Model File (NC/I7) Processing

The FEMAG models and many simulation results are saved into files with extension nc which is based on the open standard format NetCDF For FEMAG releases earlier than 9.0 the extension is I7/A7 (windows) or ISA7/AUX7 (unix) which is a proprietary format.

For both file formats corresponding modules nc and isa7 exist (filename extension is optional):

isa = femagtools.isa7.read('foo')
nc = femagtools.nc.read('foo')

The file is structured as follows:

../../_images/ncformat.png

in addition following general data is provided:

Parameter

Description

Unit

FC_RADIUS

radius to center of airgap

m

arm_length

Lenght of iron

m

poles

Number of poles

pole_pairs

Number of pole pairs

poles_sim

Number of poles in model

num_slots

Number of slots

delta_node_angle

Angle between 2 nodes in airgap

rad

pos_el_fe_induction

rotation positions (mpos)

rad

el_fe_induction_1

flux density comp 1 (radial) (nel, mpos, icur, ibeta)

T

el_fe_induction_2

flux density comp 2 (tangential) (nel, mpos, icur, ibeta)

T

eddy_cu_vpot

eddy current vector potential (nel, mpos, icur, ibeta)

Example:

plt.plot(nc.pos_el_fe_induction*180/np.pi,
         nc.el_fe_induction_1[0, :, 0, 1], label='Br')
plt.plot(nc.pos_el_fe_induction*180/np.pi,
         nc.el_fe_induction_2[0, :, 0, 1], label='Bt')
plt.xlabel('Pos / °')
plt.ylabel('Flux Density / T')
plt.grid()
plt.legend()
../../_images/fluxdens.png

The plot module provides functions for plotting the subregions and mesh:

femagtools.plot.mesh(nc)
femagtools.plot.spel(nc)
../../_images/spel.png
../../_images/mesh.png