Zofunikira zamagetsi zamagetsi zakuthamangitsa mwachanguQC imagwiritsa ntchito flyback + yachiwiri mbali (yachiwiri) synchronous rectification SSR. Kwa otembenuza ma flyback, malinga ndi njira yowonetsera ndemanga, akhoza kugawidwa mu: malamulo oyambira (oyambirira) ndi malamulo achiwiri (achiwiri); malinga ndi malo a PWM controller. Itha kugawidwa mu: kuwongolera mbali yoyamba (yoyambirira) ndi mbali yachiwiri (yachiwiri). Zikuwoneka kuti palibe chochita ndi MOSFET. Choncho,Olukeyayenera kufunsa: Kodi MOSFET yabisidwa kuti? Kodi chinachita mbali yotani?
1. Kusintha kwa mbali ya pulayimale (choyambirira) ndi kusintha kwachiwiri (kwachiwiri).
Kukhazikika kwa voliyumu yotulutsa kumafuna ulalo woyankha kuti atumize zidziwitso zake zosintha kwa wowongolera wamkulu wa PWM kuti asinthe kusintha kwa voliyumu yolowera ndi katundu wotuluka. Malingana ndi njira zosiyanasiyana zowonetsera ndemanga, zikhoza kugawidwa m'mbali zoyambira (zoyambirira) ndi kusintha kwachiwiri (kwachiwiri), monga momwe zikuwonetsera pazithunzi 1 ndi 2.
Chidziwitso chazomwe zimayendera mbali yoyambira (yoyambirira) sichimatengedwa mwachindunji kuchokera kumagetsi otulutsa, koma kuchokera pamapiritsi othandizira kapena mapindikidwe oyambira omwe amasunga ubale wina wake ndi voteji. Makhalidwe ake ndi awa:
① Njira yoyankhira mosalunjika, kusamalidwa bwino komanso kusalondola bwino;
②. Zosavuta komanso zotsika mtengo;
③. Palibe chifukwa chodzipatula optocoupler.
Chidziwitso chowongolera mbali yachiwiri (yachiwiri) chimatengedwa mwachindunji kuchokera kumagetsi otulutsa pogwiritsa ntchito optocoupler ndi TL431. Makhalidwe ake ndi awa:
① Njira yoyankhira mwachindunji, kuchuluka kwamayendedwe abwino, kuwongolera mizere, komanso kulondola kwambiri;
②. Dera lokonzekera ndilovuta komanso lokwera mtengo;
③. Ndikofunikira kudzipatula optocoupler, yomwe imakhala ndi mavuto okalamba pakapita nthawi.
2. Kuwongolera mbali yachiwiri (yachiwiri) diode ndiMOSFETsynchronous rectification SSR
Mbali yachiwiri (yachiwiri) ya chosinthira cha flyback nthawi zambiri imagwiritsa ntchito kukonzanso kwa diode chifukwa cha kutulutsa kwakukulu komwe kumathamangitsa mwachangu. Makamaka pakulipiritsa kwachindunji kapena kuthamangitsa kung'anima, zotulutsa zomwe zimatuluka zimafika mpaka 5A. Pofuna kukonza bwino, MOSFET imagwiritsidwa ntchito m'malo mwa diode ngati rectifier, yomwe imatchedwa yachiwiri (yachiwiri) synchronous rectification SSR, monga momwe zikuwonetsera mu Zithunzi 3 ndi 4.
Mawonekedwe a mbali yachiwiri (yachiwiri) kukonzanso diode:
①. Zosavuta, palibe chowongolera chowonjezera chomwe chimafunikira, ndipo mtengo wake ndi wotsika;
② Pamene linanena bungwe panopa lalikulu, dzuwa ndi otsika;
③. Kudalirika kwakukulu.
Zomwe zili mbali yachiwiri (yachiwiri) MOSFET synchronous rectification:
①. Zovuta, zomwe zimafuna chowongolera chowonjezera ndi mtengo wokwera;
②. Pamene linanena bungwe panopa lalikulu, dzuwa ndi mkulu;
③. Poyerekeza ndi ma diode, kudalirika kwawo kumakhala kochepa.
