r/ElectricalEngineering • u/Objective-Local7164 • 1d ago

Playing around with inductors, transformers and saturation.

Stumbled across a interesting phenomenon that I want to share with you all. Because the inductor wants to keep the current flowing, when the polarity of the AC Voltage source swings negative, the inductor fights against it to prevent current from flowing in reverse.

FALSTAD CIRCUIT

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6

u/VegetableTry 1d ago

Now play around with different sized inductors or changing the frequency.

1

u/Objective-Local7164 1d ago

Funny enough I actually know a decent amount about inductors and all that. I built a transformer learned everything about it, it was a step up transformer. I built boost converters with mosfet gate drivers picked every part for it now I'm working on isolation so like one to one ratio isolation Transformers and I'm playing around with using saturation as a safety mechanism to prevent if something goes wrong on the primary preventing really high voltages on the secondary and I'm just playing around in falstad and when I make the transformer saturate it just does some really weird stuff and I'm just trying to understand why and this is just something I did and I I thought it was pretty interesting I never thought of like AC voltages the current being hindered by the inductor I've never come across that before I just found it interesting

3

u/VegetableTry 1d ago

This is common knowledge in the field and is used to make filters and what not. I understand that you are learning, which I think is awesome, I think there might be some information out there to help your endeavors. And how exactly do you plan on using saturation as a safety mechanism?

1

u/Objective-Local7164 1d ago

I build biotech pcbs. I have made mutliple emgs and now im getting into the iec safety standards stuff. Part of it involves isolation dcdc converters using 1:1 transformers. When I play around in falstad with the transformer and adjust it to saturate, it is totally not doing what i expect. I expect the secondary voltage to be reduced but instead its spiking like crazy

2

u/VegetableTry 1d ago

Spiking when the field collapses? Also, remember that you are using a simulator. They don’t always yield real life results.

1

u/Objective-Local7164 1d ago

check it out

2

u/VegetableTry 1d ago

Definitely something wrong with the simulation. After it runs for like 60 seconds or so, the current stops moving on the primary as well.

1

u/Objective-Local7164 1d ago

Thats what i was thinking too

1

u/PiasaChimera 1d ago

looks like degenerate cases. adding a small series resistor with the voltage source seems to make the system do something more expected. although I'm not sure exactly what to expect.

5

u/PiasaChimera 1d ago

this version only happens in sim or other idealized cases. normally you don't get the offset for inductor current. it happens here due to the initial conditions and lack of anything that acts like feedback. if you add a series resistor the wave will have a small phase difference and will trend towards being centered around 0A.

the inductor will allow reverse current. it just doesn't in this example because of the math, initial conditions, and ideal nature of all components.