Design and optimization of a 3‐coil resonance‐based wireless power transfer system for biomedical implants

Summary This paper presents a resonance‐based wireless power transfer system using a single layer of inductor coil windings, in a pancake configuration, in order to obtain a compact system for implantable electronic applications. We theoretically analyzed the system and characterized it by measuring its inductance, self‐resonant frequency, and quality factor Q . In our resonance‐based wireless power transfer prototype, we proposed a 3‐coil system, using two 15‐mm radius implantable coils, with a resonance frequency of 6.76 MHz. This system can effectively transfer power for a distance of up to 50 mm. Moreover, our proposed 3‐coil system can achieve a high Q ‐factor and has a comparable power transfer efficiency (PTE) to previously reported works about 3‐coil and 4‐coil systems. The experimental PTE can achieve 82.4% at a separation distance of 20 mm and more than 10% PTE at a distance of 40 mm. Copyright © 2014 John Wiley & Sons, Ltd.