Free-Positioning Magnetic Resonance Wireless Power Transfer System for Biomedical Devices

This paper proposes a free-positioning magnetic resonance wireless power transfer system for biomedical devices. A bowl-shaped transmitting coil, which generates a uniform magnetic field in the charge area, is used for free-positioning. Two spiral receiver coils are attached on both sides of Rx device to be able to receive power both sides of the device. Due to the very limited receiver space, the receiver circuitry consists of a rectifier and a battery charging IC and a controller. To maximize the power conversion efficiency at the receiver, transmission power is controlled at the transmitter to minimize the rectifier-to-battery charger voltage difference using wireless communication feedback during the power transmission. The proposed system shows a maximum 15.7% overall system efficiency with a Li-Ion battery.