Equivalent circuit and coil design for spatial freedom of wireless charging

Abstract

Wireless charging is widely used as a convenience that allows users to charge electronic devices without wires. However, the receiver on the wireless charging pad is not charged if the receiver is misaligned. Therefore, it is needed to adjust the center of the receiver well. This misalignment may greatly reduce the convenience of wireless charging. To overcome this limitation of wireless charging, a coil with an increased outer diameter and a double coil were designed to improve the positional freedom of receiver. The complex circuit of a double coil is converted into the T-equivalent circuit. The efficiency is obtained by measuring and simulating the Z-parameter at the frequency of 100 kHz. The efficiency of the coil with a large outer diameter and the double coil decreased at the center, but the efficiency improved when shifted by 15 mm. The trends in measurement and simulation are observed to be similar. © 2020 IEEE.