Hello,

I have been recently wondering if it was possible to see or to write in any way the differential equations that are solved by PSpice when it simulates the behaviour of a circuit.

Does anyone know if it's possible, and if yes how ?

Thanks a lot.

 

Technically, you should not need to because you can setup the equation yourself. Setting up the equation is not hard. Solving it is Hard! That is why ability to solve it was put into the simulator.

 

Well, technically I have got to model an ignition circuit using Pspice and get simulation results that match experimental data.
This part is dealt with, but now I would like to get the differential equations (that Pspice solved) that govern the system in order to use them in another software.
If I can get them using Pspice it would be much easier than if I had to find them "manually".

 

Well, technically I have got to model an ignition circuit using Pspice and get simulation results that match experimental data.
This part is dealt with, but now I would like to get the differential equations (that Pspice solved) that govern the system in order to use them in another software.
If I can get them using Pspice it would be much easier than if I had to find them "manually".

Well, it sounds like you don't want to setup the equation yourself. Whoever gave you the circuit has the equation, ask them.

Perhaps I should say it another way. PSpice is SIMULATION software, it NOT mathematical software like MatLab/MathCAD/Maple/etc.

You could put your data into Excell/math software and see if you can match an equation to your data.

 

I made the circuit myself by looking at some information available in the literature and then tuned it myself to make the results match the experimental data.
There was however no equation provided with the schematics of the circuit that i used.

 

I made the circuit myself by looking at some information available in the literature and then tuned it myself to make the results match the experimental data.
There was however no equation provided with the schematics of the circuit that i used.

Ok, that sort of makes sense.
Are you lacking the mathematical background to derive the equation from the circuit schematic? Is that it?

 

As it is quite a complicated circuit ( at least for me ) I would say so yes. And moreover, i want to make sure that the differential equations that I will later use are the ones that Pspice solved to trace the response I asked it to give me.

 

As it is quite a complicated circuit ( at least for me ) I would say so yes. And moreover, i want to make sure that the differential equations that I will later use are the ones that Pspice solved to trace the response I asked it to give me.

Take a look at Example 5.1 on Page 210: http://books.google.com/books?id=II...e&q=differential equation of ignition&f=false

 

Thanks for this help, but my circuit is way more complex than the one in the example you gave me, so finding the equations manually would be really painful for me. That's why I wanted to know if I could get the ones used by Pspice.

( A Printscreen of my circuit should be attached to this answer )