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ʻO kahi kūlana maʻamau: Hoʻokomo ka ʻenekini hoʻolālā i kahi ferrite bead i loko o kahi kaapuni e ʻike ana i nā pilikia EMC, akā e ʻike ʻo ia e hoʻonui maoli ka leo i makemake ʻole ʻia. Pehea kēia?
He maʻalahi ka pane i kēia nīnau, akā ʻaʻole hiki ke hoʻomaopopo nui ʻia koe wale nō ka poʻe e hoʻolilo i ka hapa nui o ka manawa e hoʻoponopono ai i nā pilikia EMI. ʻO ka waiho wale ʻana, ʻaʻole ferrite beads, ʻaʻole ferrite beads, etc. he papaʻaina e helu ana i kā lākou hapa helu, impedance ma kekahi hāʻawi alapine (maʻamau 100 MHz), DC kū'ē (DCR), kiʻekiʻe helu o kēia manawa a me kekahi mau ana 'Ikepili (e nana Papa 1). ʻO ka pepa ka ʻike waiwai a me nā hiʻohiʻona hana alapine e pili ana.
ʻO nā ferrite beads kahi mea passive e hiki ke hoʻoneʻe i ka ikehu walaʻau mai ke kaapuni ma ke ʻano o ka wela. ʻO nā peʻa magnetika e hoʻohua i ka impedance ma kahi ākea ākea, a laila e hoʻopau i nā mea āpau a i ʻole ʻāpana o ka ikehu leo ​​i makemake ʻole ʻia i kēia laina alapine. e like me ka laina Vcc o kahi IC), makemake ʻia e loaʻa kahi haʻahaʻa haʻahaʻa haʻahaʻa haʻahaʻa DC e pale aku i nā poho mana nui i ka hōʻailona koi a / a i ʻole ka uila a i ʻole ke kumu o kēia manawa (I2 x DCR poho). Akā, makemake ʻia e loaʻa impedance kiʻekiʻe i kekahi mau alapine i wehewehe ʻia. No laila, pili ka impedance i ka mea i hoʻohana ʻia (permeability), ka nui o ka ferrite bead, ka helu o nā wili, a me ke ʻano wili. , ʻoi aku ka nui o ka makani, ʻoi aku ka kiʻekiʻe o ka impedance, akā ʻoi aku ka lōʻihi o ka lōʻihi o ke kino o ka coil i loko, e hana pū kēia i kahi kūʻē DC kiʻekiʻe.
ʻO kekahi o nā mea maʻamau o ka hoʻohana ʻana i nā ferrite beads i nā noi EMI, ʻo ia ka mea pono i loko o ka pae kū'ē. He aha ke ʻano? reactance).Ma nā alapine kahi XL> R (frequency haʻahaʻa), ʻoi aku ka like me ka inductor ma mua o ka resistor. ʻO ke alapine (frequency) i ʻoi aku ka nui o ka "R" ma mua o "XL" i kapa ʻia ʻo ka "crossover".
ʻO kekahiʻano'ē aʻe e nānā i kēia ma keʻano o ka hana maoli o ka mea i ka wā o kona inductance a me ke kū'ēʻana. e hāʻawi i kahi pale no nā mea hana maʻalahi ma kēlā ʻaoʻao o ka ferrite bead, akā hoʻokomo pū ʻo ia i ka "L" i loko o ke kaapuni, hiki ke hoʻoulu i ka resonance a me ka oscillation (ringing). e ʻike ʻia ka ikehu walaʻau a e hala kekahi hapa o ka ikehu walaʻau, e pili ana i ka inductance a me nā waiwai impedance.
I ka wā o ka ferrite bead i loko o kona resistive pae, ka mea hana e like me ka resistor, no laila, poloka ia ka leo ikehu a absorbs ia ikehu mai ke kaapuni, a omo ia ma ke ano o ka wela. ʻO ke kaʻina hana like, ka laina hana a me ka ʻenehana, nā mīkini, a me kekahi o nā mea ʻāpana like, hoʻohana ka ferrite beads i nā mea ferrite lossy, aʻo nā inductors e hoʻohana i ka haʻahaʻa haʻahaʻa hao Oxygen material. Hōʻike ʻia kēia ma ka pihi ma ke Kiʻi 2.
Hōʻike ke kiʻi i [μ''], e hōʻike ana i ke ʻano o ka waiwai ferrite bead nalowale.
