The inductor model contains physical and geometrical information that may be used to compute the inductance of some common topologies like solenoids and toroids, wound in air or other material with constant magnetic permeability.
name | parameter | units | default | example
|
IND | model inductance | H | 0.0 | 1e-3
|
CSECT | Cross section | meters^2 | 0.0 | 1e-3
|
LENGTH | Length | meters | 0.0 | 1e-2
|
TC1 | first order temperature coeff. | F/^oC | 0.0 | 0.001
|
TC2 | second order temperature coeff. | F/^oC^2 | 0.0 | 0.0001
|
TNOM | parameter measurement temperature | ^oC | 27 | 50
|
NT | number of turns | - | 0.0 | 10
|
MU | relative magnetic permeability | H/meters | 0.0 | -
|
The inductor has an inductance computed as:
If value is specified on the instance line then
Lnom = value * scale / m
If model inductance is specified then
Lnom = IND * scale / m
If neither value nor IND are specified, then geometrical and physical parameters are take into account. In the following formulas NT refers to both instance and model parameter (instance parameter overrides model parameter):
If LENGTH is not zero:
2 MU * mu * NT * CSECT 0 Lnom = -------------------- if MU is specified LENGTH 2 mu * NT * CSECT 0 Lnom = --------------- if MU is not specified LENGTH with: mu = 1.25663706143592e-6 H/m 0
After the nominal inductance is calculated, it is adjusted for temperature by the formula:
2 L(T) = L(TNOM) [1 + TC (T - TNOM) + TC (T - TNOM) ] 1 2 where L(TNOM) = Lnom
In the above formula, `T' represents the instance temperature, which can be explicitly using the temp keyword or calculated using the circuit temperature and dtemp, if present.