Mosfet Active Rectifier Center Tapped Version

[mercurial]

Was trying to build an active rectifier using mosfets (N channel), using a full wave configuration (that usually has 2 diodes and a center tapped transformer)
My ac voltage would be regular mains 50Hz and trying to rectify a voltage of 10 - 0 - 10 Vac from transformer secondary,  current would be around 100 to 150A.

I saw a configuration on wikipedia (image attached), but see some flaws in the design.

I see that in the positive half cycle when the top mosfet is conducting the bottom mosfet will short out through the internal diode also I think the output polarity is reverse of what is show, does this topology work at all.
Could someone explain the correct way of doing this?

[Andy Chee]

Take a look at the LM5045 and UCC28250 datasheets for some examples of synchronous rectification.

[Kleinstein]

The way the circuit is drawn, the MOSFETs should only conduct for the negative half cycle. The FETs are drawn to create a negative voltage relative to the center.

[Konkedout]

Yes this is a "full wave center tapped synchronous rectifier."  When using a MOSFET as a rectifier, current direction is opposite to normal use and it must be the same as the drain body diode which is shown in the schematic.   A full wave center tapped rectifier conducts only from one side of the secondary winding at a time.  So the transformer power output versus size and weight is not the best.

N channel MOSFETs are more better than P channel MOSFETs in performance versus (size and cost) so that aspect is also OK.  But with positive gate drive that means that they end up rectifying on the negative side of the output as this one does, not the positive side.

Fundamentally I don't see any problem with the design as shown, but it is missing details regarding the gate drive.  In simple terms you can drive the gates with RC coupling and clamp zener diodes driven by the opposite side of the winding.  But I recommend care and simulation before blowing up any parts. 

You can get better performance out of a transformer with a "current doubler" rectifier design but that requires two inductors.

https://www.how2power.com/article/2016/february/how-it-works-the-current-doubler-demystified-.php