求助：控制芯片在次級(jí)，電源怎么啟動(dòng)？
想做一個(gè)雙管正激電路，想把PWM控制芯片放在次級(jí)。芯片供電次級(jí)的儲(chǔ)能電感加一個(gè)繞組。初級(jí)開關(guān)管用MOSFET，驅(qū)動(dòng)用變壓器。想知道電源開機(jī)時(shí)怎么啟動(dòng)的？
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這個(gè)搞笑了@ymyangyong
對(duì)呀！雙管正激如何實(shí)現(xiàn)自激啟動(dòng)？這個(gè)真有點(diǎn)難！
這個(gè)是電路圖，我看不明白啟動(dòng)電路。
原文就這么一點(diǎn)文字描述。Start-up circuit
As already mentioned in the introduction section, the controller is located on the secondary side of the power
transformer, and for this reason, a start-up circuit has to be provided for a correct system activation.
The start-up circuit is based on a diac sending a train of controlled pulses to the low side drive section; the floating
drive section is energised by the second secondary gate driv
e transformer winding .
As soon as the L5991a wakes-up, it generates a pwm signal enabling the start-up circuit.
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@grtang
這個(gè)是電路圖，我看不明白啟動(dòng)電路。原文就這么一點(diǎn)文字描述。Start-upcircuitAsalreadymentionedintheintroductionsection,thecontrollerislocatedonthesecondarysideofthepowertransformer,andforthisreason,astart-upcircuithastobeprovidedforacorrectsystemactivation.Thestart-upcircuitisbasedonadiacsendingatrainofcontrolledpulsestothelowsidedrivesection;thefloatingdrivesectionisenergisedbythesecondsecondarygatedriv[圖片] etransformerwinding.AssoonastheL5991awakes-up,itgeneratesapwmsignalenablingthestart-upcircuit.
啟動(dòng)電路
由于已經(jīng)在引言部分提到，位于電源的二次側(cè)控制器變壓器，因?yàn)檫@個(gè)原因，啟動(dòng)電路必須提供正確的系統(tǒng)激活。
發(fā)送DIAC 低側(cè)驅(qū)動(dòng)部分 列車的控制脈沖啟動(dòng)電路是基于浮動(dòng)
驅(qū)動(dòng)部分由第二柵極驅(qū)動(dòng)變壓器繞組通電。一旦作為L5991a喚醒的，它會(huì)產(chǎn)生一個(gè)PWM信號(hào)，使啟動(dòng)電路。
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@grtang
這個(gè)是電路圖，我看不明白啟動(dòng)電路。原文就這么一點(diǎn)文字描述。Start-upcircuitAsalreadymentionedintheintroductionsection,thecontrollerislocatedonthesecondarysideofthepowertransformer,andforthisreason,astart-upcircuithastobeprovidedforacorrectsystemactivation.Thestart-upcircuitisbasedonadiacsendingatrainofcontrolledpulsestothelowsidedrivesection;thefloatingdrivesectionisenergisedbythesecondsecondarygatedriv[圖片] etransformerwinding.AssoonastheL5991awakes-up,itgeneratesapwmsignalenablingthestart-upcircuit.
左下角那個(gè)三極管自激啟動(dòng)電路?好像能工作,但不知道實(shí)際效果和對(duì)電路的影響會(huì)怎樣！
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@kzsc20
啟動(dòng)電路由于已經(jīng)在引言部分提到，位于電源的二次側(cè)控制器變壓器，因?yàn)檫@個(gè)原因，啟動(dòng)電路必須提供正確的系統(tǒng)激活。 發(fā)送DIAC低側(cè)驅(qū)動(dòng)部分列車的控制脈沖啟動(dòng)電路是基于浮動(dòng)驅(qū)動(dòng)部分由第二柵極驅(qū)動(dòng)變壓器繞組通電。一旦作為L(zhǎng)5991a喚醒的，它會(huì)產(chǎn)生一個(gè)PWM信號(hào)，使啟動(dòng)電路。[圖片]
開機(jī)后，電壓使DB3導(dǎo)通，下管MOSFET能夠在極端時(shí)間內(nèi)導(dǎo)通，由于上管MOSFET沒有導(dǎo)通，變壓器也不能輸出能量，次級(jí)也沒有電。還是不明白怎么啟動(dòng)的？
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@ymyangyong
驅(qū)動(dòng)變壓器次級(jí)2個(gè)繞組是同相耦合的，下管有啟動(dòng)脈沖時(shí)上管不是就有同相感應(yīng)驅(qū)動(dòng)脈沖了嗎？
這樣分析對(duì)不對(duì)：開機(jī)后，當(dāng)C25電壓充到32V時(shí)，DB3導(dǎo)通，電壓加到驅(qū)動(dòng)繞組上，相互耦合，上管也感應(yīng)出電壓，此時(shí)上下管導(dǎo)通。此時(shí)傳遞能量到次級(jí)。延遲零點(diǎn)幾u(yù)S（R20C28的時(shí)間常數(shù)為2.5uS0后，C28充電試三極管T3導(dǎo)通，驅(qū)動(dòng)線圈無(wú)電壓，上下管截止。如果一次啟動(dòng)的能量不夠，延遲幾個(gè)mS（R16C25的時(shí)間常數(shù)36mS），DB3再次導(dǎo)通。
電路正常后，DB3是會(huì)周期導(dǎo)通。如果導(dǎo)通時(shí)間剛好是開關(guān)管截止時(shí)間，會(huì)短時(shí)間把開關(guān)管再次導(dǎo)通，對(duì)電路還是有點(diǎn)影響。
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