Development of Three-Phase Wireless Power Transfer System with Reduced Radiation Noise

A three-phase wireless power transfer (WPT) system, which has six primary coils and six secondary coils is proposed in this paper. The three-phase WPT system reduces the radiation noise by canceling the noise using pairs of coils placed opposite to each other. However, a magnetic interference among the multiple coils decreases the transmission efficiency due to a circulating current among the primary coils, and the secondary coils in WPT systems with multiple coils. The proposed three-phase WPT system cancels out the effect due to the interference among the six coils on each side. First, the WPT system with the 12 coils is proposed. Then, a canceling condition of the magnetic interference among the coils is mathematically introduced from the voltage equation on the coils. Finally, the proposed WPT system is experimentally demonstrated with the 3-kW prototype. The experimental result shows that the radiation noise at the fundamental frequency is suppressed from 12.2 dB mu A to 2.1 dB mu A.