Angular misalignment is an issue for many potential wireless power transfer (WPT) applications. This paper proposes a resonator as an effort to solve this issue. In the beginning, this paper gives an example of quantitative coupling analysis on angular misalignments. Then, it proposes an omnidirectional resonator for electromagnetic coupling WPT system. The proposed resonator is based on the structure of a regular polyhedron. It is constructed of four planar spiral resonators arranged as a regular tetrahedron. The coupling between the proposed resonator and a planar spiral resonator is verified. Both the simulated and measured results show that the coupling coefficient can be kept at a certain level when the omnidirectional resonator rotates around all x, y, and z axes regardless of the orientation of the planar spiral resonator respect to the omnidirectional resonator.
2. Kurs, A., A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher, and M. Soljacic, "Wireless power transfer via strongly coupled magnetic resonances," Science, Vol. 317, 83-86, Jul. 2007.
3. Shonohara, N., Wireless Power Transfer via Radiowaves, ISTE Ltd and John Wiley & Sons, Inc., 2014.
4. Awai, I., "Magnetic resonant wireless power transfer," Nikkei Electronics, 2011 (in Japanese).
5. Ohira, T., "Maximum available efficiency formulation based on a black-box model of linear two port power transfer systems," IEICE Electronics Express, ELEX, Vol. 11, No. 13, 1-6, #20140448, Jun. 2014.
6. Zhang, J., X. Yuan, C. Wang, and Y. He, "Comparative analysis of two-coil and three-coil structures for wireless power transfer," IEEE Transactions on Power Electronics, Vol. 32, No. 1, 341-352, 2017.
7. Tierney, B. B. and A. Grbic, "Design of self-matched planar loop resonators for wireless nonradiative power transfer," IEEE Transactions on Microwave Theory and Techniques, Vol. 62, No. 4, 909-919, 2014.
8. Jonah, O., S. V. Georgakopoulos, and M. M. Tentzeris, "Orientation insensitive power transfer by magnetic resonance for mobile devices," Proc. IEEE Wireless Power Transfer, Vol. 15/16, 5-8, Perugia, Italy, 2013.
9. Ng, W. M., C. Zhang, D. Lin, and S. R. Hui, "Two- and three-dimensional omnidirectional wireless power transfer," IEEE Transactions on Power Electronics, Vol. 29, No. 9, 4470-4474, 2014.
10. Zhang, C., D. Lin, and S. Y. Hui, "Basic control principles of omnidirectional wireless power transfer," IEEE Trans. Power Electron., Vol. 31, No. 7, 5215-5227, Jul. 2016.
11. Lin, D., C. Zhang, and S. Y. Ron Hui, "Mathematic analysis of omnidirectional wireless power transfer - Part-II three-dimensional systems," IEEE Transactions on Power Electronics, Vol. 32, No. 1, 613-624, 2017.
12. Pacini, A., F. Benassi, D. Masotti, and A. Costanzo, "Design of a miniaturized omni-directional RF-to-dc IR-WPT," 2018 IEEE Wireless Power Transfer Conference (WPTC), 1-4, 2018.
13. Nam, H.-V. and C. Seo, "Analytical and experimental investigations of omnidirectional wireless power transfer using a cubic transmitter," IEEE Transactions on Industrial Electronics, Vol. 65, No. 2, 1358-1366, 2018.
14. Han, W., K. T. Chau, C. Jiang, W. Liu, and W. H. Lam, "Design and analysis of quasi-omnidirectional dynamic wireless power transfer for fly-and-charge," IEEE Transactions on Magnetics, Vol. 55, No. 7, doi: 10.1109/TMAG.2019.2895716, 2019.
15. Chabalko, M. J. and A. P. Sample, "Three-dimensional charging via multimode resonant cavity enabled wireless power transfer," IEEE Transactions on Power Electronics, Vol. 30, No. 11, 6163-6173, 2015.
16. Inada, Y., T. Kawajiri, U. Takeda, and H. Ishikuro, "Arbitrary magnetic field control technique by multi-coil transmitter voltage phase shifting for omni-directional free-positioning magnetic resonance wireless power delivery," 48th European Microwave Conference (EuMC), 186-189, 2018.
17. Zhang, Y., T. Yoshikawa, and T. Kitahara, "Magnetic and electric coupling analysis for angular misalignment of spiral resonators in WPT systems," Progress In Electromagnetics Research M, Vol. 76, 1-8, 2018.
18. Awai, I., "New expressions for coupling coefficient between resonators," IEICE Trans. Electron., Vol. 88C, No. 12, 2295-2301, Dec. 2005.
19. Awai, I., S. Iwamujra, H. Kubo, and A. Sanada, "Separation of coupling coefficient between resonators into electric and magnetic contributions," IEICE, Vol. 88-C, No. 12, 1033-1039, 2005 (in Japanese).
20. Zhang, Y., T. Yoshikawa, and I. Awai, "Analysis of electric and magnetic coupling components for spiral resonators used in wireless power transfer," 2014 Asia-Pacific Microwave Conference, 1366-1368, 2014.
21. Hong, J.-S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, John Wiley & Sons, Inc., 2001.