volume | PIER Journals

Abstract

This paper considers an ideal planar transformer wherein only the electromagnetic parasitics (stray capacitive and leakage inductance) arising out of the transformer geometry are taken into account, assuming lossless conditions. A suitable electrically equivalent circuit model for the planar transformer is used to analyze its frequency and power transfer characteristics; this model was validated by a three dimensional electromagnetic simulation of the planar transformer structure in FEKO electromagnetic simulation software. The effect of dielectric thickness on the bandwidth of the transformer has been analyzed based on the premise that the inherent stray capacitance and leakage inductance elements would affect the power transfer characteristics of the transformer. It has been found that the dielectric thickness of a planar transformer can be optimized so as to maximize the frequency bandwidth. It is also shown that the bandwidth is found to be sensitive to the thickness of the dielectric beyond the optimum thickness threshold topt. Convenient closed form analytic expressions for the optimum dielectric thickness and the resultant maximum bandwidth are derived and presented. It is argued that these results can be readily used to benefit the design of air-core PCB/Planar transformers.

1. Estrov, A., "Power transformer design for 1MHz resonant converter," High Frequency Power Conv. Conf. Rec., 36-54, 1986. Google Scholar

2. Estrov, A., "Low-profile planar transformer for use in off-line switching power supplies,", U.S.Classification 336/198, 336/183, 336/200, 336/232; International Classification H01F27/32, H01F19/04, H01F5/02, H01F27/28; Cooperative Classification H01F27/2804, H01F41/043, H01F19/04, H01F5/02; European Classification H01F19/04, H01F5/02, Apr. 1991. Google Scholar

3. Oshiro, O., H. Tsujimoto, and K. Shirae, "Structures and characteristics of planar transformers," IEEE Translation Journal on Magnetics in Japan, Vol. 4, No. 5, 332-338, May 1989.
doi:10.1109/TJMJ.1989.4564431 Google Scholar

4. Van Der Linde, D., C. A. M. Boon, and J. B. Klaassens, "Design of a high-frequency planar power transformer in multilayer technology," IEEE Transactions on Industrial Electronics, Vol. 38, No. 2, 135-141, Apr. 1991.
doi:10.1109/41.88907 Google Scholar

5. Djuric, S., G. Stojanovic, M. Damnjanovic, and E. Laboure, "Analysis of the coupling effect in different meander-type winding planar transformers," IEEE Transactions on Magnetics, Vol. 49, No. 7, 3993-3996, Jul. 2013.
doi:10.1109/TMAG.2013.2243417 Google Scholar

6. Djuric, S. M. and G. M. Stojanovic, "A compact planar transformer with an improved winding configuration," IEEE Transactions on Magnetics, Vol. 50, No. 11, 1-4, Nov. 2014.
doi:10.1109/TMAG.2014.2321630 Google Scholar

7. Ouyang, Z. and M. A. E. Andersen, "Overview of planar magnetic technology — Fundamental properties," IEEE Transactions on Power Electronics, Vol. 29, No. 9, 4888-4900, Sep. 2014.
doi:10.1109/TPEL.2013.2283263 Google Scholar

8. Ouyang, Z., O. C. Thomsen, and M. A. E. Andersen, "Optimal design and tradeoff analysis of planar transformer in high-power DC-DC converters," IEEE Transactions on Industrial Electronics, Vol. 59, No. 7, 2800-2810, Jul. 2012.
doi:10.1109/TIE.2010.2046005 Google Scholar

9. Lu, J. W., F. P. Dawson, and S. Yamada, "Analysis of high frequency planar sandwich transformers for switching converters," IEEE Transactions on Magnetics, Vol. 31, No. 6, 4235-4237, Nov. 1995.
doi:10.1109/20.489937 Google Scholar

10. Tria, L. A. R., D. Zhang, and J. E. Fletcher, "Planar PCB transformer model for circuit simulation," IEEE Transactions on Magnetics, Vol. 52, No. 7, 1-4, Jul. 2016.
doi:10.1109/TMAG.2016.2516995 Google Scholar

11. Margueron, X., A. Besri, Y. Lembeye, and J. P. Keradec, "Current sharing between parallel turns of a planar transformer: Prediction and improvement using a circuit simulation software," IEEE Transactions on Industry Applications, Vol. 46, No. 3, 1064-1071, May 2010.
doi:10.1109/TIA.2010.2046294 Google Scholar

12. Buccella, C., C. Cecati, and M. Di Domenico, "An accurate equivalent circuit of high power/high frequency planar transformers using FEM," International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008, 1300-1305, Jun. 2008.
doi:10.1109/SPEEDHAM.2008.4581177 Google Scholar

13. Chen, W., Y. Yan, Y. Hu, and Q. Lu, "Model and design of PCB parallel winding for planar transformer," IEEE Transactions on Magnetics, Vol. 39, No. 5, 3202-3204, Sep. 2003.
doi:10.1109/TMAG.2003.816147 Google Scholar

14. Cove, S. R., M. Ordonez, F. Luchino, and J. E. Quaicoe, "Applying response surface methodology to small planar transformer winding design," IEEE Transactions on Industrial Electronics, Vol. 60, No. 2, 483-493, Feb. 2013.
doi:10.1109/TIE.2012.2187416 Google Scholar

