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:

in addition following general data is provided:

Parameter	Description	Unit
FC_RADIUS	radius to center of airgap	m
arm_length	Effective lenght of iron	m
num_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()

General Functions

Function	Description
get_areas	return areas of (in m²) of inner and outer regions slots, iron, magnets
get_mass	return mass (in kg) of material conductors, iron, magnets
calc_iron_loss(icur, ibeta,	calculate iron (core) loss
pfefun, bmin=0.1)
demag_situation(icur, ibeta, hlim)	demagnetization of each magnet
rotate(angle)	rotate inner part by angle (rad)
scale_factor	scale factor of model

Plotting

The plot module provides functions for creating contour plotts nc and isa model files.

Function	Description
spel(nc, subregions=[],
with_axis=False, ax=0)	super elements (of subregions)
mesh(nc, with_axis=False, ax=0)	mesh
demag(nc, cmap=DEFAULT_CMAP, ax=0)	Demagnetization of last simulation
demag_pos(nc, pos=-1, icur=-1,
ibeta=-1, cmap=DEFAULT_CMAP, ax=0)	Demagnetization of pos, cur, beta
flux_density(nc, subreg=[],
cmap=DEFAULT_CMAP, ax=0)	Flux density of last simulation
flux_density_pos(nc, ipos, subreg=[],
icur=-1, ibeta=-1,
cmap=DEFAULT_CMAP, ax=0)	Flux density at pos with cur, beta
loss_density(isa, subreg=[],
cmap=DEFAULT_CMAP, ax=0)	Loss density of last simulation

Examples:

femagtools.plot.mesh(nc)
femagtools.plot.spel(nc)