Mutual Inductance Measurements and Calculation

[Hoangnguyen123]

I am trying to compare the analytical and experimental results of coupling factor and mutual inductance. I can measure L, Q, Rs, and measure total inductance by connecting the two windings in series and getting the highest value to calculate mutual inductance (M) as indicated here: https://electronics.stackexchange.com/questions/127881/how-to-identify-mutual-inductance. I believe all this is correct but then I input a sinusoidal signal on one side and measure the voltage of the other side and try to calculate, again, mutual inductance and coupling factor: M=V2L1/V1 or M=V2/I1 as suggested here: https://www.daycounter.com/LabBook/Mutual-Inductance.phtml. The results do no match. In my case, the copling factor k is very small so I was expecting some error but not that much. I believe the measurement setup is wrong, e.g. the load on L2 should have and effect, etc. Any thoughts or suggestions?

 

[ronsimpson]

Please give us numbers. Maybe even a picture.
How are you measuring the inductor? Using a scope? or meter?
If you inject a sine wave that is above or near the self resonant frequency thing will be strange.
If your injected wave is very low things will be strange.
What signal generator, what frequency?

 

[dr pepper]

As ron implies the test setup must operate the trans within its freq and voltage range.
Plus you might well get slightly different measurments with different methods due to all kinds of effects.

 

[ronsimpson]

Any thoughts

I have built text fixtures for the production line. I can tell if a transformer is short or long one turn. You should be able to measure accurately.