# Calculation of transformer inductance value

I am trying to find a way to calculate the primary and secondary inductance of transformer.

I learned that it is changing from one topology to another. My topology is Phase-Shifted Full-Bridge Converter.

Prof. Sam Ben Yaakov summarized the calculations of a transformer in a video so I put them as below:

[Transformer Design Stages]

[Winding window area]

[Calculation of Ap]

I understand everything in these pictures but I really dont know how should I calculate the primary or secondary inductance.

Apart from the video, there is a formula which is L1= (N1*Ae*ΔB) / Δi derived from the V= L(di/dt) = N *(dQ/dt). Some people says this formula can not be applied to all topologies and the inductance calculation is changing from one topology to another.

Although L1= (N1*Ae*ΔB) / Δi formula is derived from the fundamental formula, people says this can not be applied to all topologies.

Even in TI document the only formula given is Ls=Lp*( np/ns )*2 but, I know neither primary nor secondary inductance.

Additionally, there are some example calculation sections in IC's datasheets. There is some information about inductance but these calculations are very complex and long. Another datasheet has very different calculations for the same topologies.

I am very confused about this topic. Please can somebody clarify how should I determine the primary or secondary inductance of a transformer?

• This question is similar to: Calculation of transformer parameters. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. Commented Jul 13 at 11:09
• @winny. That post is deleted. (about 3 hours ago) Commented Jul 13 at 14:45
• I don't think it's the same, @Mhan why did you delete the other question? People are unlikely to answer your questions if you delete their answers Commented Jul 13 at 15:07
• When you simulated your converter, what inductance did you use? If you increase or decrease it by a factor of 10, what happens? Commented Jul 13 at 18:00
• I didnt simulate it, I am just trying to find a correct mathematical expression @winny
– Mhan
Commented Jul 13 at 20:33