The Design of Asymmetric Wireless Power Transmission Coils with Limited-size

Due to the limitation of the size of the receiving end of the wearable devices, the coupling coil of the wireless power transmission is usually asymmetric, which makes the design of the resonant wireless power transmission system more complicated, and especially has a certain impact on the transmission distance and efficiency. Aiming at the above problems, the transmission model of the asymmetric wireless power transmission system is established, and the expression of the transmission efficiency of the asymmetric system is calculated. The structure parameters of the transmitting and receiving coil are designed under the transmission distance and the validity is verified by experiments. The results show that there is a coupling structure within the effective transmission range of the system, i.e., the fixed radius, number of turns, and turn spacing of the transmitting coil and the receiving coil, which enables the system to receive the power to reach the critical coupling power, and ensures the high-efficiency and stable power transmission of the system.