Can I use a flyback transformer in a forward topology?

[AlienCircuits]

This is possibly a stupid question, but is it possible to use a flyback transformer as a forward converter transformer? It seems like a reset winding is an optional method for resetting the core for forward converters, so could I use a flyback and reset the core a different way and be fine with a forward topology?

Also, when I see flyback transformers rated for an input of 36-72V, they are usually for applications that need 3.3V, 1.8V, etc. on the secondary side. Should I take this 36-72V input voltage as an electrical rating, or should I use the insulation voltage rating because those input voltages are only in the context of the application?

 

[schmitt trigger]

In as few words as possible: no.

Flyback "transformers" are really coupled inductors. The basic operation is completely different.

Now, coupled inductors can have different winding ratios and use the transformer effect to achieve different voltage ratios. But they are still inductors at the core...pun intended.

 

[AlienCircuits]

In as few words as possible: no.

Flyback "transformers" are really coupled inductors. The basic operation is completely different.

Now, coupled inductors can have different winding ratios and use the transformer effect to achieve different voltage ratios. But they are still inductors at the core...pun intended.

Interesting.

The reason I ask is of course because I'd like to use an off the shelf transformer for a forward converter. I see that cooper bussman and coiltronics offer these configurable windings parts (hexapath, versapac) and they give examples for use both in a flyback and a forward mode.

I also read in "Power Electronics" by Hart

"Recall that for the flyback converter, energy was stored in Lm when the switch was closed and transferred to to the load when the switch was open. In the forward converter, Lm is not a parameter that is included in the input-output relationship and is generally made large.

I interpreted that as the intentional inductance of a flyback transformer is not something that should prevent the transformer from functioning as a forward transformer.

 

[schmitt trigger]

The inductance in a coupled inductor, while lower than that of a transformer because of the air gap, can nevertheless store energy (like an inductor should) because of that same air gap.

If you attempted to use a coupled inductor like a straight transformer, two things would happen:
1) During the "On" period, energy would have to be stored in the air gap in addition to any energy transferred thru the windings.
2) Worse, during the "Off" period, that magnetic energy would have to be dumped somewhere.