Development and optimization of printed spiral coils have significant impacts on the efficiency and operating range for magnetic resonant wireless power transfer (WPT) applications. In this paper, the effects of different material losses (substrate and conducting coating) of printed coils are considered and experimentally studied in this paper. For the purposes of comparison and finding the dominated losses, lossy loaded capacitors with equivalent series resistances have also been investigated. A four-coil system with an external capacitor-loaded (ECL) magnetic resonant WPT system is considered, and a self-resonant coil is designed and compared. Results show that the ECL resonant coil has higher efficiency than the self-resonant coil with the same size and distance between the transmitting and receiving coils. Through observing the simulated results and analyzing experimental data, it can be concluded that the dominant cause of the decrease in efficiency of this ECL-WPT system is the strip resistive loss of coil of 57% and the ohmic loss in ECL of 37%. Meanwhile, the substrate loss significantly impacts on the efficiency of the self resonant coil. The overall measured efficiency is about 66% of the ECL coil at a distance of 50 mm when the above loss factors are considered. The measured results are in good agreement with the analysis and simulations.
"Effect of Losses in Printed Rectangular Coils for Compact Wireless Power Transfer Systems," Progress In Electromagnetics Research C,
Vol. 97, 177-188, 2019. doi:10.2528/PIERC19092601
1. Jolani, F., Y. Yu, and Z. Chen, "A planar magnetically coupled resonant wireless power transfer system using printed spiral coils," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 1648-1651, 2014. doi:10.1109/LAWP.2014.2349481
2. Stein, A. L. F., P. A. Kyaw, and C. R. Sullivan, "High-Q self-resonant structure for wireless power transfer," IEEE Applied Power Electro. Conf. and Exposition, 3723-3729, Tampa, FL, 2017.
3. Stein, A. L. F., P. A. Kyaw, J. Feldman-Stein, and C. R. Sullivan, "Thin self-resonant structures with a high-Q for wireless power transfer," IEEE Appl. Power Electro. Conf. and Exposition, 1044-1051, San Antonio, TX, 2018.
4. Li, C. J. and H. Ling, "Investigation of wireless power transfer using planarized, capacitor-loaded coupled loops," Progress In Electromagnetics Research, Vol. 148, 223-231, 2014. doi:10.2528/PIER14071705
5. Karalis, A., J. D. Joannopoulos, and M. Soljacic, "Efficient wireless non-radiative mid-range energy transfer," Ann. of Phys., Vol. 323, No. 1, 34-48, 2008. doi:10.1016/j.aop.2007.04.017
6. Zhang, Y., Z. Zhao, and T. Lu, "Quantitative analysis of system efficiency and output power of four-coil resonant wireless power transfer," IEEE Trans. Emerg. Sel. Topics Power Electro., Vol. 3, No. 1, 184-190, March 2015. doi:10.1109/JESTPE.2014.2319295
7. Robichaud, A., M. Boudreault, and D. Deslandes, "Comparison between inductance topologies for resonant wireless power transmission applications," Asia Pacific Microw. Conf. Proc., 397-399, Kaohsiung, 2012.
8. Li, H., R. Banucu, and W. M. Rucker, "Accurate and efficient calculation of the inductance of an arbitrary-shaped coil using surface current model," IEEE Trans. Magn., Vol. 51, No. 3, 1-4, March 2015.
9. Sampath, J. P. K., A. Alphones, and H. Shimasaki, "Coil design guidelines for high efficiency of Wireless Power Transfer (WPT)," IEEE Region 10 Conf., 726-729, Singapore, 2016.
10. Sullivan, C. R., B. A. Reese, A. L. F. Stein, and P. A. Kyaw, "On size and magnetics: Why smal efficient power inductors are rare," Inter. Sym. 3D Power Electro. Integration Manufac., 1-23, Raleigh, NC, 2016.
11. Waters, B. H., B. J. Mahoney, G. Lee, and J. R. Smith, "Optimal coil size ratios for wireless power transfer applications," IEEE Inter. Sym. Circuits Sys., 45-2048, Melbourne, VIC, 2014.
12. Kim, D. H. and Y. J. Park, "Calculation of the inductance and AC resistance of planar rectangular coils," Electron. Lett., Vol. 52, No. 15, 1321-1323, 2016. doi:10.1049/el.2016.0696
13. Tang, S. C., S. Y. Hui, and H. S. H. Chung, "Characterization of coreless Printed Circuit Board (PCB) transformers," IEEE Trans. Power Electro., Vol. 15, No. 6, 1275-1282, November 2000. doi:10.1109/63.892842
14. Qian, G., Y. Cheng, G. Chen, and G. Wang, "New AC resistance calculation of printed spiral coils for wireless power transfer," Inter. Sym. Quality Electron. Design, 286-289, CA, 2018.
15. Cove, S. R. and M. Ordonez, "Practical inductance calculation for planar magnetics with track-width-ratio," IEEE Energy Conversion Cong. Exposition, 3733-3737, Denver, CO, 2013.
16. Supriyanto, T., A. Wulandari, T. Firmansyah, and Suhendar, "Design and comparison wireless power transfer base on copper (Cu) and aluminium (Al) rings loop magnetic coupling," Inter. J. of Infor. Electro. Eng., Vol. 6, No. 2, 110-113, March 2016.
17. Jeong, I. S., B. I. Jung, D. S. You, and H. S. Choi, "Analysis of S-parameters in magnetic resonance WPT using superconducting coils," IEEE Trans. Appl. Superconductivity, Vol. 26, No. 3, 1-4, April 2016. doi:10.1109/TASC.2016.2544139
18. Nair, V. V. and J. R. Choi, "An efficiency enhancement technique for a wireless power transmission system based on a multiple coil switching technique," Energies, Vol. 9, No. 156, 1-15, 2016.
19. Kim, D. H. and Y. J. Park, "Design of a rectangular coil for an effective magnetic resonance wireless power transfer system," IEEE Transport. Electrification Conf. Expo. Asia-Pacific, 680-683, Busan, 2016.
22. Imura, T., H. Okabe, and Y. Hori, "Basic experimental study on helical antennas of wireless power transfer for electric vehicles by using magnetic resonant couplings," IEEE Vehi. Power Propulsion Conf., 936-940, Dearborn, MI, 2009.
23. Hunter, I., Theory and Design of Microwave Filters, The Institution of Engineering and Technology, UK, 2001. doi:10.1049/PBEW048E
24. Zhao, J., "A new calculation for designing multilayer planar spiral inductors," Electron. Design, 37-39, July 2010.
25. Mohan, S. S., M. Hershenson, S. P. Boyd, and T. H. Lee, "Simple accurate expressions for planar spiral inductances," IEEE J. Solid-State Circuits, 1419-24, October 1999.
26. Pospisilik, M., L. Kouril, I. Motyl, and M. Adamek, "Single and double layer spiral planar inductors optimisation with the aid of self-organising migrating algorithm," Proc. WSEAS Int. Conf. Signal Processing, Computational Geometry Artificial Vision, Computational Geometry and System Theory, 272-277, Florence, Italy, 2011.