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Bath Plate with Two Holes (T.E.A.M. Problem 3)

Miscellaneous with MagNet for Solidworks

The Bath Plate problem consists of a conducting ladder with a current-driven coil hovering over it. The problem consists of calculating the magnetic field along the center vertical line of the model just over the surface of the plate. This is done for two cases: in the first, the coil is positioned over the middle of the plate; in the second, over the bottom hole.

The coil is 1260 Amp-turns, driven by an alternating current source. The problem is solved at two frequencies, 50 Hz and 200 Hz. MagNet for SOLIDWORKS' AC Time Harmonic solver is ideal for this situation as it automatically calculates induced eddy currents.

The following problem is based on the Testing Electromagnetic Analysis Methods (T.E.A.M.) problem #3: Bath Plate with Two Holes. The benchmark can be found on the International Compumag Society's website.

View of the two position side-by-side

METHODS and RESULTS

DEVICE MODELING: MESHING

A part assigned the material 'Air' is added to the model between the coil and plate to allow control of mesh refinement of the region (i.e. the volume of said part) in which data is collected. A small maximum element size meshing constraint is applied. The plate needs to be efficiently meshed to ensure the accuracy of the induced current calculations while keeping the solve time reasonable. MagNet for SOLIDWORKS also allows for curvature refinement mesh controls, which are ideal for circular coils like the one present in this model.

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ARROW PLOT VIEW OF THE INDUCED CURRENT IN THE PLATE

Differences in the arrow plot of the current field in the plate can be observed between the four different coil position and frequency combinations. When the coil is in position 2 the induced current seems to loop around the bottom hole while it loops around the entire plate when the coil is in position 1.

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FLUX DENSITY ON THE PLATE FACE

Using the clip mesh feature, we can examine the flux density plot at the two positions in the interior of the model (plate face).

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Bz PHASOR MAGNITUDE FOR POSITION 1

The small element size in the mesh control part allows probing the flux density field at a high density. This improves the smoothness and accuracy of the results. The results for the first coil position at the two driving frequencies are presented in this graph. The same probing was used for every graph presented here.

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Bz PHASOR MAGNITUDE FOR POSITION 2

Here are the results for the phasor magnitude of the Z-component of the flux density field. This graph includes the two data sets for the two driving frequencies.

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Bz PHASOR ANGLE FOR POSITION 2

Here are the results for the phasor angle of the Z-component of the flux density field. This graph includes the two data sets for the two driving frequencies.

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