Building lt spice transformer / help!

[ChrisP58]

I think I found the Inductance as

B=
0.003628192286234499 which is

3.628192286234499 mH How is inductance derived from this?

I think you're making it more complicated than you need to.

For now, just take the Al (L is a subscript) value from the core datasheet, and multiply that by the square of the turns.

Leave it to the core manufacturer to figure out what the Al is for any given core.

 

[alec_t]

You really don't need inductance (or any other) values to 15 decimal places .
But Chris got the inductance as '~900uHy for each of your 4 windings', so put '900u' (or '0.9m') into Spice as the inductance values.

 

[ericgibbs]

hi,
Look here for LTSpice transformer design, also check Simon Bramble's tutorials.
http://ltwiki.org/index.php5?title=Transformers
E

 

[killivolt]

Ok, I was using Mikes Calculator thinking I had one more step, I'll play around with it later.

I've taken Rons, Suggestions and this is what I have now.

 

[ericgibbs]

hi kv,
The bottom of diode D4 is not connected.?, no path to the M2 source
Eric

 

[alec_t]

Can't see an inductance value for HV-Primary?

 

[killivolt]

Eric, I tried to connect D4 I think I may need to spread thing out. M2's Path to source do you have a suggestion what to do?

alec t, I was waiting to calculate that, it's a flyback from a TV, 6 turns 18g Mag wire. I don't know how to calculate it?

 

[alec_t]

alec t, I was waiting to calculate that, it's a flyback from a TV, 6 turns 18g Mag wire. I don't know how to calculate it?

Don't see how you can calculate it if the flyback core parameters are unknown. You could guestimate it by assuming the params are similar to your ferrite. If 14 turns gave you 900uH then 6 turns should give (6/14)^2 x 900 = 165uH by my reckoning.

 

[killivolt]

There both Iron just one of them is a powder and the other, well that's where I didn't know either. I'm ok, questimate.

What does Eric mean by path?

 

[killivolt]

Never mind I figured it out.

Thanks, I'll add the Inductance to HV Primary.

I'm still not sure now who the center tap of the primary is to be done?

 

[killivolt]

Rev2......Edit: I forgot to add the Inductance of the HV Primary. Just fixed it.

 

[killivolt]

I have the free version I can't run this Simulation on the Schematic in post #51, could someone check it out? Gotta go back to work now. Later.

 

[Inquisitive]

LTSpice is 100% free.

 

[ericgibbs]

There both Iron just one of them is a powder and the other, well that's where I didn't know either. I'm ok, questimate.

What does Eric mean by path?

hi kv,
A conductive path from the bottom of the D4 diode and the M2 FET Source pin.

Without a conductive path from the bottom of the diode there will be no voltage between the Gate and Source of M2, the Gate is virtually 'floating'
E

 

[killivolt]

Maybe I haven't set up the toolbar or something. Not sure what I'm done wrong?

All I have is File, Edit, View, Window, Help.

 

[killivolt]

Thanks, I figured that one, when I re-read your post and path and source together. I have corrected it, but now I need all the tools in the toolbar? To Run it.

It might be because I'm running it on a Mac.

 

[killivolt]

I don't have a symbol for the SG3525, so I can't check those connections, but C1 and C2 will block the current that needs to flow in the two sides of the primary. They would be needed if the outputs of the SG3525 were current sourcing/sinking. But since they sink current only, they need to be DC coupled to the transformer windings.

The value for the four inductors should be the inductance of 900uHy.

Hey Chris, I don't think I ever sent this to you.

 

[killivolt]

I have a Windows version LT Spice using my VM Ware I have windows on one side of my Mac, I can share files as well.

I have a toolbar now. I don't know how much trouble I will have but, I could run it. My Version of OS X is is 10.8.5 and I think the latest version of LT Spice is 10.7+, But,

The windows version of LT Spice has the "latest" update. Not the Mac.

I contacted them to let them know the trouble.

kv

 

[killivolt]

I found I connected the left side of SG3525A wrong, I fixed them.

Here is the new Drawing.

 

[killivolt]

Here is the Original authors Schematic