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Planar Wireless Charging
Technology For Portable
Electronic Products And QiROBIN MARY MATHEW
EE7
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What is WPT?
•The transmission of energy from a
power source to an electric load
without using wires
•Wireless transmission is useful in
cases where interconnecting wires are
inconvenient, hazardous or
impossible.2
INDUCTIVE COUPLING
First introduced byNICOLA TESLA
HISTORY
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WIRELESS CHARGING
Non-Radiative Wireless
Charging
2 types:-
1)Capacitive charging
2)Inductive charging
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INDUCTIVE CHARGING v/s CAPACITIVE WIRELESS CHARGING
CAPACITIVE CHARGING
•Capacitive Coupling requires larger
coupling area, unless high operating
frequency in the MHz range is used
DISADVANTAGES
•Smaller power density
•Lack of flexibility to load locations
ADVANTAGES
•Energy can be transmitted through metal5
INDUCTIVE CHARGING
Inductive approach is dominant
Primary and secondary coils are not
connected with wires.
Energy transfer is due to Mutual
Induction
The charging pad (primary coil) and the
device(secondary coil) have to be kept
very near to each other
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DISADVANTAGES
•Inductive charging induce eddy current
in metal
REMEDY
•Thin double layer EM shields
underneath the inductive charging pad
and above the receiving coil-enables
magnetic flux to be enclosed in a
sandwich structure
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Technology Range DirectivityAntenna
devices
Current and/or possible
future applications
Inductive
couplingShort Low Wire coils
Electric tooth brush ,
razor battery
charging, Charging
portable devices (Qi),
biomedical implants,
electric vehicles,
powering busses,
MAGLEV
Capacitive
couplingShort Low Electrodes
power routing in
large scale integrated
circuits.
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Inductive Charging
• Horizontal Flux Approach
• Vertical Flux Approach
• Can be implemented in Planar structures9
Horizontal Flux Approach
• In horizontal coupling, the lines of flux flow
horizontally along the charging surface on
which the loads are placed.
• To pick up the flux, a vertical surface area
perpendicular to the lines of flux is needed.
• It imposes restrictions on the orientation of
the receiver module.10
•If the plane of vertical surface is in the
direction of lines of flux, no energy can
be transmitted.
REMEDY: having a second set of
winding perpendicular to first set of
winding.
•However, the vertical surface
requirement does not fit well with slim
design.
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DISADVANTAGES
• Requires a relative thick layer of
ferromagnetic material underneath the
charging pad to guide the magnetic flux.
• Otherwise, the flux may induce eddy
current and heat up metallic objects under
the pad.
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Vertical Flux Approach The lines of flux are perpendicular to
the charging surface.
A wireless charging surface with free-
positioning feature can be formed by
extending a single planar winding into
a winding array structure.
Winding Array Structure-
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• 3-layer winding array structure can be
used to generate a uniform M-flux over
the charging surface
• M-flux flows out of the charging
surface like a water fountain
• Receiver coil can be placed anywhere
on the charging surface and pick up the
energy regardless of its position and
orientation
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Properties Of Vertical Flux Approach
FREE POSITIONING
METHODS• Allows the user to place and charge one or
more devices anywhere on the charging
surface regardless of the position and
orientation of the load.
• Different for single load systems and
multiple load systems.Single Loaded System-
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single-load systems
A movable transmitter coil
is placed underneath the
charging surface.
With a mechanism to detect
the location of the secondary
coil, the charging station will
move a transmitter coil in the
X-Y plane directly under the
receiver coil.
Maximum mutual coupling
is obtained.16
multiple-load systems,
• The multilayer winding
array structure can be
used to generate
uniform magnetic flux
over the charging
surface.
• Thus multiple loads can
be placed and charged
on the charging surface
simultaneously.
• LOCALISED
CHARGING 17
LOCALISED CHARGING PRINCIPLE
• Instead of generating magnetic flux over the
entire charging surface, only the
appropriate transmitter coils should be
energized for both single or multiple-load
situations.
• detection techniques for identifying the load
positions.
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Objective of localized charging principle-
ensure-magnetic flux path is ‘sandwiched’
within the covered area of transmitter and
receiver coil- essential to safety issues.
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BIDIRECTIONAL COMMUNICATIONS
Load Identification and Position
Charging Compatibility Check
Load Monitoring
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A Photograph Of A Wireless Charging
Pad -With A Variety Of Compatible And
Non-compatible Items
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Charging Methods In “Qi” Standard
WPC launched- ‘Qi” standard- in October 2010
Features:-
• Inductive wireless charging
• Vertical-flux approach
• Guided or free positioning
• Localized charging
• Communications between loads and charging pad
• Load identification and compatibility 22
APPLICATIONS OF QI
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Powermat inductive
charging spots in a
coffee shop. Customers
can set their phones on
them to recharge. 24
ADVANTAGES OF WIRELESS CHARGINGConvenience
Durability - Without the need to constantly plug
and unplug the device, there is significantly less
wear and tear on the socket of the device and the
attaching cable
.
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• No more worn connectors
• Use of separate chargers is
eliminated.
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DISADVANTAGES OF WIRELESS CHARGING
• Uncommon
• Lower efficiency, waste heat - resistive
heating in comparison to direct contact.
• Slower charging
• More costly -increasing the complexity and
cost of manufacturing.
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CONCLUSION
• Planar wireless charging systems can
be incorporated into office
environment, coffee and bedside tables,
and bathroom and kitchen desktops
• powering a wide range of electric
appliances from low-power devices to
high-power devices.
• And more wireless power systems and
products are expected to enter the
consumer market in the near future. 28
REFERENCES A Novel Single-Layer Winding Array and Receiver Coil Structure for Contactless Battery Charging
Systems With Free-Positioning and Localized Charging Features
W. X. Zhong, Xun Liu, Member, IEEE, and S. Y. Ron Hui, Fellow, IEEE
Design of a Contactless Battery Charger for Cellular Phone
Chang-Gyun Kim, Student Member, IEEE, Dong-Hyun Seo, Jung-Sik You, Jong-Hu Park, and Bo H. Cho, Senior Member, IEEE
A Contactless Electrical Energy Transmission System for Portable-Telephone Battery Chargers
Yungtaek Jang, Senior Member, IEEE, and Milan M. Jovanovic, Fellow, IEEE
A Loosely Coupled Planar Wireless Power System for Multiple Receivers
Joaquin J. Casanova, Student Member, IEEE, Zhen Ning Low,Student Member, IEEE, and Jenshan Lin, Senior Member, IEEE
A New Generation of Universal Contactless Battery Charging Platform for Portable Consumer Electronic Equipment
S. Y. R. Hui, Fellow, IEEE, and Wing. W. C. Ho, Member, IEEE
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ARE YOU STILL CONNECTED?!
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