Experimental Study of Transmission Coil Configuration for Omnidirectional Power Transfer in Magnetic Field Coupling Type Contactless Power Transfer

In magnetic field coupling type contactless power transfer, there is a problem that stable power transfer is not possible to changes in the position, angle, and distance of the transmission and receiving coils. In the case of mobile devices charging the battery using the contactless power transfer, the angle between the power transmission and receiving coils is not constant. Therefore, the power transmission efficiency is influenced by changing the position between the power transmission and receiving coils. In this study, the shape of the power transmission coils was investigated with stably supply power in all directions to mobile devices. We studied three coils consisting of cubic coil with 4 squares connected in parallel(4 squares cubic coil), cubic coil with 4 L-shapes connected in parallel(L4 cubic coil) and octagonal star prism coil with 8 square coils connected in parallel(octagonal star prism coil).The S-parameters between the transmission and receiving coils were measured using a Vector Network Analyzer and after converting S-Parameters to Z-parameters. The theoretical maximum efficiency was obtained from the kQ product and compared with different coil shapes. © 2023 The Institute of Electrical Engineers of Japan.