In which case something changes, and you need to design a completely new SMPSU, including everything in it...
Everything!
thank you for your replys...
take a look at the datasheets
http://www.epcos.com/inf/80/db/fer_07/etd_44_22_15.pdf
http://www.epcos.com/inf/80/db/fer_07/er_54_18_18.pdf
etd 44 has AL around 3300-3600 nh
er 54 has AL around 5600-5800 nh
so the er 54 needs less turns and can give more power..
am i right?
why i need to design a new psu?
take a look at the datasheets
http://www.epcos.com/inf/80/db/fer_07/etd_44_22_15.pdf
http://www.epcos.com/inf/80/db/fer_07/er_54_18_18.pdf
etd 44 has AL around 3300-3600 nh
er 54 has AL around 5600-5800 nh
so the er 54 needs less turns and can give more power..
am i right?
why i need to design a new psu?
AL is not a problem. (Assuming we are talking about some push-pull topology here.)
If you put 10 turns around it you will get probably slightly worse efficiency, because of the increased copper resistance (lenght of wires) you have around the core.
Bigger core however compensates some, so therefore bigger core only slightly worse choice.
If you put less turns around the core, you will get more power out, which means you need to redesign the whole output.
Because you get more power out, you also need to put more power in, which means you need to redesign the whole input.
So put 10 turns around it.
Or redesign the whole thing.
If you put 10 turns around it you will get probably slightly worse efficiency, because of the increased copper resistance (lenght of wires) you have around the core.
Bigger core however compensates some, so therefore bigger core only slightly worse choice.
If you put less turns around the core, you will get more power out, which means you need to redesign the whole output.
Because you get more power out, you also need to put more power in, which means you need to redesign the whole input.
So put 10 turns around it.
Or redesign the whole thing.
If you want to make the ER54 core "right", you need enough isolation on both sides of the primary winding to make the transformer safe.
The "enough" is subjective, it depends on the isolation material you use.
I use 5mm isolation on both sides of the primary (in half bridge @ 325VDC/2).
That 5mm is achieved with self vulcanizing tape (in my transformers). There may be better solutions - recommendations most welcome here!
Where the primary windings get out from the window (bobbin) I use extra (double) insulation on the wires.
Between primary and secondary windings I put "ground shield" i.e. a one turn copper foil that is hard wired straight to the safety earth from its center (mid point of the "turn"). Both ends of the foil unconnected - and isolated from each other, over lapping 1mm...
This is not an excellent solution, as it may inject massive ammounts of transformer noise to the earth.
But, if primary fails, first hit will be this foil. AND YOU WILL NOT DIE!
Then the secondary to the whole window area which is left over from the primary and its shield...
Anyhow,
the point is:
Do you have enough window width in the ER54 to get the primary properly isolated from the secondary?
Also:
The minimum creepage distances and clearances must be found trough out the whole construction, on the PCB and between the components at primary/secondary or input/output, which ever you prefer, and IN THE TRANSFORMER...
At the PCB and between the primary/secondary components me, myself and I use a minimum of 10mm (ten mm) clearance - everywhere.
Now:
How much power do you actually need?
And, are you sure you want to make an SMPSU, it is lethal if made badly.
Would not just an ordinary linear transformer be much better and safer for you, or is there something wrong with it?
There are also very cheap SMPSUs for sale - very cheap, and they are rated, approved, legal and SAFE.
The "enough" is subjective, it depends on the isolation material you use.
I use 5mm isolation on both sides of the primary (in half bridge @ 325VDC/2).
That 5mm is achieved with self vulcanizing tape (in my transformers). There may be better solutions - recommendations most welcome here!
Where the primary windings get out from the window (bobbin) I use extra (double) insulation on the wires.
Between primary and secondary windings I put "ground shield" i.e. a one turn copper foil that is hard wired straight to the safety earth from its center (mid point of the "turn"). Both ends of the foil unconnected - and isolated from each other, over lapping 1mm...
This is not an excellent solution, as it may inject massive ammounts of transformer noise to the earth.
But, if primary fails, first hit will be this foil. AND YOU WILL NOT DIE!
Then the secondary to the whole window area which is left over from the primary and its shield...
Anyhow,
the point is:
Do you have enough window width in the ER54 to get the primary properly isolated from the secondary?
Also:
The minimum creepage distances and clearances must be found trough out the whole construction, on the PCB and between the components at primary/secondary or input/output, which ever you prefer, and IN THE TRANSFORMER...
At the PCB and between the primary/secondary components me, myself and I use a minimum of 10mm (ten mm) clearance - everywhere.
Now:
How much power do you actually need?
And, are you sure you want to make an SMPSU, it is lethal if made badly.
Would not just an ordinary linear transformer be much better and safer for you, or is there something wrong with it?
There are also very cheap SMPSUs for sale - very cheap, and they are rated, approved, legal and SAFE.
I find it fascinating that in this photo:
http://i123.photobucket.com/albums/o286/first2ner/P1010026.jpg
the clips are on the wrong sides of the transformer.
also, its only about 1/4th full of copper.
so I have no doubt you can push a lot more watts through it than originally intended, at least two fold.
in anycase:
you can't exceed the flux density that the inverter is able to drive.
yes, you can exceed the saturation flux density but if the inverter can't handle 50% reactive current then you're wasting your time, not to mention the leakage flux.. but i digress..
also, proximity and eddy current losses follow flux squared, so adding 20% more turns is a good thing, if copper losses do not dominate.
another problem is energy stored in the secondary side inductor.
if energy storage is of no accord in the main transformer, then with water cooled copper pipe you can shove many kilowatts through a ferrite core, and it won't even get warm.
however, you will saturate the output inductor, or the input resonant network for the case of an llc.. and it will blow up.
given only 10 turns on the primary and a full wave center tapped secondary you are probably better off using a copper foil secondary to get the most amount of copper in the transformer.
http://i123.photobucket.com/albums/o286/first2ner/P1010026.jpg
the clips are on the wrong sides of the transformer.
also, its only about 1/4th full of copper.
so I have no doubt you can push a lot more watts through it than originally intended, at least two fold.
in anycase:
you can't exceed the flux density that the inverter is able to drive.
yes, you can exceed the saturation flux density but if the inverter can't handle 50% reactive current then you're wasting your time, not to mention the leakage flux.. but i digress..
also, proximity and eddy current losses follow flux squared, so adding 20% more turns is a good thing, if copper losses do not dominate.
another problem is energy stored in the secondary side inductor.
if energy storage is of no accord in the main transformer, then with water cooled copper pipe you can shove many kilowatts through a ferrite core, and it won't even get warm.
however, you will saturate the output inductor, or the input resonant network for the case of an llc.. and it will blow up.
given only 10 turns on the primary and a full wave center tapped secondary you are probably better off using a copper foil secondary to get the most amount of copper in the transformer.
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