ʻO kaʻoiaʻiʻo o ka hāʻawiʻiaʻana o ka impedance ma 100 MHz kekahi hapa o ka pilikia koho. I nā manawa he nui o EMI,ʻo ka impedance ma kēia alapine he mea kūponoʻole a alakaʻi hewa. , lilo i palahalaha, a hiki i ka impedance i kona peak waiwai ma keia alapine (frequency), a ina paha ka mea i loko o kona inductance pae a i ole ia ua hoololiia i loko o kona kū'ē pae.ʻOiaʻiʻo, he nui ferrite bead mea hoʻohana i na mea he nui no ka like ferrite bead, a i ole. ma ka liʻiliʻi loa e like me ka mea i hōʻike ʻia ma ka pepa ʻikepili. E nānā i ke Kiʻi 3. ʻO nā ʻāpana 5 āpau i kēia kiʻi no nā pahu ferrite 120 ohm like ʻole.
A laila, ʻo ka mea e pono e loaʻa i ka mea hoʻohana, ʻo ia ka pihi impedance e hōʻike ana i nā ʻano alapine o ka ferrite bead.
Hōʻike ka Figure 4 i kahi mea nui loa. Ua koho ʻia kēia ʻāpana he 50 ohm ferrite bead me ke alapine o 100 MHz, akā ʻo kona alapine crossover ma kahi o 500 MHz, a loaʻa iā ia ma mua o 300 ohms ma waena o 1 a me 2.5 GHz. ʻO ka nānā ʻana i ka pepa ʻikepili ʻaʻole e hōʻike i ka mea hoʻohana i kēia a hiki ke alakaʻi hewa.
E like me ka mea i hōʻike ʻia ma ke kiʻi, ʻokoʻa nā waiwai o nā mea. He nui nā ʻano like ʻole o ka ferrite i hoʻohana ʻia no ka hana ʻana i nā peʻa ferrite. ka pinepine noi a me ka impedance.
ʻO kekahi pilikia maʻamau, ʻo nā mea hoʻolālā papa kaapuni i kekahi manawa i kaupalena ʻia i ke koho ʻana i nā ferrite beads i kā lākou waihona ʻāpana i ʻae ʻia. ʻAʻole pono e loiloi a ʻae i nā mea ʻē aʻe a me nā helu ʻāpana. I ka wā i hala aku nei, ua alakaʻi pinepine kēia i kekahi mau hopena koʻikoʻi o ka pilikia leo EMI kumu i hōʻike ʻia ma luna nei. ʻAʻole hiki iā ʻoe ke hahai wale i ka hoʻonā EMI o ka papahana mua, ʻoiai ke hoʻololi ke alapine o ka hōʻailona koi a i ʻole ke alapine o nā ʻāpana hoʻomālamalama e like me ka hoʻololi ʻana i nā mea hana uaki.
Inā ʻoe e nānā i nā ʻāpana impedance ʻelua ma ke Kiʻi 6, hiki iā ʻoe ke hoʻohālikelike i nā hopena waiwai o nā ʻāpana like ʻelua.
No kēia mau mea ʻelua, ʻo ka impedance ma 100 MHz he 120 ohms. No ka ʻāpana ma ka hema, me ka hoʻohana ʻana i ka mea "B", ʻo ka nui o ka impedance ma kahi o 150 ohms, a ʻike ʻia ma 400 MHz. No ka ʻāpana ma ka ʻākau. , me ka hoʻohana ʻana i ka mea "D", ʻo ka impedance kiʻekiʻe he 700 ohms, ka mea i loaʻa ma kahi o 700 MHz. Akā ʻo ka ʻokoʻa nui loa ʻo ia ke alapine crossover. ʻO nā mea hoʻololi kiʻekiʻe kiʻekiʻe "B" ma 6 MHz (R> XL) , 'oiai ke 'ano ki'eki'e 'o "D" mea i ho'omau 'ia ma kahi o 400 MHz. 'O wai ka hapa o ka ho'ohana pono?
Hōʻike ka Figure 7 i nā pilikia maʻamau a pau i ka wā i koho ʻia ai nā pahu ferrite hewa e hoʻopau i ka EMI. Hōʻike ka hōʻailona unfiltered 474.5 mV undershoot ma kahi 3.5V, 1 uS pulse.
