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Room-scale magnetoquasistatic wireless power transfer using a cavity-based multimode resonator

Abstract

Magnetoquasistatic wireless power transfer can be used to charge and power electronic devices such as smartphones and small home appliances. However, existing coil-based transmitters, which are composed of wire conductors, have a limited range. Here we show that multimode quasistatic cavity resonance can provide room-scale wireless power transfer. The approach uses multidirectional, widely distributed currents on conductive surfaces that are placed around the target volume. It generates multiple, mutually unique, three-dimensional magnetic field patterns, where each pattern is attributed to different eigenmodes of a single room-scale resonator. Using these modes together, a power delivery efficiency exceeding 37.1% can be achieved throughout a 3 m × 3 m × 2 m test room. With this approach, power exceeding 50 W could potentially be delivered to mobile receivers in accordance with safety guidelines.

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Fig. 1: Overview of M-QSCR.
Fig. 2: Constructed room-scale resonator.
Fig. 3: Evaluation of power transfer efficiency.
Fig. 4: Evaluation of safety based on SAR.
Fig. 5: Demonstration of room-scale wireless power transfer in a living environment.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

This work was supported by a Grant-in-Aid for JSPS Fellows JP18J22537, JST ERATO grant number JPMJER1501 and JST ACT-X grant number JPMJAX190F. We thank M. J. Chabalko for discussions. We also thank K. Narumi, H. Ogata and T. Ikeuchi for help in the video production.

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Authors

Contributions

T.S., Y.K. and A.P.S. designed the research. T.S. proposed the initial concept, conceived the theory, implemented the system, performed the experiments/analysis and wrote the manuscript. All the authors reviewed and commented on the manuscript. Y.K. and A.P.S. provided the resources. Y.K. supervised the project.

Corresponding author

Correspondence to Takuya Sasatani.

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The authors declare no competing interests.

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Peer review information Nature Electronics thanks Jenshan Lin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–11, Table 1 and Notes 1 and 2.

Supplementary Video 1

Overview of the room-scale resonator, including the resonator structure, mounted lumped capacitors, covered range and an animation of the oscillating current/magnetic field.

Supplementary Video 2

Demonstration of room-scale wireless power transfer in a living environment.

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Sasatani, T., Sample, A.P. & Kawahara, Y. Room-scale magnetoquasistatic wireless power transfer using a cavity-based multimode resonator. Nat Electron 4, 689–697 (2021). https://doi.org/10.1038/s41928-021-00636-3

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