Adaptive Maximum Power Transfer for Movable device in Wireless Power Transfer system

TL;DR

This paper introduces an adaptive frequency tracking method for wireless power transfer systems that improves charging efficiency for moving devices by estimating power and mutual inductance without direct communication.

Contribution

It proposes a novel estimation technique using input impedance data to adaptively optimize power transfer in dynamic wireless charging environments.

Findings

The system accurately estimates mutual inductance and power using input impedance.

Simulation results show improved efficiency over static impedance matching.

The method effectively handles frequency splitting issues at short distances.

Abstract

More and more applications are adopting the charging topology of wireless power transmission. However, most wireless charging systems can not charge mobile devices which are moving in position while charging. Currently, many commercialized wireless charging systems adopt an inductive coupling method, which has very short charging distances. In addition, the frequency of the two coupled coils that produce maximum power transfer keeps varying, depending on the coupling coefficient that relies on the separation between coils, and this tendency becomes more severe when the coupling is strengthened at a close charging distance by the phenomenon called frequency splitting. Therefore, the existing wireless power transmission system using a fixed operating frequency can not optimize power transmission for a fluctuating charging environment as the coupling between coils changes, and charging efficiency is greatly reduced by frequency splitting when charging at a very short distance. To solve this problem, we proposed the method of estimating the RX side power and mutual inductance using the information from the TX side such as input impedance rather than using a direct communication link which adds more cost and complexity. Also, we derived a mathematical model for the above estimation method. To prove this mathematical model, the proposed wireless power transmission system was implemented in a SIMULINK environment, and the system model was validated through simulation. Also comparison between the adaptive frequency tracking method and static impedance matching circuit is made by analyzing simulation results.