Parameters Extraction
Force and Torque
The force computed for an eddy current model in the harmonic magnetic field's cycle at a given position represents the average force, not the instantaneous force. Similarly, the torque represents the average torque over time because the torque computations make use of the time-averaged force. The difference between the time-averaged (or DC) force, AC force, and instantaneous force is shown below:
The instantaneous Lorentz force is given by
where
RL and GC Matrices
Unlike the 3D Eddy Current T- W solver, the 3D Eddy Current A- F solver supports the extraction of both RL and GC matrices. The matrices are set up from the Parameters > Matrix window; each matrix has its own tab and must be configured before simulation.
RL Matrix
The RL parameters extraction is performed by consecutively applying a source of 1 A to each terminal set as Signal. The other terminals set as Signal are considered to be a source of 0 A, and the terminals set as Grounded are set to 0 V. Each conduction path with a Signal terminal requires another terminal set to Ground.
This process is repeated for each terminal set as Signal, and the parameters are obtained as follows:
GC Matrix
The GC matrix extraction follows the same sequence as in the RL matrix, but applies 1 V to each terminal set as Signal and 0 V to the other Signal and Grounded terminals. For the GC matrix, if there is no ground selected, at least two signals must be selected.
The process is repeated for each Signal terminal, and the parameters are extracted by
With this release, this solver does not support complex permittivities, so the conductance is zero.
For the matrix setup, it might seem intuitive to set the other terminals of the conduction paths to 0 V as in the setup for the RL matrix.
However, with this excitation setup, there will be a voltage drop of 1 V within the Conductor 1. In the case of good conductors, an equipotential body is expected, but with this setup, there is no equipotential body. A better approach for the GC matrix extraction is to select only one terminal per conduction path as Signal and leave the others unchecked so that specific domain will behave as an equipotential body.
