Supplier for SMPS transformers?

[Nico Coesel]

I'm looking for a transformer for a push-pull forward converter. I'm
trying to find something off-the-shelve. The current circuit uses
transformers with 6 identical windings. The problem is that due to the
winding ratio I need 3 of those and due to the current they need to be
ridiculously large. I already checked Coilcraft, Premier and Wurth but
none of them have a transformer which suits the requirements:
Preferably 1:1:13 turns ratio and 15A peak current into the primary
windings, and 1.2A in the secondary.

 

[Joerg]

I'm looking for a transformer for a push-pull forward converter. I'm
trying to find something off-the-shelve. The current circuit uses
transformers with 6 identical windings. The problem is that due to the
winding ratio I need 3 of those and due to the current they need to be
ridiculously large. I already checked Coilcraft, Premier and Wurth but
none of them have a transformer which suits the requirements:
Preferably 1:1:13 turns ratio and 15A peak current into the primary
windings, and 1.2A in the secondary.

No matter how you toss and turn it that'll be a custom part. If cost is
critical and quantities are high you can have it made in China.
Otherwise there are also European companies who can do that.

 

[Wimpie]

El 06-08-11 16:16, Nico Coesel escribió:

I'm looking for a transformer for a push-pull forward converter. I'm
trying to find something off-the-shelve. The current circuit uses
transformers with 6 identical windings. The problem is that due to the
winding ratio I need 3 of those and due to the current they need to be
ridiculously large. I already checked Coilcraft, Premier and Wurth but
none of them have a transformer which suits the requirements:
Preferably 1:1:13 turns ratio and 15A peak current into the primary
windings, and 1.2A in the secondary.

Hello Nico,

Maybe you can also specify the frequency range of operation,
insulation requirements, supply voltage, primary inductance, maximum
leakage inductance (when important) and number of units.


Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

 

[Nico Coesel]

El 06-08-11 16:16, Nico Coesel escribió:

Hello Nico,

Maybe you can also specify the frequency range of operation,
insulation requirements, supply voltage, primary inductance, maximum
leakage inductance (when important) and number of units.

Frequency and inductance are not fixed, the rest of the circuit can be
designed around it. Insulation requirement is 500V (standard) no
agency approvals necessary because it is not isolated. 100 units is a
good start but a bit low for a custom design. If all goes well my
customer expects to sell way more though.

 

[Naomi Price]

Frequency and inductance are not fixed, the rest of the circuit can be
designed around it. Insulation requirement is 500V (standard) no
agency approvals necessary because it is not isolated. 100 units is a
good start but a bit low for a custom design. If all goes well my
customer expects to sell way more though.

Buy the core sets and the bobbins and make them yourself. Wise to use
Litz on the primary to maximize efficiency.

 

[Joerg]

Frequency and inductance are not fixed, the rest of the circuit can be
designed around it. Insulation requirement is 500V (standard) no
agency approvals necessary because it is not isolated. ...

Insulation requirement ... not isolated ... huh?

... 100 units is a
good start but a bit low for a custom design. If all goes well my
customer expects to sell way more though.

John's supplier might do such a small run. If you want something more
local I haven't dealt with these company personally but they make custom
ferrite transformers:

http://www.ise.nl/?pagina=b3&lan=nl
http://inductive.nl/producten.html?parent_id=15
http://www.k-w-p.nl/pages_nl/contact_1.html
http://www.haufe-uebertrager.de/
http://www.trafo-schlenker.de/kontakt/

But be prepared to pay some hefty NRE with such low quantities.

 

[Phil Allison]

"Joerg"

Insulation requirement ... not isolated ... huh?

** Could mean the output is connected to safety ground - ie not GROUND
isolated.

<scratching head>

** Lice ?



.... Phil

 

[Nico Coesel]

Insulation requirement ... not isolated ... huh?

I mean the input and output have a common ground but the wiring should
be able to withstand a couple of hundred volts.

John's supplier might do such a small run. If you want something more
local I haven't dealt with these company personally but they make custom
ferrite transformers:

http://www.ise.nl/?pagina=b3&lan=nl

I have dealt with ISE before for a custom low-profile flyback
transformer. Not bad but it took them 3 tries to get the leakage
inductance down to acceptable levels.

http://inductive.nl/producten.html?parent_id=15
http://www.k-w-p.nl/pages_nl/contact_1.html
http://www.haufe-uebertrager.de/
http://www.trafo-schlenker.de/kontakt/

But be prepared to pay some hefty NRE with such low quantities.

I'm afraid so. I'll contact these companies and see if they have
something semi-custom off the shelf. Otherwise I have to fit 6 ETD39
transformers on a long eurocard.

 

[Wimpie]

El 07-08-11 1:20, Nico Coesel escribió:

Frequency and inductance are not fixed, the rest of the circuit can be
designed around it. Insulation requirement is 500V (standard) no
agency approvals necessary because it is not isolated. 100 units is a
good start but a bit low for a custom design. If all goes well my
customer expects to sell way more though.

Hello Nico,

When you are in a stage that not everything is fixed already (nice),
try to do it yourself. You can find a reasonable optimum between the
transformer itself and the components around it (FET's, snubbers,
decoupling capacitors, etc). When done, you can have it made by some
other company.

Not all companies have the design expertise they claim to have. They
may hire some external expertise to do the job.

Even when you find a COTS part, you will probably subject it to
(severe) testing. Of course I understand when you can use some of the
shelf component it may save costs.


Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM