Need a transformer model that allows for turns entry. Also, for some reason some of my text and symbols have taken on different sizes? It seems my Voltage models have shrunk? For example...

 

Hello Sir.
I found something that I hope will help but this is for LTS IV.
LTspice simulates the transformer using individual component values, the inductance of the individual inductors, not the turns ratio of the transformer.
https://www.analog.com/en/technical-articles/ltspice-basic-steps-for-simulating-transformers.html

 

Link :
http://bordodynov.ltwiki.org/
For axample:

 

@Delta Prime That should work since I just need a simple straight forward ideal model for now.

@Bordodynov I already have your model set but seems this is in addition? I do want to thank you for your extensive model set. Impressive work!

Seems I need more education on the net list programming.

 

Need a transformer model that allows for turns entry. Also, for some reason some of my text and symbols have taken on different sizes? It seems my Voltage models have shrunk? For example...

View attachment 263193

Text and symbols changing sizes indicates there may be other problems of which you are not aware. The inability to find the subcircuit for a symbol is indicative of a broken link between the symbol called out in the schematic, the first occurrence of that symbol name in your directory tree, and the name of the subcircuit called out by the symbol.

Size changes for symbols happen when you have multiple symbols with the same name and they each have different graphics.
Changing text sizes happen when you have old schematics with a text size of 0, which used to be the "default", but now represents the smallest size.

Your transformer symbol is used for the "mythical" DC-DC transformer described in Basso's book on Switch-Mode Power Supplies.

EDIT: Found it

 

Need a transformer model that allows for turns entry. Also, for some reason some of my text and symbols have taken on different sizes? It seems my Voltage models have shrunk? For example...

View attachment 263193

A quick way is to calculate pri/sec inductance using "the square of the turns ratio" method.
Then adjust the values for frequency.

 

A quick way is to calculate pri/sec inductance using "the square of the turns ratio" method.
Then adjust the values for frequency.

See how the transformer consisting of L! & L2 is defined using the turns ratio N.

 

See

 

A quick way is to calculate pri/sec inductance using "the square of the turns ratio" method.
Then adjust the values for frequency.

This is something new that I have not seen before in my studies. I understood the video that DeltaPrime linked to using the square root of the inductance to determine the turns ratio. Which is obviously the reverse method of getting inductance from turns. How does that then get adjusted for frequency? What I am presently working with is all 60Hz power supplies at various voltages.

 

This is something new that I have not seen before in my studies. I understood the video that DeltaPrime linked to using the square root of the inductance to determine the turns ratio. Which is obviously the reverse method of getting inductance from turns. How does that then get adjusted for frequency? What I am presently working with is all 60Hz power supplies at various voltages.

Spice transformers can get complex in a hurry. But to keep it simple, once you have the correct inductance values, adjust the inductance values, while keeping the ratio constant, so that the reactance satisfies the (current transfer) load requirement.

Here is an LTspice transformer document:

 

This is something new that I have not seen before in my studies. I understood the video that DeltaPrime linked to using the square root of the inductance to determine the turns ratio. Which is obviously the reverse method of getting inductance from turns. How does that then get adjusted for frequency? What I am presently working with is all 60Hz power supplies at various voltages.

As you know the inductive reactance is a linear function of the frequency. As the frequency goes up you want to make the inductance smaller so that the inductive reactance does not get too large. You can easily use a spreadsheet to compute the reactance for a fixed frequency. Like this:

Inductive Reactance​	​	​	​
Frequency​	60​	Hz.​	​
​	​	​	​
Inductance​	​	Reactance​	​
10.00E-06​	​	0.00376991118430775​	Ω​
100.00E-06​	​	0.0376991118430775​	Ω​
1.00E-03​	​	0.376991118430775​	Ω​
10.00E-03​	​	3.76991118430775​	Ω​
100.00E-03​	​	37.6991118430775​	Ω​
​	​	​	​
Reactance is not of much concern at low frequency​	​	​	​
​	​	​	​
Frequency​	100.00E+03​	Hz.​	​
​	​	​	​
Inductance​	​	Reactance​	​
10.00E-06​	​	6.28318530717959​	Ω​
100.00E-06​	​	62.8318530717959​	Ω​
1.00E-03​	​	628.318530717959​	Ω​
10.00E-03​	​	6283.18530717959​	Ω​
100.00E-03​	​	62831.8530717959​	Ω​
​	​	​	​
Even 1mH has significant reactance @ 100kHz​	​	​	​

 

OK, what I am doing is using the ideal model for the XFMR so the reactive inductance does not come into play. One of these days I will get around to finishing Malvino's Resistive and Reactive Circuits...

 

OK, what I am doing is using the ideal model for the XFMR so the reactive inductance does not come into play. One of these days I will get around to finishing Malvino's Resistive and Reactive Circuits...

If you're using inductors in an AC transformer, there is still inductive reactance.
So unless you want get fooled, better to check the output with the anticipated load.

 

OK, what I am doing is using the ideal model for the XFMR so the reactive inductance does not come into play. One of these days I will get around to finishing Malvino's Resistive and Reactive Circuits...

The model you posted originally, is for an ideal "DC-DC Transformer". This part does not exist in reality. It is used to investigate the behavior of DC-DC converters. I believe it is a serious mistake to use it in conjunction with the circuit in your original post. Just use the coupled inductors. You will avoid getting tricked by the results that you observe.

 

The model you posted originally

That was just noodling around with what was available in my libraries. Think I have the answer to what I am currently working on from the old LTS4 video on the AD site.

 

That was just noodling around with what was available in my libraries. Think I have the answer to what I am currently working on from the old LTS4 video on the AD site.

Nothing wrong with that, but it helps to have some context when that is available. I did not come by all these examples that I've posted overnight.