Optimal design of the rectangular transmission coils for dual-load wireless power transfer system

This paper presents a systematical transmission coil design method for a dual-load wireless power transfer (WPT) system based on a rectangular coil structure. The main design steps are as follows: (1) The system circuit model and the mathematical dimension model of the coupling coils are established to determine the inductance range of the receiving coil and the transmitting coil. (2) Three coil inductance calculation methods such as the finite element method (FEM), greenhouse formula method and backpropagation neural network (BPNN) are analyzed and compared. The FEM and BPNN hybrid method are finally selected for determining the relationship between rectangular coil size, coil turns, and inductance, which is a more efficient modeling scheme and can achieve enough modeling accuracy. (3) Based on calculated inductance characteristics, the length and width of the rectangular coil can be obtained with a geometric mapping scheme, and moreover, the coil size with optimal costs can be estimated. Detailed theoretical analyses are provided. Finally, simulations and experiments are performed for verification.