Now let’s open a new project and pickup the XFRM_NONLINEAR model from the BREAKOUT library:

Place the component, select it, mouse dx button/Edit Properties

the property window pops up

write the name of implementation and the path to the library

Report the number of turns of primary and secondary, for example L1_TURNS=29 and L2_TURNS=4

Write tha name of model on the Value property

To calculate the leakage inductance, assuming a primary inductance L1 of 90.4uH, we have before calculate the coupling factor K

K = SQRT( 1-Lps/Lpo)

where

Lps is the primary inductance measured with the secondary inductance shorted

Lpo is the primary inductance measured with the secondary inductance open unconnected.

assuming to obtain k = 0.99, the leakage inductance will be

Lleak = Lp*(1-k^2)

In our case Lleak is 1.79uH.

Calculating in 50mOhm the resistance to the primary, our dual winding transformer model can be this:

9. **Bibliography**

1. FERRITES and Accessories, Siemens Matsushita Components

2. Soft FERRITES – Data Handbook, Philips Components

3. O. Kilgenstein, Switched-Mode Power Supplies in Practice, John Wiley & Sons

4. H.W. Whittington, B.W. Flaynn, D.E. Macpherson, Switched Mode Power Supplies, John Wiley & Sons

5. R. Martinelli, C.Hymowitz, Magnetic Design and Modelling, Power’s Specialit’s

6. Intusoft, Magnetic Designer, Intusoft, 1997

7. M. Pezzi, Campi elettrici, magnetici e circuiti, Zanichelli Bologna

8. S. Ramo, J.R. Whinnery, T. Van Duzer, Campi e onde nell’ elettronica per le comunicazioni, F. Angeli, Milano

9. Technical Standard CEI EN 60950, 1996-10

10. Technical Standard CEI EN 60950/A4, 1997-10

11. Web site 135.145.4.41, New England Electric Wire Co, Technical Information

12. Web site http://www.wiretron.com, Litz wire – general information

13. Web site http://www.neewcweb.com, New England Electric Wire Co.

14. Web site http://www.dartmounth.edu/~sullivan/litzwire/litz.html, CR Sullivan, optimal choiche for Number of Strand in a Litz-Wire Transformer Winding, PESC’97

15. Web site http://www.piremag.com, Pirelli Magnetic Wire.

16. Magnetic Core and BH Curve, OrCAD PSpice A/D, OrCAD PSpice AA and AMS Simulator, Wei Ling