Flyback SMPS design an transformer that can handle universal ac

Thread Starter

Danilo1988

Joined Dec 14, 2020
13
Hi every one im projecting an power supply and have few doubt about how to design an transformer that can handle 80v-240v (universal AC) im think in use the very know 1200p60 of the ON semiconductors.

some one know some online calculator or some program to aid in the designed of this transformer ? i want an output of 40-50v.

so please if some one can help me i will be very happy thanks
 

Deleted member 440916

Joined Dec 31, 1969
0
I may be mistaken but I think PFC is required for >75W in which case the PFC stage would solve your universal problem for you.
 

Thread Starter

Danilo1988

Joined Dec 14, 2020
13
I may be mistaken but I think PFC is required for >75W in which case the PFC stage would solve your universal problem for you.
yes sure but this SMPS will not have active PFC but an passive one and sinze 1200p60 have a lot of feature to minimize EMI i will do an old and simple passive PFC (like the chinese people do )
 

Ian0

Joined Aug 7, 2020
2,597
I may be mistaken but I think PFC is required for >75W in which case the PFC stage would solve your universal problem for you.
Only if it's for lighting. If it's for any other application, you will probably pass the harmonics requirements quite easily.
 

Thread Starter

Danilo1988

Joined Dec 14, 2020
13
Try the Power Integrations website for some suggestion.
Or look at the reference design for Fairchild and On-Semi parts
https://www.onsemi.com/products/power-management/ac-dc-controllers-regulators
You'll find some examples of flyback circuits around 50 Watts.
Hi my good friend my main problem is not much the design of the circuit because i will do an copy form an Chinese well constructed driver, but more with the wiring direction of the transformer and what means the black dot in the schematics.
but now i realize what they means(the beginning of the wiring at bottom probably ) and about how much turns need i found an app that calculate automatically named flayback app (the guy apparently is Russian and spelled wrong flyback)
 

Ian0

Joined Aug 7, 2020
2,597
For a horizontal bobbin, call one row of pins the "dot" end (and put a dot on it in white paint) so you don't forget if you put it down. But make sure that all of your windings go around the bobbin in the same direction.
Easier to remember for vertical bobbins, as there are pins at one end and not at the other.

A neat winding, with no gaps between the turns is important (it keeps leakage inductance low). Also,make sure your windings are full layers if possible.
 

Ian0

Joined Aug 7, 2020
2,597
I mean that the winding goes from one side of the bobbin, all the way to the other, that adjacent turns touch each other with no gaps and no overlaps. Once you apply a layer of tape, then it is a smooth surface for the next winding.
If your winding only covers say 90% or the bobbin, increase the wire size by 10% to make it cover the entire bobbin.
Gaps = leakage inductance. Leakage inductance = inefficiency.
In other words: it looks TIDY! A tidy transformer is an efficient transformer!
 

Thread Starter

Danilo1988

Joined Dec 14, 2020
13
I mean that the winding goes from one side of the bobbin, all the way to the other, that adjacent turns touch each other with no gaps and no overlaps. Once you apply a layer of tape, then it is a smooth surface for the next winding.
If your winding only covers say 90% or the bobbin, increase the wire size by 10% to make it cover the entire bobbin.
Gaps = leakage inductance. Leakage inductance = inefficiency.
In other words: it looks TIDY! A tidy transformer is an efficient transformer!
Very nice back ground master, by increase the wire size, you say the diameter or to put for example 2 wire or to spread better (but that will cause gaps isnt ?) because changing the diameter i would have problem with skin effect right ?
You recommend too put the primary divide in 2 splits and the secondary in the middle like most people do?
 
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