上圖是飛思卡爾數字電源的方案,這里表示的是DC-DC的全橋拓撲,后面是同步整流,從圖來看應該是全波同步整流,但是沒做過同步整流,還請高手解釋一下這張圖同步整流的原理,并且我有個疑惑,如果負載開路,難道L1和L2不會造成變壓器原邊短路.還請高手支招!
關于數字方式控制的同步整流的問題(有圖)??
上圖是飛思卡爾數字電源的方案,這里表示的是DC-DC的全橋拓撲,后面是同步整流,從圖來看應該是全波同步整流,但是沒做過同步整流,還請高手解釋一下這張圖同步整流的原理,并且我有個疑惑,如果負載開路,難道L1和L2不會造成變壓器原邊短路.還請高手支招!
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@周挺巧
正半波過來時Q6導通Q5斷開L11進入儲能過程同時對C(C幾看不清楚),負半波過來時Q6斷開Q5導通L11進入續流狀態,同時L12進入儲能過程.如此循環
500) {this.resized=true; this.width=500; this.alt='這是一張縮略圖，點擊可放大。\n按住CTRL，滾動鼠標滾輪可自由縮放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/76/2504931239180983.jpg');}" onmousewheel="return imgzoom(this);">
As shown in Figure 6-5, the control of the synchronous rectifier is derived from the DC/DC converter
main switches’ signals. To avoid short circuiting the transformer when voltage is established, the
synchronous rectifier must turn off when the switch in the lag leg turns on. Also, to avoid the current
flows from the synchronous rectifier’s body diode, it must turn on when the lead leg switches on. But to
avoid a short circuit, there must be a delay time between the rectifier’s turn on and the lead leg’s turn off.
上面的圖以及后面的描述怎么理解,如果時序不對,變壓器短路是怎么造成的?
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@cailiang00
[圖片]500){this.resized=true;this.width=500;this.alt='這是一張縮略圖，點擊可放大。\n按住CTRL，滾動鼠標滾輪可自由縮放';this.style.cursor='hand'}"onclick="if(!this.resized){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/76/2504931239180983.jpg');}"onmousewheel="returnimgzoom(this);">AsshowninFigure6-5,thecontrolofthesynchronousrectifierisderivedfromtheDC/DCconvertermainswitches’signals.Toavoidshortcircuitingthetransformerwhenvoltageisestablished,thesynchronousrectifiermustturnoffwhentheswitchinthelaglegturnson.Also,toavoidthecurrentflowsfromthesynchronousrectifier’sbodydiode,itmustturnonwhentheleadlegswitcheson.Buttoavoidashortcircuit,theremustbeadelaytimebetweentherectifier’sturnonandtheleadleg’sturnoff.上面的圖以及后面的描述怎么理解,如果時序不對,變壓器短路是怎么造成的?
不錯!有新的發現!!!!! 這電路設計得很巧,由于移相是PWM是由MCU提供的,MCU理所當然可以準確的將同步整流信號提供給同步整流MOS管,而不必像其它同步IC需要檢測電路電流.不知這芯片多少錢?如果貴的話我們同樣可以將這功能移植到其它MCU上.另:你說的哪兩個電感是倍流電路典型應用電路了,電源網上已發很多了.查查看吧!!!
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