In-Band Parallel Feedback Communication for Magnetic MIMO Wireless Power Transfer System

In recent years, we have witnessed the advancement of wireless charging technology, which has become the de facto power supply solution for a vast number of smart or IoT devices. Notably, magnetic resonant coupling (MRC) enabled wireless power transfer (WPT) continues to be a key technology for current and future wireless charging. This article studies receiver (RX) feedback communication for the MRC-WPT system in general multiple-input multiple-output (MIMO) scenarios, which is the critical preliminary step necessary to enhance system charging performance. To overcome the inherent technical drawbacks of out-of-band methods, and to support multi-device communication simultaneously, we propose an in-band parallel feedback communication mechanism based on the coil coupling effect, that is, RX-related equivalent impedance matching. In a nutshell, we can decode the feedback data from RXs by identifying distinct RX-related equivalent impedances at the TX side. We present a case study on an implemented prototype to showcase the potential of the proposed mechanism. Experimental results demonstrate that our mechanism can provide accurate and fast feedback communication for a dozen or more RX devices. Furthermore, we discuss the research directions for feedback communication in MRC-WPT systems that are worth in-depth investigation.