M'magwiritsidwe ntchito, MOSFET ya synchronous rectification SSR nthawi zambiri imasunthidwa kuchokera kumapeto mpaka kumapeto kuti athe kuyendetsa galimoto, monga momwe tawonetsera pa Chithunzi 5.
Makhalidwe a MOSFET apamwamba kwambiri a synchronous rectification SSR:
①. Pamafunika bootstrap galimoto kapena zoyandama galimoto, amene ndi okwera mtengo;
②. EMI yabwino.
Makhalidwe a synchronous rectification SSR MOSFET yoyikidwa kumapeto otsika:
① Kuyendetsa molunjika, kuyendetsa kosavuta komanso mtengo wotsika;
②. EMI yoyipa.
3. Ulamuliro wa mbali yoyamba (yoyambirira) ndi yachiwiri (yachiwiri).
Woyang'anira wamkulu wa PWM amayikidwa kumbali yoyamba (yoyambirira). Kapangidwe kameneka kamatchedwa “primary side” (primary) control. Pofuna kuwongolera kulondola kwamagetsi otulutsa, kuchuluka kwa kasamalidwe ka katundu, komanso kuwongolera kwa mzere, mbali yayikulu (yoyambirira) kuwongolera kumafuna optocoupler yakunja ndi TL431 kuti apange ulalo woyankha. Dongosolo la bandwidth ndi laling'ono ndipo liwiro loyankhira limachedwa.
Ngati wolamulira wamkulu wa PWM ayikidwa kumbali yachiwiri (yachiwiri), optocoupler ndi TL431 akhoza kuchotsedwa, ndipo mphamvu yotulutsa mphamvu imatha kuyendetsedwa mwachindunji ndikusinthidwa ndikuyankha mofulumira. Kapangidwe kameneka kamatchedwa kulamulira kwachiwiri (kwachiwiri).
Mawonekedwe a gawo loyambirira (loyamba) kuwongolera:
①. Optocoupler ndi TL431 amafunikira, ndipo liwiro loyankhira limachedwa;
②. Kuthamanga kwa chitetezo chotuluka kumachedwa.
③. Mu njira yosinthira yosinthika CCM, mbali yachiwiri (yachiwiri) imafuna chizindikiro cholumikizira.
Mawonekedwe achiwiri (achiwiri) kuwongolera:
①. Kutulutsa kumawonekera mwachindunji, palibe optocoupler ndi TL431 omwe amafunikira, liwiro la kuyankha kuli mwachangu, ndipo liwiro lachitetezo limakhala lothamanga;
②. Mbali yachiwiri (yachiwiri) synchronous rectification MOSFET imayendetsedwa mwachindunji popanda kufunikira kwa ma siginecha olumikizana; zida zowonjezera monga ma pulse transformers, maginito couplings kapena capacitive couplers zimafunikira kuti zitumize ma siginecha oyendetsa mbali yoyambira (primary) high-voltage MOSFET.
③. Mbali yoyamba (yoyambirira) imafunikira dera loyambira, kapena yachiwiri (yachiwiri) ili ndi magetsi othandizira poyambira.
4. Mayendedwe a CCM mosalekeza kapena mawonekedwe a DCM osapitilira
The flyback converter imatha kugwira ntchito mosalekeza CCM mode kapena discontinuous DCM mode. Ngati mafunde achiwiri (wachiwiri) akufika pa 0 kumapeto kwa kusintha kosinthika, amatchedwa discontinuous DCM mode. Ngati mphepo yamkuntho yachiwiri (yachiwiri) siili 0 kumapeto kwa kusintha kosinthika, imatchedwa kuti CCM yopitilira, monga momwe zikuwonetsera pazithunzi 8 ndi 9.
Zitha kuwoneka kuchokera ku Chithunzi 8 ndi Chithunzi 9 kuti maiko ogwira ntchito a synchronous rectification SSR ndi osiyana m'njira zosiyanasiyana zogwiritsira ntchito flyback converter, zomwe zikutanthauzanso kuti njira zowongolera za synchronous rectification SSR zidzakhalanso zosiyana.
