# Qspice 电感如何自定义磁化b-h曲线

I would like to inquire about how to customize the magnetization curve in QSPICE when simulating saturable inductors. The default model seems to be S-shaped, but I need a Z-shaped curve. Is there any tutorial available to guide me on this?

I have a Device Reference Guide in my Github you can download, and you can search for `L. Inductor` section for topic related to non-linear inductance. Isat, Lsat, Satfrac are instance parameters for non-linear inductance modeling, OR you can use flux model. Both with examples in this guide. But I am really not sure if it can help you for Z-shaped inductance curve.

Qspice/Guideline/Qspice - Device Reference Guide by KSKelvin.pdf at main · KSKelvin-Github/Qspice

Thank you for your reply, the information provided was very useful. I wonder if you have any more theoretical materials that introduce how the equivalent circuit model of inductors is derived. This would be very helpful for me to grasp how to set these parameters to fit the waveforms from my actual measurements. Thank you!

I actually tested the inductance voltage as a square wave, but the simulation always shows spikes, which seems to be caused by the inductance current changing too quickly. How can the inductance current be slowly increased, and immediately saturated beyond a certain level, as shown in the figure.

Simulated voltage waveform

I’m not sure if I understand the situation correctly. If you are setting up a simulation to test an inductor with a square wave, there are at least two things that need to be taken into consideration.

1. Assign an initial condition for the current to prevent the .op calculation from producing a huge initial value
2. To achieve a symmetric current profile with the midpoint at 0A, the square wave must be set with a delay of 1/4*period