Nonlinear inductors in SPICE

[Dr. Adrian Wrigley]

Hi guys!

I'm trying to model an inductor which varies inductance according to
the terminal potential (don't ask why!).

The inducance is high when the terminals are close to 0V,
and reduces according to 1/(V1+V2)^3. (where V1 and V2
are the absolute terminal potentials above ground.

Perhaps the formula is:

(V2-V1) = di/dt L/(V1+V2)**3

What is the best way to simulate this with SPICE (eg ngspice)?
I'm relatively new to SPICE simulation, so I'm sorry if this
is a FAQ!

(note that the terminal voltages always stay above 0V)

Thanks in advance!
--
Adrian

 

[Jim Thompson]

On Fri, 19 Jan 2007 14:10:28 GMT, "Dr. Adrian Wrigley"
<amtw@linuxchip.demon.co.uk.uk.uk> wrote:

Hi guys!

I'm trying to model an inductor which varies inductance according to
the terminal potential (don't ask why!).

The inducance is high when the terminals are close to 0V,
and reduces according to 1/(V1+V2)^3. (where V1 and V2
are the absolute terminal potentials above ground.

Perhaps the formula is:

(V2-V1) = di/dt L/(V1+V2)**3

What is the best way to simulate this with SPICE (eg ngspice)?
I'm relatively new to SPICE simulation, so I'm sorry if this
is a FAQ!

(note that the terminal voltages always stay above 0V)

Thanks in advance!

Most any Spice can do that using polynomial notation.

But it's easier in Spice variants that support behavioral (Algebraic)
notation.

I posted one here many moons ago that was an inductor that varied with
current.

Someone else more recently had a different way of doing it.

Surf ;-)

...Jim Thompson
--
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