cikin inductance.
Hakazalika, alaƙar da ke tsakanin ripples fitarwa da masu ƙarfin fitarwa: VRIPPLE = IMAX/(CO × F). Ana iya ganin cewa haɓaka ƙimar capacitor na fitarwa zai iya rage ripple.
Hanyar da aka saba amfani da ita ita ce amfani da aluminum electrolytic capacitors don ƙarfin fitarwa don cimma manufar babban iko. Duk da haka, electrolytic capacitors ba su da tasiri sosai wajen hana hayaniyar mita mai girma, kuma ESR yana da girma sosai, don haka zai haɗa da yumbu capacitor kusa da shi don gyara rashin aluminum electrolytic capacitors.
A lokaci guda, lokacin da wutar lantarki ke aiki, wutar lantarki VIN na tashar shigarwar ba ta canzawa, amma halin yanzu yana canzawa tare da sauyawa. A wannan lokacin, shigar da wutar lantarki ba ta samar da rijiyar yanzu, yawanci kusa da tashar shigar da yanzu (ɗaukar nau'in buck a matsayin misali, yana kusa da Switch), kuma yana haɗa ƙarfin don samar da halin yanzu.
Bayan amfani da wannan ma'auni, ana nuna wutar lantarki ta Buck a cikin hoton da ke ƙasa:
Hanyar da ke sama ta iyakance ga rage ɗigon ruwa. Saboda iyakar ƙarar, inductance ba zai zama babba ba; ƙarfin fitarwa yana ƙaruwa zuwa wani mataki, kuma babu wani tasiri mai tasiri akan rage raguwa; haɓakar mitar sauyawa zai ƙara asarar sauyawa. Don haka lokacin da buƙatun sun kasance masu tsauri, wannan hanyar ba ta da kyau sosai.
Don ƙa'idodin sauya wutar lantarki, zaku iya komawa zuwa nau'ikan ƙirar ƙirar wutar lantarki daban-daban.
2. Tace-mataki biyu shine ƙara matatun LC matakin farko
Tasirin hanawa na tacewa LC akan ripple ɗin amo ya fito fili. Dangane da mitar ripple da za a cire, zaɓi inductor capacitor da ya dace don samar da da'irar tacewa. Gabaɗaya, yana iya rage ripples da kyau. A wannan yanayin, kuna buƙatar yin la'akari da ma'anar samfurin ƙarfin ƙarfin amsawa. (Kamar yadda aka nuna a kasa)
An zaɓi wurin samfurin kafin tacewar LC (PA), kuma za a rage ƙarfin fitarwa. Domin duk wani inductance yana da juriya na DC, idan aka samu abin da ake fitarwa a halin yanzu, za a sami raguwar wutar lantarki a cikin inductance, wanda ke haifar da raguwar ƙarfin wutar lantarki. Kuma wannan juzu'in wutar lantarki yana canzawa tare da fitarwa na halin yanzu.
Ana zaɓar wurin samfurin bayan LC filter (PB), don haka ƙarfin fitarwa shine ƙarfin da muke so. Koyaya, ana shigar da inductance da capacitor a cikin tsarin wutar lantarki, wanda zai iya haifar da rashin kwanciyar hankali na tsarin.
3. Bayan fitarwa na wutar lantarki mai sauyawa, haɗa LDO tacewa
Wannan ita ce hanya mafi inganci don rage ripples da hayaniya. Ƙarfin wutar lantarki yana da dindindin kuma baya buƙatar canza tsarin mayar da martani na asali, amma kuma shine mafi yawan farashi - mafi inganci kuma mafi girman amfani da wutar lantarki.
Duk wani LDO yana da ma'ana: rabon rage amo. Yana da lanƙwan mita-DB, kamar yadda aka nuna a cikin adadi a ƙasa shine lanƙwan LT3024 LT3024.
Bayan LDO, juzu'in sauyawa gabaɗaya yana ƙasa da 10mV. Hoto mai zuwa shine kwatancin ripples kafin da bayan LDO:
Idan aka kwatanta da lankwasa na adadi da ke sama da kuma nau'in igiyar ruwa a hagu, ana iya ganin cewa tasirin hanawa na LDO yana da kyau sosai don sauyawar ripples na daruruwan KHz. Amma a cikin babban kewayon mitar, tasirin LDO ba shi da kyau sosai.
Rage ripples. Wayoyin PCB na samar da wutar lantarki shima yana da mahimmanci. Don ƙarar ƙararrawa mai girma, saboda yawan yawan mita mai yawa, kodayake tacewa bayan-mataki yana da wani tasiri, sakamakon ba a bayyane yake ba. Akwai nazari na musamman dangane da wannan. Hanya mai sauƙi ita ce kasancewa akan diode da capacitance C ko RC, ko haɗa inductance a cikin jerin.
Hoton da ke sama daidai yake da da'irar ainihin diode. Lokacin da diode yana da sauri-sauri, dole ne a yi la'akari da sigogi na parasitic. A lokacin dawowar diode, daidaitaccen inductance da ƙarfin ƙarfin daidai ya zama oscillator na RC, yana haifar da oscillation mai girma. Domin murkushe wannan babban mitar oscillation, ya zama dole a haɗa capacitance C ko RC buffer cibiyar sadarwa a duka ƙarshen diode. Juriya gabaɗaya 10Ω-100 ω, kuma ƙarfin ƙarfin shine 4.7PF-2.2NF.
Ana iya tantance ƙarfin ƙarfin C ko RC akan diode C ko RC ta maimaita gwaje-gwaje. Idan ba a zaɓe shi da kyau ba, zai haifar da firgita mai tsanani.
Lokacin aikawa: Jul-08-2023
