Capacitive power transfer to car through wheel  is it possible?
(2012) In CODEN:LUTEDX/TEIE EIE920 20121Industrial Electrical Engineering and Automation
 Abstract
 Introduction: This work aims to evaluate the possibility to transfer electrical
power from a metal plate to the steelcord within a car tire. If the tire stands on the
plate, a connecting surface occurs which can be interpreted as a capacitor, where
the rubber compound acts as a dielectric.
Method: First the impedance of the tire is evaluated: An analytical model is
setup to describe the system; a nite element simulation is made using the FEMM
software and nally measurements using a Hewlett Packard 4194A impedance analyzer
is made on a Dunlop SP Sport Maxx Tire.
Secondly, the possible power transfer is analyzed, both by creating an analytical
model including the wheel impedance and a load, and by doing experiments on
a real... (More)  Introduction: This work aims to evaluate the possibility to transfer electrical
power from a metal plate to the steelcord within a car tire. If the tire stands on the
plate, a connecting surface occurs which can be interpreted as a capacitor, where
the rubber compound acts as a dielectric.
Method: First the impedance of the tire is evaluated: An analytical model is
setup to describe the system; a nite element simulation is made using the FEMM
software and nally measurements using a Hewlett Packard 4194A impedance analyzer
is made on a Dunlop SP Sport Maxx Tire.
Secondly, the possible power transfer is analyzed, both by creating an analytical
model including the wheel impedance and a load, and by doing experiments on
a real tire. The experiments and simulations are conducted both with and without
a resonant inductor. LTspice models are made to support the practical results as
far as possible and to investigate the limits for the capacitive power transfer.
Finally, a discussion is held regarding which parameters that can be improved
to enhance the technique.
Results: The impedance measurements show that the impedance coupling has a
capacitance of around 200 pF, and an equivalent series resistance which is inversely
dependent on the frequency and has a value of 4400
at a frequency of 10 kHz.
The LTspice simulations show that the imperfections in the transformer and
the inductance that are used in the practical experiments give rise to a lot of losses.
This makes the results from the analytical model and the practical experiments
dier, especially when a resonant inductance is introduced.
For a square wave source voltage of 1600 V and 10 kHz, and a load of 50 k
,
the analytical model give a load power of 20.1 W with an efficiency of 89 %. The
practical experiments give a load power of 19.5 W with an efficiency of 81 % when a
DClink voltage of 30 V which results in a voltage about 1600 V on the secondary
side of the transformer  is used. For the same source voltage and load conditions,
but with a resonant inductor introduced, the simulations give a load power of 34 W
with an efficiency of 89 %. The practical experiments give a load power of 25 W
with an efficiency of 76% (33 V out from the DC link).
Conclusion: This thesis shows that the impedance feature of the tire that is investigated
makes it inappropriate for a big electrical power transfer. The capacitive
element of the impedance can be compensated for with a resonant inductor, but the
resistive part of the tire impedance is much too big to pass a lot of electrical energy.
With a dierent rubber compound though, that would have a smaller dielectric loss
angle, the technique could be worth evaluating more. For example, a tire with silica
filler instead of carbon black filler  which is used in the tire of this project  could
be worth analyzing. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/studentpapers/record/3710545
 author
 Hall, Sebastian
 supervisor

 Avo Reinap ^{LU}
 Mats Alaküla ^{LU}
 organization
 course
 EIE920 20121
 year
 2012
 type
 H3  Professional qualifications (4 Years  )
 subject
 publication/series
 CODEN:LUTEDX/TEIE
 report number
 5305
 language
 English
 id
 3710545
 date added to LUP
 20130521 06:49:40
 date last changed
 20140904 08:29:55
@misc{3710545, abstract = {Introduction: This work aims to evaluate the possibility to transfer electrical power from a metal plate to the steelcord within a car tire. If the tire stands on the plate, a connecting surface occurs which can be interpreted as a capacitor, where the rubber compound acts as a dielectric. Method: First the impedance of the tire is evaluated: An analytical model is setup to describe the system; a nite element simulation is made using the FEMM software and nally measurements using a Hewlett Packard 4194A impedance analyzer is made on a Dunlop SP Sport Maxx Tire. Secondly, the possible power transfer is analyzed, both by creating an analytical model including the wheel impedance and a load, and by doing experiments on a real tire. The experiments and simulations are conducted both with and without a resonant inductor. LTspice models are made to support the practical results as far as possible and to investigate the limits for the capacitive power transfer. Finally, a discussion is held regarding which parameters that can be improved to enhance the technique. Results: The impedance measurements show that the impedance coupling has a capacitance of around 200 pF, and an equivalent series resistance which is inversely dependent on the frequency and has a value of 4400 at a frequency of 10 kHz. The LTspice simulations show that the imperfections in the transformer and the inductance that are used in the practical experiments give rise to a lot of losses. This makes the results from the analytical model and the practical experiments dier, especially when a resonant inductance is introduced. For a square wave source voltage of 1600 V and 10 kHz, and a load of 50 k , the analytical model give a load power of 20.1 W with an efficiency of 89 %. The practical experiments give a load power of 19.5 W with an efficiency of 81 % when a DClink voltage of 30 V which results in a voltage about 1600 V on the secondary side of the transformer  is used. For the same source voltage and load conditions, but with a resonant inductor introduced, the simulations give a load power of 34 W with an efficiency of 89 %. The practical experiments give a load power of 25 W with an efficiency of 76% (33 V out from the DC link). Conclusion: This thesis shows that the impedance feature of the tire that is investigated makes it inappropriate for a big electrical power transfer. The capacitive element of the impedance can be compensated for with a resonant inductor, but the resistive part of the tire impedance is much too big to pass a lot of electrical energy. With a dierent rubber compound though, that would have a smaller dielectric loss angle, the technique could be worth evaluating more. For example, a tire with silica filler instead of carbon black filler  which is used in the tire of this project  could be worth analyzing.}, author = {Hall, Sebastian}, language = {eng}, note = {Student Paper}, series = {CODEN:LUTEDX/TEIE}, title = {Capacitive power transfer to car through wheel  is it possible?}, year = {2012}, }