def get_slipfreq_torque():
# call this after mi_analyze
femm.mi_loadsolution()
# Physical Amount on the Rotor
femm.mo_groupselectblock(100) # rotor iron
femm.mo_groupselectblock(101) # rotor bars
# Fx = femm.mo_blockintegral(18) #-- 18 x (or r) part of steady-state weighted stress tensor force
# Fy = femm.mo_blockintegral(19) #--19 y (or z) part of steady-state weighted stress tensor force
torque = femm.mo_blockintegral(
22) #-- 22 = Steady-state weighted stress tensor torque
freq = femm.mo_getprobleminfo()[1]
femm.mo_clearblock()
femm.mo_close()
return freq, torque
def computedLz(self, ite=0, rType="linear"):
"""Compute dLz
Compute the variation of inductance while the
projectile moves on the axis. If ite is zero,
some guess is made about the number of iterations required
for decent approximation.
By default the projectile is moved linearly, but it
is possible to set the movement type to tchebychev in order
to minimize the Runge phenomenom. However not all the code
is compatible with it.
Rather than computing the variation of inductance, we compute
the force on the projectile and correct it (explanations are available
somewhere on this git :) ).
Keyword Arguments:
ite {number} -- number of steps (default: {0})
rType {str} -- type of movement, linear or tchebychev (default: {"linear"})
"""
self.deleteProjectile()
self.drawProjectile()
(pas, pos, ite) = self._compute_range(ite, rType)
force = numpy.zeros(ite)
femm.mi_selectgroup(1)
femm.mi_movetranslate2(0, pos[0], 4)
for i in tqdm(range(ite // 2), disable=self.bHide):
femm.mi_analyze()
femm.mi_loadsolution()
femm.mo_groupselectblock(1)
force[i] = femm.mo_blockintegral(19)
force[ite - i - 1] = -force[i]
femm.mi_selectgroup(1)
femm.mi_movetranslate2(0, pas[i], 4)
self.dLz = 2 * force / self._i0**2
self.dLz_z = pos * 10**-3
self.dLz_nyquist = 1 / (2 * numpy.mean(pas) * 10**-3)
def comp_FEMM_torque(FEMM_dict, sym=1):
"""Compute the torque of the current FEMM simulation result
"""
# Select rotor groups
mo_seteditmode("area")
mo_groupselectblock(FEMM_dict["groups"]["GROUP_RC"])
mo_groupselectblock(FEMM_dict["groups"]["GROUP_RH"])
mo_groupselectblock(FEMM_dict["groups"]["GROUP_RW"])
# sym = 2 => Only half the machine
return sym * mo_blockintegral(22)
def calc_inductance(tg, currents, inductances=(None, None), **kwargs):
''' Setup of magneto-static problem in femm to calculate inductance and
resistance of planar transformer.
Args:
tg (:obj:'TransformerGeometry'): tg contains all geometry information
of the transformer.
currents (list of float): currents in the primary and secondary side
circuits on the form [I_prim, I_sec].
inductances (list of float): self-inductances of the primary and
secondary side circuits on the form [L_prim, L_sec]. Used to calculate
mutual inductance.
Returns:
(inductance, resistance): calculated self or mutual inductance and
equivalent series resistance of either primary or secondary circuit.
'''
etiquettes_dict = {} # Dictionary to store coordinates of nodes
# initialitiation of the magneto-static problem
boundary_radius = 2 * tg.radius_dielectric
initial_setup(boundary_radius, currents, **kwargs)
# draw geometry and add block labels
add_conductors(tg, etiquettes_dict)
add_pcbs(tg)
add_isolation(tg)
add_block_labels(tg, etiquettes_dict)
# mi zoomnatural()
# From manual: zooms to a “natural” view with sensible extents.
femm.mi_zoomnatural()
# Saving geometry file
femm.mi_saveas('inductance_transformer.fem')
# Meshing and analysis
# From manual: Note that it is not necessary to run mesh before performing
# an analysis, as mi_analyze() will make sure the mesh is up to date before
# running an analysis.
# mi analyze(flag)
# From manual: runs fkern to solve the problem. The flag parameter controls
# whether the fkern window is visible or minimized. For a visible window,
# either specify no value for flag or specify 0. For a minimized window,
# flag should be set to 1.
femm.mi_analyze(1)
# Post-processing
femm.mi_loadsolution()
# mo_seteditmode(mode)
# From manual: Sets themode of the postprocessor to point, contour, or area
# mode. Valid entries for mode are "point", "contour", and "area".
femm.mo_seteditmode('area')
