模塊電源的功率密度高,這時(shí)業(yè)界公認(rèn)的.但功率提高的同時(shí),自身的散熱就成了問題,當(dāng)然,我們可以通過提高效率等等途徑進(jìn)行改進(jìn),但并不是每一款電源都能大幅度提升的.
小弟是剛剛?cè)胄心K電源的人,有很多不懂的地方,需要像各DX們請教,萬望各位DX不要吝嗇,大家共同探討,共同提高.
前些天在實(shí)驗(yàn)一塊模塊的時(shí)候,功率并不高,只有100W,Vin24V Vout5V,采用單管正激電路,使用的是UC3843B芯片控制,沒有采用有源嵌位和同步整流,工作頻率300KHZ,發(fā)現(xiàn)它并不能長期實(shí)際工作在100W,長期工作的話,會(huì)使MOSFET或者次級(jí)二極管擊穿,應(yīng)該是熱擊穿,現(xiàn)在,我想能不能想辦法讓它可以長期工作在100W下,模塊尺寸82*56*15mm
曾經(jīng)試過:1 增加MOSFET,使用多MOSFET并聯(lián),當(dāng)然,驅(qū)動(dòng)也有更改,3843B驅(qū)動(dòng)不了多MOSFET,但是效果并不好,增加了成本,還沒解決問題.多個(gè)MOSFET并不能同時(shí)導(dǎo)通,總會(huì)有先有后,所以總是會(huì)有一個(gè)MOSFET擊穿.
2 增加次級(jí)二極管,使用多個(gè)并聯(lián),效果與方案1類似,也不理想.
小弟實(shí)在是沒法子了,各位DX幫忙出個(gè)主意吧.
(因空間限制,加散熱片不現(xiàn)實(shí),)
關(guān)于模塊電源散熱的問題
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@dadodo
5V100W輸出20A電流,次級(jí)還用二極管整流?發(fā)熱很厲害的,換同步整流吧.輸入24V平均5A電流,不是太差的MOS管都能勝任,那用得著多個(gè)并呢?
首先謝謝dadodo的回復(fù),UC3843B的驅(qū)動(dòng)峰值電流1A,我已經(jīng)把驅(qū)動(dòng)電路更改了,改成用3843驅(qū)動(dòng)兩個(gè)對管,對管接的自供電,然后驅(qū)動(dòng)MOSFET的,應(yīng)該不是驅(qū)動(dòng)能力不足吧?
如果換成同步整流,我對同步整流沒接觸過,曾經(jīng)試過用電壓自驅(qū)動(dòng)的方式,但是效果很不理想,空載的輸入電流很大,并且有的時(shí)候,續(xù)流MOSFET會(huì)被擊穿,換成IC驅(qū)動(dòng)的,因?yàn)槌杀締栴},老板一直沒通過,真不知道該如何是好了.
如果換成同步整流,我對同步整流沒接觸過,曾經(jīng)試過用電壓自驅(qū)動(dòng)的方式,但是效果很不理想,空載的輸入電流很大,并且有的時(shí)候,續(xù)流MOSFET會(huì)被擊穿,換成IC驅(qū)動(dòng)的,因?yàn)槌杀締栴},老板一直沒通過,真不知道該如何是好了.
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@alexandler
我是做散熱的,從散熱的角度看,如果主要發(fā)熱元件是貼在PCB表面的話,在layout時(shí)增加表面銅的面積或加熱過孔,讓熱更好的擴(kuò)散,都會(huì)有降低溫度的作用.另,如果是用在風(fēng)冷環(huán)境中,還可改善發(fā)熱元件的吹風(fēng)條件;如果是自然冷的環(huán)境,也可以通過其他方式優(yōu)化散熱使其溫度降低.希望對你有幫助,:)
首先多謝 alexandler 的回復(fù),我現(xiàn)在弄的是模塊電源,因空間限制,我沒有把發(fā)熱器件直接焊接在PCB上,而是反方向焊接,讓發(fā)熱器件與金屬外殼絕緣后接觸,幫助散熱.還有,模塊電源是要灌膠的,所以不存在風(fēng)冷直吹發(fā)熱器件的條件.
