This blog shows how to perform a magnetostatic 3D analysis in Ansys Maxwell to calculate the torque generated by the interaction between a current-carrying coil and a permanent magnet. In this example, the current in the coil generates a magnetic field pointing along the Y-axis, while the permanent magnet is magnetized along the X-axis. This configuration results in a torque around the Z-axis. The step-by-step workflow includes building the geometry, assigning materials and excitations, setting up the simulation, and reviewing the results.
Simulation Workflow
Begin by creating a coil by drawing a 12-segment regular polygon on the XY plane, then setting its center and start positions as shown below.
Next, sweep the created object 360 degrees around the X-axis with 30 segments using the Sweep Around Axis tool. Rotate it 45 degrees around the Z-axis, then assign copper material.
Model the bar magnet in the AEDT 3D Modeler by drawing a box with the dimensions and position shown below, then assign NdFe35 material to it.
Assign current excitation to the coil by first creating the coil’s cross section. Section the Coil object along the XY plane using the Surface > Section tool. Separate the resulting Terminal object with Boolean > Separate Bodies and delete the extra separated Terminal object. Right-click the Terminal object and select Assign Excitation > Current to apply a stranded current excitation of 100 A. Note that for static solvers, this current value is interpreted as Ampere-Turns.
Assign a torque parameter to the magnet by selecting the Magnet object, right-clicking, and choosing Assign Parameters > Torque. In the Torque window, set the type to Virtual, the axis to Global::Z, and ensure Positive is checked.
Create the simulation region by going to Draw > Region. In the Region window, check “Pad all directions similarly,” set the padding type to Percentage Offset, and enter a value of 100. Click OK to confirm.
Set up and run the simulation by right-clicking Analysis in the Project Manager and selecting Add Solution Setup. Accept the default settings and click OK, then save the project. Expand Analysis > Setup1 and click Analyze to run the simulation.
After completion, expand Analysis > Setup1 > Solutions and review the calculated torque in the Torque tab.
The video below walks through these steps in detail, and the model shown is available in the downloadable resources.
Downloadable Resources
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