An Investigation of Electromagnetic Radiated Emissions from Wireless Charging System for Mobile Device using Qi Standard


In this paper, the electromagnetic radiated emissions from 30 MHz to 1 GHz of a wireless charging system for a mobile device using Qi standard are investigated. It has been found that the common mode current on USB cable is the main cause of radiation and the noise source is the full bridge inverter in power transmitter. The common mode current path is highlighted to explain the radiation mechanism. The switch node voltage in time domain and frequency domain are measured for more understanding of noise source. A full wave simulation model is built to roughly estimate the far field radiation. Methods to reduce the radiated emissions are also discussed and demonstrated experimentally.

Meeting Name

2018 IEEE Symposium on Electromagnetic Compatibility, Signal Integrity and Power Integrity, EMC, SI and PI 2018 (2018: Jul. 30-Aug. 3, Long Beach, CA)


Electrical and Computer Engineering

Keywords and Phrases

Busbars; Energy transfer; Ferrite; Frequency domain analysis; Inductive power transmission; Common mode currents; Far-field radiation; Full-bridge inverters; Full-wave simulations; Radiated emissions; Wireless charging; Wireless charging system; Wireless power transfer; Electromagnetic compatibility; Common-mode current; Qi standard; Radiated emissions

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2018 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Jul 2018