leakage inductance of transformer

[Romeo shashi]

Hi,

I would like to caluculate the leakage inductance of transformer? i have caluculated the mutual inductance and self inductance can any one provide me formula to find the leakage inductance of transformer?

Mutual Inductance(Lm)
Lm = (1.256*10^-6 * Np * Ns * Ac) / (Le)

Self inductance inductance w.r.to priary turns

L1 = (1.256*10^-6 * Np^2 * Ac) / (Le)

Self inductance inductance w.r.to secndary turns

L2 = (1.256*10^-6 * Ns^2 * Ac) / (Le)

 

[chuckey]

The leakage inductance is the part of each inductor that is not magnetically coupled to the other one. So it is related to the physical disposition and the method of winding the coils. For instance your formula for the mutual inductance (above) makes no reference to the coupling factor, so the formula "works" even if the coils are not wound on the same former. For a proper transformer, this is taken as 1 (no leakage inductance), I would have thought that .95 -.99 would be more accurate given a leakage of 1-> 5% of flux and hence leakage inductance.
Frank

 

[Romeo shashi]

Hi thank you for your reply,
I want to simulate fullbridge DC DC converter with the following parameters in LT spice with 95% efficiency. Here the problem is how to find the transformer specifications like leakage inductance and inductance and Resistance of primary and secondary with out using core parameters. can any one provide me the formulas to find these parameters? if you provide me the spice model for this i would be thank full.
my specifications are:
i/p vol - 400v
o/p voltage - 28v
o/p power - 3kw
Frequency - 1mhz

 

[Romeo shashi]

Hi,
I want to simulate fullbridge DC DC converter with the following parameters in LT spice with 95% efficiency. Here the problem is how to do softswitching(ZVS)? i have atached my LT spice file. andd also i want to find the transformer specifictions like leakage inductance and resistance of primary and secondary. can any one provide me the formulas to find these parameters? if you provide me the LTspice model for this i would be thank full.
my specifications are:
i/p vol - 400v
o/p voltage - 28v
o/p power - 3kw
Frequency - 1mhz

 

[mtwieg]

Accurately estimating leakage inductance is usually not feasible, since it's very dependent on the fine details of how the windings are created and the shape of the core and gap. Unless you have some very good magnetic simulation tools, you'll probably just have to find out by building a transformer and measuring the true leakage.