Modeling Magnetic Core Offers Insight into Behavior, Operating Range, Saturation
by Gregory Mirsky, Electronic Design, Sep 09 2016
Focus:
For designers to understand the behavior of chokes and inductors used for energy storage and
release, they need to model how the magnetic core in these components will behave, especially
how the core will saturate. This first half of this article derives key equations for modeling
core saturation. It starts by deriving an equation for generating the classical B-H curve and
then derives an expression for inductance as a function of magnetizing current, which
ultimately is what’s needed to determine the current at which the core saturates. A simple
rearrangement of the last expression yields magnetizing current as a function of inductance,
which will be used directly to determine the saturation current. The second half of this
article gives examples of how these derived equations can be applied, plugging in actual values
to plot a B-H curve, a graph of inductance versus magnetic field strength, and a graph of
inductance versus magnetizing current. The article calculates permeability as the slope of a B-
H curve; and determines the saturation current from a graph of inductance vs. magnetizing
current.
What you’ll learn:
- How to model the saturation of an inductor or choke
- How to generate a classic B-H curve and plots of Inductance vs magnetic field strength and inductance vs magnetizing current for an inductor or choke
- How to determine core permeability from a B-H curve
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