Summary

Starting with EMSolution r10.0, the inductance of the air core COIL (external current field source) is now calculated internally, eliminating the need to manually input it separately ("Inductance calculation for COIL (external current magnetic field source"). Normally, the circuit calculation is coupled with a finite element mesh containing magnetic materials and conductors, but with EMSolution, it is possible to perform the circuit calculation with only an air core COIL without the need for mesh input. We will explain how to do this through an example. As an example, we use the model of "(4) Analysis using NETWORK" in Handling of inductance in external current field source (COIL)".

Explanation

As an ordinary method using mesh, an air-core analysis can be performed by setting the specific permeability of the magnetic material in the model (property number 3, see sample data) to 1.0. The original magnetic material region is air, but it must be a total potential region (POTENTIAL=0). Also, use the inductance calculation function (CALC_IND=1), add ARC- as an integral element in the COIL definition, and delete the L and M inputs in NETWORK. The COIL integral element should be consistent with REGION_FACTOR in NETWORK. In other words, multiply the COIL matching element by REGION_FACTOR so that it becomes the entire COIL (input4_2).

When this is executed, the current and voltage values of each circuit element are output to output as shown in Table 1. If L and M are input, the inductance portion is separated and output, but in this example, the coil series is considered as one circuit element and is added together (ID No. 1 and 3).

Table 1

************************************************************************** * Step No. 1 Time -2.5000000000e-03 sec * ************************************************************************** *** Network elements *************************************************** ID No. Current Voltage Flux 1 6.12323e-17 -7.71052e+02 7.51424e-17 3 6.12323e-17 7.71052e+02 11 -1.18175e-17 7.88119e-07 -7.68056e-26 13 -1.18175e-17 0.00000e+00 ************************************************************************** * Step No. 2 Time 0.0000000000e+00 sec * ************************************************************************** *** Network elements *************************************************** ID No. Current Voltage Flux 1 1.00000e+00 0.00000e+00 1.22717e+00 3 1.00000e+00 0.00000e+00 11 -1.92994e-01 0.00000e+00 -1.25433e-09 13 -1.92994e-01 0.00000e+00

In the case of air core without magnetic material, the analysis can be performed without a mesh, eliminating the need to create a mesh. To perform such an analysis, set INPUT_MESH_FILE=0 and MESHLESS=1 (input4_3). The input portion of the material properties data is left out but may be removed by setting NO_MAT_IDS=0.

The results are shown in Table 2. The values are slightly different but are in close agreement. This difference is mainly due to errors in the finite element method. The unmeshed analysis is more accurate because the inductance is analytically integrated.

Table 2

************************************************************************** * Step No. 1 Time -2.5000000000e-03 sec * ************************************************************************** *** Network elements *************************************************** ID No. Current Voltage Flux 1 6.12323e-17 -7.70977e+02 7.51350e-17 3 6.12323e-17 7.70977e+02 11 -1.18194e-17 0.00000e+00 0.00000e+00 13 -1.18194e-17 0.00000e+00 ************************************************************************** * Step No. 2 Time 0.0000000000e+00 sec * ************************************************************************** *** Network elements *************************************************** ID No. Current Voltage Flux 1 1.00000e+00 -0.00000e+00 1.22705e+00 3 1.00000e+00 0.00000e+00 11 -1.93026e-01 0.00000e+00 0.00000e+00 13 -1.93026e-01 0.00000e+00

This calculation does not read mesh data, but if MESH=1 is specified as the output file, only the coil geometry will be output in post_geom. In the example above, NETWORK was used, but the same input and calculation can be done in CIRCUIT. Electromagnetic force calculations for COIL can also be done independently of the mesh.　Please read " COIL Inductance and Electromagnetic Force Calculations".