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[SOLVED] Ferrite core transformer inductance calculation

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Vaughn

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I was going to build an smps (220VAC to 12VDC)and constructing the transformer my own but before working physically i wanted to simulate the transformer in LTspice but there it is asking for Inductance of the side primary and secondary side, can you please tell me that how can I calculate the inductance. My core size is gonna be E13/8/5 with 270 primary turns and 14 on secondary, frequence 60kHz.
 

get AL value OF CORE, then inductance = (AL * N^2) * 1E-9
 
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    Vaughn

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get AL value OF CORE, then inductance = (AL * N^2) * 1E-9

Thank you sir It worked for me but one thing you forgot to tell is that the value of AL should be in nH for the result in H, am I right? One more thing I wanted to know that whether the number of turns for primary and secondary is good to go for 20W 12VDC output from 220VAC in 60kHz, Core is actually E19/8/5, E13/8/5 was written mistakenly.
 

Here is a spice model that you can use:

Code:
*SRC=Untitled;Untitled;Transformers;;Siemens Matsushita, E19/8/5
*SYM=Untitled
.SUBCKT Untitled 1 2 3 4
*Siemens Matsushita, E          Ferrite, N67_30300K_100C, E19/8/5
** ** ** **
Rdc1	N41	N61	16.83
Lmag	N41	2	0.2237
Rcore	N41	2	504.1k
Rac1	N61	1	52.30
Lac1	N61	1	97.10u
** ** ** **
L12	N41	in2	262.0u
C1_2	in2	2	17.55p
C2_23	2	4	139.2p
C3_23	2	N42	-86.51p
Efwd2	N82	4	in2	2	51.85m
Vsens2	N82	N42	
Ffbk2	in2	2	Vsens2	51.85m
Rdc2	N42	N62	55.30m
Rac2	N62	3	0.3194
Lac2	N62	3	440.9n
.ENDS
 

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    Vaughn

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but one thing you forgot to tell is that the value of AL should be in nH for the result in H, am I right?
for some reason AL is always in nh/turn^2, that's why I put the 1e-9 multiplier, to get it in H for you.

AL is effectively the "allowance", kind of the reciprocal of reluctance, reluctance = 1e9/AL
 
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    Vaughn

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Sir, I have never created any customized model or subcircuit before but what I understood by your post and by searching on the web is that I need to create a subcircuit and need to change it's value as "Untitled" as you have named it in your spice model and then need to link it. In a video tutorial I saw that if it is a single component then the value of the it can be changed "Untitled" easily by ctrl+right clicking but since the transformer I have created is the combination of two inductor(with K L1 L2 1) then how can i implement the spice model on it or whether the spice model will be implemented on the image you provided (as a new component) if it is, then how can I do so?
 

If you are using LTSpice then you should use the format that is suitable.

You can just copy the model to notepad and save as say Transformer.MOD

Then import into LTSpice and right click Transformer and "create symbol"

- - - Updated - - -

Remember to generate Expanded Listing as well to go with the symbol.

Model seems to work fine.
 

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