flyback calculation

[sk614]

Hi I want design a multiple outputs flyback converter with outputs as following.

Vo1=5@2A
Vo2=12@1A
Vo3=24@.5A
Total 34W.

My question is when I start calculating do I calculate for each individual output or can I use the maximum output voltage (24@ 1.41A) for my calculation? Does my question make sense?

[Benta]

For primary and core calculations, just use the total output power in some form, eg, like modelling it with one secondary such as your 24 V @ 1.41 A.
How the secondary voltages are split is unimportant, and can even be changed along the way.
In the end, you'll need some sensible turns ratios, of course.

[sk614]

Thanks for the input.  So after getting the primary side calculations I can then use each outputs separately (Vo1, Vo2, Vo3) to calculate each secondary parameters? i.e. I1_peak,I2_peak, I3_peak..etc

[Benta]

You' have to define which one of your outputs is the "master" from where you do the feedback. Calculate that one, the other two will be given automatically from the turns ratios. Same with wire gauge, this will be apparent from the wanted output current.
You probably won't be able to get a perfect relationship between 5 V and 12/24 V, as "fractional" windings normally aren't possible.