Cancellation mechanism of electromagnetic leakage for wireless power transmission system based on magnetic resonant coupling

Wireless power transmission using magnetic resonant coupling has attracted considerable attention as a key technology to realize high efficiency in mid-range transmission. Suppressing unwanted electromagnetic radiation is an important criterion in terms of electromagnetic compatibility. This paper proposes a new resonator design to suppress electromagnetic leakage based on a loop-antenna analysis. Although the power efficiency of our proposed resonator is lower than that of conventional loop coils, electromagnetic leakage is reduced dramatically. The power efficiency is more than 80% when the vertical and horizontal air gaps are less than 20 and 10 mm, respectively, for a 50-mm resonator radius.