volume | PIER Journals

Abstract

In the field of wireless power transmission (WPT) for electric vehicles, the challenge of magnetic shielding technology is particularly prominent. Achieving effective magnetic shielding often comes at the cost of transmission efficiency, creating a significant technical bottleneck. As a result, research into improving transmission efficiency while minimizing magnetic leakage has become a primary focus in the industry. This is seen as critical for driving the sustainable development of the electric vehicle sector. In response to this challenge, this paper presents the construction of an active magnetic shield using an isotropic coil configuration, which not only optimizes system efficiency but also significantly reduces magnetic leakage in WPT systems. The paper begins by introducing the concept of an active magnetically shielded isotropic coil structure for wireless power transmission. Next, it details the design methodology and operational principles of the structure, followed by the derivation of the mathematical model and equivalent circuit. The effectiveness of the magnetic shielding mechanism is examined from a theoretical standpoint, and the influence of coil parameters on both shielding performance and transmission efficiency is analyzed. Finally, based on the optimized coil parameters, the design of the wireless charging system incorporating the magnetic shielding structure is completed. This includes relevant theoretical calculations, simulation analyses, and experimental validation to confirm the feasibility of the design. The results demonstrate that the active magnetically shielded isotropic coil significantly reduces magnetic leakage, lowering it by approximately 95.68% compared to traditional coils, while achieving a transmission efficiency of 95.68% in experiments.

1. Li, Zhongqi, Xinbo Xiong, Pengsheng Kong, and Liquan Ren, "Research on electromagnetic shielding and efficiency optimization technology of wireless power transfer system," Journal of Electronic Measurement and Instrumentation, Vol. 37, No. 5, 151-162, 2023.

2. Qiu, Dongyuan, D. Qiu, W. Xiao, et al. "Review of key technologies of three-phase wireless charging system for electric vehicles," Journal of Power Supply, Vol. 20, 24-33, 2022.

3. Deng, J. W., "Adaptation and substitution: A governance picture and response strategy for sustainable transformation of urban transportation," Journal of East China University of Science and Technology (Social Science Edition), Vol. 35, 110-124, 2020.

4. Wu, X. K., Q. X. Yang, X. Zhang, L. H. Zhu, and G. X. Qi, "Coil structure study and efficiency analysis for the driving wireless charging system of electric car," Advanced Technology of Electrical Engineering and Energy, Vol. 35, No. 9, 8-13, 2016.

5. Yang, Q., Xian Zhang, and P. Zhang, "Intelligent wireless power transmission cloud network for electric vehicles," J. Electr. Eng. Technol, Vol. 38, 1-12, 2023.

6. Chen, L. S., "Present status and future trends of electric vehicles," Science and Technology Review, Vol. 23, 24-28, 2005.

7. Wu, Lihao and Bo Zhang, "Overview of static wireless charging technology for electric vehicles: Part I," Transactions of China Electrotechnical Society, Vol. 35, No. 6, 1153-1165, 2020.

8. Mohammad, Mostak, Moinul Shahidul Haque, and Seungdeog Choi, "A litz-wire based passive shield design to limit EMF emission from wireless charging system," 2018 IEEE Energy Conversion Congress and Exposition (ECCE), 97-104, Portland, OR, USA, Sep. 2018.

9. Campi, Tommaso, Silvano Cruciani, Francescaromana Maradei, and Mauro Feliziani, "Magnetic field mitigation by multicoil active shielding in electric vehicles equipped with wireless power charging system," IEEE Transactions on Electromagnetic Compatibility, Vol. 62, No. 4, 1398-1405, 2020.

10. Zhu, Qingwei, Deqing Chen, Lifang Wang, Chenglin Liao, and Yanjie Guo, "Study on the magnetic field and shielding technique for an electric vehicle oriented wireless charging system," Transactions of China Electrotechnical Society, Vol. 30, No. S1, 143-147, 2015.

11. Lee, Sang-Yun, Yun-Seog Lim, In-Hyuk Choi, Dong-Il Lee, and Sang-Beom Kim, "Effective combination of soft magnetic materials for magnetic shielding," IEEE Transactions on Magnetics, Vol. 48, No. 11, 4550-4553, 2012.

12. Su, Y., J. Liu, Z. Wang, D. Xin, and Y. Jian, "Influence analysis of metal in the same plane with pickup coil on magnetic coupler and suppression method," Transactions of China Electrotechnical Society, Vol. 37, No. 3, 578-588, 2022.

13. Meng, J., Y. Zhang, et al. "Research of active magnetic shielding for wireless power transfer system of electric vehicles," Advanced Technology of Electrical Engineering and Energy, Vol. 40, No. 4, 44-51, 2021.

14. Li, K., H. Wen, K. Zhang, et al. "Research progress on electromagnetic interference suppression of magnetically-coupled wireless power transfer system," Progress of electromagnetic interference suppression in magnetically coupled wireless energy transmission systems, Vol. 42, 7387-7403, 2022.

15. Kim, S., J. Kim, S. Kong, H. Kim, I.-S. Suh, N. P. Suh, D.-H. Cho, J. Kim, and S. Ahn, "Coil design and shielding methods for a magnetic resonant wireless power transfer system," Proceedings of the IEEE, Vol. 101, No. 6, 1332-1342, 2013.

16. H., Moon, S. Kim, H. H. Park, et al. "Design of a resonant reactive shield with double coils and a phase shifter for wireless charging of electric vehicles," IEEE Transactions on Magnetics, Vol. 51, No. 3, 1-4, 2015.

17. S., Cruciani, T. Campi, M. Feliziani, et al. "Active shielding design for a dynamic wireless power transfer system," 2020 International Symposium on Electromagnetic Compatibility --- EMC EUROPE, Vol. 51, No. 3, 23-25, Rome, Italy, Sep. 2020.

18. Li, Z. Q., J. Li, C. H. Quan, X. Y. Zhang, S. D. Huang, et al. "Mutual inductance calculation of arbitrarily positioned rectangular coils with magnetic shielding in wireless power transfer systems," Transaction of China Electrotechnical Society, Vol. 37, No. 17, 4294-4305, 2022.

Dr. Yonghong Long

Dr. Hui Li

Dr. Zhongqi Li

Mr. Bin Li

Dr. Ziyue Gan