volume | PIER Journals

Abstract

The safety of the electromagnetic environment of wireless power transfer (WPT) systems is one of the prerequisites for the application of wireless charging technology for electric vehicles (EVs). The electromagnetic characteristics of a wireless charging EV with a new 7.7 kW WPT system were modeled and analyzed in this paper. Firstly, a complete model of the magnetic coupler was built as a source of electromagnetic radiation, and an external excitation source was added by coupling the resonant coils to the double inductor-capacitor-capacitor (LCC-LCC) topology circuit model. Secondly, the finite element analysis software COMSOL Multiphysics was used to solve for the magneto-quasi-static values to verify the electromagnetic safety of the wireless charging process. Then, two charging scenarios were investigated when the GA and VA aligned and misaligned, involving lateral offset and longitudinal offset cases. Finally, the simulation results were compared and analyzed, showing that the values of electromagnetic fields become higher as the offset distance increases. In worst-case scenarios, the highest magnetic flux density (1.1 μT) is observed in the virtual plane of the test on the left side of the vehicle, which occupies only 17.6% of the limits specified in ICNIRP 1998 (6.25 μT), indicating a good EMF safety performance of the wireless charging system.

1. Patil, D., M. K. McDonough, J. M. Miller, B. Fahimi, and P. T. Balsara, "Wireless power transfer for vehicular applications: overview and challenges," IEEE Trans. Transp. Electrification, Vol. 4, No. 1, 3-37, Mar. 2018.
doi:10.1109/TTE.2017.2780627

2. Sun, L., D. Ma, and H. Tang, "A review of recent trends in wireless power transfer technology and its applications in electric vehicle wireless charging," Renew. Sust. Energ. Rev., Vol. 91, 490-503, Aug. 2018.
doi:10.1016/j.rser.2018.04.016

3. Vaka, R. and R. k. Keshri, "Review on contactless power transfer for electric vehicle charging," Energies, Vol. 10, No. 5, 636, May 2017.
doi:10.3390/en10050636

4. Garnica, J., R. A. Chinga, and J. Lin, "Wireless power transmission: from far field to near field," Proc. IEEE, Vol. 101, No. 6, 1321-1331, Jun. 2013.
doi:10.1109/JPROC.2013.2251411

5. Mahesh, A., B. Chokkalingam, and L. Mihet-Popa, "Inductive wireless power transfer charging for electric vehicles-a review," IEEE Access, Vol. 9, 137667-137713, Sep. 2021.
doi:10.1109/ACCESS.2021.3116678

6. Mou, X., D. T. Gladwin, R. Zhao, and H. Sun, "Survey on magnetic resonant coupling wireless power transfer technology for electric vehicle charging," IET Power Electron., Vol. 12, No. 12, 16, Oct. 2019.

7. Liu, J., X. Zhang, J. Yu, Z. Xu, and Z. Ju, "Performance analysis for the magnetically coupled resonant wireless energy transmission system," Complexity, Vol. 2019, 1-13, 2019.

8. Wireless Power Transfer for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology, SAE J2954, Oct. 2020.

9. Andre, K., K. Aresteidis, M. Robert, J. D. Joannopoulos, P. Fisher, and M. Soljacic, "Wireless power transfer via strongly coupled magnetic resonances," Science (New York, N.Y.), Vol. 317, No. 5834, 83-86, Jul. 2007.

10. Campi, T., S. Cruciani, F. Maradei, and M. Feliziani, "Magnetic field during wireless charging in an Electric Vehicle according to standard SAE J2954," Energies, Vol. 12, No. 9, 1795-1819, May 2019.
doi:10.3390/en12091795

11. Electrically Propelled Road Vehicles --- Magnetic Field Wireless Power Transfer --- Safety and Interoperability Requirements, ISO 19363, Apr. 2020.

12. Electric Vehicle Wireless Power Transfer: Part 4, Limits and Test Methods of the Electromagnetic Environment, GB/T 38775.4-2020 (in Chinese), Apr. 2020.

13. Electric Vehicle Wireless Power Transfer (WPT) System: Part 1, General Requirements, IEC 61980-1, Nov. 2020.

14. International Commission on Non-Ionizing Radiation Protection (ICNIRP) "Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz)," Health Phys., Vol. 99, No. 6, 818-836, Dec. 2010.
doi:10.1097/HP.0b013e3181f06c86

15. Park, S., "Evaluation of electromagnetic exposure during 85 kHz wireless power transfer for electric vehicles," IEEE Trans. Magn., Vol. 54, No. 1, 1-8, Jan. 2018.

16. Santis, V. D., T. Campi, S. Cruciani, S. 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, 684-693, Mar. 2018.
doi:10.3390/en11030684

17. Mou, W. and M. Lu, "Research on shielding and electromagnetic exposure safety of an electric vehicle wireless charging coil," Progress In Electromagnetics Research, Vol. 117, 55-72, Dec. 2021.
doi:10.2528/PIERC21072701

18. Electric Vehicle Wireless Power Transfer: Part 6, Interoperability Requirements and Testing --- Ground Side, GB/T 38775.6-2021 (in Chinese), Oct. 2021.

19. Electric Vehicle Wireless Power Transfer: Part 7, Interoperability Requirements and Testing --- Vehicle Side, GB/T 38775.7-2021 (in Chinese), Oct. 2021.

20. Jiang, C., K. T. Chau, C. Liu, and C. H. T. Lee, "An overview of resonant circuits for wireless power transfer," Energies, Vol. 10, No. 7, 894, Jun. 2017.
doi:10.3390/en10070894

21. Campi, T., S. Cruciani, F. Maradei, and M. Feliziani, "Near-field reduction in a wireless power transfer system using LCC compensation," IEEE Trans. Electromagn. Compat., Vol. 59, No. 2, 686-694, Apr. 2017.
doi:10.1109/TEMC.2016.2641383

22. Shen, D., G. Du, W. Zeng, Z. Yang, and J. Li, "Research on optimization of compensation topology parameters for a wireless power transmission system with wide coupling coefficient fluctuation," IEEE Access, Vol. 8, 59648-59658, Apr. 2020.
doi:10.1109/ACCESS.2020.2983612

23. Liu, J., X. Zhang, J. Yu, Z. Xu, and Z. Ju, "Performance analysis for the magnetically coupled resonant wireless energy transmission system," Complexity, Vol. 2019, 1-13, Nov. 2019.

Dr. Songtao Liu

Mr. Deguan Li

Prof. Chuanmin Chen

Dr. Wenbo Jia

Dr. Kai Che

Dr. Jinxing Yu