A novel three-coil wireless power transfer system and its optimization for implantable biomedical applications

The technology of wireless power transfer (WPT) has broad applications especially in implantable biomedical devices. Because of the limitation of the size of the receiver coil, how to lengthen the power transfer distance is crucial in biomedical applications. In order to address this problem, in this paper, a novel three-coil WPT system is proposed and analyzed. In the system, there are two transmitter coils and one receiver coil. Based on the Biot-Savart's law, the electromagnetic property of the square coil is analyzed using finite element method. Moreover, the structural design of the system is optimized by a memetic algorithm. The memetic algorithm combines features of the artificial bee colony method and the covariance matrix adaption evolutionary strategy method. The simulation and experiment results show that the receiver coil can receive about dozens of millivolt when the power transfer distance is about 15 cm. This means the proposed system is suitable for implantable biomedical devices. Compared with the two-coil WPT system, in addition, the power received in the receiver coil of three-coil WPT system can increase about 48%.