panfilero <
panf...@gmail.com> wrote:
>On Mar 10, 1:24=A0pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat>
>wrote:
>> On Sat, 10 Mar 2012 17:21:33 GMT, the renowned n...@puntnl.niks (Nico
>>
>> Coesel) wrote:
>> >IMHO its not the easiest design to start with. The OP needs
>> >5W output power. A flyback is the easiest topology to achieve his
>> >goal.
>>
>> If he wants to give it a try, here's a relevant article:-
>>
>>
http://powerelectronics.com/mag/510PET22b.pdf
>>
>> Best regards,
>> Spehro Pefhany
>> --
>> "it's the network..." =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
>"The Journey is the reward"
>>
sp...@interlog.com =A0 =A0 =A0 =A0 =A0 =A0 Info for manufacturers:http://=
>
www.trexon.com
>> Embedded software/hardware/analog =A0Info for designers: =A0
http://www.sp=
>
eff.com
>
>thanks for the article, I believe it's a forward converter as well...
>I've let myself slip into a long back and forth in another forum with
>someone who keeps arguing it's a flyback. That person doesn't care
>about the inductor at the output
>
>
http://forum.allaboutcircuits.com/showthread.php?t=3D67195
>
>but i've analyzed the circuit, it's a buck derived topology Vo =3D DVin,
>it can't boost
IMHO you can think of a forward converter like a buck/boost converter
with the transformer doing a current conversion between input and
output. This helps to figure out the output inductor.
>have you guys designed a transformer before? there seems to be a lot
>to it
I did a couple of months ago. This application note has a very clear
recipe on how to determine the core size and number of windings:
http://www.fairchildsemi.com/an/AN/AN-4134.pdf
I ordered a whole bunch of core size and material types and wound
several prototypes to get a feeling what would be the best solution.
One thing the remember: a big part in the transformer design procedure
is driven by the number of windings a core can hold.
You'll also need a current probe. Otherwise you'll flying blind.
I made a couple of current probes myself using this transformer loaded
with a 5 Ohm resistor which gives me 100mV/A.
http://nl.farnell.com/wuerth-elektronik/749251050/transformer-we-cst-500uh-10a-1/dp/1961657
You'll need to use stranded wire to keep the inductance low. Having
multiple probes allows you to see various currents throughout the
circuit.
Its fun if you have the time.
Anyway, I would use a flyback topology with an off-the shelf
transformer for your project.