Improving the Critical Transmission Distance of Inductively Coupled Wireless Power Transfer Having Parity-Time Symmetry

Abstract

A wireless power transfer (WPT) system with parity-time symmetry has a critical magnetic coupling coefficient (k_mc). A small k_mc results in a highly robust, long-distance WPT. We found that the series-series/parallel topology is a good choice to obtain a small k_mc. Additionally, a k_mc value of 0.04 was achieved by a combination of a solenoid coil of 46µH, low frequency range of 47-56kHz, and buck converter. We investigated the optimal shape of the solenoid coil using an electromagnetic field simulator, and a critical transmission distance (d_c) of 77mm was achieved by small transmitter and receiver coils (dimensions: 100mm × 20mm × 10mm). We succeeded in extending d_c by 1.8 times over the results from our previous work. d_c of 77mm is 2.8 times as large as the cube root of the coil volume.