# [Getdp] GetDP - diode as non-linear resistant

A.Eckert at eunda.ch A.Eckert at eunda.ch
Wed Apr 17 09:31:44 CEST 2019

```Hello everyone

I currently try enlarge the machine model to include external connections.
On of the aims is to model a 3-phased diode rectifier (B6-Bridge) which
uses 6 diodes to rectify the incoming waveforms.
In the example file Lib_Magnetodynamics2D_av_Cir.pro  (
https://gitlab.onelab.info/getdp/getdp/blob/master/templates/Lib_Magnetodynamics2D_av_Cir.pro
), there's a hint/comment to use nonlinear resistors to simulate diodes.
Unfortunately I coudln't find an exact example how to implement it.

Following three lines are basically those related to the diodes out of the
above example:

Diode_Cir = Region[{}] ;

GlobalTerm { NeverDt[ Dof{Uz} , {Iz} ]; In Diode_Cir; }
GlobalTerm { NeverDt[ Resistance[{Uz}] * Dof{Iz} , {Iz} ]; In Diode_Cir; }

According to my understanding, the definition of such a resistance is
missing. I simplified the example to one diode.
I added the regions and allocated it to the Diode_Cir.

R_DIODE_1_A0 = Region[{1000012}];

Diode_Cir += Region[{R_DIODE_1_A0}];

In the last step, I set the dynamic resistance. In that case it's just the
input voltage.

Resistance[Region[{R_DIODE_1_A0}]] = \$1

The program itself successfully finishes. But basically all values are
-nan, so something runs badly wrong. When I replace \$1 in the line above,
through a fix number (e.g. 10 ), the program behaves as it should.
So there's probably still a mistake in the dynamic resistance calculation.

Any help is highly appreciated. Thank you very much.

Mit freundlichen Grüssen

Andreas Eckert
Forschung und Entwicklung / Research and Development
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