hi i need to design inductor i will use ir in boost circuit and i have these information
f=30khz
po=10w
v (input) from 50 t0 120 vdc
vo=200vdc
the inductance of the inductor about 166 micro henry
so how can i calculate the gap and select the core which not saturate
thanks

 

Here, have a look at Micrometals' design notes:
http://www.micrometals.com/appnotes_index.html