Four-MOSFET Synchronous Rectification for High-Efficiency LLC Converter

[munter]

have completed the design and simulation of a synchronous rectification circuit using four MOSFETs. The full circuit is built and connected, including the transformer and output stage. However, I am not getting any output voltage during simulation. I've double-checked the transformer connections, MOSFET orientation, and gate signals, but the output remains at zero. i am very new to simulink matlab


I urgently need help troubleshooting this issue to identify what might be missing or incorrectly configured in the circuit. i put in the matlab file also

 

[Easy peasy]

how about a clear pdf ?

 

[dick_freebird]

What's in front of you is an opportunity to develop
your own debug skills. What's here is an ask for
easy answers.

What should the circuit need, to function? That's
a list. If you're cognizant of the design (not one
you found and redrew*) it'd be a linked list.

*quality of same, source and rendering, likely the
issue

Now that list can be checked, order might be by
likelihood if you can assess that, or just plod
on down the list and reap clues anyhow.

You will find something if you look and then we
can have a conversation if one is useful; perhaps
you will just solve the problem(s) on your own.
Perhaps you'll learn to like the feeling. .

 

[munter]

iknow i have to learn but debuged for month now and i am running out of time , i checked with many sources and stuff. i just wanted some assist if someone saw the problem . just some help

 

[munter]

how about a clear pdf ?

what do u mean

 

[FvM]

what do u mean

Only very few engineers are using Simulink for simulation of power electronic circuits. Posting a .pdf schematic will significantly increase the outreach of your question.

 

[munter]

Only very few engineers are using Simulink for simulation of power electronic circuits. Posting a .pdf schematic will significantly increase the outreach of your question.

hey know i understand what u mean , i will add it

 

[munter]

here is my circuit

 

[FvM]

Q1 seems to have drain and source flipped. As shown Q1 + Q4 diodes are shorting transformer 1.

What's the purpose of transformer series connection?

 

[24vtingle]

There is indeed a t.com app note showing LLC with two series primaries in two transformers, i just cant find it now.

 

[munter]

Q1 seems to have drain and source flipped. As shown Q1 + Q4 diodes are shorting transformer 1.

What's the purpose of transformer series connection?

do have suggestion how i should correct it qith the q1 and q4

 

[FvM]

As stated, flip Q1 drain and source.

 

[munter]

i try this this time , i changed my model into only two mosfets but dont get 48 volt out

 

[FvM]

The schematic doesn't make sense either.

 

[munter]

The schematic doesn't make sense either.

i mean i am new to this and want to learn so i am sorry for that. can point what u think is so wierd so i can learn and maybe fix my problem. when i do the circuit in real life i get it but i simulink program is just to new for me but i want to learn.

 

[FvM]

Why don't you start with a known working LLC circuit?

 

[munter]

i using there information to build on my own , i have to learn otherwise i wont if already got a workin one

 

[dick_freebird]

Probably better off breaking a good schematic and learning
how, why it fails, so as not to.

A handmade bodge has so much more potential garbage
in it, that you may never (as you are seeing) get it all wrung
back out.

You might benefit by breaking it down into "chunks" you
can understand and optimize. Like, maybe you get to where
you are confident and satisfied about driving one FET. Then
all 4 with their own loads. Then all 4 ganged up. Baby steps.

Of you could take the elevator to the penthouse and see
if you can fly. How's that going?

 

[Easy peasy]

Q3 - wrong way round - likely there are other errors - the clearer and less cluttered the sch -the easier it is to get right !

--- Updated May 13, 2025 ---

also get rid of the CT if not using it in the sim.