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@化生
兄臺(tái)建議不錯(cuò),今天裝好了.你說的損耗是導(dǎo)通損耗和開關(guān)損耗嗎?我使用的是IRF840的開關(guān)管,32CTQ030的整流管.輸入電壓18V到144V,輸出電壓5到48V.導(dǎo)通損耗就已經(jīng)很大了,何況還有開關(guān)損耗.有源嵌位和同步整流我還不會(huì)弄,因?yàn)楦叨鹊脑?用這幾個(gè)管子只能平面焊接在PCB上,利用外殼幫助散熱,我也想給加上散熱片,但是不知道怎么加啊.高度受限制了
你24V模塊的電壓范圍太寬了點(diǎn)吧!18~144V?24V的模塊一般是18V~36V啊!那么寬的范圍不適合做模塊!IRF840的損耗太大了,建議用740!
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@化生
嗯,我也是這么想的,但是問題的關(guān)鍵是即使換成同步整流技術(shù),效率也不可能在提高多少了,我現(xiàn)在已經(jīng)90%左右了,大多數(shù)達(dá)到89%.用同步整流效率不會(huì)更高多少了,那樣還是有很大的損耗,散熱還是問題
My personal suggestion: pick-up ideas form your compaitors is the best way!! Especially the world-wide brands, their products has a lot of solutions! Once you solved it then back to tell us your result! good luck!
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@化生
汗......教我去借鑒別人的方法啊?但是每個(gè)R&D的設(shè)計(jì)思路不一樣啊,這樣就像是大海里撈針,困難重重.
The same as you came here to get other engineers' advices!
Actually you have to see some good products or well designs then you can got so many ideas for your design! Every long-standing products are have a lot of wisedom in it! Not olny you even me also pick-up ideas form others! It isn't copy, You have to implement that idea into your case solve your problem, you have to over-come some difficults then done! For this case: if you don't change the circuit then you have two ways only: one is better components(SIC?) the other one is heat-sink(mini-size? copper attach? or better potting?) the gap is "因空間限制,加散熱片不現(xiàn)實(shí)" You have to add some kind of 散熱片!!
Actually you have to see some good products or well designs then you can got so many ideas for your design! Every long-standing products are have a lot of wisedom in it! Not olny you even me also pick-up ideas form others! It isn't copy, You have to implement that idea into your case solve your problem, you have to over-come some difficults then done! For this case: if you don't change the circuit then you have two ways only: one is better components(SIC?) the other one is heat-sink(mini-size? copper attach? or better potting?) the gap is "因空間限制,加散熱片不現(xiàn)實(shí)" You have to add some kind of 散熱片!!
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@temp1234
Thesameasyoucameheretogetotherengineers'advices!Actuallyyouhavetoseesomegoodproductsorwelldesignsthenyoucangotsomanyideasforyourdesign!Everylong-standingproductsarehavealotofwisedominit!Notolnyyouevenmealsopick-upideasformothers!Itisn'tcopy,Youhavetoimplementthatideaintoyourcasesolveyourproblem,youhavetoover-comesomedifficultsthendone!Forthiscase:ifyoudon'tchangethecircuitthenyouhavetwowaysonly:oneisbettercomponents(SIC?)theotheroneisheat-sink(mini-size?copperattach?orbetterpotting?)thegapis"因空間限制,加散熱片不現(xiàn)實(shí)"Youhavetoaddsomekindof散熱片!!
您的建議非常好!!!其實(shí)我不光是這款產(chǎn)品有散熱問題要解決,我大多數(shù)產(chǎn)品都多多少少會(huì)有這方面的問題,與其一點(diǎn)點(diǎn)的探索,不如直接站在別人的肩膀上.
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@化生
您的建議非常好!!!其實(shí)我不光是這款產(chǎn)品有散熱問題要解決,我大多數(shù)產(chǎn)品都多多少少會(huì)有這方面的問題,與其一點(diǎn)點(diǎn)的探索,不如直接站在別人的肩膀上.
Yes! Especially, Standing on a Giant shoulder may better! But You have to be very carefully on patent trips! They also protect their property well! By the way, you are wellcome to discussion on your ideas!
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