[Simetrix] Error in simulation

[guitarnoob123]

Good day,
I have this circuit and I can't start the simulation (AC analysis).
I forgot how to debug this. I think it has something to do with the transformer and the placement of the ground node. Also, can I have 2 different ground nodes for my circuit?
Any ideas?

 

[godfreyl]

Also, can I have 2 different ground nodes for my circuit?

Yes, it's normal to have several points connected to ground.

I can't see your circuit, but you will need something on the primary side of the transformer connected to ground, and something on the secondary side connected to ground. Actually, as a general rule: every node in the circuit must have some sort of DC path to earth, to avoid "floating" nodes.

Two nonos for simulators:
1) Two capacitors in series with nothing connected to the midpoint. In this case the voltage at the midpoint can't be calculated.
2) Two inductors in parallel with no resistance in or between them. In this case the circulating current can't be calculated.

 

[guitarnoob123]

Two nonos for simulators:
1) Two capacitors in series with nothing connected to the midpoint. In this case the voltage at the midpoint can't be calculated.
2) Two inductors in parallel with no resistance in or between them. In this case the circulating current can't be calculated.

I didn't know this before. This is helpful thanks!
So does a secondary side of the transformer parallel with an inductance considered 2 inductors in parallel?
The reason I did this is because I wanted the secondary side of the transformer to have an inductance value because I can't see any other way to do it (the component is an ideal transformer: **broken link removed**)
This was my circuit **broken link removed**

Just now: I tried putting the inductor in series with the transformer. Simulations can be run now, but the output is not the one I expected - well time for some debugging.
**broken link removed**. Just in case you want to know my purpose, supposedly I want to simulate inductive power transfer through coupling of the inductors - wireless charging and the likes

 

[godfreyl]

The reason I did this is because I wanted the secondary side of the transformer to have an inductance value because I can't see any other way to do it (the component is an ideal transformer: **broken link removed**)

I think you'll find that setting the primary inductance automatically sets the secondary inductance as well. You can test that quite easily in the simulator e.g. by driving the secondary with an AC source through a resistor (with the primary left open circuit).

This was my circuit **broken link removed**

The trick with that kind of circuit is to put a very small resistor (say 0.01 Ohm) in series with the inductor. It's too small to make any practical difference, but keeps the simulator happy.

 

[guitarnoob123]

I think you'll find that setting the primary inductance automatically sets the secondary inductance as well. You can test that quite easily in the simulator e.g. by driving the secondary with an AC source through a resistor (with the primary left open circuit).

Is there a way to alter the secondary inductance? Or should I use 2 inductors instead of a transformer?
I don't know how to manage the coupling between inductors in simetrix. Maybe I should look more into this

Thanks for the tips. I learned a lot.

 

[godfreyl]

IIRC, the ratio of secondary inductance to primary inductance is equal to the square of the turns ratio.
Then I think the leakage inductance is determined by the coupling factor, but I've no idea how to calculate that. Books (and Google) are much better at remembering this stuff than I am. Maybe someone else will chip in with the right formulas.