SMPS Transformer Primary Turns Calculations

MicrosiM

Administrator
Staff member
Here some informations about calculating PRIMARY TURNS for SMPS transformer
 

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  • Switch Mode Power Supply Transformer Calculations.rar
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ravs

Member
hi microsim,

thats only for half bridge .would appreciate if you add information for choosing wire guage for multiple strands to avoid skin effects ie for a given guage using multiple wires of higher guages.post a complete example of smps right from start to end.thanks for sharing



thanks

ravs


be a vegeterian........
 

MicrosiM

Administrator
Staff member
Foil

hi microsim,
thats only for half bridge .would appreciate if you add information for choosing wire guage for multiple strands to avoid skin effects ie for a given guage using multiple wires of higher guages.post a complete example of smps right from start to end.thanks for sharing

thanks

ravs


be a vegeterian........

You can use Foil to avoide skin effect at 125KHz as an example, Also if you tel more about the SMPS you want to build, it will be easier to hellp you out :)
 

lakone

New member
Hi, all. Greeting from me. I'm wondering about the ferrite core that used to be in the PC power supply ( half bridge)?
What kind of ferrite is that? Should I use datasheet from ferroxcube or epcos?
 

MicrosiM

Administrator
Staff member
Formula in Excel 2003

can you post the formula file as an "xls" file? some of us are still using MS Excel 2003 :(


Here is the Converted sheet into Excel 2003, Hope it will work with you.
 

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  • 2003Transformer_Formula.rar
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soundmax

New member
Here is the Converted sheet into Excel 2003, Hope it will work with you.

My Friend MicroSim,
As I had already reviewed it, I'm developing the power switch quasi resonant, but now I have two serious problems:
Its formula can be used with Quasi Resonant power supplies? if so how should I proceed to calculate the inductor and capacitor are in series with the transformer?
I need urgent help from you guys,
awaiting,
a hug to everyone,
Cleber
 

MicrosiM

Administrator
Staff member
Resonant

My Friend MicroSim,
As I had already reviewed it, I'm developing the power switch quasi resonant, but now I have two serious problems:
Its formula can be used with Quasi Resonant power supplies? if so how should I proceed to calculate the inductor and capacitor are in series with the transformer?
I need urgent help from you guys,
awaiting,
a hug to everyone,
Cleber

From my experiance.

Tuning that kind of SMPS, or reaching the resonant is not an easy task.

for me, I have no idea about your SMPS, or even any other details to help you out.

See below formula for calculations

Formula.JPG
 

ravs

Member
My Friend MicroSim,
As I had already reviewed it, I'm developing the power switch quasi resonant, but now I have two serious problems:
Its formula can be used with Quasi Resonant power supplies? if so how should I proceed to calculate the inductor and capacitor are in series with the transformer?
I need urgent help from you guys,
awaiting,
a hug to everyone,
Cleber

hi soundmax,

check this stuffView attachment res1.PDFView attachment res2.PDF

regards

ravs


be a vegeterian....
 

sphinx

New member
Be mindful of the voltage requirements for the resonant capacitor. I designed a 120/240Vac resonant SMPS with Vin max = 400Vdc due to voltage doubler when configured as 120V AC Input. That required a film capacitor with an AC voltage rating of 650 V. Considering temperature de-rating, a 1KVAC rating was more appropriate. This was not easy to find at a reasonable price so I used two 500Vac capacitors in series.
 

IGBT

Switching Fanatic!
Pfc

Be mindful of the voltage requirements for the resonant capacitor. I designed a 120/240Vac resonant SMPS with Vin max = 400Vdc due to voltage doubler when configured as 120V AC Input. That required a film capacitor with an AC voltage rating of 650 V. Considering temperature de-rating, a 1KVAC rating was more appropriate. This was not easy to find at a reasonable price so I used two 500Vac capacitors in series.

I agree with the capacitor voltage, But where did you get the 400V from? are you using PFC?
 

sphinx

New member
IGBT, I target high AC line condition at + 20% so:

240VAC + 20% = 288VAC

288 VAC * 1.414 = about 400VDC with diode and in-rush current limiter voltage drops

Cleber,

I used MKP but others are acceptable depending on your particular circuit. Low ESR is obviously preferred.
 

ravs

Member
hi microsim,

can u post the formula for finding out the secondary turns.for centre tapped winding .i am following marty
browns power supply cookbook and practical switching power supply.both have different calculations.
thanks in advance

ravs

be a vegeterian.....
 

ravs

Member
Here you go with the formula, I know that its not available on the web, even its easy.

Enjoy..

hi microsim,

thanks a lot but can you post the equations involved.i am getting difference in secondary turns.
primary is same as mine.

thanks

ravs

be a vegeterian.....
 

MicrosiM

Administrator
Staff member
Formula

hi microsim,

thanks a lot but can you post the equations involved.i am getting difference in secondary turns.
primary is same as mine.

thanks

ravs

be a vegeterian.....

You have to edit, the fields in the formula * in yellow* to your needs
 

MicrosiM

Administrator
Staff member
Ravs

ravs



I see that you are taking too much informations from this site, and acting like you know nothing, while you acting like a professional SMPS guy on other forums, that *I do Hate it* alot.

If you found this place helpful to you, you should mention it there *at least*. other wise it wont be good idea.


Its much better to share here what you are sharing there, or what do you think?
 
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