Model for current transformer is now available in ANR Q-lib:
Implementation of this CT model is not merely a simple transformer, qhich is to ensure proper simulation of the transformer behavior and at the same time ensure fast runtime operation.
In the example EMF and core reset requirement is emulated well by this CT model.
Github for the library: QSPICE/ANR Q-Lib at main · physicboy/QSPICE · GitHub
Github for the example: QSPICE/Current Transformer Test at main · physicboy/QSPICE · GitHub
So, the primary side is completely free of inductance, but the secondary side includes it, allowing you to simulate the inductance effect in the pickup circuit without having to add any inductance to the power section. Is this what you are aiming to achieve with this symbol?
That’s the side effect of my design choice actually, but not the goal. And, primary side inductance of a CT is actually also nH range typically, so rather negligible.
The main reason why I do that is because in the putting a few inductors in series (i.e. you use the CT to measure LLC resonant tank current), your simulation becomes very slow somehow.
So, I avoid that by placing V source on the primary current path. Then copy the current magnitude with F source which then finally connected to the actual transformer.
This is smart — a current transformer that avoids adding primary inductance to the power stage simulation to keep it as fast as possible, while still modeling the current sense output inductance on the secondary side. The common approach is usually just a simple current-to-voltage converter using a 0V voltage source to sense current and a B-source output a scaled voltage for the secondary, but that completely removes all inductive effects.
Just curious, LLC resonant tank should have inductance in its resonant tank and why that extra few nH can slow down your simulation?
I already have current sensor model in my library, it uses V-source to sense the current then H-source as current to voltage converter. Anyway, no inductive effect at all, even if I replace the H-source with F-source without the transformer model.
I have no idea why… I guess having multiple transformer in series with different secondary side current behavior is not easy to converge…