# mo_blockintegral(type)
# From manual: Calculate a block integral for the selected blocks
# Type Definition
# 0 A · J
# 1 A
# 2 Magnetic field energy
# 3 Hysteresis and/or lamination losses
# 4 Resistive losses
# 5 Block cross-section area
# 6 Total losses
# 7 Total current
# 8 Integral of Bx (or Br) over block
# 9 Integral of By (or rBz) over block
# 10 Block volume
# ...
# mo_getcircuitproperties("circuit")
# From manual: Used primarily to obtain impedance information associated
# with circuit properties. Properties are returned for the circuit property
# named "circuit". Three values are returned by the function. In order,
# these results are:
# – current Current carried by the circuit
# – volts Voltage drop across the circuit
# – flux_re Circuit’s flux linkage
# mo_groupselectblock(n)
# From manual: Selects all the blocks that are labeled by block labels
# that are members of group n. If no number is specified (i.e.
# mo_groupselectblock() ), all blocks are selected.
# Calculate the inductance of the circuit with non-zero current. If both
# currents are given, we calculate the mutual inductance.
L1, L2 = inductances
if (currents[0] > 0) and (currents[1] == 0):
circ = femm.mo_getcircuitproperties('phase_prim')
resistance = circ[1].real
inductance = abs(circ[2] / circ[0])
elif (currents[0] == 0) and (currents[1] > 0):
circ = femm.mo_getcircuitproperties('phase_sec')
resistance = circ[1].real
inductance = abs(circ[2] / circ[0])
else:
femm.mo_groupselectblock()
# axisymmetric problem, integral is multiplied by 2
Wm = femm.mo_blockintegral(2) * 2
inductance = ((Wm - 0.5 *
(L1 * currents[1]**2 + L2 * currents[0]**2)) /
(currents[0] * currents[1]))
resistance = 0
femm.mo_clearblock()
if kwargs.get('close') is True:
femm.closefemm()
return (inductance, resistance)
def write_Torque_and_B_data_to_file(str_rotor_position, rotation_operator):
# call this after mi_analyze
femm.mi_loadsolution()
# Physical Amount on the Rotor
femm.mo_groupselectblock(100) # rotor iron
femm.mo_groupselectblock(101) # rotor bars
Fx = femm.mo_blockintegral(
18) #-- 18 x (or r) part of steady-state weighted stress tensor force
Fy = femm.mo_blockintegral(
19) #--19 y (or z) part of steady-state weighted stress tensor force
torque = femm.mo_blockintegral(
22) #-- 22 = Steady-state weighted stress tensor torque
femm.mo_clearblock()
# write results to a data file (write to partial files to avoid compete between parallel instances)
handle_torque.write("%s %g %g %g\n" % (str_rotor_position, torque, Fx, Fy))
# Field Amount of 1/4 model (this is valid if we presume the suspension two pole field is weak)
number_of_elements = femm.mo_numelements()
stator_Bx_data = []
stator_By_data = []
stator_Area_data = []
rotor_Bx_data = []
rotor_By_data = []
rotor_Area_data = []
# one_list = []
for id_element in range(1, number_of_elements + 1):
_, _, _, x, y, area, group = femm.mo_getelement(id_element)
if y > 0 and x > 0:
if group == 10: # stator iron
# 1. What we need for iron loss evaluation is the B waveform at a fixed point (x,y).
# For example, (x,y) is the centeroid of element in stator tooth.
Bx, By = femm.mo_getb(x, y)
stator_Bx_data.append(Bx)
stator_By_data.append(By)
stator_Area_data.append(area)
if group == 100: # rotor iron
# 2. The element at (x,y) is no longer the same element from last rotor position.
# To find the exact element from last rotor position,
# we rotate the (x,y) forward as we rotate the model (rotor), get the B value there: (x,y)*rotation_operator, and correct the (Bx,By)/rotation_operator
complex_new_xy = (x + 1j * y) * rotation_operator
Bx, By = femm.mo_getb(complex_new_xy.real, complex_new_xy.imag)
complex_new_BxBy = (Bx + 1j * By) * rotation_operator
rotor_Bx_data.append(complex_new_BxBy.real)
rotor_By_data.append(complex_new_BxBy.imag)
rotor_Area_data.append(area)
# one_list.append(sqrt(Bx**2 + By**2))
# one_list.append(area)
# option 1
handle_stator_B_data.write(str_rotor_position + ',' + ','.join([
'%g,%g,%g' % (Bx, By, A)
for Bx, By, A in zip(stator_Bx_data, stator_By_data, stator_Area_data)
]) + '\n')
handle_rotor_B_data.write(str_rotor_position + ',' + ','.join([
'%g,%g,%g' % (Bx, By, A)
for Bx, By, A in zip(rotor_Bx_data, rotor_By_data, rotor_Area_data)
]) + '\n')
# option 2: one_list
# handle_B_data.write(str_rotor_position + ',' + ','.join(['%g'%(B) for B in B_data ]) + ','.join(['%g'%(A) for A in Area_data ]) + '\n')
