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