Design of Dual Frequency Mixed Coupling Coils of Wireless Power and Data Transfer to Enhance Lateral and Angular Misalignment Tolerance

A dual-resonant mixed coupling structure is proposed to enable lateral and angular misalignment immunity in wireless power and data transfer systems. By considering the duality property of electrical coupling and magnetic coupling, mixed coupling coils make the efficiency of wireless power transfer nearly insensitive to axial and angular misalignment. A complete, sophisticated equivalent circuit is proposed and demonstrates the features of the dual-resonant characteristic and lateral and angular misalignment tolerance. Compared to traditional printed spiral coil systems, the proposed mixed coupling structure reduces decline rate of S₂₁ by 26.4% and 78.1% at 35-mm axial misalignment and 90° angular misalignment at low resonant frequency, respectively. Moreover, at high resonant frequency, S₂₁ only drops 16.5% with 60-mm lateral misalignment and is almost flat for 90° angular misalignment. Last but not least, data communication is also validated by transmitting a 200-kHz frequency shift keying signal, and the probability errors remain at acceptable level when misalignment occurs.