Large-Area Free-Positioning Wireless Power Transfer to Movable Receivers

Abstract

This article introduces a method for efficient and robust free-positioning wireless power transfer (WPT) in a large area, which can be applied to many use cases, including wireless charging of industrial robots, drones, and electric scooters. In these large areas of WPT applications, multiple transmitters (Txs) are placed in a pad-like area, and the Tx coils are optimally excited to enable robust and efficient power transfer to movable receivers within the charging area. The proposed configuration enables almost continuous magnetic flux path from a set of Tx coil(s) to another set of Tx coil(s) through the receiver coil ferrite core. Therefore, efficient power transfer is ensured throughout the whole Tx coverage area. The article introduces a novel method to detect the position and orientation of the receiver only from the Tx-side measurements. The proposed solution is experimentally verified in a laboratory prototype, and the experimental results show dc-to-dc efficiency of 91% with only 1% variation in most of the Rx positions.