Hi, circuit newbie here. I've been challenged to design and build a rectifier with an emphasis on efficiency. I found designs of mosfet bridge rectifier here (http://uwspace.uwaterloo.ca/bitstream/10012/7722/1/Yilmaz_Mehmet.pdf) but when I try to simulate the design in LTSpice, the mosfet bridge rectifier doesn't perform any differently than a normal bridge rectifier.

Does anyone know what the problem is or have advice on designing rectifiers in general?

 

perhaps results would change if you selected specific devices and did not use the generic models

 

Oh.... That worked, thanks

Any advice on how to smooth the output?

 

The reason it doesn't work is that you have no gate voltage to turn on the MOSFETS at the zero crossing and thus the current is being conducted by the MOSFET's parasitic drain-source diode, so it acts just like a normal diode bridge. You need to use a specialized circuit to turn the MOSFETs ON (apply the Vgs required to fully turn on the MOSFET) at the zero crossing, such as shown here: View attachment eficient input bridge.pdf

 

It seems like my main problem was not selecting a specific device.

This design wasn't too complicated and provided a smoother output so I'll probably go with this one.

Thanks people.