Date of Award

Fall 2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

First Advisor

James V. Krogmeier

Committee Chair

James V. Krogmeier

Committee Member 1

David J. Love

Committee Member 2

Mark R. Bell

Committee Member 3

Xiaojun Lin

Abstract

The technology to wirelessly power mobile devices has started to gain momentum especially in industry. Cables have started to become the thing of the past as both wireless power efficiency and communication speeds become viably attractive. The first part of this work gives analysis and practical considerations in implementing multiple transmitters for wireless power transfer via coupled magnetic resonance. Through the multiple transmitter scheme, there is an increase in gain and `diversity' of the transmitted power according to the number of transmit coils. The effect of transmitter resonant coil coupling is also shown. Resonant frequency detuning due to nearby metallic objects is observed and the extent of how much tuning can be done is demonstrated. A practical power line synchronization technique is proposed to synchronize all transmit coils. This reduces additional dedicated synchronization wiring or the addition of an RF front end module. The second part of this study introduces a time division multiplexing (TDM) technique for tightly coupled receivers via the same method of coupled magnetic resonance. Two or more receivers can be powered simultaneously using a single transmit coil. In a tightly coupled receiver scenario, the received power is significantly reduced. Experimental and simulation results implementing TDM show vast improvements in received power in the tightly coupled case. Resonant frequency splitting is eliminated through synchronized detuning between receivers, which divide power equally between receivers at specific time slots. The last chapter gives insight on the capacity of a single-input single-output system at varying distances between receiver and transmitter. It is shown that the highest information rate is achieved at critical coupling.

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