Method for Estimating Optimum Free Resonant Frequencies in Overcoupled WPT System

Abstract

In our previous work, we proposed the method to maximize the output power even in the overcoupled state of the wireless power transfer (WPT) system by controlling free resonant frequencies and derived closed-form expression for optimum free resonant frequencies of the primary and secondary resonators. In this paper, we propose the mutual coupling approach to derive the optimum free resonant frequencies and show the measured power transfer efficiency (PTE) using the transmission efficiency as well as the system energy efficiency. The results of the proposed approach exactly coincide with those of the previous work, and the fabricated prototype achieves the transmission efficiency of about 80% by tuning the free resonant frequencies to the optimum values in the overcoupled state.

Efficiency Analysis of Multiple-Transmitter Wireless Power Transfer Systems

“…The research of magnetic-resonance coupling is particularly prized in the areas of wireless power transfer (WPT) since this research was published in the US journal Science in 2007 [1]. Many interesting fields on magnetic-resonance WPT have been studied in just the last 10 years alone [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

“…Methods of Kirchhoff's voltage law, band-pass filter theory, and coupled-mode theory are compared and discussed in [7,8]. Based on those methods, characteristic analysis of goal setting WPT systems are implemented in [9][10][11][12][13][14][15][16][17][18][19]. The systems consisting of multiple receivers (RXs) can be applied well to the scenario of a single charging platform.…”