1-port Measurement Method of the Coupling Factor and Receiver Q for Spatial and State Freedom in Wireless Power Transfer Systems

Abstract

For spatial and state freedom in wireless power transfer (WPT) systems, the coupling factor and receiver Q have been estimated, using a loop current flowing into the transmitting coil by 1-port measurement method. Since the power transfer efficiency is related to the coupling factor and the load impedance, it is required to estimate and analyze them. In strongly and loosely coupled regions, the proposed measurement method can evaluate the location and battery states of the receiver by tracking the operating frequency of the transmitter. Compared to the calculated results obtained by conventional 2-port measurements against the k between the transmitting and receiving coils and the receiver Q, the proposed 1-port estimation method for frequency-tuned WPT systems is relatively simple and efficient, and has been experimentally verified.