Kodi zimayambitsa kutentha mu MOSFET ya inverter ndi chiyani?

The inverterZithunzi za MOSFETzimagwira ntchito posintha ndipo zomwe zikuyenda m'machubu ndizokwera kwambiri. Ngati chubu sichinasankhidwe bwino, matalikidwe amagetsi oyendetsa si aakulu mokwanira kapena kutentha kwa dera sikwabwino, kungayambitse MOSFET kutentha.

 

1, inverter MOSFET Kutentha ndi koopsa, ayenera kulabadira kusankha MOSFET

MOSFET mu inverter m'malo osinthira, nthawi zambiri amafunikira kukhetsa kwake kwakukulu momwe kungathekere, kukana pang'ono momwe kungathekere, komwe kumatha kuchepetsa kutsika kwamagetsi a chubu, potero kuchepetsa chubu kuyambira kumwa, kuchepetsa kutentha.

Yang'anani buku la MOSFET, tiwona kuti kukweza kwa mphamvu yamagetsi ya MOSFET, kukulirakulira kwa kukana kwake, komanso omwe ali ndi madzi othamanga kwambiri komanso otsika kupirira mtengo wa chubu, kukana kwake nthawi zambiri kumakhala pansi pa makumi khumi. mamiliyoni.

Kungotengera katundu wamakono wa 5A, timasankha inverter yomwe imagwiritsidwa ntchito kwambiri MOSFET RU75N08R ndi voliyumu yolimbana ndi 500V 840 ikhoza kukhala, kukhetsa kwawo kuli mu 5A kapena kupitilira apo, koma kukana kwa machubu awiriwa ndikosiyana, kuyendetsa komweko komweko. , kusiyana kwawo kwa kutentha ndi kwakukulu kwambiri. 75N08R on-resistance ndi 0.008Ω yokha, pomwe kukana kwa 840 ndi 0.85Ω, pamene katundu womwe ukuyenda mu chubu ndi 5A, 75N08R chubu kutsika kwamagetsi ndi 0.04V yokha, panthawiyi, kugwiritsa ntchito chubu cha MOSFET ndi. kokha 0.2W, pamene 840 chubu voteji dontho akhoza mpaka 4.25W, kumwa chubu ndi mkulu monga 21.25W. Kuchokera pa izi zitha kuwoneka, zocheperako zotsutsana ndi MOSFET ya inverter ndizabwinoko, kukana kwa chubu kumakhala kwakukulu, kugwiritsa ntchito chubu pansi pakali pano Kukaniza kwa MOSFET kwa inverter ndikocheperako. momwe zingathere.

 

2, dera loyendetsa galimoto lamagetsi amplitude silokwanira

MOSFET ndi chipangizo chowongolera magetsi, ngati mukufuna kuchepetsa kugwiritsa ntchito chubu, kuchepetsa kutentha,MOSFETchipata pagalimoto voteji matalikidwe ayenera kukhala lalikulu mokwanira kuyendetsa kugunda m'mphepete kukhala otsetsereka ndi molunjika, mukhoza kuchepetsa chubu voteji dontho, kuchepetsa kumwa chubu.

 

3, kutentha kwa MOSFET si chifukwa chabwino

InverterMOSFETKutentha ndi koopsa. Monga inverter MOSFET mphamvu yogwiritsira ntchito mphamvu ndi yayikulu, ntchitoyo nthawi zambiri imafuna malo okwanira kunja kwa heatsink, ndipo heatsink yakunja ndi MOSFET yokha pakati pa heatsink iyenera kukhala yogwirizana kwambiri ndi (nthawi zambiri imafunika kuti ikhale yokutidwa ndi mafuta a silicone conductive thermally conductive). ), ngati heatsink yakunja ndi yaying'ono, kapena kukhudzana ndi heatsink ya MOSFET sikuyandikira mokwanira, kungayambitse kutentha kwa chubu.

 

Inverter MOSFET Kutentha kwambiri pali zifukwa zinayi zachidule.

Kutentha pang'ono kwa MOSFET ndi chinthu chabwinobwino, koma kutentha kwakukulu, komwe kumatsogolera ku chubu kumawotchedwa, pali zifukwa zinayi izi:

 

1, vuto la kapangidwe ka dera

Lolani MOSFET igwire ntchito motsatira mzere, m'malo mosintha dera. Ichinso ndi chimodzi mwazoyambitsa kutentha kwa MOSFET. Ngati N-MOS ikusintha, voliyumu ya G-level iyenera kukhala yocheperako V pang'ono kuposa mphamvu kuti ikhale yokwanira, pomwe P-MOS ndiyosiyana. Osatsegulidwa kwathunthu ndipo kutsika kwamagetsi ndikokulirapo kwambiri zomwe zimapangitsa kugwiritsa ntchito mphamvu, chofanana ndi DC impedance ndi yayikulu, kutsika kwamagetsi kumawonjezeka, kotero U * inenso ndikuwonjezera, kutayika kumatanthauza kutentha. Ichi ndiye cholakwika chopewedwa kwambiri pamapangidwe a dera.

 

2, pafupipafupi kwambiri

Chifukwa chachikulu ndi chakuti nthawi zina kufunafuna kwambiri voliyumu, zomwe zimabweretsa kuchuluka kwafupipafupi, kutayika kwa MOSFET pazikuluzikulu, kotero kutentha kumakulitsidwanso.

 

3, matenthedwe osakwanira

Ngati panopa ndipamwamba kwambiri, mtengo wamakono wa MOSFET, nthawi zambiri umafunikira kutentha kwabwino kuti mukwaniritse. Chifukwa chake ID ndi yocheperako kuposa yomwe ilipo, imathanso kutentha kwambiri, imafunika kuzama kothandizira kutentha kokwanira.

 

4, kusankha kwa MOSFET ndikolakwika

Kuweruza kolakwika kwa mphamvu, kukana kwamkati kwa MOSFET sikuganiziridwa mokwanira, zomwe zimapangitsa kuti pakhale kusintha kosinthika.