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Numerical Calculations of Wireless Power Transfer Coil Parameters

Nyström, Jonatan LU (2020) EITL01 20191
Department of Electrical and Information Technology
Abstract
Wireless Power Transfer (WPT) has become a commercially viable technology.
The technology uses the phenomenon of electromagnetic induction between coils
to transfer electrical power wirelessly. Due to the increasing interest in WPT,
the need to understand how the power transfer between coils behaves in different
settings, as well as the ability to simulate the process, have become increasingly
important for further development of the technology.
This thesis investigates some of the existing methods for calculating the mutual
inductance between coils. For arbitrarily wound coils the Neumann formula is
used. And for taking the presence of ferrite plates into account an expression
derived by Hurley and Duffy is used. The methods are... (More)
Wireless Power Transfer (WPT) has become a commercially viable technology.
The technology uses the phenomenon of electromagnetic induction between coils
to transfer electrical power wirelessly. Due to the increasing interest in WPT,
the need to understand how the power transfer between coils behaves in different
settings, as well as the ability to simulate the process, have become increasingly
important for further development of the technology.
This thesis investigates some of the existing methods for calculating the mutual
inductance between coils. For arbitrarily wound coils the Neumann formula is
used. And for taking the presence of ferrite plates into account an expression
derived by Hurley and Duffy is used. The methods are implemented in Matlab [1]
and compared to physical measurements and full-wave electromagnetic simulations
made in the commercial software Ansys Maxwell [2].
The thesis focuses on 2 aspects: 1) The extent to which mutual inductance is
affected by the presence of ferrites of varying size. The thesis shows that previously
stated finite ferrite margins for expressions derived using the assumption of infinite
ferrite plates in a magnetostatic setting, do not seem to hold for a simple two-coil
system, and new margins are obtained. 2) The possibility of homogenizing the
magnetic field for increased spatial coupling, using a multicoil array. The thesis
shows that it is possible to increase the field homogeneity of an initial setup, at the
cost of the field strength. It also finds that for a tri-coil system with coil centers
forming an equilateral triangle, the optimal separation distance of the coil-centers
in terms of providing a homogeneous field, is between 30% to 60% larger than the
outer coil radius. (Less)
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author
Nyström, Jonatan LU
supervisor
organization
course
EITL01 20191
year
type
M2 - Bachelor Degree
subject
keywords
WPT, Wireless, Charging, Qi, Inductance, Calculation, Inductive, Coupling
report number
LU/LTH-EIT 2020-764
language
English
id
9018746
date added to LUP
2020-06-17 09:41:56
date last changed
2020-06-17 09:41:56
@misc{9018746,
  abstract     = {{Wireless Power Transfer (WPT) has become a commercially viable technology.
The technology uses the phenomenon of electromagnetic induction between coils
to transfer electrical power wirelessly. Due to the increasing interest in WPT,
the need to understand how the power transfer between coils behaves in different
settings, as well as the ability to simulate the process, have become increasingly
important for further development of the technology.
This thesis investigates some of the existing methods for calculating the mutual
inductance between coils. For arbitrarily wound coils the Neumann formula is
used. And for taking the presence of ferrite plates into account an expression
derived by Hurley and Duffy is used. The methods are implemented in Matlab [1]
and compared to physical measurements and full-wave electromagnetic simulations
made in the commercial software Ansys Maxwell [2].
The thesis focuses on 2 aspects: 1) The extent to which mutual inductance is
affected by the presence of ferrites of varying size. The thesis shows that previously
stated finite ferrite margins for expressions derived using the assumption of infinite
ferrite plates in a magnetostatic setting, do not seem to hold for a simple two-coil
system, and new margins are obtained. 2) The possibility of homogenizing the
magnetic field for increased spatial coupling, using a multicoil array. The thesis
shows that it is possible to increase the field homogeneity of an initial setup, at the
cost of the field strength. It also finds that for a tri-coil system with coil centers
forming an equilateral triangle, the optimal separation distance of the coil-centers
in terms of providing a homogeneous field, is between 30% to 60% larger than the
outer coil radius.}},
  author       = {{Nyström, Jonatan}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Numerical Calculations of Wireless Power Transfer Coil Parameters}},
  year         = {{2020}},
}