Magnetic Field Resonant Coupling in Wireless Power Transfer Comparison of Multiple Circuits Using LCL

The purpose of this study is to develop a theory for design circuits depending on the application for LCL-S, LCL-P, S-LCL, P-LCL, and LCL-LCL circuits in Inductive Power Transfer (IPT) of Wireless Power Transfer (WPT). Under unified conditions, transmission characteristics were compared in terms of Constant Voltage (CV) characteristics, Constant Current (CC) characteristics, transmission efficiency, optimum load, output power, and coupling factor
$\boldsymbol{k}=\mathbf{0}$
characteristic. The results show that the optimal load of the LCL-S circuit is about
$\boldsymbol{k}^{\mathbf{2}}$
times that of LCL-P, S-LCL, P-LCL, and LCL-LCL circuits. S-LCL circuit can get more power when a voltage source is connected, and LCL-S, LCL-P, P-LCL, and LCL-LCL circuits can get more power when a current source is connected. Furthermore, it was found that each circuit has a different tendency to change in efficiency and power with load variations.