A Receiver-Controlled Coupler for Multiple Output Wireless Power Transfer Applications

Abstract

Multiple output wireless power transfer (WPT) system has a great potential to be used in applications where multiple receivers need to be powered simultaneously, including wireless office table, logistic sorting robots, and magnetic resonant imaging (MRI) equipment. For the sake of reducing no-load losses and avoiding leakage magnetic fields, it is desirable to only switch on those transmitter coils that are covered by receivers and switch off the rests. To realize this, however, bidirectional power switches, sensors and control logic are needed, which are expensive, bloated, and lossy. This paper proposed a novel receiver-controlled coupler (RC-Coupler) that can realize switching on/off of transmitter coils without using bidirectional switches, sensors, and control. The structure, design considerations, and leakage fields of the proposed RC-coupler are researched, and its feasibility has been confirmed with a GaN-based 120 W, 6.78 MHz prototype. A power density of 2.78 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> is reached benefiting from the receiver-controlled characteristics.