Phase shift full bridge converter with synchronous rectification

Thread Starter

shashi0007

Joined Oct 3, 2013
3
Hello all

I am working on 3K phase shift Fullbridge converter here Iam getting softswitching in the primary and in the secondary I am using Diode rectification and Iam getting around 85% efficiency at 1Mhz But I would like to replace these Diodes with MOSFETS to improve the efficiency. How can i give the timing for Synchronous MOSFETS when it is operating in Phase shift mode?
Here I am attaching the timing diagram which i followed


Thank you
 

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crutschow

Joined Mar 14, 2008
27,163
Why is there overlap of the signals during the "zero state" time. I would think you would want both control signals to be off during that time to prevent cross conduction.

The polarity of Q5 and Q6 indicate you want a negative DC output. Is that correct?
 

Thread Starter

shashi0007

Joined Oct 3, 2013
3
Thank you all for reply,

I guess there is something wrong with Q5 and Q6 timing in the above figure but I am using the same concept of diode rectification for the mosfets with some dead time between them and its working good. I need 28v Dc output with 95% efficiency what parameters i can change to increase the efficiency?
 
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