A Cuttable Wireless Power Transfer Sheet

Abstract

We propose a cuttable wireless power transfer sheet which allows users to modify its size and shape. This intuitive manipulation allows users to easily add wireless power transmission capabilities to everyday objects. The properties of the sheet such as thinness, flexibility, and lightness make our sheet highly compatible with various configurations. We contribute a set of technical principles for the design of circuitry, which integrates H-tree wiring and time division power supply techniques. H-tree wiring allows the sheet to remain functional even when cut from the outside of the sheet, whereas time division power supply avoids the reduction in power transfer efficiency caused by the magnetic interference between adjacent transmitter coils. Through the evaluations, we found that our time division power supply scheme mitigates the degradation of power transfer efficiency and successfully improves the average efficiency. Furthermore, we present four applications which integrates our sheet into daily objects: wireless charging furniture, bag, jacket, and craft; these applications confirmed the feasibility of our prototype.

Speculative engineering technology and future insight

“…A two-dimensional system becomes indispensable if we have a surface arrangement like a desk, a wall, or a floor. 1 There is also a need to add wireless power feeding functionality to all surfaces in a living space, a storage space, and rooms and enable wireless power feeding to entire walls and floors so that a user can charge his or her electronic devices without thinking about it. Although we called it "two-dimensional wireless power feeding," when incorporating a coil used for wireless power transmission into furniture, clothes, etc, the typical design flow includes determining the design of the object and, then, designing and installing the coil shape.…”

“…As such, as shown in Figure 1, we proposed a wireless power transfer sheet that all a user has to do is cut it into a desired shape and affix in to an adherend. 1 There is also a need to add wireless power feeding functionality to all surfaces in a living space, a storage space, and rooms and enable wireless power feeding to entire walls and floors so that a user can charge his or her electronic devices without thinking about it. Therefore, we are working on a system that can supply power to devices placed at any location on a plane such as a desk, floor, or wall simply by arranging a standardized coil module on said plane (Figure 2).…”

Alvus

“…Typical 2-D systems are constructed by arranging transmitter resonators into arrays; operations on these arrays can be roughly divided into (a) selective activation, which activates the transmitter in proximity of the receiver [12,20,25,47] and (b) phased array-inspired operation, which adjusts the gain/phase of each transmitter element to form a constructive interference at the receiver [11,16,40,52]. In both (a) and (b), it is premised that the transmitter elements are wired to the central power source, which limits shape modification.…”

“…In both (a) and (b), it is premised that the transmitter elements are wired to the central power source, which limits shape modification. As a countermeasure to this issue, Takahashi et al proposed a "cuttable" WPT sheet, which can be modified into various shapes [47]. However, many rules for cutting still exist; moreover, it is based on irreversible modification.…”

Genetic Algorithm-Based Receiving Resonator Array Design for Wireless Power Transfer

“…In particular, 2-D TX arrays offer advantages such as flexible layout and convenient installation [27], [28]. Typical 2-D TX arrays dynamically activate the TX most strongly coupled to the RX to achieve high efficiency throughout the deployed surface However, these 2-D TX arrays involve "null zones," where the retrorse magnetic fields are canceled out and the efficiency drops significantly near the edges of each TX [31], which requires users to avoid these areas when placing devices.…”