Excel Connection Example
A very simple example of how one might go about connecting an Excel spreadsheet to FEMM using
ActiveX.
Mechanical and Electrostatic Analogies to Permanent Magnets
For the purposes of developing an intuitive feel for the fashion in which energy is stored in a permanent magnet and its environment, it is useful to use analogies to other types of physical consideration. In this note, the magnetic circuit representation of a magnet driving an external reluctance will be reviewed. Then, capacitive and mechanical analogies to a permanent magnet will be considered. These analogies have an equivalent circuit representation that is identical to the one used to describe a permanent magnet.
Analysis of a Cylindrical Permanent Magnet
Magnetic circuit representation of a PM cylinder including expressions for stored energy, coenergy, and magnetometric demagnetization factor
Magnetic Circuit Derivation of Energy Stored in a Permanent Magnet
A note that considers an intuitive approach to computing the energy stored in permanent magnets based on the magnetic circuit representation of a permanent magnet.
Wire Size Worksheet
A fairly widely used analytical formula for the diameter of bare wire as a function of AWG wire gauge is:
dwire = (0.324861*inch)*exp(-0.115943*AWG)
A Mathcad worksheet that implements this function (and a few other functions related to wire resistance and weight calculation) is linked below.
ComplexLua
Lua is distributed with double precision numbers as the standard number type. However, for many scientific applications (
e.g. FEMM), it would be nice to have complex numbers as the standard number type.
ComplexLua is a project in which Lua 4.0 has been recompiled in C++ using the complex number class from FEMM as its standard number type. There is also a dialog-based interpreter program that demonstrates the use of
ComplexLua embedded inside another program. A more
detailed description of ComplexLua is available, along with the
ComplexLua source distribution (compiles with MSVC++ 6 or later).
Force on NdFeB Disc Magnets Including Eddy Current Effects
A note that examines the effect of eddy current effect in thin disks of
NdFeB.
GNU Octave
Various distributions of
GNU Octave: