Three-Dimensional Charging via Multimode Resonant Cavity Enabled Wireless Power Transfer

Abstract

The majority of existing wireless power solutions are capable of 2-Dimensional surface charging of one or two devices, but are not well suited to deliver power efficiently to large numbers of devices placed throughout a large 3-Dimensional volume of space. In this work we propose an unexplored type of wireless power transfer system based on electromagnetic cavity resonance. Here we use the natural electromagnetic modes of hollow metallic structures to produce uniform magnetic fields which can simultaneously power multiple small receiver coils contained almost anywhere inside.An analytical model is derived that predicts the coupling coefficient and power transfer efficiency from the cavity resonator to a small coil. These predictions are verified against simulated results with a coefficient of determination of 0.9943. By using two resonant modes we demonstrate that a 3 inch diameter receiver can be powered in nearly any location in a 140 cubic foot test chamber, at greater than 50% efficiency. Additionally, we show that 10 receivers can be powered simultaneously and that this system is capable of recharging consumer electronics such as a cell phone.

Wireless power transfer via dielectric loaded multi-moded split cavity resonator

“…For the muti-moded cavity case, however, the modes are very close to one another such that in the vicinity of a given mode, the effect of other nearby modes can widely vary and more terms in the Taylor's series need to be retained. Additionally for an accurate construction of the circuit representation (7) and (8), the identification process must be repeated for all excited modes. To overcome the challenges of the traditional identification approach, we apply a different identification procedure that relies on fitting the frequency domain Z 21 to a rational function such that, in the vicinity of a given mode frequency, it behaves much like (8).…”

“…It is worth noting that although the circuit model relies on the terminal characteristics, the modal decomposition of equations (7) and (8) allow the symmetrical nature of the modes to be determined as exhibited by the sign of r 21 . Furthermore, the different RLC resonators represent the coupled modes resulting from the interaction of the DRs with the SCR modes.…”

“…Due to their very high Q values, the modes of Dielectric Resonators (DRs) have been exploited to transfer power efficiently over short and mid-range distances [4][5][6] . The performance of resonant coupled schemes correlates directly with the product κQ, which represents the system On the other hand, the modes of cavity resonators were exploited to transfer power within an enclosure [7][8][9] . This approach allows power to be transferred to almost any point in a 3D region.…”

Wireless Power Transfer System Based on Strapping Resonators

“…For example, a group from Massachusetts Institute of Technology(MIT) demonstrated that WPT efficiency can be enhanced via resonant coupling [3]. Since then, after years of development, many scientific researchers have been attracted to this concept [8][9][10][11][12][13]. Several solutions based on various types of resonators have been proposed to deal with the most pressing problems of improving efficiency and transmission distance, and meaningful results were obtained.…”

Frequency Splitting Elimination and Cross-Coupling Rejection of Wireless Power Transfer to Multiple Dynamic Receivers

“…The three-dimensional Tx coil structure is investigated for the maximum power transfer to single dynamic Rx irrespective of the orientation [21,22]. However, the uniform power distribution to multiple Rx with three-dimensional structure is difficult to control and requires additional control circuitry at the Tx coil.…”