Redresör - Rectifier

Rostlantiruvchi diod (kremniy bilan boshqariladigan rektifikator ) va tegishli o'rnatish uskunalari. Og'ir tishli tirgak qurilmani a ga mahkamlaydi kuler issiqlikni tarqatish.

A rektifikator bu elektr qurilmasi konvertatsiya qiladi o'zgaruvchan tok (AC), vaqti-vaqti bilan yo'nalishni o'zgartiradi, ga to'g'ridan-to'g'ri oqim (DC), faqat bitta yo'nalishda oqadi. Orqaga operatsiya inverter.

Jarayon sifatida tanilgan tuzatish, chunki u oqim yo'nalishini "to'g'rilaydi". Jismoniy jihatdan, rektifikatorlar bir qator shakllarga ega, shu jumladan vakuum trubkasi diodalari, nam kimyoviy hujayralar, simob-boshq valflari, mis va selen oksidi plitalari to'plamlari, yarimo'tkazgichli diodlar, kremniy bilan boshqariladigan rektifikatorlar va boshqa silikon asosidagi yarimo'tkazgichli kalitlar. Tarixiy jihatdan, hatto sinxron elektromexanik kalitlar va dvigatellar ishlatilgan. Dastlabki radio qabul qiluvchilar kristall radiolar, ishlatilgan "mushukning mo'ylovi "ning simini kristallga bosish galena (qo'rg'oshin sulfidi) nuqta-kontaktli rektifikator yoki "kristall detektori" sifatida xizmat qiladi.

Redresörler juda ko'p foydalanishga ega, lekin ko'pincha ular DC ning tarkibiy qismlari bo'lib xizmat qiladi quvvat manbalari va yuqori voltli to'g'ridan-to'g'ri oqim elektr uzatish tizimlari. Rektifikatsiya kuch manbai sifatida foydalanish uchun to'g'ridan-to'g'ri oqim hosil qilishdan boshqa rollarda xizmat qilishi mumkin. Ta'kidlanganidek, detektorlar ning radio signallari rektifikator sifatida xizmat qiladi. Gaz isitish tizimlarida olovni to'g'irlash olov borligini aniqlash uchun ishlatiladi.

O'zgaruvchan tok manbai turiga va rektifikator sxemasining joylashishiga qarab, chiqish voltaji bir hil barqaror kuchlanish hosil qilish uchun qo'shimcha yumshatishni talab qilishi mumkin. Radio, televidenie va kompyuter uskunalari uchun quvvat manbalari kabi rektifikatorlarning ko'pgina dasturlari barqaror doimiy doimiy voltaj (a tomonidan ishlab chiqarilgandek batareya ). Ushbu dasturlarda rektifikatorning chiqishi an bilan tekislanadi elektron filtr bo'lishi mumkin kondansatör, bo'g'ish, yoki kondensatorlar to'plami, choklar va rezistorlar, ehtimol a voltaj regulyatori barqaror kuchlanish ishlab chiqarish uchun.

Qarama-qarshi funktsiyani bajaradigan, ya'ni doimiy o'zgaruvchan tokni o'zgaruvchan tokka aylantiradigan yanada murakkab sxemalar deyiladi inverter.

Redresör qurilmalari

Kremniy yarimo'tkazgichli rektifikatorlar ishlab chiqilishidan oldin vakuum trubkasi termion diodlar va mis oksidi yoki selenga asoslangan metall rektifikator steklardan foydalanilgan.^[1] Yarimo'tkazgich elektronikasining joriy etilishi bilan vakuum naychasini to'g'rilash moslamalari eskirdi, faqat vakuum naychasining ba'zi ixlosmandlari bundan mustasno. audio uskunalar. Har xil turdagi yarimo'tkazgichli diodlarni juda pastdan yuqori oqimgacha quvvatni to'g'irlash uchun (birlashma diodalari, Shotki diodalari va boshqalar) keng qo'llaniladi.

Boshqaruv elektrodlari bo'lgan va bir tomonlama oqim klapanlari vazifasini bajaradigan boshqa qurilmalar oddiy rektifikatsiyadan ko'proq talab qilinadigan joylarda qo'llaniladi, masalan, o'zgaruvchan chiqish voltaji zarur bo'lganda. Ishlatilgan kabi yuqori quvvatli rektifikatorlar yuqori voltli to'g'ridan-to'g'ri oqim elektr energiyasini uzatish, har xil turdagi kremniy yarimo'tkazgich qurilmalarini ishlatish. Bular tiristorlar yoki faqat bitta yo'nalishda oqim o'tkazadigan diodlar sifatida samarali ishlaydigan boshqa boshqariladigan kommutatorli qattiq holatli kalitlar.

Tekshirish davrlari

Rectifier davrlari bo'lishi mumkin bir fazali yoki ko'p fazali. Mahalliy uskunalar uchun past quvvatli rektifikatorlarning aksariyati bir fazali, ammo uch fazali rektifikatsiya sanoat dasturlari va energiyani doimiy (HVDC) sifatida uzatish uchun juda muhimdir.

Bir fazali rektifikatorlar

Yarim to'lqinli rektifikatsiya

Bir fazali ta'minotning yarim to'lqinli rektifikatsiyasida, o'zgaruvchan tok to'lqinining ijobiy yoki salbiy yarmi o'tadi, qolgan qismi esa bloklanadi. Matematik jihatdan bu a qadam funktsiyasi (ijobiy o'tish, salbiy blok uchun): ijobiy o'tish rampa funktsiyasiga mos keladi, bu ijobiy kirishlarda identifikator, salbiy blokirovka qilish salbiy kirishda nolga to'g'ri keladi. Kirish to'lqin shaklining faqat yarmi chiqishga etib kelganligi sababli, o'rtacha kuchlanish past bo'ladi. Yarim to'lqinli rektifikatsiya qilish uchun bitta talab qilinadi diyot a bir fazali ta'minot, yoki uchtasi uch fazali ta'minot. Rektifikatorlar bir yo'nalishli, ammo pulsatsiyalanuvchi doimiy oqim hosil qiladi; yarim to'lqinli rektifikatorlar bundan ham ko'proq narsani ishlab chiqaradi dalgalanma to'liq to'lqinli rektifikatorlarga qaraganda va yo'q qilish uchun ko'proq filtrlash kerak harmonikalar chiqish chastotasining o'zgarishi.

Yarim to'lqinli rektifikator

Sinusoidal kirish zo'riqishida uchun ideal yarim to'lqinli rektifikatorning ishlamaydigan doimiy voltaji:^[2]

${ displaystyle { begin {aligned} V _ { mathrm {rms}} & = { frac {V _ { mathrm {peak}}} {2}} [8pt] V _ { mathrm {dc}} & = { frac {V _ { mathrm {peak}}} { pi}} end {aligned}}}$

qaerda:

V_DC, V_av - doimiy yoki o'rtacha chiqish kuchlanishi,

V_tepalik, fazali kirish voltajlarining eng yuqori qiymati,

V_rms, o'rtacha kvadrat Chiqish kuchlanishining (RMS) qiymati.

To'liq to'lqinli rektifikatsiya

To'liq to'lqinli rektifikator, vakuum trubkasi ikkita anodga ega.

To'liq to'lqinli rektifikator kirish to'lqin shaklini butun chiqindagi doimiy kutuplulukka (ijobiy yoki salbiy) o'zgartiradi. Matematik jihatdan, bu mos keladi mutlaq qiymat funktsiya. To'liq to'lqinli rektifikatsiya kirish to'lqin shaklining ikkala kutupluluğunu pulsatsiyalanuvchi DC ga (to'g'ridan-to'g'ri oqim) o'zgartiradi va o'rtacha o'rtacha chiqish voltajini beradi. Ikkita diod va markaz tegib turdi transformator, yoki to'rtta diod ko'prikni sozlash va har qanday o'zgaruvchan tok manbai (shu jumladan markaziy kransiz transformator) kerak.^[3] Yagona yarimo'tkazgichli diodlar, umumiy katodli yoki oddiy anodli ikkita diodli va to'rt yoki oltitadiodli ko'priklar bitta komponent sifatida ishlab chiqariladi.

