High frequency electromagnetic links for wireless power transfer
File(s)
Author(s)
Lawson, J
Type
Thesis or dissertation
Abstract
This thesis investigates inductive links used in wireless power transfer systems. Inductive power transfer can be used as a power delivery method for a variety of portable devices, from medical implants to electric vehicles and is gaining increased interest. The focus is on high quality factor coils and MHz operation, where accurate measurements are difficult to achieve. Fast models of all pertinent aspects of inductive power transfer systems for constant cross section coils are developed. These models are used to optimise a new coil winding pattern that aims to increase efficiency in volume constrained scenarios. Measurement systems are developed to measure coil Q factors in excess of 1,000. The prototype measurement systems are verified against models of that system, as well as finite element simulations of the coil under test. Shielding of inductive power transfer systems is then investigated. A structure typically used at GHz frequencies, the artificial magnetic conductor, is miniaturised as an alternative to conventional ferrite backed ground plane shielding. Finite element simulation shows this structure significantly improves link efficiency. The artificial magnetic conductor prototype does not result in a gain in efficiency expected, however it does display the properties expected of an artificial magnetic conductor, including increased coupling factor. Finally, an unconventional inductive power transfer system is presented where transmitter and receiver are up to 6m away from each other and of radically different size. This system provides mW level power to remote devices in a room, for example thermostats or e-ink displays. Conventional approaches to design do not consider the distortion of the magnetic field caused by metallic objects in the room. It was found that treating the system as a decoupled receiver and transmitter provides a better prediction of received power in real world environments.
Version
Open Access
Editor(s)
Mitcheson, Paul
Date Issued
2017-11-01
Date Awarded
2017-11
Citation
2017
Advisor
Mitcheson, Paul
Sponsor
Engineering and Physical Sciences Research Council
Great Britain. HM Government
Identifier
https://spiral.imperial.ac.uk:8443/handle/10044/1/54841
Grant Number
11220474
Publisher Department
Electrical and Electronic Engineering
Publisher Institution
Imperial College London
Subjects
wireless power
IPT
AMC
Metamaterials
Measurement
Long Range
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)