Forward transformer Winding

Thread Starter


Joined May 17, 2023

I'm designing a forward transformer to be used in a forward converter

Input: 22V-28V-35V (Min-Nom-Max)
Output: 5V /5A
Power: 30W
Primary Turns : 16
Primary Strands : 6
Secondary Turns : 9
Secondary Strands :10

My Question is
How to wind this transformer in real life?, how to achieve the demagnetizing winding?, what would be a good ratio of tape between the windings?

Also in the Transformer & Inductor Design handbook it states "To ensure smooth transfer of the magnetizing current, the primary and demagnetizing winding must be tightly coupled (bifilar)"
How to connect primary and demagnetizing winding togther


Joined Aug 7, 2020
I would wind it choosing the wire gauge that would make each winding take up exactly one complete layer.
If you use multiple strands of wire and that results in needing more layers, then you will lose more than you have gained in terms of wire resistance because of the proximity effect.
The amount of tape is determined by the voltage that the insulation has to withstand. i.e the isolation voltage required.
If both sides are referenced to the same ground then one layer would do (but if both sides are referenced to the same ground a buck regulator would be a better choice)
I'm not too sure about winding the primary and demagnetising windings bifilar, although it might be OK with a relatively low voltage primary.
For a mains-fed converter working from a 325V power supply, there is a lot of voltage between those two windings!