To address the problems of large volume, heavy weight, and inconvenient installation of the shield board of a wireless charging coil (WCC) installed on the body of an electric vehicle (EV), a new shielding method is proposed in this paper. From the perspective of engineering practice, according to the principle of passive shielding, and in line with the vertical direction of WCC with ferromagnetic material shielding, this novel shielding method involves only a low permeability metal shielding ring set around the transmitting coil in the horizontal direction. Using the finite element simulation software COMSOL Multiphysics, the EV model, the magnetic coupling resonance (MCR) WCC model, and the pedestrian body model at the observation point are designed. The influence of the metal shielding ring on the self-inductance and mutual inductance of WCC is calculated. The magnetic induction strength (B) and electric field strength (E) of pedestrian body at observation points before and after adding a metal shielding in the horizontal direction are evaluated, and the electromagnetic exposure safety of a pedestrian body in this electromagnetic environment is analyzed. Compared with the shielding method of only adding ferromagnetic material in the vertical direction and after using new shielding, the maximum B of a human trunk is reduced by 43%, the maximum E reduced by 44%, the maximum B of human head reduced by 44%, and the maximum E reduced by 39%. After adding the metal shielding ring, the maximum B and E of human trunk decreased from 8.56 × 10-1 times and 2.28 × 10-1 times of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limit to 4.89 × 10-1 times and 1.27 × 10-1 times, respectively, and the maximum B and E of human head decreased from 1.62 × 10-3 times and 8.58 × 10-4 times of the ICNIRP exposure limit to 9.18 × 10-4 and 5.25 × 10-4 times, respectively. The simulation results show that the new shielding method can significantly reduce the electromagnetic radiation of the pedestrian's trunk and head central nervous system (CNS) at the observation point. The effectiveness of the shielding method is proven, and this work provides a certain guidance for the engineering design of WCCs.
"Research on Shielding and Electromagnetic Exposure Safety of an Electric Vehicle Wireless Charging Coil," Progress In Electromagnetics Research C,
Vol. 117, 55-72, 2021. doi:10.2528/PIERC21072701
1. Ahmad, A., M. S. Alam, and R. Chabaan, "A comprehensive review of wireless charging technologies for electric vehicles," IEEE Transactions on Transportation Electrification, Vol. 4, No. 1, 38-63, 2017. doi:10.1109/TTE.2017.2771619
2. Li, S. and C. C. Mi, "Wireless power transfer for electric vehicle applications," IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol. 3, No. 1, 4-17, 2015. doi:10.1109/JESTPE.2014.2319453
3. Zhang, X., P. Zhang, Q. Yang, Z. Yuan, and H. Su, "Magnetic shielding design and analysis for wireless charging coupler of electric vehicles based on finite element method," Transactions of China Electrotechnical Society, Vol. 31, No. 1, 71-79, 2016. doi:10.1149/2.0401602jes
4. Campi, T., S. Cruciani, F. Maradei, and M. Feliziani, "Magnetic shielding design of wireless power transfer system," 2015 31st International Review of Progress in Applied Computational Electromagnetics (ACES), 1-2, Williamsburg, 2015.
5. Kim, J., H. Kim, C. Song, I.-M. Kim, Y.-I. Kim, and J. Kim, "Electromagnetic interference and radiation from wireless power transfer systems," 2014 IEEE International Symposium on Electromagnetic Compatibility (EMC), 171-176, Raleigh, 2014.
6. Zhang, X., Z. Wang, B. Wei, S. Wang, and Q. Yang, "Analysis of the influence of electric shield on space magnetic field in electric vehicle wireless charging system," Transactions of China Electrotechnical Society, Vol. 34, No. 8, 1580-1588, 2019.
7. Pavelek, M., M. Frivaldsky, and P. Spanik, "Influence of the passive shielding on the transfer characteristics of the wireless power transfer systems," 2017 19th International Conference on Electrical Drives and Power Electronics (EDPE), 94-99, Dubrovnik, 2017.
8. Lu, M. and K. D. T. Ngo, "Circuit models and fast optimization of litzshield for inductive-power- transfer coils," IEEE Transactions on Power Electronics, Vol. 34, No. 5, 4678-4688, 2019. doi:10.1109/TPEL.2018.2865649
9. Lu, M. and K. D. T. Ngo, "Comparison of passive shields for coils in inductive power transfer," IEEE Applied Power Electronics Conference and Exposition --- APEC, 1419-1424, 2017.
10. Park, S. W., "Evaluation of elecromagnetic exposure during 85 kHz wireless power transfer for electric vehicles," IEEE Transactions on Magnetics, Vol. 54, No. 1, 1-8, 2018.