Ngati nthawi yakufa imanyalanyazidwa, pogwira ntchito mosalekeza mu CCM mode, synchronous rectification SSR ili ndi zigawo ziwiri:
①. Mbali yoyamba (yoyambirira) yothamanga kwambiri MOSFET imayatsidwa, ndipo mbali yachiwiri (yachiwiri) yogwirizanitsa MOSFET imatsekedwa;
②. Mbali yoyamba (yoyambirira) yothamanga kwambiri MOSFET imazimitsidwa, ndipo mbali yachiwiri (yachiwiri) yogwirizanitsa MOSFET imayatsidwa.
Mofananamo, ngati nthawi yakufa imanyalanyazidwa, kukonzanso kosinthika kwa SSR kumakhala ndi zigawo zitatu pamene ikugwira ntchito mu DCM mode:
①. Mbali yoyamba (yoyambirira) yothamanga kwambiri MOSFET imayatsidwa, ndipo mbali yachiwiri (yachiwiri) yogwirizanitsa MOSFET imatsekedwa;
②. Mbali yoyamba (yoyambirira) yothamanga kwambiri ya MOSFET imazimitsidwa, ndipo mbali yachiwiri (yachiwiri) yogwirizanitsa synchronous MOSFET imatsegulidwa;
③. Mbali yoyamba (yoyambirira) yothamanga kwambiri MOSFET imazimitsidwa, ndipo mbali yachiwiri (yachiwiri) yogwirizanitsa MOSFET imazimitsidwa.
5. Sekondale mbali (yachiwiri) synchronous rectification SSR mu kupitiriza CCM mode
Ngati chosinthira mwachangu cha flyback chikugwira ntchito mumayendedwe opitilira a CCM, njira yowongolera mbali yoyambira (yoyambirira), mbali yachiwiri (yachiwiri) yolumikizirana MOSFET imafuna chizindikiro cholumikizira kuchokera kugawo loyambirira (loyamba) kuti liwongolere kuzimitsa.
Njira ziwiri zotsatirazi nthawi zambiri zimagwiritsidwa ntchito kupeza chizindikiro cholumikizira cha mbali yachiwiri (yachiwiri):
(1) Gwiritsani ntchito mwachindunji mafunde achiwiri (wachiwiri), monga momwe tawonetsera pa Chithunzi 10;
(2) Gwiritsani ntchito zigawo zina zodzipatula monga ma pulse transformers kuti mutumize chizindikiro cha synchronous drive kuchokera kumbali yoyamba (yoyambirira) kupita kumbali yachiwiri (yachiwiri), monga momwe tawonetsera pa Chithunzi 12.
Mwachindunji pogwiritsa ntchito njira yachiwiri (yachiwiri) kuti mupeze chizindikiro choyendetsa galimoto, kulondola kwa chizindikiro cha synchronous drive kumakhala kovuta kwambiri kulamulira, ndipo n'zovuta kukwaniritsa bwino komanso kudalirika. Makampani ena amagwiritsanso ntchito olamulira a digito kuti apititse patsogolo kuwongolera, monga momwe tawonetsera pa Chithunzi 11 Show.
Kugwiritsira ntchito pulse transformer kuti mupeze zizindikiro zoyendetsa galimoto zimakhala zolondola kwambiri, koma mtengo wake ndi wokwera kwambiri.
Njira yoyendetsera mbali yachiwiri (yachiwiri) nthawi zambiri imagwiritsa ntchito pulse transformer kapena maginito coupling njira kuti ipereke chizindikiro cha synchronous drive kuchokera kumbali yachiwiri (yachiwiri) kupita ku mbali yoyamba (yoyambirira), monga momwe tawonetsera pa Chithunzi 7.v
6. Sekondale mbali (yachiwiri) synchronous rectification SSR mu discontinuous DCM mode
Ngati chosinthira mwachangu cha flyback chikugwira ntchito mosapitilira DCM mode. Mosasamala kanthu za njira yoyendetsera mbali yoyamba (yoyambirira) kapena njira yachiwiri (yachiwiri) yowongolera, madontho amagetsi a D ndi S a synchronous rectification MOSFET amatha kuzindikirika ndikuwongoleredwa.
