Author Topic: Flyback transformer: What causes such a temperature rise?  (Read 2547 times)

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Offline bmxseshTopic starter

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Flyback transformer: What causes such a temperature rise?
« on: December 20, 2024, 06:57:53 pm »
Hello
I am wiring an SMD flyback transformer to generate multiple voltages in a circuit
I had to change a regulator to a different one due to the presence of an Enable function, and this one has switching frequency 100kHz instead of 52kHz
I am using a TDK 13/7/4 core but the software I use to model it has the same dimension core from a different manufacturer
Does anyone know what causes such a temperature rise if the parameters are almost the same? I am satisfied with everything else although so few turns look a bit weird
 

Offline mikerj

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Re: Flyback transformer: What causes such a temperature rise?
« Reply #1 on: December 20, 2024, 07:47:53 pm »
The wire gauge (38) is ridiculously small for the 100kHz design, look at the calculated resistance and copper loss values for both designs.
 
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Offline bmxseshTopic starter

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Re: Flyback transformer: What causes such a temperature rise?
« Reply #2 on: December 20, 2024, 10:16:52 pm »
Yeah, now it looks much better
I am going to tap the 13 turn secondary winding three times - 100%, 66% and 33% to get +15V (full winding), +10V (66% tap) and +5V (33% tap)
So it is going to be 12 turns to split it nicely
It seems to only depend on the air gap at this point
 


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