# numpy is slower than open().write!!!
# tic = time()
# # savetxt(handle_B_data, c_[one_list])
# savetxt(handle_B_data, one_list)
# toc = time()
# print toc - tic, 's\n\n'
femm.mo_close()
if not os.path.exists(output_file_name + '.ans'):
tic = time()
femm.opendocument(output_file_name + '.fem')
# femm.callfemm_noeval('mi_smartmesh(0)')
try:
# femm.mi_createmesh() # [useless]
femm.mi_analyze(1) # None for inherited. 1 for a minimized window,
# print '[debug]', deg_per_step*i*number_of_instances, 'deg'
# rotor_position = deg_per_step*i*number_of_instances / 180. * pi
# write_Torque_and_B_data_to_file(output_file_name[-4:], exp(1j*rotor_position)) # this function is moved to FEMM_Solver.py as keep...
if True:
# call this after mi_analyze
femm.mi_loadsolution()
# Physical Amount on the Rotor
femm.mo_groupselectblock(100) # rotor iron
femm.mo_groupselectblock(101) # rotor bars
Fx = femm.mo_blockintegral(
18
) #-- 18 x (or r) part of steady-state weighted stress tensor force
Fy = femm.mo_blockintegral(
19
) #--19 y (or z) part of steady-state weighted stress tensor force
torque = femm.mo_blockintegral(
22) #-- 22 = Steady-state weighted stress tensor torque
femm.mo_clearblock()
# write results to a data file (write to partial files to avoid compete between parallel instances)
handle_torque.write(
"%s %g %g %g\n" %
(output_file_name[-4:], torque, Fx,
Fy)) # output_file_name[-4:] = str_rotor_position
def computeMuImpact(self,
mus=[5, 10, 50, 100, 500, 1000, 5000],
error=0.1):
"""Compute the impact of Mu
The model is NOT LINEAR in mu. It is hard to guess what would be the effect
of an increased suceptibility and it may highly modify the response of the coil.
However, for some configuration the error is low (typically a long coil and a small projectile).
This function provides some help to know if we can consider the model linear in Mu.
Simply provide a range of possible susceptibilities for your projectile, and an
acceptable relative error.
We do not check the whole linearity, but simply in two points selected empirically.
Therefore some care should be taken regarding the output of this helper method.
Keyword Arguments:
mus {list} -- [description] (default: {[5, 10, 50, 100, 500, 1000, 5000]})
error {number} -- [description] (default: {0.1})
"""
_mu = self.mu
res = []
test_res = []
print("Coil " + self._seed + " mus")
for mu in mus:
self.mu = mu
self.deleteProjectile()
self.drawProjectile()
femm.mi_clearselected()
femm.mi_selectgroup(1)
femm.mi_analyze()
femm.mi_loadsolution()
femm.mo_groupselectblock(1)
res.append(femm.mo_getcircuitproperties("Bobine")[2] / self._i0)
femm.mi_movetranslate2(0, self.Lb / 4, 4)
femm.mi_analyze()
femm.mi_loadsolution()
femm.mo_groupselectblock(1)
test_res.append(
femm.mo_getcircuitproperties("Bobine")[2] / self._i0)
self.mu = _mu
success = True
errors = []
for i in range(0, len(test_res)):
errors.append(
numpy.abs((res[i] / res[0]) / (test_res[i] / test_res[0]) - 1))
if errors[-1] > error:
success = False
# break
if success:
return {
'valid': True,
'mus': mus,
'mu_Lz_0': res,
'mu_Lz_1': test_res,
'errors': errors
}
else:
return {
'valid': False,
'mus': mus,
'mu_Lz_0': res,
'mu_Lz_1': test_res,
'errors': errors
}
import femm
import matplotlib.pyplot as plt
femm.openfemm()
femm.opendocument("coilgun.fem")
femm.mi_saveas("temp.fem")
femm.mi_seteditmode("group")
z = []
f = []
for n in range(0, 16):
femm.mi_analyze()
femm.mi_loadsolution()
femm.mo_groupselectblock(1)
fz = femm.mo_blockintegral(19)
z.append(n * 0.1)
f.append(fz)
femm.mi_selectgroup(1)
femm.mi_movetranslate(0, -0.1)
femm.closefemm()
plt.plot(z, f)
plt.ylabel('Force, N')
plt.xlabel('Offset, in')
plt.show()
def postGetTorque(group):
femm.mo_groupselectblock(group)
T = femm.mo_blockintegral(22)
femm.mo_clearblock()
return T