A Frequency-Selective EMI Reduction Method for Tightly Coupled Wireless Power Transfer Systems using Resonant Frequency Control of a Shielding Coil in Smartphone Application
Current wireless power transfer (WPT) technology is widely used for various applications because of convenience and safety. However, WPT systems have problems with electromagnetic field (EMF) leakage, which can cause electromagnetic interference (EMI) issues for nearby electrical devices at various frequency ranges. In the case of the Qi standard that operates from 105 to 205 kHz frequency range, the third or fifth harmonic can cause EMI problems for the amplitude modulation bands of a radio corresponding from 530 to 1700 kHz. For the first time, in this article, we propose a frequency-selective EMI reduction method with an additional shielding coil for the effective suppression of EMI radiation of a WPT system. The proposed method reduces the EMI in a specific frequency range and has insignificant effect on the power transfer efficiency (PTE). We experimentally verified that the proposed method with the shielding coil reduced the EMF leakage by 8.96 dB of the third harmonics without reduction of the PTE. Furthermore, we mathematically designed the shielding coil using the proposed method. The mathematical calculation based on the equivalent circuit models is strongly correlated with the experimental measurement results.
S. Hong et al., "A Frequency-Selective EMI Reduction Method for Tightly Coupled Wireless Power Transfer Systems using Resonant Frequency Control of a Shielding Coil in Smartphone Application," IEEE Transactions on Electromagnetic Compatibility, vol. 61, no. 6, pp. 2031-2039, Institute of Electrical and Electronics Engineers (IEEE), Dec 2019.
The definitive version is available at https://doi.org/10.1109/TEMC.2019.2951775
Electrical and Computer Engineering
Electromagnetic Compatibility (EMC) Laboratory
Keywords and Phrases
Electromagnetic Fields (EMFs); Electromagnetic Interference (EMI); Harmonics; Shielding Coil; Wireless Power Transfer (WPT)
International Standard Serial Number (ISSN)
Article - Journal
© 2019 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.
01 Dec 2019