Design of adaptive optimal load circuit for maximum wireless power transfer efficiency

Abstract

An adaptive optimal load circuit (ALC) for the maximum wireless power transfer (WPT) efficiency is presented for a magnetically coupled resonant WPT system at 13.56 MHz. The ALC is based on the lumped-element matching circuit. The series part is composed of a series capacitor block and an inductor. The shunt part is composed of a varactor and a capacitor block with switches. The tunable range of the optimal load impedance is from 0.2 to 50 Ω. The provided examples demonstrate the usefulness and effectiveness of the ALC to achieve the maximum efficiency.