# The Chan model

**The Chan model** is a hysteretic core model based on a model first proposed in by John Chan et al. in the *IEEE Transactions On Computer-Aided Design*, Vol. 10. No. 4, April 1991 but extended with the methods in United States Patent 7,502,723. Compared to older core models, the Chan model is particularly robust, computationally efficient and compact, requiring only three parameters to define most any commonly encountered magnetic hysteresis loop.

Once the core material's generic magnetic properties are set, establishing the circuit-level non-linear inductance requires specifying three more parameters to set the geometry of the specific core and one additional parameter to set the core winding turn-count. The Chan model as implemented in LTspice does not directly support Mutual Inductance, so unless only a single-winding inductor is being modeled, multiple windings must be added on via additional circuitry.

This page is incomplete. Perhaps a link to the original paper should be given along with some discussion of how the model works and why and how it is more robust and computationally efficient than other core models. Equations supported with illustrative graphs would be helpful.

## example

Ferrite bead inductor using fair rite 73 material ref 2673000101

Instead of entering 1.5uH as inductor value, use Hc=19.1 Bs=.39 Br=.15 A=3.575u Lm=6.9m N=1 Lg=0

Parameters are derived from the fair-rite documentation page

- HC is in A/M and corresponds to the 0.24 Oersted coercive force (multiply by 1000 and divide by 4*PI)
- BS is the saturation in Tesla and corresponds to the 3900 Gauss value (divide by 10000)
- Br is the remanence (remnant) and correspond to the 1500 Gauss value
- A is the bead magnetic cross section, use dimensions C*(A-B)/2, area is in mm2 hence the u
- Lm is the length of the magnetic flux lines, use PI*(A-B/2)
- N is the number of turns, use value between 1 and 0.5 in the case of a ferrite bead
- Lg=0 since we have no gaps