A Novel Type of 3-D Transmitter for Omnidirectional Wireless Power Transfer

In a wireless power transfer (WPT) system based on coupled magnetic resonance, 2-D planar coils are commonly used as coupling structures. As the spatial position between the coupling structures changes, the system transmission efficiency decreases dramatically, seriously reducing the flexibility of power transfer. To solve this problem and achieve a power transfer with a high degree of freedom in a 3-D space, a novel 3-D coil based on a 26-faced polyhedron is proposed as the transmitting coil winding structure, which is wound using the regular monolithic winding method without overlapping. By means of this coil, it is ensured that the winding direction of each planar coil is different from those of the adjacent planes so that the magnetic fields between adjacent coils are mutually reinforced, thus enhancing the spatial magnetic field density of the system and enabling a stable and efficient transmission of power at any position. The transmitting coil can be enlarged by changing the coil structure, thereby enabling omnidirectional WPT in a larger space. Through experimental research, the system can achieve omnidirectional WPT with an efficiency of 60%, and its transmission efficiency can remain stable within a defined range as the receiver moves.