Electrical – How does inductance change with presence of different directional magnetic fields


If I design a coil driver for a certain application, I assume there is a fixed load right? It may have drive any inductance between an interval but you can not drive any coil, because the driver is designed for a certain application.

So, how does a coil's inductance change with a magnet's presence?


Assume I want to drive the coil with sinus wave. Just under the coil, there is a magnet that its center is fixes to a shaft and its in release.


So, say that my coil is designed to draw peak to peak 1A in 10KHz.

How would that change? How can we calculate the change?

Best Answer

The moving magnet will induce a voltage in the coil. If the magnet is fixed there will be some effect on the inductance due to eddy currents in the magnet (assuming it is conductive). If you have a non-conductive magnet, then there will be no effect on the inductance of an air-core inductor.

If there is a core, the inductance is a nonlinear function of the current (and the magnetic field) and an externally applied field can bias the core and (most likely) reduce the inductance.

It's not easy to calculate these changes, you'd need a field simulation program like COMSOL.