A novel application of frequency response analysis for wireless power transfer system

A method of frequency response analysis (FRA) is broadly used to observe a deformation of power transformers. The transmitting and receiving windings in magnetically coupled wireless power transfer (WPT) system can be considered as an air core transformer. This paper presents a new application of FRA with the circuit analysis, finite element method (FEM) simulations and the practical analyses on the prototype of two-winding WPT system that operates at the resonance frequency of 1.16 MHz. The FRA results contribute to a verification of the power transfer coefficient over the distance and to an enhancement of the transfer efficiency of WPT system. In addition, the critical distance occurring the maximum power transfer and the decline of the efficiency due to the frequency bifurcation at the near gap between the windings can be analyzed.