I ka hopena o ka hoʻohana ʻana i kahi mea ʻano pohō kiʻekiʻe (koko waena), piʻi ka undershoot o ke ana ma muli o ke alapine crossover kiʻekiʻe o ka hapa. ke alapine crossover haʻahaʻa a me ka hana maikaʻi. ʻO ia ka mea kūpono e hoʻohana ai i kēia noi (kiʻi ma ka ʻākau).
E like me ka piʻi ʻana o ke au pololei ma o nā pahu, hoʻomaka ka mea nui e saturate. ʻike ʻia ka hopena o ka saturation i ka emi ʻana o ka waiwai impedance me ka pinepine. ʻO kēia hāʻule i ka impedance e hōʻemi ana i ka pono o nā pahu ferrite a me ko lākou hiki ke hoʻopau i ka walaʻau EMI (AC).
Ma kēia kiʻi, ua helu ʻia ka ferrite bead ma 100 ohms ma 100 MHz. ʻO kēia ka impedance maʻamau i ana ʻia inā ʻaʻohe o DC o ka ʻāpana. hoʻokomo), hāʻule nui ka impedance kūpono. Ma ka pihi ma luna, no ka 1.0 A i kēia manawa, hoʻololi ka impedance maikaʻi mai 100 ohms a 20 ohms.100 MHz. ʻAʻole paha koʻikoʻi nui, akā he mea pono e hoʻolohe ai ka mea hoʻolālā. ʻAʻole ʻike ka mea hoʻohana i kēia ʻano DC bias.
E like me ke kiʻekiʻe-frequency RF inductors, ka winding direction o ka inner coil i loko o ka ferrite bead he nui ka mana i ka pinepine o ka bead.Winding kuhikuhi 'aʻole wale pili i ka pilina ma waena o ka impedance a me ka pinepine pae, akā, hoʻololi i ka pinepine pane. Ma ke Kiʻi 9, hōʻike ʻia ʻelua 1000 ohm ferrite beads me ka nui o ka hale a me ka mea like, akā me ʻelua mau hoʻonohonoho wili ʻokoʻa.
ʻO nā'ōwili o kaʻaoʻao hema eʻehaʻia ma luna o ka mokulele a hoʻopaʻaʻia ma kaʻaoʻao ākea, kahi e hana ai i ka impedance kiʻekiʻe a me ka pane pinepine kiʻekiʻe ma mua o kaʻaoʻao ma kaʻaoʻao'ākau eʻeha i ka mokulele ākea a hoʻopaʻaʻia ma ke kuhikuhi pololei. i ka haʻahaʻa capacitive reactance (XC) pili me ka ho'ēmi parasitic capacitance ma waena o ka hopena terminal a me ka loko coil.A haʻahaʻa XC e hua mai i ka 'oi aʻe iho-resonance alapine (frequency), a laila e ae i ka impedance o ka ferrite bead e hoʻomau i ka hoʻonui a hiki i ka mea. hiki i kahi kiʻekiʻe kiʻekiʻe, ʻoi aku ka kiʻekiʻe ma mua o ke ʻano maʻamau o ka bead ferrite ʻO ka waiwai impedance. Hōʻike ʻia nā pihi o nā 1000 ohm ferrite beads ma luna o ke kiʻi 10.
No ka hōʻike hou aku i nā hopena o ke koho ʻana i ka ferrite bead pololei a me ka hewa, ua hoʻohana mākou i kahi kaapuni hoʻāʻo maʻalahi a me ka papa hoʻāʻo e hōʻike i ka hapa nui o nā mea i kūkākūkā ʻia ma luna. "A", "B" a me "C", aia ma kahi mamao mai ka mea hoʻopuka transmitter (TX).
Ua anaʻia ka pono o ka hōʻailona ma kaʻaoʻao puka o ka ferrite beads i kēlā me kēia o nā kūlanaʻekolu, a ua hana houʻia meʻelua ferrite beads i hanaʻia i nā mea likeʻole. "A", "B" a me "C". Ma hope mai, ua hoʻohana ʻia kahi mea kiʻekiʻe aʻe "D". Hōʻike ʻia nā hopena kiko-i-kahi e hoʻohana ana i kēia mau ferrite ʻelua ma ke Kiʻi 12.
