Effects of Foreign Metal Object on Soft-Switching Conditions of Class-E Inverter in WPT

Abstract

A foreign metal object will deteriorate the performance of wireless power transfer (WPT) systems and cause insecurity issues. Therefore, the influence principles and rules of foreign metal objects on soft-switching conditions of Class-E inverters and the performance of WPT systems are developed in this paper. The effects of different metal materials on coil parameters at different frequencies and positions are analyzed first, then the effects of foreign metal objects on soft-switching conditions of Class-E inverters and the power transfer capability of WPT systems are investigated. Principle analyses and simulation results demonstrate that there are significantly different effects on the soft-switching conditions and power transfer when a foreign metal object is placed near the transmitter coil or the receiver coil. In addition, the monotonicity of the variation in power transfer also depends on the position of the foreign metal object. Finally, a WPT experimental prototype with a Class-E inverter is implemented to verify the influence principles and rules of foreign metal objects. The experimental results are highly consistent with the principle analyses and simulation results.

Multiple Parameters Estimation Based on Transmitter Side Information in Wireless Power Transfer System

“…Specifically, substituting the partial derivative value of the Equation (23) into Equation (24), the Hessian matrix now becomes…”

“…However, all these algorithms assume that the inductance and compensation capacitance are constant. But in the actual application scenario, uncontrolled electromagnetic environments such as foreign metallic material can cause coil inductance to deviate from nominal value [23]. Similarly, due to the aging effect of compensated capacitor, the capacitance would drift as well.…”

Analysis and design of a class E current-driven rectifier for 1 MHz wireless power transfer system

“…The effective power transfer by means of coupled coils is possible only after the leakage inductance compensation, which is obtained through the serial or parallel connection of resonance capacitors. In order to improve the efficiency of processing of energy by transformers, designs which allow the application of the soft switching technique is used, ie the inverters of class E [6][7][8], DE [9,10], EF [11,12] and Φ rectifiers [13]. The soft switching of the transistor and/or diode enables the reduction in switching losses which increase together with an increase in the operating frequency.…”