Load Optimization Factors for Analyzing the Efficiency of Wireless Power Transfer Systems Using Two-Port Network Parameters

Abstract

This paper models and analyzes the power efficiency of wireless power transfer systems with arbitrary load impedances using passive two-port network parameters. In this formulation, two novel indices--the load resistance optimization factor and the load reactance optimization factor--are defined and introduced to indicate the deviation of the load resistance and load reactance from their optimal values. It is shown that the power efficiency of these systems can be formulated using only their k-Q product and the defined load optimization factors. Additionally, we show that the ratio of efficiency to maximum available efficiency can be characterized with one single complex factor. The proposed approach helps the quantitive interpretation of the efficiency deterioration by the difference between the load impedance and its optimal value.