Discussion Forum

Hi Ahmed,

i've got the same problem.

"The special implementation used here defines a subcircuit that
really is a COMSOL Multiphysics model, referenced with the option
COMSOL: <file name>|<physics_interface_name>|*. The asterisk means that
COMSOL Multiphysics looks for the first occurrence of the specified parameters
V_coiland I_coilin the current model. These parameters are the variables that link
the model with the circuits, and must be defined in the model in a certain way. The
variable V_coilmust give the voltage over the device, defined in the global scope.
I_coilmust be a global variable used in the model as a current through the device."

I read this more than 10 times but i also cannnot find V_coil, I_coil, nor have I understood the syntax

<file name>|<physics_interface_name>|*.

So did you find something yet ?


Also greetings from germany

Marius

Dear Marius.


I think its better to ignore the Circuit_example they really documented it in a bad way a

So after importing your circuit. and integrating it to your comsol modell you should look in under your component list foe the electrical componenets ann click on external I vs U and then electrical potenial take care not to choose used defined then you will have this strange V_coil if you declared it in your netlist.. choose another optin depends to your modell esc ...Tell me if it worekd.


Greetings from Germany !

Thanks Ahmed,

i will try it and i will post, if it worked.

Viele Grüße

Marius

Hello Marius

If you do the same with the comsol example. You will see when you click on V_coil " same steps like I wrote before" that comsol says V coil ist not a defined parameter ....strange ... this is why I said dont count on this example ;)

Hi Ahmed,

thanks for your advise.
I've now managed it to connect a simple Comsol model of two condensator plates to a ciruit in SPICE. I simply replaced the
"V_coil I_coil" with "a b". And with this I got two external-I-Terminals in my Circuit in Comsol. The next step was to connect them with the Terminals in the model and i could do a time dependent study.

But now I'm wondering how to run a frequency domain study with a connected SPICE-Circuit.

There are 4 Voltage sources in the Comsol circuit: sine, DC, pulse and AC.
But how can I make Comsol perform the frequency domain analysis using a source in the Circuit ?

Is there some way to roote the input voltages of the FD analysis to the circuit?

Hi Ahmed,

I'm not at work anymore. So I don't have acces to the model. Tomorrow morning I will sent it.

Ich wünsche noch n schönen Abend ;)

Viele Grüße

Marius

Hi

here is my modell. It is a simple resonating circuit consiting of a voltage source, inductor, capacitor and a resistance. They all are connected in series.
The capacitor is a model in 2D in Comsol 4.3.

The attached model contains a study which performs a time dependend analysis.

My attempt is to do a frequency domain analysis with the EMF physics.

I also attached the netlist. Because *.cir is not allowed in attachments I renamed it in

netlist.mph

Thank your for your help


Marius

Hi Ahmed,

sorry, i couldn't answer yesterday.

I created the circuit with LT-Spice and exported the the netlist. I attach both files. The draft-File is the circuit in LT-Spice.

Hi Marius


So I see that you followed my advices for I_coil an dV_Coil to be able to integrate the Electrical circuit. It looks good and im at the same level now...

I also have the same problem I want to have AC (FD) Source and sin (time dependend) but I dont know how

I attached to sorces to comsol AC and Sin the same nood .... it didnt help... I think this is laos your problem or ??


Please let me know if you have any progress or a new idea


greetings

Hi Ahmed,

yes, that's the problem. I now believe, that It is not possible to place the source for the FD-Analysis into the circuit.

The usual way to do a FD-Analysis in Comsol is to build two Terminals in the model where current or voltage for the analysis is applied.

So I'm thinking of setting the voltage source in the circuit to zero volts and applying a current into the capacitor in the model. Maybe one can "mesure" the voltage at the nodes of the zero voltage source in the circuit.

I'm already trying this, but now im having trouble with the FD-Analysis itself. So I have to solve that issue first befor I can try it.

I wrote you a Private message with the same text in german.