TWO MOSFETs FORWARD CONVERTER - NEED HELP PLEASE

[obiwan]

Hi, I am trying to build a 60 Watt SMPS using this topology:



I am using this transformer design tool:

http://www.diysmps.com/forums/showthread.php?522-Calculation-programs-for-transformers-and-inductors

My question: for the calculation of the transformer, is this a Half or a Full bridge topology ?
Playing a little bit with the program by choosing one of the two options , it sounds reasonable to see that the program results in the primary winding in one case has half the number of turns of the other.
These are the the screenshots of the primary winding for both cases



Aditional information:
Core: E 30/15/7
Input 80VDC ~ 150 VDC
Output 12V 4A ; 5V 0.1 A ; 5V 0.5A ; 14V 0.1A

Thank you in advance

 

[Voitano]

Hi , no this is forward topology http://schmidt-walter-schaltnetzteile.de/smps_e/hdw_smps_e.html

 

[obiwan]

Hi , no this is forward topology http://schmidt-walter-schaltnetzteile.de/smps_e/hdw_smps_e.html

Thank you Voitano
I know Dr. Schmidt-Walter's page many years.
He is not calculating more than one secondary, and I need 4.
This IS a forward converter.
I think you didn't understand my question.
It is about transformer calculation.
If this is a half bridge or a full bridge option for the program I mentioned.
Thank you very much.

 

[Voitano]

I think, that no one of the mentioned topology is applicable. Use Schmidt pages with Two-Transistor Forward Converter for transformer and 12V output coil(very important) calculation. But better is full bridge option, it uses full voltage for calculation. Hope you understand my poor english

 

[obiwan]

I think, that no one of the mentioned topology is applicable. Use Schmidt pages with Two-Transistor Forward Converter for transformer and 12V output coil(very important) calculation. But better is full bridge option, it uses full voltage for calculation. Hope you understand my poor english

You are right Voitano, comparing Dr. Walter-Schmidt results to those obtained from those of the Excellent 7000 program, there are differences in both the primary turns and the secondary.
It seems that you are explaining that 2 switch forward converter is not the same as a full bridge with 4 switches.

So my problem here is that Dr. Walter-Schmidt calculator does not offer the results for the 4 secondaries I need.
Could you please tell me how can I calculate the rest of the secondaries by using this same Walter-Schmidt calculator program ?

Your english is very good, but I would ask you for more of your valuable explanations.

Thank you.

 

[zeus_threat]

Hi I don't want to deviate you from your project but check my posts here for SMPs there is a low power half bridge I built using EI33+TL494 and Microsim's transformer formula. You should be able to replicate the same for 60watts

 

[Voitano]

By the way, 60W at this topology, there are no advantages to use it. Think about Zeus_threat idea using and modifying his project. Half bridge has smaller voltage changes when output current changes and voltage feedback is changing duty cycle. You entered not enough data about suggested frequency and current consumption changes. U will probably use high skilled strategy - try and change . Try this: Enter your data for 12V 4A output (4,3A is better - 0,3A*12V= rest of consumptoin recalculated to 12V ) and write down proposal for transformer and coil. Then uncheck proposal N1/N2, reenter new secondary voltage and current , let program calculate again, write down data for coil and so on. http://schmidt-walter-schaltnetzteile.de/smps_e/hgw_smps_e.html

 

[obiwan]

Hi I don't want to deviate you from your project but check my posts here for SMPs there is a low power half bridge I built using EI33+TL494 and Microsim's transformer formula. You should be able to replicate the same for 60watts

Thank you zeus_threat, could you please provide a link to that project ?
My project was initially based upon a half bridge, but I couldn't fight a glitch, so I decided to switch to a different topology.
I am using TL494 too.