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ECE PhD Dissertation Defense: Kai Li

December 1, 2021 @ 9:00 am - 10:00 am

PhD Dissertation Defense: Reconfigurable and Intelligent Wireless Charging Surfaces

Kai Li

Location: 432 ISEC

Abstract: Reconfigurable intelligent surfaces (RISs) have received significant attention for theirpotential to transform the environments by intelligently reconfiguring the surfaces, infrastructures,and engineering the electrical and magnetic fields. On the other hand, while wireless power transfer has advanced, there has been limited progress on increasing the charging coverage, such as charging over large surfaces, multi-device charging, and automation. This dissertation aims to address these challenges and design and develop first-of-its-kindtheory and practice to transform ordinary surfaces into contactless, intelligent, and multi-devicewireless chargers. First, the combination between magnetic resonance and the so-called concept of‘energy hopping’ across wireless inter-connected coils turns a large surface into a programmablewireless charging surface. The magnetic fields are carefully shaped on the fly over the surface,enabling them to distribute energy efficiently at multiple locations on demand and charge differenttypes of devices. Two frameworks are developed: SoftCharge can deliver 23 W up-to 20cm over a larger surface, and iSurface enables the creation of arbitrary and configurable power spots and power flow paths over 2D and 3D resonator surfaces. Inspired by the strong coupled magnetic resonance wireless power transfer, two intelligentsurface sensing frameworks, SoftSense, and iSense, are introduced that create collaborative surface-based object sensing and tracking using networked coils. SoftSense allows detection of the type of object and where it is placed on a large surface. iSense enables robot tracking over large surfaces.We validate our design on real sensing prototypes, and experimental results show that each sensing coil only consumes few milliwatts and has 90% accuracy for velocity estimation.Combined with meta-surface, we extended the intelligent charging surfaces to enhances safety, end-to-end power transfer efficiency, and customized power pattern over the surface.Toward this, we design and develop a new system call meta-resonance wireless power transfer system that consists of power distribution layer and meta-resonance layer, along with a new theory and prototype for fine-tuned and controllable power amplifying, power blocking and normal power passing over the surface. We aim to create customized pattern and different application from portable devices(phone, tablet) to medical devices, and industrial devices with high safety and high power transfer efficiency.


December 1, 2021
9:00 am - 10:00 am


Electrical and Computer Engineering
MS/PhD Thesis Defense