(1) Kuyatsa synchronous rectification MOSFET
Mphamvu ya VDS ya synchronous rectification MOSFET ikasintha kuchoka ku zabwino kupita ku zoyipa, diode yamkati ya parasitic imayatsidwa, ndipo pakachedwa pang'ono, kukonzanso kosinthika kwa MOSFET kumayatsidwa, monga momwe tawonetsera pa Chithunzi 13.
(2) Kuzimitsa synchronous rectification MOSFET
Pambuyo pokonzanso kolumikizana MOSFET kutsegulidwa, VDS=-Io*Rdson. Pamene mafunde achiwiri (wachiwiri) akutsika kufika pa 0, ndiye kuti, mphamvu ya VDS yodziwika bwino ikasintha kuchoka ku 0, MOSFET yokonzanso synchronous imazimitsidwa, monga momwe tawonetsera pa Chithunzi 13.
M'magwiritsidwe ntchito, MOSFET yosinthira ma synchronous imazimitsidwa isanakwane (yachiwiri) yokhotakhota isanafike 0 (VDS=0). Makhalidwe amakono ozindikiritsa magetsi omwe amaikidwa ndi tchipisi zosiyanasiyana ndi osiyana, monga -20mV, -50mV, -100mV, -200mV, etc.
Mphamvu yamagetsi yamagetsi yamagetsi yamagetsi yakhazikitsidwa. Kuchulukirachulukira kokwanira kwa voliyumu yodziwikiratu yomwe ilipo, kumachepetsa zolakwika zosokoneza komanso kulondola kwabwinoko. Komabe, katundu wapano wa Io akatsika, MOSFET yosinthira ma synchronous idzazimitsidwa pamlingo wokulirapo, ndipo diode yake yamkati ya parasitic imayenda kwa nthawi yayitali, kotero kuti magwiridwe antchito amachepetsedwa, monga momwe tawonetsera pa Chithunzi 14.
Kuphatikiza apo, ngati mtengo wokwanira wa voteji yodziwika pano ndi yaying'ono kwambiri. Zolakwika zamakina ndi kusokoneza kungayambitse kukonzanso kolumikizana kwa MOSFET kuzimitsidwa pambuyo poti yachiwiri (yachiwiri) yokhotakhota ipitilira 0, zomwe zimabweretsa kubweza kwapano, kusokoneza magwiridwe antchito komanso kudalirika kwadongosolo.
Zizindikiro zodziwika bwino kwambiri zamakono zimatha kukonza bwino komanso kudalirika kwadongosolo, koma mtengo wa chipangizocho udzawonjezeka. Kulondola kwa chizindikiro chodziwikiratu chomwe chilipo chikugwirizana ndi izi:
①. Kulondola komanso kutsika kwa kutentha kwa voteji yapano;
②. Kukondera voteji ndi offset voltage, kukondera panopa ndi offset panopa, ndi kutentha kutengeka kwa amplifier panopa;
③. Kulondola komanso kutentha kwa Rdson pa-voltage ya synchronous rectification MOSFET.
Kuphatikiza apo, pamawonekedwe adongosolo, imatha kupitilizidwa kudzera pakuwongolera kwa digito, kusintha voliyumu yodziwikiratu, ndikusintha ma voliyumu oyendetsa a MOSFET.
Pamene linanena bungwe katundu panopa Io amachepetsa, ngati galimoto voteji wa mphamvu MOSFET amachepetsa, lolingana MOSFET kuyatsa voteji Rdson ukuwonjezeka. Monga momwe tawonetsera pa Chithunzi 15, ndizotheka kupewa kutsekedwa koyambirira kwa synchronous rectification MOSFET, kuchepetsa nthawi ya conduction ya parasitic diode, ndikuwongolera magwiridwe antchito.
