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Slot Configurations for Reducing Stray Losses (T.E.A.M. Problem 21a)

Transformers with MagNet for SOLIDWORKS

Shielding can be used to substantially reduce magnetic field strengths outside of a transformer. Considerations, such as its electric properties and geometry, are needed to determine the type of shielding required.

Presented here is MagNet for SOLIDWORKS benchmark involving two exciting coils directed in opposite directions and shielded by a non-magnetic steel plate.

This example involves four different configurations of shielding steel plate: a plate with no slots, one slot, two slots, and three slots. The magnetic field density is measured along contours on the surface of the plate, and compared with measured results.

The following is based on the Testing Electromagnetic Analysis Methods (T.E.A.M.) problem #21a: 3-D Stray Field Loss. The benchmark can be found on the International Compumag Society's website.

Transformer with Shielding

METHODS and RESULTS

MAGNETIC FLUX DENSITY in the TRANSFORMER SHIELDING

TEAM Problem 21a is simulated in MagNet for SOLIDWORKS by creating an AC Time Harmonic study with a sinusoidal source current. Shown here are snapshots of the flux density in the four different steel plates, with views from both the underside and the topside.

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OHMIC LOSS in the TRANSFORMER SHIELDING

MagNet for SOLIDWORKS can also predict the ohmic losses. Displayed here is a plot of the ohmic loss in the steel plate for each of the four plate configurations.

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CURRENT DENSITY IN THE SHIELDING

A plot of the current density (J field) inside each steel plate can be generated using MagNet for SOLIDWORKS. Shown here is the current density inside the steel shielding for each of the four configurations.

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EDDY CURRENT ANALYSIS

Here are the eddy currents inside of the steel shielding. Shown here is a plot of the J-field intensity and direction at the instant θ=0°.

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COMPARING POWER LOSSES

MagNet for SOLIDWORKS can calculate the power loss due to eddy currents in the non-magnetic steel plates. Displayed here is a graphical comparison of the eddy current losses calculated by MagNet for SOLIDWORKS compared to the total power losses measured in the experiment.

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COMPARING MEASURED RESULTS

TEAM Problem 21a presents measured magnetic flux densities along contours off of the surface of the steel plates for each slot configuration. Here is a comparison between MagNet for SOLIDWORKS and the measured results.

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