Graets ko'prigi to'g'rilagichi: to'rtta dioddan foydalangan holda to'lqin to'lqinli rektifikator.

Bir fazali o'zgaruvchan tok uchun, agar transformator markazdan urilgan bo'lsa, u holda ikkita diod orqaga qarab (katoddan katodgacha yoki anoddan anodga, zarur bo'lgan chiqish polaritesiga qarab) to'liq to'lqinli rektifikatorni hosil qilishi mumkin. Ko'prikni to'g'rilash moslamasiga qaraganda bir xil chiqish voltajini olish uchun ikkilamchi transformatorda ikki marta ko'p burilish kerak, ammo quvvat darajasi o'zgarmaydi.

A yordamida to'liq to'lqinli rektifikator markaziy teging transformator va 2 diod.

The o'rtacha va ideal bir fazali to'liq to'lqinli rektifikatorning RMS-ning chiqishsiz kuchlanishlari:

${ displaystyle { begin {aligned} V _ { mathrm {dc}} = V _ { mathrm {av}} & = { frac {2 cdot V _ { mathrm {peak}}} { pi}} [8pt] V _ { mathrm {rms}} & = { frac {V _ { mathrm {peak}}} { sqrt {2}}} end {aligned}}}$

Juda keng tarqalgan ikki diodli rektifikator vakuumli quvurlar bitta umumiy narsani o'z ichiga olgan katod va ikkitasi anodlar bitta konvert ichida, ijobiy chiqishi bilan to'liq to'lqinli rektifikatsiyaga erishish. 5U4 va 80 / 5Y3 (4 pin) / (sakkizta) ushbu konfiguratsiyaning mashhur namunalari edi.

Uch fazali rektifikatorlar

Bir fazali rektifikatorlar odatda mahalliy uskunalar uchun quvvat manbalari uchun ishlatiladi. Biroq, ko'pgina sanoat va yuqori quvvatli dasturlar uchun uch fazali rektifikator sxemalari odatiy holdir. Bir fazali rektifikatorlarda bo'lgani kabi, uch fazali rektifikatorlar ham yarim to'lqinli, markazlashtiruvchi transformator yordamida to'liq to'lqinli yoki to'liq to'lqinli ko'prikli sxema shaklida bo'lishi mumkin.

Tiristorlar chiqish zo'riqishini tartibga soladigan sxemani yaratish uchun odatda diodlar o'rniga ishlatiladi. To'g'ridan to'g'ri oqimni ta'minlaydigan ko'plab qurilmalar yaratish uch fazali o'zgaruvchan tok. Masalan, an avtomobil alternatori tarkibida oltita diod mavjud bo'lib, ular batareyani zaryadlash uchun to'liq to'lqinli rektifikator sifatida ishlaydi.

Uch fazali, yarim to'lqinli elektron

Uch fazali yarim to'lqinli rektifikator sxemasi yordamida boshqariladi tiristorlar kommutatsiya elementlari sifatida, ta'minot indüktansını e'tiborsiz qoldiradi

Nazorat qilinmaydigan uch fazali, yarim to'lqinli o'rta nuqta davri uchun har bir fazaga bittadan ulangan uchta diod kerak. Bu uch fazali rektifikatorning eng oddiy turi, ammo nisbatan yuqori darajada azoblanadi harmonik buzilish ikkala o'zgaruvchan va doimiy ulanishlarda. Ushbu turdagi rektifikatorning zarbasi uchta, deyiladi, chunki shahar tomonidagi chiqish voltajida tarmoq chastotasining har bir tsiklida uchta aniq impuls mavjud:

Eng yuqori qiymatlar ${ displaystyle V _ { mathrm {peak}}}$ ushbu uch pulsli doimiy kuchlanish RMS qiymatidan hisoblanadi ${ displaystyle V _ { mathrm {LN}}}$ kirish fazasining voltaji (tarmoq neytral kuchlanishga, Shimoliy Amerikada 120 V, Evropada elektr tarmog'ida 230 V): ${ displaystyle V _ { mathrm {peak}} = { sqrt {2}} cdot V _ { mathrm {LN}}}$. O'rtacha chiqishsiz kuchlanish ${ displaystyle V _ { mathrm {av}}}$ natijalari ajralmas davri davomiyligi bilan musbat yarim to'lqin grafigi ostida ${ displaystyle { frac {2} {3}} pi}$ (30 ° dan 150 ° gacha):

⇒ ${ displaystyle V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot { sqrt {3}} cdot { sqrt {2}} cdot V _ { mathrm {LN}}} {2 pi}}}$ ⇒ ${ displaystyle V _ { mathrm {av}} = { frac {3 cdot { sqrt {6}} cdot V _ { mathrm {LN}}} {2 pi}}}$ ≈ 1,17 ⋅ ${ displaystyle V _ { mathrm {LN}}}$

Uchta fazali, to'liq to'lqinli elektr o'tkazgich

Uch fazali to'liq to'lqinli rektifikator sxemasidan foydalangan holda boshqariladi tiristorlar kommutatsiya elementlari sifatida, markazlashtiruvchi transformator bilan, ta'minot induktivligini e'tiborsiz qoldiradi

Agar o'zgaruvchan tok manbai transformator orqali markaziy kran bilan ta'minlansa, harmonik ko'rsatkichlari yaxshilangan rektifikator sxemasi olinishi mumkin. Ushbu rektifikator endi oltita diodni talab qiladi, har bir transformatorning ikkinchi sarg'ishining har bir uchiga ulangan. Ushbu sxema oltitadan iborat impuls-raqamga ega va aslida olti fazali yarim to'lqinli elektron deb hisoblash mumkin.

Oldin qattiq holat qurilmalar mavjud bo'lib, yarim to'lqinli elektron va to'liq tebranish markazida joylashgan transformator yordamida, odatda sanoat rektifikatorlarida ishlatilgan simob-boshq valflari.^[4] Buning sababi shundaki, uchta yoki oltita o'zgaruvchan tok manbai, bitta katakchada tegishli miqdordagi anodli elektrodlarga berilib, umumiy katod bilan bo'lishishi mumkin edi.

Diyotlar va tiristorlar paydo bo'lishi bilan ushbu sxemalar kamroq ommalashib ketdi va uch fazali ko'prik sxemasi eng keng tarqalgan sxemaga aylandi.

Uch fazali ko'prikni to'g'rilash moslamasi nazoratsiz

Ajratilgan avtomobil alternator, to'liq to'lqinli uch fazali ko'prikni to'g'irlash moslamasini o'z ichiga olgan oltita diodani ko'rsatib beradi.

Nazorat qilinmaydigan uch fazali ko'prikni to'g'rilash uchun oltita diod ishlatiladi va elektron yana oltita zarba soniga ega. Shu sababli, odatda oltita impulsli ko'prik deb ham ataladi. B6 sxemasini ikkita uchta impulsli markaziy zanjirlarning ketma-ket ulanishi sifatida soddalashtirilgan deb ko'rish mumkin.

Kam quvvatli dasturlar uchun ketma-ket ikkita diod, birinchi diyotning anodi ikkinchisining katodiga ulangan holda, shu maqsadda bitta komponent sifatida ishlab chiqariladi. Savdoda mavjud bo'lgan ikkita diodli to'rtta terminalning hammasi mavjud, shuning uchun foydalanuvchi ularni bir fazali bo'linish ta'minoti, yarim ko'prik yoki uch fazali rektifikator uchun sozlashi mumkin.

