有關(guān)于LT1248 pfc 控制芯片的問題 有uc3854的經(jīng)驗(yàn)者也同時(shí)請(qǐng)教
大家好,我是一個(gè)剛剛接觸電源的新手,現(xiàn)在正在做交換機(jī)的電源,遇到很多問題,主要是沒有經(jīng)驗(yàn),這里謝謝大家的幫助!!
我正在調(diào)試基于LT1248的功率因數(shù)校正,要出500w.
現(xiàn)在的問題是到了250w就很難做上去,變壓器是EI-30,輸出400v,具體表現(xiàn)是占空比很高,有時(shí)候是百分之百
我通過調(diào)整電感(由大到小),調(diào)整頻率(由高到低),可以帶到250w的負(fù)載.但這時(shí)候就很難在提高了,我調(diào)大了線電流(12a)和保護(hù)電流(14a),但剛一啟動(dòng)保險(xiǎn)絲就壞掉了(7A,而且加了ETC).IC及mos管都?jí)牧?IC的pin15,pin16短路了.IC 的擊穿是不是MOS 管的周圍沒有保護(hù)措施?
請(qǐng)大家?guī)兔?謝謝了!!!
有關(guān)于LT1248 pfc 控制芯片的問題 有uc3854的經(jīng)驗(yàn)者也同時(shí)請(qǐng)教
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Check the power rating of all the components
For PFC, the duty cycle will change with input line voltage: At peak, duty cycle is small; At zero crossing, duty cycle is close to 100%
If you want to increase the Power capacity of PFC, you can simply decrease the current detection resistance or equivalent.
When you turn on, the inrush current is high. If your circuit is not reliable, the components can be easily damaged. Try to bring up the circuit slowly.
For PFC, the duty cycle will change with input line voltage: At peak, duty cycle is small; At zero crossing, duty cycle is close to 100%
If you want to increase the Power capacity of PFC, you can simply decrease the current detection resistance or equivalent.
When you turn on, the inrush current is high. If your circuit is not reliable, the components can be easily damaged. Try to bring up the circuit slowly.
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@wolong
CheckthepowerratingofallthecomponentsForPFC,thedutycyclewillchangewithinputlinevoltage:Atpeak,dutycycleissmall;Atzerocrossing,dutycycleiscloseto100%IfyouwanttoincreasethePowercapacityofPFC,youcansimplydecreasethecurrentdetectionresistanceorequivalent.Whenyouturnon,theinrushcurrentishigh.Ifyourcircuitisnotreliable,thecomponentscanbeeasilydamaged.Trytobringupthecircuitslowly.
我明白了
你說的我都明白,我已經(jīng)實(shí)驗(yàn)過了,不過IC 都?jí)牡袅?我覺得ic的過流保護(hù)不是很好用.我發(fā)現(xiàn)uc3854的功能和LT1248差不多,接下來準(zhǔn)備實(shí)驗(yàn)一下.
是的,一般啟動(dòng)時(shí)候電流會(huì)很大,我體會(huì)到了,而且發(fā)現(xiàn)保護(hù)會(huì)在啟動(dòng)時(shí)候起作用.我的輸出濾波電容比較大,應(yīng)該首先讓電容充滿電.充電時(shí)間 要小于IC的工作時(shí)間.
但有時(shí)候會(huì)有一些問題:
當(dāng)時(shí)我在關(guān)斷電源時(shí),不是很徹底,關(guān)一會(huì)就很快又加電.結(jié)果保險(xiǎn)絲壞了,MOS 和IC 都?jí)牧?
我想是這樣的,關(guān)電后輸出電容會(huì)很快由于負(fù)載放電完畢,但I(xiàn)C 的啟動(dòng)電容的電壓還保持著,所以一加電,IC 就開始工作,這時(shí)候啟動(dòng)電容還沒有充電,電流會(huì)很大.7A的保險(xiǎn)絲壞掉應(yīng)該是正常.
但我還是想不明白,IC 的保護(hù)為甚末不好 用,我很頭疼.
你說的我都明白,我已經(jīng)實(shí)驗(yàn)過了,不過IC 都?jí)牡袅?我覺得ic的過流保護(hù)不是很好用.我發(fā)現(xiàn)uc3854的功能和LT1248差不多,接下來準(zhǔn)備實(shí)驗(yàn)一下.
是的,一般啟動(dòng)時(shí)候電流會(huì)很大,我體會(huì)到了,而且發(fā)現(xiàn)保護(hù)會(huì)在啟動(dòng)時(shí)候起作用.我的輸出濾波電容比較大,應(yīng)該首先讓電容充滿電.充電時(shí)間 要小于IC的工作時(shí)間.
但有時(shí)候會(huì)有一些問題:
當(dāng)時(shí)我在關(guān)斷電源時(shí),不是很徹底,關(guān)一會(huì)就很快又加電.結(jié)果保險(xiǎn)絲壞了,MOS 和IC 都?jí)牧?
我想是這樣的,關(guān)電后輸出電容會(huì)很快由于負(fù)載放電完畢,但I(xiàn)C 的啟動(dòng)電容的電壓還保持著,所以一加電,IC 就開始工作,這時(shí)候啟動(dòng)電容還沒有充電,電流會(huì)很大.7A的保險(xiǎn)絲壞掉應(yīng)該是正常.
但我還是想不明白,IC 的保護(hù)為甚末不好 用,我很頭疼.
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@allenmvp
我明白了你說的我都明白,我已經(jīng)實(shí)驗(yàn)過了,不過IC都?jí)牡袅?我覺得ic的過流保護(hù)不是很好用.我發(fā)現(xiàn)uc3854的功能和LT1248差不多,接下來準(zhǔn)備實(shí)驗(yàn)一下.是的,一般啟動(dòng)時(shí)候電流會(huì)很大,我體會(huì)到了,而且發(fā)現(xiàn)保護(hù)會(huì)在啟動(dòng)時(shí)候起作用.我的輸出濾波電容比較大,應(yīng)該首先讓電容充滿電.充電時(shí)間要小于IC的工作時(shí)間.但有時(shí)候會(huì)有一些問題:當(dāng)時(shí)我在關(guān)斷電源時(shí),不是很徹底,關(guān)一會(huì)就很快又加電.結(jié)果保險(xiǎn)絲壞了,MOS和IC都?jí)牧?我想是這樣的,關(guān)電后輸出電容會(huì)很快由于負(fù)載放電完畢,但I(xiàn)C的啟動(dòng)電容的電壓還保持著,所以一加電,IC就開始工作,這時(shí)候啟動(dòng)電容還沒有充電,電流會(huì)很大.7A的保險(xiǎn)絲壞掉應(yīng)該是正常.但我還是想不明白,IC的保護(hù)為甚末不好用,我很頭疼.
你沒加軟啟動(dòng)吧
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