Conductive cylinder in rotating magnetic field - QuickField simulation example
Engineering question
How to find eddy currents in conductive cylinders under rotating magnetic fields?
Engineering answer
Set up a plane-parallel QuickField Transient Magnetics problem for a conductive cylinder in a rotating magnetic field and evaluate eddy currents from computed field results.
Typical applications
conductive cylinders in rotating fields, induction motor rotors, rotating magnetic field conductors
Download
- Download simulation files (files may be viewed using any QuickField Edition).
Simulation problem
Problem TypePlane-parallel problem of transient magnetics.
Geometry
Given
Copper conductivity σ = 63 MS/m;
Magnitude of external field B0 = 1 T;
Number of poles 2p = 6;
Frequency f = 50 Hz.
Solution
To specify rotating magnetic field on the outer boundary of the region, Bn = B0 cos(pφ + ωt), we apply the Dirichlet boundary condition, using the formula:
A = (1/60) * cos(3*phi + 360*50*t).
The coefficient A0 = 1/60 arises from consideration
B = rot A
Bn = (1/R)(∂A/∂φ) =
= (1/R)*A0p·sin(ωt - pφ)
thus A0 = B0·R/p = 1 * 0.05 / 3 = 1/60
Due to periodicity of the problem, only half of the model is presented, and odd periodic boundary condition A1 = -A2 is applied on the cut. In fact, it would be enough to simulate just 60° sector of the model. In time domain, problem is simulated with automatic adaptive time step.
Results
Rotor eddy currents changing in time:
Video
- Conductive cylinder in rotating magnetic field. Watch on YouTube
- View simulation report in PDF.