spice - How to determine equivalent circuit of inductor

I'm wondering what is the best model for a real inductor. I used RLC parallel circuit to explain inductor, however the simulation result is not well fitting to experiment data. I'm wondering how to plot the best equivalent circuit of an real inductor For example, Coilcaraft's SPICE model looks better than RLC parallel circuit, however I can't find any paper which introduce this kind of model. Does the scheme has a reasonable physical meaning?

Answer

I'm wondering what is the best model for a real inductor

Simple answer is "it depends".

It depends on how you are using the inductor. For instance if you are using the inductor in a buck converter then you will be interested in its inductance for sure (because this stores the energy transferred) but you will also be interested in the series DC resistance because this limits the energy you can transport from input to output. You will likely be also interested in parallel capacitance in that you want the self resonant frequency (formed by L and C) to be significantly higher than the buck converter's switching frequency.

Would you be interested in the series DC resistance increasing with frequency (aka skin effect)? Possibly not so, the model you develop will probably not contain this feature. However, the Coilcraft model does not factor in core saturation and hysteresis and these are of significant interest to the designer in switch mode power supplies.

Would you be interested in transmission line or distributed capacitance effects for this type of application (buck converter)? Almost certainly not but, if you were designing a coil to base load a monopole antenna then you almost certainly would be.

So it depends.