Hi,

I have been working on a PFC circuit and ran into a problem with my MOSFET. It is making a vibrating sound and gets hot. I get a decent output in my load though. I have no idea what is going on with the MOSFET and how to fix it.



Specification:

I design the circuit by following the guideline here :
http://www.onsemi.com/pub_link/Collateral/AND8184-D.PDF

And this is the schematic of the circuit

 

How is L2 looking? Does it saturate when passing that 8 amps of DC current?

 

As I said in your other post on this subject, and as ErnieM stated, you need to check the inductor for saturation.
So you do have an idea what's going on, you just choose to ignore it.