Yuqori quvvatli dasturlar uchun odatda ko'prikning oltita qo'lining har biri uchun bitta diskret moslama ishlatiladi. Eng yuqori quvvat uchun ko'prikning har bir qo'li parallel ravishda o'nlab yoki yuzlab alohida qurilmalardan iborat bo'lishi mumkin (bu erda juda yuqori oqim zarur, masalan alyuminiy eritish ) yoki ketma-ket (juda yuqori kuchlanish kerak bo'lgan joylarda, masalan yuqori voltli to'g'ridan-to'g'ri oqim elektr uzatish).

Uch fazali to'liq to'lqinli ko'prikni to'g'rilash davri (B6C) yordamida boshqariladi tiristorlar kommutatsiya elementlari sifatida, ta'minot indüktansını e'tiborsiz qoldiradi. V1-V6 tartibida tiristorlar urishi.

Pulsatsiyalanuvchi doimiy voltaj bir lahzali ijobiy va salbiy fazali kuchlanishlarning farqlaridan kelib chiqadi ${ displaystyle V _ { mathrm {LN}}}$, faza 30 ° ga siljigan:

O'rtacha chiqish quvvati uchun ideal, yuk ${ displaystyle V _ { mathrm {av}}}$ B6 davri davri davomiyligi bilan doimiy voltaj pulsining grafigi ostidagi integraldan kelib chiqadi ${ displaystyle { frac {1} {3}} pi}$ (60 ° dan 120 ° gacha) eng yuqori qiymati bilan ${ displaystyle { hat {v}} _ { mathrm {DC}} = { sqrt {3}} cdot V _ { mathrm {peak}}}$:

⇒ ${ displaystyle V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot { sqrt {3}} cdot { sqrt {2}} cdot V _ { mathrm {LN}}} { pi}}}$ ⇒ ${ displaystyle V _ { mathrm {av}} = { frac {3 cdot { sqrt {6}} cdot V _ { mathrm {LN}}} { pi}}}$ ≈ 2,34 ⋅ ${ displaystyle V _ { mathrm {LN}}}$

3 fazali o'zgaruvchan tok kiritish, yarim to'lqinli va to'liq to'lqinli rektifikatsiyalangan shahar chiqish to'lqin shakllari

Agar uch fazali ko'prikni to'g'rilash moslamasi nosimmetrik tarzda ishlasa (quvvat manbai ijobiy va salbiy bo'lsa), transformatorning markaziy nuqtasi (yoki neytral) qarama-qarshi tomonidagi rektifikatorning markaziy nuqtasi (yoki izolyatsiya qilingan mos yozuvlar potentsiali deb ataladi) dirijyor) uchburchak shaklida potentsial farqiga ega umumiy rejimdagi kuchlanish. Shu sababli, ushbu ikkita markaz hech qachon bir-biriga ulanmasligi kerak, aks holda qisqa tutashuvdagi oqimlar oqishi mumkin edi. The zamin nosimmetrik ishlashda uch fazali ko'prikni to'g'rilash moslamasi neytral o'tkazgichdan yoki er tarmoq voltajining Transformator tomonidan quvvat oladigan holda, ko'prikning markaziy nuqtasini topraklama mumkin, bunda transformatorning ikkilamchi o'rni elektr zo'riqishidan elektr bilan ajratib olinadi va ikkilamchi o'rashning yulduz nuqtasi er yuzida bo'lmaydi. Biroq, bu holda, (ahamiyatsiz) qochqin oqimlari transformator sariqlari bo'ylab oqadi.

Umumiy rejimdagi kuchlanish pulsatsiyalanuvchi doimiy voltajni hosil qiladigan ijobiy va salbiy fazalar orasidagi farqlarning tegishli o'rtacha qiymatlaridan kelib chiqadi. Delta kuchlanishining eng yuqori qiymati ${ displaystyle { hat {v}} _ { mathrm {common-mode}}}$ fazali kirish voltajining eng yuqori qiymatining amounts miqdori ${ displaystyle V _ { mathrm {peak}}}$ va bilan hisoblanadi ${ displaystyle V _ { mathrm {peak}}}$ davrning 60 ° da doimiy voltajining minus yarmi:

${ displaystyle { hat {v}} _ { mathrm {common-mode}} = V _ { mathrm {peak}} - { frac {{ sqrt {3}} cdot V _ { mathrm {peak} } cdot sin 60 ^ { circ}} {2}} = V _ { mathrm {peak}} cdot { Biggl (} 1 - { frac {{ sqrt {3}} cdot sin 60 ^ { circ}} {2}} { Biggl)}}$ = ${ displaystyle V _ { mathrm {peak}}}$ · 0,25

Umumiy rejimdagi kuchlanishning RMS qiymati uchburchak tebranishlari uchun form faktoridan hisoblanadi:

${ displaystyle V _ { mathrm {common-mode}} = { frac {{ hat {v}} _ { mathrm {common-mode}}} { sqrt {3}}}}$

Agar sxema assimetrik ravishda ishlasa (faqat bitta musbat qutbga ega oddiy besleme zo'riqishi sifatida), ikkala ijobiy va salbiy qutblar (yoki ajratilgan mos yozuvlar potentsiali) kirish voltajining markaziga (yoki erga) qarama-qarshi pulsatsiyalanadi va o'zgarishlar voltajlarining salbiy to'lqin shakllari. Shu bilan birga, o'zgarishlar kuchlanishidagi farqlar oltita impulsli shahar kuchlanishiga olib keladi (davr davomida). Transformator markazini manfiy qutbdan qat'iy ajratish (aks holda qisqa tutashuvdagi oqimlar oqadi) yoki ajratuvchi transformator bilan quvvat olganda manfiy qutbning mumkin bo'lgan topraklanması nosimmetrik ishlashga mos keladi.

Uch fazali ko'prikni to'g'rilash moslamasi boshqariladi

Boshqariladigan uch fazali ko'prikni to'g'irlash moslamasi diodlar o'rniga tiristorlardan foydalanadi. Chiqish kuchlanishi cos (a) faktor bilan kamayadi:

${ displaystyle V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot { sqrt {3}} cdot V _ { mathrm {peak}}} { pi} } cdot cos alfa}$

Yoki kirish voltajidan chiziqgacha ifodalangan:^[5]

${ displaystyle V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot V _ { mathrm {LLpeak}}} { pi}} cdot cos alpha}$

Qaerda:

V_LLpeak, kirish voltajini yo'naltirish uchun chiziqning eng yuqori qiymati,

V_tepalik, fazaning eng yuqori qiymati (chiziqdan neytralgacha) kirish voltajlari,

a, tiristorning otish burchagi (agar rektifikatsiyani amalga oshirish uchun diodlardan foydalanilsa 0)

Yuqoridagi tenglamalar faqat o'zgaruvchan tok manbaidan tok olinmasa yoki nazariy holatda o'zgaruvchan tok manbai ulanishlari indüktansga ega bo'lmaganda amal qiladi. Amalda, etkazib berish indüktansı, doimiy yuk ko'tarilganda, odatda, 10-20% oralig'ida doimiy ravishda chiqish voltajining pasayishiga olib keladi.

Ta'minot indüktansının ta'siri, uzatish jarayonini (kommutatsiya deb ataladi) bir bosqichdan ikkinchisiga sekinlashtirishdir. Natijada, juft qurilmalar orasidagi har bir o'tish paytida, ko'prikdagi uchta (ikkitadan emas) moslamalarni bir vaqtning o'zida o'tkazadigan bir-birining ustiga chiqish davri mavjud. Qatnashish burchagi odatda m (yoki u) belgisi bilan ataladi va to'liq yuklanganda 20 30 ° bo'lishi mumkin.

