2kW Dual Rail Full Bridge SMPS

Fethiyeli

New member
Hi everyone. I have designed 2kW SMPS for my friend but i am stuck in designing feedback voltage regulation for -70V. I saw a circuit that it was sharing the feedback currents for dual rails. I have also read in book and it says the aim is to share feedback currents. I did it but i dont know whether it is correct or not.





 

lupusaudio

New member
Your approach will work in principle. Maybe for dealing with the VFB-Signal , the following proposal is somewhat simpler.





TL431_DualRails.jpg
Figure 1 Voltage Regulation for Dual Rails

By the way: I guess the values of the voltage divider R60,R61 and R51,R55 in your schematic are not correct. For propper operation the TL431 needs 2V5 at its Ref Input.
 

Fethiyeli

New member
This is the final schematic for now.
 

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lupusaudio

New member
Check the Cathode voltage of the TL431 ! What is the switching frequency of your converter and what is the target crossover frequency of the compensator ?
 

chas11

New member
Gate drive transformer PO585

View attachment 4933
This is my design layout.

I think if you can, modify this design with a gate drive transformer like the Pulse Electronics PO585, then the design will be more robust (less parts), PCB layout could be smaller and gain more isolation.I have an LTspice simulation of a fullbridge using ETD49 at about 2kW and more.PCB 180mm x 240mm and can be smaller.Your layout can improved
 
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chas11

New member
Sample Schematic

I think if you can, modify this design with a gate drive transformer like the Pulse Electronics PO585, then the design will be more robust (less parts), PCB layout could be smaller and gain more isolation.I have an LTspice simulation of a fullbridge using ETD49 at about 2kW and more.PCB 180mm x 240mm and can be smaller.Your layout can improved

Sample schematic, note this is a simulation(work in progress), not a working design ,don't construct supplied as a reference.FB.jpg
 

chas11

New member
I think you can improve your design by using a Gate Drive Transformer (cost is below 6 dollars in single quantities ) silicon works well with halfbridge (NCP5181 onsemi)but the support parts add costs but large draw back is isolation. Using a gate transformer you can place control on the secondary side and simplify the fedback.(fewer parts, robust design)
 
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