Inductance of a simple coil
Greetings
I am trying to confirm some basic quantities, before design more complicated topologies, in Maxwell 3D. So, I begun with the inductance of a simple coil, as shown below
Coil is copper, core and region vacuum and current is set to 0.1 A.
On parameters, I setup a matrix for current and in post processing I set the 20 turns
Now, from equation
L = μ0 * Ν^2*Α / L
with μ0 = 4π*10^7, N = 20, A = 7.854e3 and L = 0.086, inductance must be ~ 45.9 μH. But, simulation computes a value of 31.239 μΗ
Assigning a different material to core (eg ferrite), produces even worse results.
Why is this? Any suggestions? Simulation file is attached.
Thank you for your time :)
Best Answer

thece Member
OK, apparently I was wrong on how inductance is calculated for such a "short" coil.
By using Wheeler's approximation formula
L = 30.534 μH, pretty close to simulation results (with 2% error)
I attach Wheelers' paper (which is nearly 100 years old)
Answers
OK, apparently I was wrong on how inductance is calculated for such a "short" coil.
By using Wheeler's approximation formula
L = 30.534 μH, pretty close to simulation results (with 2% error)
I attach Wheelers' paper (which is nearly 100 years old)
sorry for being late. you already realized the scale of the problem with coils... luckily it is not microwave.