Is it possible to simulate a flyback transformer in LtSpice?

Thread Starter

Zouglou LeMagicien

Joined Feb 12, 2019

I'm wondering if is it possible to simulate my flyback transformer in LtSpice, I'm a beginner in LtSpice, so I don't know how to write a correct code ...
Here is the schema :
So, I need to simulate the transformer who has 3 primary and 1 secondary...


Last edited:


Joined Apr 5, 2008

The numbers of turns does not tell you much about the transformer.
You will need the properties of the transformer core to calculate the inductance, before you can simulate the circuit.


Thread Starter

Zouglou LeMagicien

Joined Feb 12, 2019
All right, I calculate the different inductance, here it is :
First primary -> 2,96mH
Second primary -> 2,96mH
Third primary -> 0.119mH
Secondary -> 0.252mH

Don't know if it will help :/


Joined Jun 8, 2013
it's on the first post...
The transformers in LTspice don't simulate a metal core or saturation effects. They can be modeled to behave that way but it gets fairly complicated.

There are models made by Wurth Elektronik that might fit you application.

Try looking here:

There might already be one available. If there is one close to the one you need, we might be able to modify it and use it for your simulation.



Joined Mar 14, 2008
Note to add in any leakage inductance and parasitic capacitance between windings, as those can have a significant effect on the generated transient voltages.


Joined Oct 7, 2019
The 15 turns + 15 turns on the transformer should be 30 turns for SPICE. For LT Spice you state the inductance not the turns. We don't know the inductance. I would start out with 30T=1mH. Remember "turns squared". 3T=10uH. Also remember to use the "K1 L1 L2 L3 1".

I do not use "120/220Vac 50/60hz" That used computer time and makes the results hard to understand. I would not use the "power line" and everything including the 4 Diodes. There is a large unknown capacitor inside the Diode Bridge. There is where you should put a 160 volts dc supply. (or 320V dc supply) This will help the complexity.

I think the rest of the circuit will likely work.


Joined Jul 3, 2021
Not really sure if this is the correct thing to do, but I modified some lines of the .asc files to this:

SYMATTR Value core
SYMATTR Value2 Hc=13 Bs=0.4 Br=0.14
SYMATTR SpiceLine A=60u Lm=67m Lg=0.18m
SYMATTR SpiceLine2 Fe=1.5Meg

Basically added the attribute-value pair "Value core" so that it will be similar to the definition on the Core.asy file.


Joined May 20, 2015
I apologize for the problems. It's like the proverb: "The best is the enemy of the good. I have improved the symbols (this is related to usability). But I have circuits with old symbols. When you take a scheme like this and already have new symbols, you get confused. I am sending you the updated diagram. I put a new core on the circuit, corrected the parameters as in the old one and threw away the old one.