# Inductor Simulation with current

#### beorza

##### Newbie Hi everybody

Question: I designed a helical inductor 130uH with the range of current from 0ADC to 35ADC I tested that inductor in the workbench and I got the chart how the inductance decreases with the current. With this chart I got the equation of that curve L(uh)= 130-55*((tanh(x/15)^4). I followed the LTspice example " Flux= 1m*thanh(5*x).
I added my equation to the model "Flux=130u -55u*pow(tanh(x/15),4)". Unfortunately the chart I got from LTspice is opposite (curve is going up). Do you have any idea what I missed or did I make something wrong?

I really appreciate you help

Thank you very much and have a wonderful day

#### Prototyp_V1.0

##### Advanced Member level 2 Just a suggestion - maybe that chart show reactance instead of inductance ?

#### beorza

##### Newbie Just a suggestion - maybe that chart show reactance instead of inductance ?
Thank you for your answer

This is the equation I have for my coil, Flux=14u-4u*(pow(tanh(x/49),4))
If I put that one in the boost converter it gives and output value larger (more then 10V) than I expected. it is a boost converter from 3.3 V to 5.0 V. If I multiply by -1 , Flux=-14u+4u*(pow(tanh(x/49),4)) it works. I do not understand why, supposedly LTspice should take the original equation.

Thanks

#### vfone

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