Ta'minot indüktansını hisobga olgan holda, rektifikatorning chiqish kuchlanishi quyidagicha kamayadi:

${ displaystyle V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot V _ { mathrm {LLpeak}}} { pi}} cdot cos ( alpha + mu)}$

Qoplanish burchagi m to'g'ridan-to'g'ri doimiy oqim bilan bog'liq va yuqoridagi tenglama quyidagicha ifodalanishi mumkin:

${ displaystyle {V _ { mathrm {dc}} = V _ { mathrm {av}} = { frac {3 cdot V _ { mathrm {LLpeak}}} { pi}} cdot cos ( alpha )} - {6fL _ { mathrm {c}} I _ { mathrm {d}}}}$

Qaerda:

L_v, o'zgarishlar uchun o'zgaruvchan indüktans

Men_d, to'g'ridan-to'g'ri oqim

Alpha = 0 ° da uch fazali Graets ko'prigi rektifikatori bir-birining ustiga chiqmasdan

Alpha = 0 ° da uch fazali Graetz ko'prigi rektifikatori, 20 ° qoplama burchagi bilan

Alpha = 20 ° da uch fazali boshqariladigan Graetz ko'prikni to'g'irlash moslamasi 20 ° ga teng

Alpha = 40 ° da uch fazali boshqariladigan Graetz ko'prikni to'g'irlash moslamasi 20 ° ga teng

O'n ikki pulsli ko'prik

O'n ikkita impulsli ko'prikni to'g'rilash vositasi tiristorlar kommutatsiya elementlari sifatida. Oltita impulsli ko'prikning biri juft raqamli tiristorlardan iborat, ikkinchisi - toq sonli to'plam.

Bir fazali rektifikatorlardan yoki uch fazali yarim to'lqinli rektifikatorlardan yaxshiroq bo'lishiga qaramay, oltita impulsli rektifikator sxemalari hali ham o'zgaruvchan tok va doimiy ulanishlarda sezilarli darajada harmonik buzilishlarni keltirib chiqaradi. Juda yuqori quvvatli rektifikatorlar uchun odatda o'n ikki pulsli ko'prik aloqasi ishlatiladi. O'n ikki pulsli ko'prik ketma-ket ulangan ikkita oltita pulsli ko'prikli zanjirlardan iborat bo'lib, ularning o'zgaruvchan tok ulanishlari ikkita ko'prik o'rtasida 30 ° fazali siljish hosil qiluvchi besleme transformatoridan oziqlanadi. Bu oltita impulsli ko'priklar ishlab chiqaradigan ko'plab o'ziga xos harmonikalarni bekor qiladi.

30 graduslik o'zgarishlar siljishiga odatda ikkilamchi sariqlarning ikkita to'plami, biri yulduz (vye) va delta aloqasi bo'lgan transformator yordamida erishiladi.

Kuchlanishni ko'paytiruvchi rektifikatorlar

O'zgaruvchan to'liq ko'prik / kuchlanishli dubler.

Oddiy yarim to'lqinli rektifikator diodlarni qarama-qarshi yo'nalishlarga yo'naltirilgan holda ikkita elektr konfiguratsiyasida qurilishi mumkin, bir versiyasi chiqadigan manfiy terminalni to'g'ridan-to'g'ri o'zgaruvchan tok manbaiga, ikkinchisi esa chiqadigan musbat terminali to'g'ridan-to'g'ri o'zgaruvchan tok bilan bog'laydi. . Ularning ikkalasini ham alohida chiqish tekislash bilan birlashtirib, chiqish voltajini deyarli ikki baravar yuqori o'zgaruvchan tok kuchlanishiga erishish mumkin. Bu shuningdek, o'rtada kranni ta'minlaydi, bu esa ajratilgan temir yo'lning elektr ta'minoti kabi sxemasidan foydalanishga imkon beradi.

Buning bir varianti shundaki, ko'prikni to'g'rilash moslamasida chiqishni tekislash uchun ketma-ket ikkita kondansatkichdan foydalanish, so'ngra ushbu kondansatörlerin o'rta nuqtasi va AC kirish terminallari o'rtasida kalitni o'rnatish kerak. Kalit ochilganda, ushbu sxema oddiy ko'prikni to'g'rilash vositasi kabi ishlaydi. Kalit yopiq holda, u kuchlanishni ikki baravar oshiruvchi rektifikator kabi ishlaydi. Boshqacha qilib aytganda, bu dunyodagi har qanday 120 V yoki 230 V tarmoq manbalaridan taxminan 320 V (± 15%) doimiy voltajni olishni osonlashtiradi, keyinchalik bu nisbatan sodda bo'lishi mumkin. yoqilgan quvvat manbai. Shu bilan birga, ma'lum bir kerakli dalgalanma uchun ikkala kondansatör qiymati oddiy ko'prikni to'g'rilash uchun zarur bo'lgan bitta qiymatdan ikki baravar ko'p bo'lishi kerak; tugmachani yopganda ularning har biri yarim to'lqinli rektifikatorning chiqishini filtrlashi kerak va kalit ochiq bo'lganda ikkita kondansatör ularning yarmining teng qiymatiga teng ketma-ket ulanadi.

Cockcroft Walton kuchlanish multiplikatori

Kuchaytirgichni hosil qilish uchun kaskadli diod va kondansatör bosqichlarini qo'shish mumkin (Cockroft-Walton davri ). Ushbu sxemalar amaldagi oqim quvvati va voltajni tartibga solish masalalari bilan cheklangan, doimiy oqim kuchlanishining potentsialini o'n baravar yuqori darajaga qadar ishlab chiqarishga qodir. Tez-tez kuchayib boruvchi bosqich yoki asosiy yuqori kuchlanish (HV) manbai sifatida ishlatiladigan diodli kuchlanish multiplikatorlari HV lazerli quvvat manbalarida, masalan, quvvat oluvchi qurilmalarda qo'llaniladi. katod nurlari naychalari (CRT) (CRT asosidagi televizion, radiolokatsion va sonar displeylarda bo'lgani kabi), tasvirni kuchaytiruvchi va foto multiplikatorli naychalarda (PMT) topilgan fotonni kuchaytiruvchi qurilmalar va magnitron asosidagi radio chastotali (chastotali) qurilmalar radar transmitterlari va mikroto'lqinli pechlarda. Yarimo'tkazgich elektronikasini joriy etishdan oldin, transformatorsiz vakuum trubkasi qabul qilgichlari to'g'ridan-to'g'ri AC quvvatidan quvvat oladigan, ba'zida 100-120 V elektr uzatish liniyasidan taxminan 300 VDC hosil qilish uchun kuchlanish dublörlaridan foydalanilgan.

Rektifikatorlarning miqdori

Ushbu bo'lim kamida uch fazali yarim to'lqinli va to'liq to'lqinli rektifikatsiya qilish uchun konversiya koeffitsientlari to'g'risida ma'lumot etishmayapti, chunki ushbu rektifikatorlar ushbu maqolada o'z bo'limlariga ega.. Iltimos, ushbu ma'lumotni kiritish uchun bo'limni kengaytiring. Qo'shimcha tafsilotlar munozara sahifasi. (2017 yil oktyabr)

Transformatorlardan foydalanish koeffitsienti (TUF), konversiya koeffitsienti (rektifikatorlar) funktsiyasini va ishlash ko'rsatkichlarini yoki ularning chiqishini hisoblash uchun bir nechta nisbatlar qo'llaniladi.η), dalgalanma koeffitsienti, form faktor va eng yuqori omil. Ikkala asosiy o'lchov - bu chiqish voltajining tarkibiy qismlari bo'lgan doimiy voltaj (yoki ofset) va eng yuqori pik to'lqinlanish kuchlanishi.

