A Phase-controlled Stacked-transmitter Wireless Power Transfer System for Magnetic Field Beamforming

Abstract

Wireless power transfer (WPT) systems operating in MHz have the advantages of small size and a high tolerance for coil misalignment. Existing MHz WPT systems are urgently needed to increase transmission distance and coupling coils efficiency. Although there are some methods for improving the transmission distance and coils efficiency, such as introduced repeaters coils and using the special coils structures. However, the lack of magnetic field strength often limits the transmission distance of the WPT system, and the excessive coupling coefficient can cause inefficiencies in the coupling coils. This paper proposes a compact 2-D stacked-transmitter structure to shape the 3-D magnetic field so as to maximize the transmission distance and coils efficiency. Only the phase angle difference of the drive signals is controlled, and the parameters of compensation capacitors for compensating the cross coupling are designed. The experimental results are in good agreement with the theoretical analysis and simulation. Therefore, a stacked transmitter WPT system with phase angle control has advantages in terms of transmission distance and coupling coil efficiency compared to a single transmitter WPT system.