15. De Jong, E. C. W., B. J. A. Ferreira, and P. Bauer, "Toward the next level of PCB usage in power electronic converters," IEEE Transactions on Power Electronics, Vol. 23, No. 6, 3151-3163, Nov. 2008.
doi:10.1109/TPEL.2008.2004276 Google Scholar

16. Zhang, K., T. X. Wu, N. Kutkut, J. Shen, D. Woodburn, L. Chow, W. Wu, H. Mustain, and I. Batarseh, "Modeling and design optimization of planar power transformer for aerospace application," Proceedings of the IEEE 2009 National Aerospace Electronics Conference (NAECON), 116-120, Jul. 2009. Google Scholar

17. Bowen, D., A. Lee, C. Krafft, and I. D. Mayergoyz, "Performance effects of device scale and core aspect-ratio on dielectric-core circuit board transformers," Journal of Applied Physics, Vol. 115, No. 17, 17E717, 2014.
doi:10.1063/1.4868920 Google Scholar

18. Panchal, C. and J. W. Lu, "High frequency planar transformer (HFPT) for universal contactless battery charging platform," IEEE Transactions on Magnetics, Vol. 47, No. 10, 2764-2767, Oct. 2011.
doi:10.1109/TMAG.2011.2156768 Google Scholar

19. Saravi, S. E., A. Tahani, F. Zare, and R. A. Kordkheili, "The effect of different winding techniques on the stray capacitances of high frequency transformers used in yback converters," IEEE 2nd International Power and Energy Conference, 2008. PECon 2008, 1475-1478, Dec. 2008. Google Scholar

20. Maswood, A. I. and L. K. Song, "Design aspects of planar and conventional SMPS transformer: A cost benefit analysis," IEEE Transactions on Industrial Electronics, Vol. 50, No. 3, 571-577, Jun. 2003.
doi:10.1109/TIE.2003.812469 Google Scholar

21. Ambatipudi, R., H. B. Kotte, and K. Bertilsson, "High performance planar power transformer with high power density in MHz frequency region for next generation switch mode power supplies," 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2139-2143, Mar. 2013.
doi:10.1109/APEC.2013.6520591 Google Scholar

22. Bowen, D., A. Lee, C. Krafft, and I. D. Mayergoyz, "Design control of performance in nested and interleaved winding printed circuit board transformers for ethernet applications," IEEE Transactions on Magnetics, Vol. 49, No. 7, 4013-4016, Jul. 2013.
doi:10.1109/TMAG.2013.2238513 Google Scholar

23. Bowen, D., A. Lee, C. Krafft, and I. D. Mayergoyz, "Zero-footprint ethernet transformers using circuit-board embedded ferrites," Journal of Applied Physics, Vol. 115, No. 17, 17E716, 2014.
doi:10.1063/1.4868697 Google Scholar

24. Costa, E. M. M., "Planar transformers excited by square waves," Progress In Electromagnetics Research, Vol. 100, 55-68, 2010.
doi:10.2528/PIER09110103 Google Scholar

25. Ouyang, Z., J. Zhang, and W. G. Hurley, "Calculation of leakage inductance for high-frequency transformers," IEEE Transactions on Power Electronics, Vol. 30, No. 10, 5769-5775, Oct. 2015.
doi:10.1109/TPEL.2014.2382175 Google Scholar

26. Li, J., Y. Shi, Z. Niu, and D. Zhou, "Modeling, simulation and optimization design of PCB planar transformer," 2005 International Conference on Electrical Machines and Systems, Vol. 3, 1736-1739, Sep. 2005. Google Scholar

27. Ammouri, A., T. B. Salah, and F. Kourda, "Modeling and simulation of a high-frequency planar power transformers," 2015 4th International Conference on Electrical Engineering (ICEE), 1-6, Dec. 2015. Google Scholar

28. Tria, L. A. R., D. Zhang, and J. E. Fletcher, "High-frequency planar transformer parameter estimation," IEEE Transactions on Magnetics, Vol. 51, No. 11, 1-4, Nov. 2015.
doi:10.1109/TMAG.2015.2443791 Google Scholar

29., Ferroxcube, Ferroxcube E64/PLT, http://www.ferroxcube.com/FerroxcubeCorporateReception/datasheet/e641050.pdf, Accessed: Mar. 28, 2017.
doi:10.1109/TMAG.2015.2443791 Google Scholar

30. Bowen, D., I. Mayergoyz, C. Krafft, D. Kroop, and M. Beyaz, "On design of air-core ethernet transformers," Journal of Applied Physics, Vol. 105, No. 7, 07A307, 2009.
doi:10.1063/1.3063071 Google Scholar

31. Hui, S. Y., H. S.-H. Chung, and S. C. Tang, "Coreless printed circuit board (PCB) transformers for power mosfet/igbt gate drive circuits," IEEE Transactions on Power Electronics, Vol. 14, No. 3, 422-430, May 1999.
doi:10.1109/63.761685 Google Scholar

Dr. Hyma Harish Vallabhapurapu

Dr. Ivan William Hofsajer