Sizing

The machine sizing module includes functions that creates a machine model dict (see Machine) for following types of radial flux machines:

• Surface Mounted PM (spm)

• Interior Magnet PM (ipm)

• Electric Excited SM (eesm)

• Induction Machine (im)

Each function has three mandatory parameters:

• pnom: nominal (rated) power in W

• speed: shaft speed in 1/s

• p: pole pairs

In addition a couple of optional parameters with default values are available:

Name	Description	Unit	Value
airgap	airgap width	m	1.5e-3
eta	efficiency		0.92
cos_phi	power factor		0.95
m	number of phases		3
ui_u	ratio U ind / U		0.62
lda	length/taup ratio		1.33
J	current density 3 .. 6	A/m²	3.8e6
sigmas	shear force 10 .. 45 kN/m2	N/m²	17e3
Ba	flux density in airgap	T	0.7
Bth	flux density in teeth	T	1.5
By	flux density in yoke	T	1.2
Bthr	flux density in rotor teeth	T	1.7
Byr	flux density in rotor yoke	T	1.4
kq	stator winding fill factor		0.42
kqr	rotor winding fill factor		0.6
mag_width	rel magnet width		0.8
Hc	max. coercitive field strength	kA/m	700
brem	remanence	T	1.15
demag	safety factor for demagnetisation		1.5
external_rotor	external rotor		False
coil_span	coil span		0
hfe	iron height between magnet and airgap	m	1e-3

For IM the default values are as following:

Name	Description	Unit	Value
airgap	airgap width	m	0.75e-3
eta	efficiency		0.87
cos_phi	power factor		0.8

Sizing Example for a SPM:

p2 = 1.5e3
speed = 1500/60
udc = 550
p = 4

machine = femagtools.machine.sizing.spm(
   p2, speed, p, udc=udc, Q1=36,
   Hc=700, sigmas=12e3, brem=1.1, Ba=0.77,
   cos_phi=0.7, eta=0.8, demag=1.7, lda=0.9)