Coil Coupling Design for Resonant Inductive Wireless Power Transfer System

The coil coupling structure in wireless power transfer (WPT) system plays a crucial role when power is transferred by magnetic coupling. The coupling coefficient between linked coils and resistive coil losses determine the efficiency and power transfer of WPT system. In this paper, the commonly used coil coupling shapes, including helix and spiral, are compared, and spiral coil structure is developed for EV charging. The inductance characteristics of the coil structure are measured and compared with the theoretically calculated values. The developed spiral coil coupling system is tested for different heights and misalignment. Moreover, the simulations of resonant inductive WPT system with series-series (SS) and LCL-LCL topologies are done in MATLAB/Simulink environment. The LCL-LCL topology aids in mitigating harmonic distortions and improving the power quality of the WPT system, by enabling effective filtering and resonance establishment.