Downsizing of Three-Phase Wireless Power Transfer System with 12 coils by Reducing Magnetic Interference

Abstract

In this paper, the placement of 12 coils for a three-phase WPT system with low-radiation noise is proposed for a reduction of a coil area. Increasing the charging power of a wireless power transfer (WPT) system is required in order to improve user convenience. One of the problems caused by the transmission of large power in a WPT system is radiation noise from the transmission coils. The proposed three-phase WPT system with the 12 coils suppresses radiation emission and cancels out the magnetic interference caused by multiple coils. However, it is necessary to increase the radius of the 12 coils, which are circularly placed, to satisfy the cancellation conditions of the magnetic interference. The proposed placement of the 12 coils reduces a radius by rotating each pair of the primary coils and the secondary coils. Simultaneously, the magnetic interference is canceled out and the radiation noise is suppressed. First, the principle of the cancellation of magnetic interference and radiation noise reduction is explained with an electromagnetic field analysis. Then, the emission from the 22-kW prototype has been measured according to the CISPR11 in an anechoic chamber. The magnetic interference is canceled out and the radiation noise is suppressed as same as the conventional placement with a reduced area by 74.5% in comparison with the conventional method.