An improved three-coil wireless power link to increase spacing distance and power for magnetic resonant coupling system

When wireless power transfer (WPT) technology is used to power the sensor networks, it is necessary to increase the transmission power and distance. We strictly deduced two necessary conditions for strong coupling by coupled mode theory. Next, the transmission power and efficiency as a function of coupling coefficient and quality factor are derived, and the maximum active power of the load depends on the coupling coefficient between resonators, quality factor of the resonator and the drive power. In order to increase transmission power and distance, an improved three-coil wireless power link is proposed. Meanwhile, an experimental platform was established, and the experimental results show that the transmission power can reach 120 W at a distance of 2.5 m. This proves that the improved three-coil wireless power link is very effective.