Is there a preferred tool to get from transformer specs to actual part?

[Thomas Ranz]

Posted on March 07, 2017 at 23:06

HI:

I've designed a SMPS with a viper controller, 3 outputs.  Is there a preferred way/tool to apply the design parameters to make an actual flyback transformer?  Magnetics has never been my strong area.

Thanks!  Tom

[Emil Nierges]

Posted on March 08, 2017 at 12:28

Hi Tom,

You may want to try out the online tool Smart Transformer Selector:

http://www.we-online.com/sts/

With minimal inputs, like input / output voltages and currents , switching frequency ... you could get access to an already design transformer that may work in your application. Here is one example:

If you find a transformer that could fit in your application, you can order here:

http://www.we-online.com/web/en/passive_components_custom_magnetics/university/students/studentsample.php

Hope it helps.

Regards,

Emil NiergesProduct Applications Engineer - Europe

http://katalog.we-online.com/en/midcom/

[Thomas Ranz]

Posted on March 08, 2017 at 15:28

Hi Emil:

I already had an account with Wurth but did not realize they had a design tool.  I tried it but unfortunately I could not use an 'off the shelf' product.  I considered having them do a custom design but since this is mostly a personal project I did not want to use their resources.  I wish the tool would give suggestions even if nothing exact is available.

Thank You, I really appreciate your suggestion!

Thomas Ranz

[Emil Nierges]

Posted on March 08, 2017 at 15:39

Hi Tom,

You are welcomed.

Three outputs applications are not so common and indeed there are not to many transformers designs that you can choose from. But if you can share the project specifications, I can take a quick look and probably I can find something good enough for your application.

Regards,

Emil

[Thomas Ranz]

Posted on March 08, 2017 at 17:32

Hi Emil:

Here are the specs from the ST eDesignSuite... I'm also trying PowerESim app and the Magnetic Builder with some success.

IC: VIPer38LE - SDIP 10

Input: 108 Vac - 132 Vac - 60 Hz - Operating Vdc [111 V - 186.7 V]Output Power: 8.84 W Out 1: 135 Vdc (100 mVpp ripple) - 40 mA max - 5.4 W - Regulated Out 2: 3.3 Vdc (38 mVpp ripple) - 1 A max - 3.3 W Out 3: 7 Vdc (77 mVpp ripple) - 20 mA max - 0.14 WSwitching Frequency (fsw): 60 kHz

Transformer Specifications:

fsw: 60 kHz - Isat ≥ 982 mA - Lp: 2.39 mH ± 15 % - leakage ≤ 3 % Primary: Ipk 406 mA - Irms 159 mA - Iavg 93 mA Aux: Ipk 156 mA - Irms 16 mA - Iavg 3 mA - Prim/Aux turn ratio 6.77 Out 1: Ipk 195 mA - Irms 72 mA - Iavg 40 mA - Prim/Out 1 turn ratio 660.31 m Out 2: Ipk 5.86 A - Irms 1.98 A - Iavg 1 A - Prim/Out 2 turn ratio 23.75 Out 3: Ipk 574 mA - Irms 87 mA - Iavg 20 mA - Prim/Out 3 turn ratio 11.39

Design Settings:

IdrainLim: 766 mA output overvoltage: 24.5 %

IC Working Condition: @(Vin 120.1 Vac - Pout 8.84 W - Ta 36.9 °C)

Tj: 65.6 °C - Rth(j-a): 85 °C/W (100 mm² of Cu) Current Mode: Discontinuous

At this point I am looking in to using a 

EE25 PowerEsim

= ( PowerMaterial1 PowerEsim, Ae_min=0.518cm²) Transformer.  Magnetic Builder is specifying the build parameters of the transformer.

I'm still very interested in your recommendations!

Thanks, Tom

[Emil Nierges]

Posted on March 14, 2017 at 19:25

Hi Tom,

I was looking for an existing solution to your request and unfortunately I do not have something available.

However, I would still like to help you with a custom transformer but I need more information from you on the application/possible future opportunity.

Maybe we can have a call?

Let me know

Regards,

Emil

[Thomas Ranz]

Posted on March 15, 2017 at 03:23

HI Emil:

Actually after some long hours reviewing relevant info on ferrite core power transformers for isolated flyback SMPS I think I finally have this problem worked out (just 1 day ago).  It seems some core and component manufacturers use slightly different notations and equations for component parameters and not being familiar it was very confusing.  I'm not 100% but I'm well on my way.

Thanks for your offer to help more!

Tom