Konversiya koeffitsienti

Konversiya koeffitsienti ("rektifikatsiya koeffitsienti" va chalkashlik bilan "samaradorlik" deb ham ataladi) η doimiy oqim kuchining o'zgaruvchan tok manbaidan kirish quvvatiga nisbati sifatida aniqlanadi. Hatto ideal rektifikatorlar bilan ham bu nisbat 100% dan kam, chunki ba'zi chiqish quvvati doimiy oqimdan ko'ra o'zgaruvchan tok kuchiga ega bo'lib, ular doimiy ravishda to'lqin shakli ustiga o'rnatilgan dalgalanma sifatida namoyon bo'ladi. Dalgalanishni kamaytiradigan va shuning uchun chiqindining o'zgaruvchan tok miqdorini kamaytiradigan silliqlash sxemalari yordamida bu nisbat yaxshilanishi mumkin. Konversiya koeffitsienti transformator sarg'ishidagi yo'qotishlar va rektifikator elementining o'zida quvvat tarqalishi bilan kamayadi. Bu nisbat amaliy ahamiyatga ega emas, chunki rektifikator deyarli doimo doimiy voltajni oshirish va to'lqinlanishni kamaytirish uchun filtr bilan ta'minlanadi. Ba'zi uch fazali va ko'p fazali dasturlarda konversiya nisbati etarlicha yuqori bo'lib, tekislash sxemasi kerak emas.^[6]Boshqa mikrosxemalarda, masalan, yuk deyarli rezistent bo'lgan vakuum naychali elektronikadagi filamentli isitgich zanjirlari singari, rezistorlar ham o'zgaruvchan, ham doimiy quvvatni tarqatib yuborishi mumkin, shuning uchun hech qanday kuch yo'qolmaydi.

Yarim to'lqinli rektifikator uchun bu nisbat juda kamtar.

${ displaystyle P _ { mathrm {AC}} = {V _ { mathrm {peak}} over 2} cdot {I _ { mathrm {peak}} over 2}}$ (bo'linuvchilar o'rniga 2 ga teng √2 chunki salbiy yarim tsiklda quvvat berilmaydi)

${ displaystyle P _ { mathrm {DC}} = {V _ { mathrm {peak}} over pi} cdot {I _ { mathrm {peak}} over pi}}$

Shunday qilib yarim to'lqinli rektifikator uchun maksimal konversiya koeffitsienti quyidagicha:

${ displaystyle eta = {P _ { mathrm {DC}} over P _ { mathrm {AC}}} taxminan 40.5 \%}$

Xuddi shunday, to'liq to'lqinli rektifikator uchun,

${ displaystyle P _ { mathrm {AC}} = {V _ { mathrm {peak}} over { sqrt {2}}} cdot {I _ { mathrm {peak}} over { sqrt {2} }}}$

${ displaystyle P _ { mathrm {DC}} = {2 cdot V _ { mathrm {peak}} over pi} cdot {2 cdot I _ { mathrm {peak}} over pi}}$

${ displaystyle eta = {P _ { mathrm {DC}} over P _ { mathrm {AC}}} 81.0 \%}$

Uch fazali rektifikatorlar, ayniqsa uch fazali to'liq to'lqinli rektifikatorlar konvertatsiya qilish koeffitsientlariga ega, chunki dalgalanma ichki jihatdan kichikroq.

Uch fazali yarim to'lqinli rektifikator uchun

${ displaystyle P _ { mathrm {AC}} = 3 cdot {V _ { mathrm {peak}} over 2} cdot {I _ { mathrm {peak}} over 2}}$

${ displaystyle P _ { mathrm {DC}} = { frac {3 cdot { sqrt {3}} cdot V _ { mathrm {peak}}} {2 pi}} cdot { frac {3 cdot { sqrt {3}} cdot I _ { mathrm {peak}}} {2 pi}}}$

Uch fazali to'liq to'lqinli rektifikator uchun

${ displaystyle P _ { mathrm {AC}} = 3 cdot {V _ { mathrm {peak}} over { sqrt {2}}} cdot {I _ { mathrm {peak}} over { sqrt {2}}}}$

${ displaystyle P _ { mathrm {DC}} = { frac {3 cdot { sqrt {3}} cdot V _ { mathrm {peak}}} { pi}} cdot { frac {3 cdot { sqrt {3}} cdot I _ { mathrm {peak}}} { pi}}}$

Transformatordan foydalanish koeffitsienti

Rektifier zanjirining transformatordan foydalanish koeffitsienti (TUF) kirish qarshiligida mavjud bo'lgan doimiy quvvatning transformatorning chiqish bobini AC darajasiga nisbati sifatida aniqlanadi.^[7][8]

${ displaystyle T.U.F = { frac {P_ {odc}} { mathrm {VA rating of transformator}}}}$

The ${ displaystyle VA}$ transformatorning reytingini quyidagicha aniqlash mumkin: ${ displaystyle VA = V _ { mathrm {rms}} { nuqta {I}} _ { mathrm {rms}} ( mathrm {For secondary coil.})}$

Rektifikatorning kuchlanish pasayishi

Haqiqiy rektifikator xarakterli ravishda kirish voltajining bir qismini pasaytiradi (a kuchlanishning pasayishi, kremniy qurilmalari uchun odatda 0,7 volts plyus ekvivalent qarshilik, umuman chiziqsiz) va yuqori chastotalarda to'lqin shakllarini boshqa yo'llar bilan buzadi. Ideal rektifikatordan farqli o'laroq, u ba'zi kuchlarni tarqatadi.

Ko'pgina rektifikatsiya qilishning bir jihati - bu diodalarda o'rnatilgan voltaj tushishi (oddiy kremniy uchun 0,7 V atrofida) tufayli yuqori kirish voltajidan eng yuqori chiqish voltajigacha bo'lgan yo'qotish. p – n birikmasi diodlar va 0,3 V uchun Shotki diodalari ). Yarim to'lqinli rektifikatsiya va markaziy tejamkor ikkilamchi yordamida to'liq to'lqinli rektifikatsiya bitta diyot tushishining eng yuqori kuchlanish yo'qolishini keltirib chiqaradi. Ko'prikni to'g'rilashda ikkita diodli tomchilar yo'qoladi. Bu chiqish voltajini pasaytiradi va juda past o'zgaruvchan kuchlanishni to'g'rilash zarur bo'lsa, mavjud chiqish kuchlanishini cheklaydi. Diyotlar ushbu kuchlanishdan past darajada harakat qilmagani uchun, zanjir faqat har yarim tsiklning bir qismi uchun oqim o'tkazib, nol kuchlanishning qisqa bo'laklarini (bu erda bir lahzali kirish kuchlanishi bir yoki ikkita diod tushishidan past) har bir "bo'rtma" o'rtasida paydo bo'lishiga olib keladi. ".

Peak yo'qotish past kuchlanishli rektifikatorlar uchun juda muhimdir (masalan, 12 V yoki undan kam), lekin HVDC elektr uzatish tizimlari kabi yuqori voltli dasturlarda ahamiyatsiz.

Garmonik buzilish

Rostlagichlar kabi chiziqli bo'lmagan yuklar o'zgaruvchan xatti-harakatlar tufayli o'zgaruvchan tok tomonidagi manba chastotasining oqim oqim harmonikalarini va shahar tomonidagi manba chastotasining kuchlanish harmonikalarini ishlab chiqaradi.

Rektifiyerning chiqishini tekislash

Tenglashtiruvchi kondansatkichli yarim to'lqinli rektifikatorning o'zgaruvchan tok manbai (sariq) va doimiy chiqishi (yashil). DC signalidagi dalgalanmaya e'tibor bering.

Yarim to'lqinli va to'liq to'lqinli rektifikatsiya bir yo'nalishli oqimni etkazib berganda ham, doimiy voltaj hosil qilmaydi. Katta o'zgaruvchan tok mavjud dalgalanma yarim to'lqinli rektifikator uchun manba chastotasidagi kuchlanish komponenti va to'liq to'lqinli rektifikator uchun manba chastotasidan ikki baravar yuqori. Dalgalanma kuchlanishi odatda tepalikdan tepaga qadar belgilanadi. Rektifikatsiyalangan o'zgaruvchan tok manbaidan doimiy doimiy tok ishlab chiqarish uchun tekislash davri yoki kerak filtr. Eng sodda shaklda bu faqat kondansatör (filtr, rezervuar yoki yumshatuvchi kondansatör deb ham ataladi), bo'g'uvchi, qarshilik, Zener diodasi va qarshiligi yoki rektifikatorning chiqishiga joylashtirilgan voltaj regulyatori bo'lishi mumkin. Amalda, yumshatuvchi filtrlarning aksariyati to'lqinlanish kuchlanishini zanjir tomonidan bardoshli darajaga qadar samarali ravishda kamaytirish uchun bir nechta komponentlardan foydalanadi.

Parallel RC shunt filtrli to'liq to'lqinli diodli ko'prikli rektifikator

Filtrni kondansatörü o'zgaruvchan tok manbai hech qanday quvvat bermasa, ya'ni o'zgaruvchan tok manbai tok oqimining yo'nalishini o'zgartirganda o'zgaruvchan tok davrining bir qismida o'z energiyasini chiqaradi.

Kam impedansli manba bilan ishlash

Yuqoridagi diagrammada suv omborining nolga yaqin ishlashi ko'rsatilgan empedans manba, masalan, elektr ta'minoti. Tuzatuvchi sifatida Kuchlanish ortadi, u kondansatkichni zaryad qiladi va etkazib beradi joriy yukga. Chorak tsiklining oxirida kondansatör rektifikator kuchlanishining eng yuqori Vp qiymatiga zaryadlanadi. Shundan so'ng, rektifikator voltaji keyingi chorak tsikliga kirganda minimal qiymati Vmingacha pasayishni boshlaydi. Bu kondansatörün yuk orqali tushirilishini boshlaydi.

Kondensatorning kattaligi toqat qilinishi mumkin bo'lgan r miqdori bilan aniqlanadi, bu erda r = (Vp-Vmin) / Vp.^[9]

Ushbu sxemalar juda tez-tez oziqlanadi transformatorlar va muhim ahamiyatga ega qarshilik. Transformatorning qarshiligi rezervuar kondansatörünün to'lqin shaklini o'zgartiradi, eng yuqori kuchlanishni o'zgartiradi va tartibga solish masalalarini kiritadi.

Kondansatör kiritish filtri

Ma'lum bir yuk uchun, yumshatuvchi kondansatörning o'lchamlari dalgalanma voltajini kamaytirish va to'lqin oqimini oshirish o'rtasidagi o'zaro bog'liqlikdir. Tepalik oqim transformator sargilarining qarshiligi kamaygan holda keladigan sinus to'lqinning ko'tarilgan chetiga besleme zo'riqishining ko'tarilish tezligi bilan belgilanadi. Yuqori to'lqin oqimlari I ni oshiradi²Kondensator, rektifikator va transformator sargilaridagi R yo'qotishlari (issiqlik ko'rinishida) va komponentlarning kuchliligidan yoki transformatorning VA darajasidan oshib ketishi mumkin. Vakuum naychali rektifikatorlar kirish kondansatörünün maksimal sig'imini belgilaydi va SS diodli rektifikatorlari ham joriy cheklovlarga ega. Ushbu dastur uchun kondansatörler past bo'lishi kerak ESR yoki dalgalanma oqimi ularni qizib ketishi mumkin. Dalgalanma voltajini belgilangan qiymatga cheklash uchun zarur bo'lgan kondansatör hajmi yuk oqimiga mutanosib va ​​besleme chastotasi va kirish tsikli bo'yicha rektifikatorning chiqish tepaliklari soniga teskari proportsionaldir. To'liq to'lqinli rektifikatsiyalangan chiqish uchun kichikroq kondansatör kerak, chunki u yarim to'lqinli rektifikatsiyalangan chiqish chastotasining ikki baravariga teng. Bitta kondansatör bilan to'lqinlanishni qoniqarli chegaraga kamaytirish uchun ko'pincha amaliy bo'lmagan hajmdagi kondansatör kerak bo'ladi. Buning sababi shundaki, kondansatörün dalgalanma tok kuchi hajmi bilan chiziqli ravishda ortmaydi va balandlik cheklovlari ham bo'lishi mumkin. Yuqori joriy dasturlar o'rniga kondensatorlarning banklari ishlatiladi.

Chokni kiritish filtri

Bundan tashqari, rektifikatsiya qilingan to'lqin shaklini a ga qo'yish mumkin siqish filtri. Ushbu sxemaning afzalligi shundaki, oqim to'lqin shakli yumshoqroq bo'ladi: har bir yarim tsikldagi kondansatör kirish filtridagi kabi o'zgaruvchan tok kuchlanishining eng yuqori nuqtalarida pulslarda tortish o'rniga, oqim butun tsiklda olinadi. Kamchilik shundaki, kuchlanish chiqishi ancha past - o'zgaruvchan tokning yarim tsiklining o'rtacha darajasi; bu RMS kuchlanishining 90% ga nisbatan ${ displaystyle { sqrt {2}}}$ kondansatör kirish filtri uchun RMS kuchlanishidan (tushirilgan) marta. Buning o'rnini bosish yuqori voltaj regulyatsiyasi va mavjud bo'lgan yuqori oqimdir, bu esa quvvat manbai komponentlariga eng yuqori kuchlanish va to'lqin oqimining talablarini kamaytiradi. Induktorlar talab qiladi yadrolari temir yoki boshqa magnit materiallardan tayyorlang va og'irlik va hajmni qo'shing. Shuning uchun ularni elektron uskunalar uchun quvvat manbalarida ishlatish voltaj regulyatorlari kabi yarimo'tkazgichli davrlar foydasiga kamayib ketdi.^[10]

Kirish filtri sifatida qarshilik

Batareyani zaryadlovchi qurilmalar singari to'lqinlanish kuchi ahamiyatsiz bo'lgan hollarda, kirish filtri chiqish kuchlanishini zanjir talab qiladigan darajada sozlash uchun bitta ketma-ket qarshilik bo'lishi mumkin. Qarshilik chiqish voltajini ham, to'lqinlanish kuchlanishini ham mutanosib ravishda kamaytiradi. Rezistorli kirish filtrining kamchiligi shundaki, u yuk uchun mavjud bo'lmagan chiqindi issiqlik shaklida quvvat sarflaydi, shuning uchun u faqat past oqim davrlarida ishlaydi.

Yuqori darajadagi va kaskadli filtrlar

To further reduce ripple, the initial filter element may be followed by additional alternating series and shunt filter components, or by a voltage regulator. Series filter components may be resistors or chokes; shunt elements may be resistors or capacitors. The filter may raise DC voltage aswell as reduce ripple. Filters are often constructed from pairs of series/shunt components called RC (series resistor, shunt capacitor) or LC (series choke, shunt capacitor) sections. Two common filter geometries are known as Pi (capacitor, choke, capacitor) and T (choke, capacitor, choke) filters.Sometimes the series elements are resistors - because resistors are smaller and cheaper - when a lower DC output is desirable or permissible. Anotherkind of special filter geometry is a series resonant choke or tuned choke filter. Unlike the other filter geometries which are low-pass filters, a resonant choke filter is a band-stop filter: it is a parallel combination of choke and capacitor which resonates at the frequency of the ripple voltage, presenting a very high impedance to the ripple. It may be followed by a shunt capacitor to complete the filter.

Voltaj regulyatorlari

A more usual alternative to additional filter components, if the DC load requires very low ripple voltage, is to follow the input filter with a voltage regulator. A voltage regulator operates on a different principle than a filter, which is essentially a voltage divider that shunts voltage at the ripple frequency away from the load. Rather, a regulator increases or decreases current supplied to the load in order to maintain a constant output voltage.

A simple passive shunt voltage regulator may consist of a series resistor to drop source voltage to the required level and a Zener diodi shunt with reversevoltage equal to the set voltage. When input voltage rises, the diode dumps current to maintain the set output voltage. This kind of regulator is usually employed only in low voltage, low current circuits because Zener diodes have both voltage and current limitations. It is also very inefficient, because it dumps excess current, which is not available to the load.

