For wireless power transfer via magnetic resonant coupling (MRC-WPT), magnetic coupling between resonant coils can be greatly enhanced when a ferrite core is introduced inside the coils. Based on the equivalent circuit model of wireless power transfer system, transfer characteristics of the MRC-WPT system with air resonant coils and a ferrite core are respectively analyzed in this paper. The influence mechanism of the load on the power transfer efficiency is investigated. Also, the requirement of load for improving transfer efficiency is derived when adding the ferrite core to the system. The numerical simulation and experiment result indicate that the transmission efficiency in the MRC-WPT system with ferrite core is higher than that in the counterpart with air resonant coils in the whole transfer region when the load is larger than the maximal critical load. In addition, for different transfer distances, the system efficiency for the system using the ferrite core tends to become lower than that in the air coil system when the load is smaller than the critical load.
2. Parise, M. and G. Antonini, "On the inductive coupling between two parallel thin-wire circular loop antennas," IEEE Transactions on Electromagnetic Compatibility, Vol. 1, 1865-1872, 2018.
3. Casanova, J. J., Z. N. Low, and J. Lin, "A loosely coupled planar wireless power system for multiple receivers," IEEE Transactions on Industrial Electronics, Vol. 56, 3060-3068, 2009.
4. Jiang, C., K. T. Chau, W. Han, and W. Liu, "Development of multilayer rectangular coils for multiple-receiver multiple-frequency wireless power transfer," Progress In Electromagnetics Research, Vol. 163, 15-24, 2018.
5. Kim, J. G., G. Wei, M. H. Kim, J. Y. Jong, and C. Zhu, "A comprehensive study on composite resonant circuit-based wireless power transfer systems," IEEE Trans. Ind. Electron., Vol. 65, No. 6, 4670-4680, 2018.
6. Wang, M., J. Feng, Y. Fan, M. Shen, J. Liang, and Y. Shi, "A novel planar wireless power transfer system with distance-insensitive characteristics," Progress In Electromagnetics Research Letters, Vol. 76, 13-19, 2018.
7. 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.
8. Fan, Y., L. Li, S. Yu, C. Zhu, and C. H. Liang, "Experimental study of efficient wireless power transfer system integrating with highly sub-wavelength metamaterials," Progress In Electromagnetics Research, Vol. 141, 769-784, 2013.
9. Zhong, W. X. and S. Y. R. Hui, "Maximum energy efficiency operation of series-series resonant wireless power transfer systems using ON-OFF keying modulation," IEEE Trans. Power Electron., Vol. 33, No. 4, 3595-3603, 2018.
10. Zhang, J., X. Yuan, C.Wang, and Y. He, "Comparative analysis of two-coil and three-coil structures for wireless power transfer," IEEE Trans. Power Electron., Vol. 32, No. 1, 341-352, 2017.
11. Kim, J., W. S. Choi, and J. Jeong, "Loop switching technique for wireless power transfer using magnetic resonance coupling," Progress In Electromagnetics Research, Vol. 138, 197-209, 2013.
12. Lee, S. B., S. Ahn, and I. G. Jang, "Simulation-based feasibility study on the wireless charging railway system with a ferriteless primary module," IEEE Trans. Veh. Technol., Vol. 64, No. 2, 1004-1010, 2017.
13. Tran, D. H., V. B. Vu, and W. Choi, "Design of a high-efficiency wireless power transfer system with intermediate coils for the On-Board chargers of electric vehicles," IEEE Trans. Power Electron., Vol. 33, No. 1, 175-187, 2018.
14. Kong, S., et al., "An investigation of electromagnetic radiated emission and interference from multicoil wireless power transfer systems using resonant magnetic field coupling," IEEE Trans. on Micro. Theory Techn., Vol. 63, No. 3, 833-846, 2015.
15. Liu, X. C. and G. F. Wang, "A novel wireless power transfer system with double intermediate resonant coils," IEEE Trans. Ind. Electron., Vol. 63, No. 4, 2174-2180, 2016.
16. Hu, H. and S. V. Georgakopoulos, "Multiband and broadband wireless power transfer systems using the conformal strongly coupled magnetic resonance method," IEEE Trans. Ind. Electron., Vol. 64, No. 5, 3595-3607, 2017.
17. Wang, M., J. Feng, Y. Shi, and M. Shen, "Demagnetization weakening and magnetic field concentration with ferrite core characterization for efficient wireless power transfer," IEEE Trans. Ind. Electron., to be published. DOI 10.1109/TIE.2018.2840485.
18. Zhang, W., C. J.White, M. A. Abraham, and C. C. Mi, "Loosely coupled transformer structure and interoperability study for EV wireless charging systems," IEEE Trans. Power Electron., Vol. 30, No. 11, 6356-6367, 2015.
19. Wang, S., D. G. Dorrell, Y. Guo, and M. F. Hsieh, "Inductive charging coupler with assistive coils," IEEE Trans. Magn., Vol. 52, No. 7, 1-4, 2016.
20. Antalunai, S., C. Thongsopa, and T. Thosdeekoraphat, "An increasing the power transmission efficiency of flat spiral coils by using ferrite materials for wireless power transfer applications," International Conference on Electrical Engineering/electronics, 1-4, Nakhon Ratchasima, Thailand, 2014.
21. Mohammad, M., S. Choi, Z. Islam, S. Kwak, and J. Baek, "Core design and optimization for better misalignment tolerance and higher range of wireless charging of PHEV," IEEE Trans. on Transport. Electrific., Vol. 3, No. 2, 445-453, 2017.
22. Ding, W. and X. Wang, "Magnetically coupled resonant using Mn-Zn ferrite for wireless power transfer," 15th International Conference on Electronic Packaging Technology, 1561-1564, Chengdu, China, 2014.
23. Mohammad, M., S. Kwak, and S. Choi, "Core design for better misalignment tolerance and higher range of wireless charging for HEV," Applied Power Electronics Conference and Exposition (APEC), 1748-1755, Long Beach, CA, USA, 2016.
24. Huang, R., B. Zhang, D. Qiu, and Y. Zhang, "Frequency splitting phenomena of magnetic resonant coupling wireless power transfer," IEEE Trans. Magn., Vol. 50, No. 11, 1-4, 2014.
25. Theilmann, P. T. and P. M. Asbeck, "An analytical model for inductively coupled implantable biomedical devices with ferrite rods," IEEE Trans. Biomed. Circuits Syst., Vol. 3, No. 1, 43-52, 2009.
26. Salas, R. A. and J. Pleite, "Simulation of waveforms of a ferrite Inductor with saturation and power losses," Materials, Vol. 7, No. 3, 1850-1865, 2014.