Hello,
Can someone provide info on the step-down isolation transformer model I see in these Resonant LLC designs.
In particular, the transformer shows three windings (N:1:1) Lm, and a 1:1 turns ratio; primary(Lp) to secondary(Ls)).
My question concerns the primary-secondary side for correct simulations.
How does one calculate the primary/secondary coupling inductance (1:1) for a correct simulation?
For instance, if Lm=160uH, and a turns ratio N = 3, then a proper inductance for the coupling step-down transformer (1:1)
would equal Lm/N^2 for Lp and Ls. But you can't put a low primary coupled inductor (Lp) in parallel with Lm. That would affect the current
through Lm. It would not be linear (i.e. triangle wave).
Would one use a very large primary Lp in parallel with Lm and Lp/N^2 for the secondary inductor value?
Can't find a good reference for this question. And transformer companies just provide turns ratio.
I guess they leave it up to us to characterize the value for Lm.
Thanks Doug