A more efficient alternative to a shunt voltage regulator is an active voltage regulator elektron. An active regulator employs reactive components to store and discharge energy, so that most or all current supplied by the rectifier is passed to the load. It may also use negative and positive feedback in conjunction with at least one voltage amplifying component like a transistor to maintain output voltage when source voltage drops. The input filter must prevent the troughs of the ripple dropping below the minimum voltage required by the regulator to produce the required output voltage. The regulator serves both to significantly reduce the ripple and to deal with variations in supply and load characteristics.

Ilovalar

The primary application of rectifiers is to derive DC power from an AC supply (AC to DC converter). Rectifiers are used inside the power supplies of virtually all electronic equipment. AC/DC power supplies may be broadly divided into linear quvvat manbalari va yoqilgan quvvat manbalari. In such power supplies, the rectifier will be in series following the transformer, and be followed by a smoothing filter and possibly a voltage regulator.

Converting DC power from one voltage to another is much more complicated. One method of DC-to-DC conversion first converts power to AC (using a device called an inverter ), then uses a transformer to change the voltage, and finally rectifies power back to DC. A frequency of typically several tens of kilohertz is used, as this requires much smaller inductance than at lower frequencies and obviates the use of heavy, bulky, and expensive iron-cored units. Another method of converting DC voltages uses a zaryad nasosi, using rapid switching to change the connections of capacitors; this technique is generally limited to supplies up to a couple of watts, owing to the size of capacitors required.

Output voltage of a full-wave rectifier with controlled thyristors

Rectifiers are also used for aniqlash ning amplitude modulated radio signals. The signal may be amplified before detection. If not, a very low voltage drop diode or a diode biased with a fixed voltage must be used. When using a rectifier for demodulation the capacitor and load resistance must be carefully matched: too low a capacitance makes the high frequency carrier pass to the output, and too high makes the capacitor just charge and stay charged.

Rectifiers supply polarised voltage for payvandlash. In such circuits control of the output current is required; this is sometimes achieved by replacing some of the diodes in a ko'prikni to'g'irlovchi bilan tiristorlar, effectively diodes whose voltage output can be regulated by switching on and off with phase fired controllers.

Thyristors are used in various classes of temir yo'l harakatlanuvchi tarkib systems so that fine control of the traction motors can be achieved. Darvozani o'chirish tiristorlari are used to produce alternating current from a DC supply, for example on the Eurostar Trains to power the three-phase traction motors.^[11]

Rectification technologies

Elektromekanik

Before about 1905 when tube type rectifiers were developed, power conversion devices were purely electro-mechanical in design. Mechanical rectifiers used some form of rotation or resonant vibration driven by electromagnets, which operated a switch or commutator to reverse the current.

These mechanical rectifiers were noisy and had high maintenance requirements. The moving parts had friction, which required lubrication and replacement due to wear. Opening mechanical contacts under load resulted in electrical arcs and sparks that heated and eroded the contacts. They also were not able to handle AC chastotalar above several thousand cycles per second.

Synchronous rectifier

To convert alternating into direct current in elektrovozlar, a synchronous rectifier may be used.^{[iqtibos kerak ]} It consists of a synchronous motor driving a set of heavy-duty electrical contacts. The motor spins in time with the AC frequency and periodically reverses the connections to the load at an instant when the sinusoidal current goes through a zero-crossing. The contacts do not have to almashtirish a large current, but they must be able to olib yurmoq a large current to supply the locomotive's DC tortish dvigatellari.

Vibrating rectifier

A vibrator battery charger from 1922. It produced 6 A DC at 6 V to charge automobile batteries.

These consisted of a resonant qamish, vibrated by an alternating magnetic field created by an AC elektromagnit, with contacts that reversed the direction of the current on the negative half cycles. They were used in low power devices, such as batareyani zaryadlovchi, to rectify the low voltage produced by a step-down transformer. Another use was in battery power supplies for portable vacuum tube radios, to provide the high DC voltage for the tubes. These operated as a mechanical version of modern solid state switching invertorlar, with a transformer to step the battery voltage up, and a set of vibrator contacts on the transformer core, operated by its magnetic field, to repeatedly break the DC battery current to create a pulsing AC to power the transformer. Then a second set of rectifier contacts ustida vibrator rectified the high AC voltage from the transformer secondary to DC.

Motor-generator set

A small motor-generator set

A motor-generator set, or the similar aylanadigan konvertor, is not strictly a rectifier as it does not actually tuzatish current, but rather hosil qiladi DC from an AC source. In an "M-G set", the shaft of an AC motor is mechanically coupled to that of a DC generator. The DC generator produces multiphase alternating currents in its armatura windings, which a komutator on the armature shaft converts into a direct current output; yoki a homopolar generator produces a direct current without the need for a commutator. M-G sets are useful for producing DC for railway traction motors, industrial motors and other high-current applications, and were common in many high-power D.C. uses (for example, carbon-arc lamp projectors for outdoor theaters) before high-power semiconductors became widely available.

Elektrolitik

The elektrolitik rektifikator^[12] was a device from the early twentieth century that is no longer used. A home-made version is illustrated in the 1913 book Bola mexanikasi^[13] but it would be suitable for use only at very low voltages because of the low buzilish kuchlanishi va xavfi elektr toki urishi. A more complex device of this kind was patented by G. W. Carpenter in 1928 (US Patent 1671970).^[14]

When two different metals are suspended in an electrolyte solution, direct current flowing one way through the solution sees less resistance than in the other direction. Electrolytic rectifiers most commonly used an aluminum anode and a lead or steel cathode, suspended in a solution of tri-ammonium ortho-phosphate.

The rectification action is due to a thin coating of aluminum hydroxide on the aluminum electrode, formed by first applying a strong current to the cell to build up the coating. The rectification process is temperature-sensitive, and for best efficiency should not operate above 86 °F (30 °C). Shuningdek, a buzilish kuchlanishi where the coating is penetrated and the cell is short-circuited. Electrochemical methods are often more fragile than mechanical methods, and can be sensitive to usage variations, which can drastically change or completely disrupt the rectification processes.

Similar electrolytic devices were used as lightning arresters around the same era by suspending many aluminium cones in a tank of tri-ammonium ortho-phosphate solution. Unlike the rectifier above, only aluminium electrodes were used, and used on A.C., there was no polarization and thus no rectifier action, but the chemistry was similar.^[15]

Zamonaviy elektrolitik kondansatör, an essential component of most rectifier circuit configurations was also developed from the electrolytic rectifier.

Plasma type

Ning rivojlanishi vakuum trubkasi technology in the early 20th century resulted in the invention of various tube-type rectifiers, which largely replaced the noisy, inefficient mechanical rectifiers.

Mercury-arc

Early 3-phase industrial mercury vapor rectifier tube

150 kV mercury-arc valve da Manitoba Hydro power station, Radisson, Canada converted AC gidroenergetika to DC for transmission to distant cities.

A rectifier used in high-voltage direct current (HVDC) power transmission systems and industrial processing between about 1909 to 1975 is a mercury-arc rectifier yoki mercury-arc valve. The device is enclosed in a bulbous glass vessel or large metal tub. One electrode, the katod, is submerged in a pool of liquid mercury at the bottom of the vessel and one or more high purity graphite electrodes, called anodlar, are suspended above the pool. There may be several auxiliary electrodes to aid in starting and maintaining the arc. When an electric arc is established between the cathode pool and suspended anodes, a stream of electrons flows from the cathode to the anodes through the ionized mercury, but not the other way (in principle, this is a higher-power counterpart to flame rectification, which uses the same one-way current transmission properties of the plasma naturally present in a flame).

