Question about ferrit core gap
Hi,
PI Expert 9 calculated that for EF16 ferrite core which is in the PI database there should be 0.185 mm air gap and ALG= 120nh/T2 .I have (from the producer) EF16 core with gap = 0.25mm and ALG=111nh/T2 .Will that do? The schematic was calculated for 5v X 1.5a and with TNY275PN chip.
Thanks
Comments
Hi,thank you for your answer.I made the file with specs from 2 files.In my case the material is TP4a and the core is EF16.
If you need any additional data please let me know .Thanks.
I found a formula for Epcos ferrit cores.It looks like :
s = (Al/K1)^1/K2
K1= -0.701 K2 = 42.2
where s is a total gap.So according to this formula the ALG of the cores whose properties I attached to the previous message are correct.
s= 0.1 ALG ~ 212
s = 0.25 ALG ~ 111
s = 0.5 ALG ~ 69
When combining two gaps with 0.1 we can get
s = 0.2 ALG ~ 130
Could you please give a hint how PI expert calculates the gap?Perhaps I am simplifing the whole matter and there should be taken many other factors when calculating the gap and PI expert does the whole thing much more accurately.
The equation to calculate the gap is Lg=(uo*L*Ipeak)^2/(Bp^2*Ac)
You can find this equation in "Fundamentals of Power Electronics" byErickson and Maksimovic
The equation number is 14.17. It mean it is locate in Cahper 14
uo = 4*pi*10EE-7 H/m
Could you please attach the specs form the core producer ?
Thank you