Hōʻike ʻia ka hōʻailona "ma" unfiltered ma ka lālani waena, e hōʻike ana i kekahi overshoot a undershoot ma ka piʻi ʻana a me ka hāʻule ʻana o nā kihi, kēlā me kēia. a me ka hoʻomaikaʻi ʻana i ka hōʻailona ma lalo o ka piʻi ʻana a me ka hāʻule ʻana o nā ʻaoʻao. Hōʻike ʻia kēia mau hopena ma ka lālani kiʻekiʻe o ka Figure 12. ʻO ka hopena o ka hoʻohana ʻana i nā mea kiʻekiʻe-frequency hiki ke hoʻoulu i ke kani, e hoʻonui ai i kēlā me kēia pae a hoʻonui i ka manawa o ka instability. hōʻike ʻia ma ka lālani lalo.
Ke nānā nei i ka hoʻomaikaʻi ʻana o EMI me ka alapine ma ka ʻaoʻao luna i ʻōlelo ʻia (Figure 12) i ka scan horizontal i hōʻike ʻia ma ka Figure 13, hiki ke ʻike ʻia no nā alapine a pau, ʻo kēia ʻāpana e hōʻemi nui i nā spike EMI a hoʻemi i ka pae leo holoʻokoʻa ma 30 ma kahi kokoke I ka laulā 350 MHz, ʻoi loa ka pae ʻae ʻia ma lalo o ka palena EMI i hōʻike ʻia e ka laina ʻulaʻula. ʻO kēia ka maʻamau hoʻoponopono maʻamau no nā lako papa B (FCC Part 15 ma ʻAmelika Hui Pū ʻIa). ʻO ka mea "S" i hoʻohana ʻia i nā ferrite beads ua hoʻohana pono ʻia no kēia mau alapine haʻahaʻa. Loaʻa ka hopena o ka mea "S" i ka pae leo EMI mua, unfiltered, akā e hōʻemi i kahi spike nui ma 750 MHz ma kahi o 6 dB. Inā ʻoi aku ka nui o ka pilikia leo EMI ma mua o 350 MHz, pono ʻoe e e noʻonoʻo i ka hoʻohana ʻana i nā mea ferrite kiʻekiʻe i ʻoi aku ka nui o ka impedance i ka spectrum.
ʻOiaʻiʻo, hiki ke pale ʻia ke kani ʻana a pau (e like me ka hōʻike ʻana ma ka ʻaoʻao lalo o ke Kiʻi 12) e ka hoʻāʻo ʻana i ka hana maoli a/a i ʻole ka polokalamu simulation, akā manaʻo ʻia e ʻae kēia ʻatikala i ka poʻe heluhelu e kāpae i nā hewa maʻamau a hōʻemi i ka pono koho i ka manawa ferrite bead pololei, a hāʻawi i kahi "hoʻonaʻauao" hoʻomaka i ka wā e pono ai nā ferrite beads e kōkua i ka hoʻoponopono ʻana i nā pilikia EMI.
ʻO ka mea hope loa, ʻoi aku ka maikaʻi o ka ʻae ʻana i kahi moʻo a i ʻole nā ​​ʻāpana ferrite beads, ʻaʻole hoʻokahi helu hapa wale nō, no nā koho hou aʻe a me ka hoʻolālā hoʻolālā. , ʻoi aku ka nui o nā kūʻai ʻana no ka papahana hoʻokahi. He mea maʻalahi ke hana i kēia i ka manawa mua, akā i ka manawa e hoʻokomo ʻia ai nā ʻāpana i loko o ka waihona waihona ma lalo o kahi helu mana, a laila hiki ke hoʻohana ʻia ma nā wahi āpau. ʻO ka mea nui, ʻo ka hana pinepine ʻana o nā ʻāpana mai nā mea hoʻolako like ʻole e like me ka hoʻopau ʻana i ka hiki o nā noi ʻē aʻe i ka wā e hiki mai ana Ua hiki mai ka pilikia. E hōʻoia pū kēia i ka hoʻohana ʻia ʻana o nā pahu ferrite kūpono e hoʻoponopono i kāu pilikia EMI.
Ke hana nei ʻo Chris Burket ma TDK mai ka makahiki 1995 a he ʻenekini noi noi nui ʻo ia, e kākoʻo ana i ka nui o nā mea passive. Ua kākau a hoʻopuka ʻo Burket i nā pepa ʻenehana ma nā ʻaha kūkā. Ua loaʻa iā Burket ʻekolu mau patent US ma nā hoʻololi optical/mechanical a me nā capacitors.
ʻO In Compliance ke kumu nui o ka nūhou, ka ʻike, ka hoʻonaʻauao a me ka hoʻoikaika ʻana no ka poʻe loea ʻenehana uila a me ka uila.
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