These devices can be used at power levels of hundreds of kilowatts, and may be built to handle one to six phases of AC current. Mercury-arc rectifiers have been replaced by silicon semiconductor rectifiers and high-power tiristor circuits in the mid 1970s. The most powerful mercury-arc rectifiers ever built were installed in the Manitoba Hydro Nelson daryosi Bipol HVDC project, with a combined rating of more than 1 GW and 450 kV.^[16][17]

Argon gas electron tube

Tungar bulbs from 1917, 2 ampere (chapda) and 6 ampere

The General Electric Tungar rectifier was a simob bug'i (ex.:5B24) or argon (ex.:328) gas-filled electron tube device with a tungsten filament cathode and a carbon button anode. It operated similarly to the thermionic vacuum tube diode, but the gas in the tube ionized during forward conduction, giving it a much lower forward voltage drop so it could rectify lower voltages. It was used for battery chargers and similar applications from the 1920s until lower-cost metal rectifiers, and later semiconductor diodes, supplanted it. These were made up to a few hundred volts and a few amperes rating, and in some sizes strongly resembled an akkor chiroq with an additional electrode.

The 0Z4 was a gas-filled rectifier tube commonly used in vakuum trubkasi car radios in the 1940s and 1950s. It was a conventional full-wave rectifier tube with two anodes and one cathode, but was unique in that it had no filament (thus the "0" in its type number). The electrodes were shaped such that the reverse breakdown voltage was much higher than the forward breakdown voltage. Once the breakdown voltage was exceeded, the 0Z4 switched to a low-resistance state with a forward voltage drop of about 24 V.

Diode vacuum tube (valve)

Vacuum tube diodes

The termionik vakuum trubkasi diyot, dastlab Fleming valfi, was invented by John Ambrose Fleming in 1904 as a detector for radio waves in radio receivers, and evolved into a general rectifier. It consisted of an evacuated glass bulb with a filament heated by a separate current, and a metal plate anod. The filament emitted elektronlar tomonidan termion emissiya (the Edison effect), discovered by Tomas Edison in 1884, and a positive voltage on the plate caused a current of electrons through the tube from filament to plate. Since only the filament produced electrons, the tube would only conduct current in one direction, allowing the tube to rectify an alternating current.

Thermionic diode rectifiers were widely used in power supplies in vacuum tube consumer electronic products, such as phonographs, radios, and televisions, for example the Hammasi Amerika beshligi radio receiver, to provide the high DC plate voltage needed by other vacuum tubes. "Full-wave" versions with two separate plates were popular because they could be used with a center-tapped transformer to make a full-wave rectifier. Vacuum tube rectifiers were made for very high voltages, such as the high voltage power supply for the katod nurlari trubkasi ning televizor receivers, and the kenotron used for power supply in Rentgen uskunalar. However, compared to modern semiconductor diodes, vacuum tube rectifiers have high internal resistance due to kosmik zaryad and therefore high voltage drops, causing high power dissipation and low efficiency. They are rarely able to handle currents exceeding 250 mA owing to the limits of plate power dissipation, and cannot be used for low voltage applications, such as battery chargers. Another limitation of the vacuum tube rectifier is that the heater power supply often requires special arrangements to insulate it from the high voltages of the rectifier circuit.

Qattiq holat

Kristal detektori

Galena cat's whisker detector

The crystal detector was the earliest type of semiconductor diode. Tomonidan ixtiro qilingan Jagadish Chandra Bose tomonidan ishlab chiqilgan G. W. Pickard starting in 1902, it was a significant improvement over earlier detectors such as the coherer. The crystal detector was widely used prior to vacuum tubes becoming available. One popular type of crystal detector, often called a cat's whisker detector, consists of a crystal of some yarim o'tkazgich mineral, odatda galena (lead sulfide), with a light springy wire touching its surface. Its fragility and limited current capability made it unsuitable for power supply applications. In the 1930s, researchers miniaturized and improved the crystal detector for use at microwave frequencies.

Selenium and copper oxide rectifiers

Selenium rectifier

Once common until replaced by more compact and less costly silicon solid-state rectifiers in the 1970s, these units used stacks of oxide-coated metal plates and took advantage of the yarim o'tkazgich xususiyatlari selen or copper oxide.^[18] Esa selen rektifikatorlari were lighter in weight and used less power than comparable vacuum tube rectifiers, they had the disadvantage of finite life expectancy, increasing resistance with age, and were only suitable to use at low frequencies. Both selenium and copper oxide rectifiers have somewhat better tolerance of momentary voltage transients than silicon rectifiers.

Typically these rectifiers were made up of stacks of metal plates or washers, held together by a central bolt, with the number of stacks determined by voltage; each cell was rated for about 20 V. An automotive battery charger rectifier might have only one cell: the high-voltage power supply for a vakuum trubkasi might have dozens of stacked plates. Current density in an air-cooled selenium stack was about 600 mA per square inch of active area (about 90 mA per square centimeter).

Silicon and germanium diodes

A variety of silicon diodes of different current ratings. Chapda a ko'prikni to'g'irlovchi. On the 3 center diodes, a painted band identifies the cathode terminal

Silikon diodes are the most widely used rectifiers for lower voltages and powers, and have largely replaced other rectifiers. Due to their substantially lower forward voltage (0.3V versus 0.7V for silicon diodes) germanium diodes have an inherent advantage over silicon diodes in low voltage circuits.

High power: thyristors (SCRs) and newer silicon-based voltage sourced converters

Two of three high-power thyristor valve stacks used for long-distance transmission of power from Manitoba Hydro to'g'onlar. Compare with mercury-arc system from the same dam-site, above.

In high-power applications, from 1975 to 2000, most mercury valve arc-rectifiers were replaced by stacks of very high power tiristorlar, silicon devices with two extra layers of semiconductor, in comparison to a simple diode.

In medium-power transmission applications, even more complex and sophisticated voltage sourced converter (VSC) silicon semiconductor rectifier systems, such as insulated gate bipolar transistors (IGBT) va gate turn-off thyristors (GTO), have made smaller high voltage DC power transmission systems economical. All of these devices function as rectifiers.

2009 yildan boshlab^[yangilash] it was expected that these high-power silicon "self-commutating switches", in particular IGBTs and a variant thyristor (related to the GTO) called the integrated gate-commutated thyristor (IGCT), would be scaled-up in power rating to the point that they would eventually replace simple thyristor-based AC rectification systems for the highest power-transmission DC applications.^[19]

Active rectifier

Voltage drop across a diode and a MOSFET. The low on-resistance property of a MOSFET reduces ohmic losses compared to the diode rectifier (below 32 A in this case), which exhibits a significant voltage drop even at very low current levels. Paralleling two MOSFETs (pink curve) reduces the losses further, whereas paralleling several diodes won't significantly reduce the forward-voltage drop.

Active rectification is a technique for improving the efficiency of rectification by replacing diodlar with actively controlled switches such as tranzistorlar, odatda quvvat MOSFET-lari yoki power BJTs.^[20] Whereas normal semiconductor diodes have a roughly fixed voltage drop of around 0.5-1 volts, active rectifiers behave as resistances, and can have arbitrarily low voltage drop.

Historically, vibrator driven switches or motor-driven komutatorlar have also been used for mechanical rectifiers and synchronous rectification.^[21]

Active rectification has many applications. It is frequently used for arrays of photovoltaic panels to avoid reverse current flow that can cause overheating with partial shading while giving minimum power loss.

Hozirgi tadqiqotlar

A major area of research is to develop higher frequency rectifiers, that can rectify into terahertz and light frequencies. These devices are used in optik geterodinni aniqlash, which has myriad applications in optik tolalar communication and atom soatlari. Another prospective application for such devices is to directly rectify light waves picked up by tiny antennalar, deb nomlangan nantennas, to produce DC electric power.^[22] It is thought that arrays of antennas could be a more efficient means of producing quyosh energiyasi dan quyosh xujayralari.

A related area of research is to develop smaller rectifiers, because a smaller device has a higher cutoff frequency. Research projects are attempting to develop a unimolecular rectifier, bitta organik molekula that would function as a rectifier.

Shuningdek qarang

• AC adapter
• Karl Ferdinand Braun (point-contact rectifier, 1874)
• Nozik rektifikator
• Rectiformer
• Vena rektifikatori

Adabiyotlar