11. Ding, P.-P., L. Bernard, L. Pichon, and A. Razek, "Evaluation of electromagnetic fields in human body exposed to wireless inductive charging system," IEEE Transactions on Magnetics, Vol. 20, No. 2, 1037-1040, 2014. doi:10.1109/TMAG.2013.2284245
12. Shimamoto, T., I. Laakso, and A. Hirata, "In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle," Physics in Medicine and Biology, Vol. 60, No. 1, 163-173, 2015. doi:10.1088/0031-9155/60/1/163
13. Shimamoto, T., I. Laakso, and A. Hirata, "Internal electric field in pregnant-woman model for wireless power transfer systems in electric vehicles," Electronics Letters, Vol. 51, No. 25, 2136-2137, 2015. doi:10.1049/el.2015.2457
14. Shah, I. A., Y. Cho, and H. Yoo, "Safety evaluation of medical implants in the human body for a wireless power transfer system in an electric vehicle," IEEE Transactions on Electromagnetic Compatibility, Vol. 62, No. 2, 338-345, 2020. doi:10.1109/TEMC.2019.2903844
15. De Santis, V., T. Campi, S. Cruciani, I. Laakso, and M. Feliziani, "Assessment of the induced electric fields in a carbon-fiber electrical vehicle equipped with a wireless power transfer system," Energies, Vol. 11, No. 3, 684, 2018. doi:10.3390/en11030684
16. Miw, K., T. Takenaka, and A. Hirata, "Electromagnetic dosimetry and compliance for wireless power transfer systems in vehicles," IEEE Transactions on Electromagnetic Compatibility, Vol. 61, No. 6, 2024-2030, 2019. doi:10.1109/TEMC.2019.2949983
17. Lan, J. and A. Hirata, "Effect of loudspeakers on the in situ electric field in a driver body model exposed to an electric vehicle wireless power transfer system," Energies, Vol. 13, No. 14, 3635, 2020. doi:10.3390/en13143635
18. SAE TIR J2954, , Wireless Power Transfer for Light-Duty Plug-In/Electric Vehicles and Alignment Methodology; SAE International: Warrendale, PA, USA, 2016.
19., , IEC 61980-1. Electric Vehicle Wireless Power Transfer (WPT) Systems-Part 1: General Requirements; International Electrotechnical Commission: Geneva, Switzerland, 2015.
20. Zhou, W., M. Lu, and B. Chen, "Safety evaluation on high frequency electromagnetic exposure in driver's cab of subway train," China Railway Science, Vol. 36, No. 5, 116-121, 2015.
21. Lu, M. and S. Ueno, "Comparison of the induced fields using different coil configurations during deep transcranial magnetic stimulation," Plos One, Vol. 12, No. 6, 1-12, 2017.
22. Lu, M. and S. Ueno, "Deep transcranial magnetic stimulation using figure-of-eight and halo coils," IEEE Transactions on Magnetics, Vol. 51, No. 11, 1-4, 2015.
23. Rush, S. and D. A. Driscoll, "Current distribution in the brain from surface electrodes," Anesthesia and Analgesia, Vol. 47, No. 6, 717723, 1968. doi:10.1213/00000539-196811000-00016
24. Gabriel, S., R. W. Lau, and C. Gabriel, "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues," Physics in Medicine and Biology, Vol. 41, No. 11, 2271-2293, 1996. doi:10.1088/0031-9155/41/11/003
25. Li, J. and M. Lu, "Safety evaluation on electromagnetic exposure of radio frequency antenna in typical subway platform," China Railway Science, Vol. 41, No. 2, 157-164, 2020.
26. Tian, R. and M. Lu, "Safety assessment of electromagnetic exposure in high-speed train carriage with full passengers," Annals of Work Exposures and Health, 1-14, 2020.
27. Başyiğit, I. B., A. Genç, and S. Helhel, "Effect of orientation of RF sources maintained within the enclosures on electrical shielding effectiveness performance," Turkish Journal of Electrical Engineering and Computer Sciences, Vol. 27, No. 4, 3088-3097, 2019. doi:10.3906/elk-1902-68
28. Basyigit, I. B., H. Dogan, and S. Helhel, "The effect of aperture shape, angle of incidence and polarization on shielding effectiveness of metallic enclosures," Journal of Microwave Power and Electromagnetic Energy, Vol. 53, No. 2, 115-127, 2019. doi:10.1080/08327823.2019.1607496
29. Basyigit, I. B. and M. F. Caglar, "Investigation of the magnetic shielding parameters of rectangular enclosures with apertures at 0 to 3 GHz," Electromagnetics, Vol. 36, No. 7, 434446, 2016. doi:10.1080/02726343.2016.1220907
30. Zamanian, Z., S. M. J. Mortazavi, E. Asmand, and K. Nikeghbal, "Assessment of health consequences of steel industry welders' occupational exposure to ultraviolet radiation," International Journal of Preventive Medicine, Vol. 6, No. 1, 123, 2015. doi:10.4103/2008-7802.172379
31. ICNIRP, "Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz)," Health Physics, Vol. 99, No. 6, 818-836, 2010. doi:10.1097/HP.0b013e3181f06c86
32. ICNIRP, "Guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz)," Health Physics, Vol. 118, No. 5, 483-524, 2020. doi:10.1097/HP.0000000000001210