Zitha kuwoneka kuchokera pa Chithunzi 14 kuti pamene katundu wamakono wa Io akuchepa, mphamvu yowunikira yomwe ikupezekapo imachepetsanso. Mwanjira iyi, pamene kutulutsa kwa Io komweku kuli kwakukulu, mphamvu yamagetsi yamagetsi yamagetsi yamagetsi imagwiritsidwa ntchito kuwongolera kuwongolera kolondola; pamene zotulutsa zamakono za Io ndizochepa, magetsi otsika omwe amawunikira amagwiritsidwa ntchito. Ikhozanso kupititsa patsogolo nthawi yoyendetsera ma synchronous rectification MOSFET ndikuwongolera magwiridwe antchito.
Pamene njira yomwe ili pamwambayi singagwiritsidwe ntchito kukonza, ma diode a Schottky amathanso kulumikizidwa mofanana pa malekezero onse a synchronous rectification MOSFET. Pambuyo kukonzanso kolumikizana kwa MOSFET kuzimitsidwa pasadakhale, diode yakunja ya Schottky imatha kulumikizidwa kuti ikhale yaulere.
7. Yachiwiri (yachiwiri) kulamulira CCM + DCM hybrid mode
Pakadali pano, pali njira ziwiri zomwe zimagwiritsidwa ntchito kwambiri pakuyitanitsa mafoni am'manja mwachangu:
(1) Kuwongolera mbali yoyambira (yoyambirira) ndi mawonekedwe a DCM. Mbali yachiwiri (yachiwiri) kukonzanso kofanana kwa MOSFET sikufuna chizindikiro cholumikizira.
(2) Ulamuliro wachiwiri (wachiwiri), CCM+DCM yosakaniza machitidwe (pamene katundu wamakono akuchepa, kuchokera ku CCM kupita ku DCM). Mbali yachiwiri (yachiwiri) yogwirizanitsa MOSFET imayendetsedwa mwachindunji, ndipo mfundo zake zoyatsa ndi kuzimitsa zikuwonetsedwa Chithunzi 16:
Kuyatsa kukonzanso kosinthika MOSFET: Pamene voteji ya VDS ya synchronous rectification MOSFET isintha kuchokera ku zabwino kupita ku zoyipa, diode yake yamkati imayatsidwa. Pambuyo pa kuchedwa kwina, kukonzanso kofanana kwa MOSFET kumayatsidwa.
Kuzimitsa MOSFET kukonzanso kosinthika:
① Mphamvu yotulutsa ikakhala yochepa kuposa mtengo wokhazikitsidwa, chizindikiro cha wotchi yofananira chimagwiritsidwa ntchito kuwongolera kuzimitsa kwa MOSFET ndikugwira ntchito mu CCM.
② Pamene mphamvu yotulutsa imakhala yaikulu kuposa mtengo woikidwiratu, chizindikiro cha wotchi ya synchronous chimatetezedwa ndipo njira yogwirira ntchito ndi yofanana ndi DCM mode. Chizindikiro cha VDS=-Io*Rdson chimayang'anira kuyimitsidwa kwa synchronous rectification MOSFET.
Tsopano, aliyense akudziwa gawo lomwe MOSFET imachita mu QC yonse yothamangitsa mwachangu!
Za Olukey
Gulu lalikulu la Olukey layang'ana kwambiri zigawo kwa zaka 20 ndipo likulu lake lili ku Shenzhen. Bizinesi yayikulu: MOSFET, MCU, IGBT ndi zida zina. Zogulitsa zazikulu ndi WINSOK ndi Cmsemicon. Zogulitsa zimagwiritsidwa ntchito kwambiri m'makampani ankhondo, kuyang'anira mafakitale, mphamvu zatsopano, mankhwala azachipatala, 5G, intaneti yazinthu, nyumba zanzeru, ndi zinthu zosiyanasiyana zamagetsi zamagetsi. Kutengera zabwino za wothandizila wamkulu wapadziko lonse lapansi, timatengera msika waku China. Timagwiritsa ntchito mautumiki athu opindulitsa kudziwitsa makasitomala athu zida zamakono zamakono zamakono kwa makasitomala athu, kuthandiza opanga kupanga zinthu zapamwamba komanso kupereka ntchito zambiri.
Nthawi yotumiza: Dec-14-2023
