Which is the best way to do a Current Sense Transformer for a Full Bridge SMPS?

[zenerbjt]

Hi,
Please advise which is the best position/configuration for a primary side current sense transformer for a Full Bridge SMPS? (Comparative Schems are as attached).

Also, the 100:1 Current sense transformer that will be used is shown in cross section….but two different winding configurations. Please advise which is the best winding configuration? (one is sandwiched and one isn’t)

 

[BradtheRad]

When I picture where the lines of flux are strongest, and where the wires interact most closely, I believe the sandwiched winding scheme creates better coupling. I can't prove it with a formula. Just my educated guess.

 

[KlausST]

Hi,

Best... what means "best".
Low cost, smallest, lowest capacitive coupling, best pri sec coupling, lowest series inductance....

Klaus

 

[zenerbjt]

Thanks, i mean best pri-sec coupling.....we can reduce the capacitance of the sandwiched one by using TIW for the primary.
I believe that the non-sandwiched one would suffer very poor coupling because its just one turn on top of 100 turns, and it is only in a single place, and not even covering the whole layer. Woudld you agree?