AnsweredAssumed Answered

Confused about the transformer Design

Question asked by mattoo.anuj on Feb 25, 2017
Latest reply on Mar 4, 2017 by Emil Nierges

I am using ST's eDesign Suite for designing power supply. (AC-DC Converter)

I contacted the transformer design firm to get my transformer designed. I gave them all the information regarding the number of turns and length of wire etc..

 

Here is my power supply specs

 

Input: 95 Vac - 265 Vac - 50 Hz - Operating Vdc [96.9 V - 374.8 V]

Output Power: 14.96 W

Output -: 17 Vdc (38 mVpp ripple) - 880 mA max - 14.96 W - Regulated

Switching Frequency (fsw): 60 kHz

 

Transformer Specs :-

 

  •  fsw: 60 kHz
  •  Prim/Aux turn ratio 6.39
  • Prim/Out 1 turn ratio 4.77. (Np/Ns)

 

Design Specs :-

 

  • Type EE20/10/6 (EF20) TH-V 10-Pin
  • Core Gap: 0.28 mm expected

 

   Primary: Turns 105 - Layers 6 - Paralleled wires 3

   Secondary: Turns 22 - Layers 3 - Paralleled wires 3

   Auxiliary: Turns 16

 

Power Supply Layout :- Attached

 

 

Now I need to order the design for transformer and the transformer design centre asking for dot polarity/Start-End point of pins. According to circuit, there are only 4 pins used on AC side and 2 pins on DC Side. The ST recommends EE-10 size Bobbin. 

 

 

Wurth Electronics Transformer Winding Layout :- Attached 

 

 

 

Do I need to use Pin 2 for interleaving/CenterTapping, though in schematic it is not mentioned, but only in transformer layout. Or should I go with simple 3 windings (without Center Tape) as mentioned in schematic i.e For Primary (Pin 1 -> Pin3),

For Aux (Pin 4 -> 5),

For Secondary(Pin 7 & Pin 8 -> Pin 9 & Pin 10).

 

I only need 6 pin for my circuit, but the layout for Transformer shows 10 Pins. I am confused about the it.

 

Outcomes