WiTricity: Future of Electricity
Mr. Abhinav Bansal
Department of ECE
Roll no.: 1103331064
Department of electronics & Communication
• What do you mean by WiTricity?
• Need of WiTricity
• History of Wireless power
• Experimental design of WiTricity technology
• WiTricity basics
• Wireless energy transfer techniques
• Working principle of WiTricity
• Is WiTricity safe?
• WiTricity Applications
• Benefits and Advantages
What is WiTricity
• WiTricity is nothing but Wireless Electricity.
• Transmission of electrical energy from one object to
another without the use of wire is called WiTricity.
• Because of the wiTricity, some of the devices won’t
require batteries to operate.
Cables are going to be replaced by WiTricity
Why not wires??
• As per studies, most electrical energy transfer is throughwires.
• Most of the energyloss is during transmission
• On an average, more than30%
• In India, it exceeds by 40%
Why not batteries??
Estimated that 40 billionbatteries per year add to the e-waste burden.
And of courseits not a good sign.
And this is possible due to
Imagine your cell phones, laptops, i-pods and
other power hungry devices getting charged on
their own, eliminating the need of plugging in.
History of Wireless power
In late 1890’s, Sir Nikola Tesla proposed the method of
wireless power transmission.
In 1899, he was able to light 200 lamps over 25 miles away
without using wires.
As it was in radiative mode, most of the power was wasted
and less efficiency.
In 2005, Dave Gerding coined the term WiTricity which is
being used today.
Built the wardenclyffe
tower(Tesla tower) which could
broadcast power wirelessly using
far-field techniques. Called off as
it radiated power into
surroundings raising issues of
The forgotten invention is reborn in
The idea of wireless
electricity has been
around since the early
days of the Tesla coil.
But thanks to a group of MIT
scientists, "WiTricity" (as these
scientists call it) is now one
step closer to practical reality.
In 2007,6 MIT members headed
by Marin Soljacic were able to
successfully transmit power to a
bulb within a distance of 2m at a
freq of 9.9MHz .
They use concepts of non
radiative mid range energy
Efficiency at that point was
just approximately 43%.
Our experimental scheme consists of two Self-resonant
coils. One coil (source coil) is coupled inductively to an
oscillating circuit; the other (device coil) is coupled
inductively to a resistive load. Self-resonant coils rely
on the interplay between distributed inductance and
distributed capacitance to achieve resonance.
Power source is connected to ac power.
Bulb is connected to capture device.
Blue lines represent the magnetic near field
induced by the power source.
Yellow lines represent the flow of energy from
the source to the capture coil.
This power lights up the bulb.
The magnetic field can wrap around the obstacle
between power source and capture coil.
• Electricityis a general term that
encompasses a variety of phenomena
resulting from the presence and flow of
• Magnetism is a force that acts at a
distance due to a magnetic field. This field
is caused by moving electrically charged
particles or is inherent in magnetic
objects such as magnet.
• Electromagneticinduction is the
production of voltage across a
conductor moving through a
• Electromagnetism is one of the four
fundamental interactions of nature,
along with strong interaction, weak
interaction and gravitation. It is the
force that causes the interaction
between electrically charged particles;
the areas in which this happens are
called electromagnetic fields
• Energy/Power Coupling: Energy
couplingoccurs when an energy
source has a means of transferring
energy to another object.
• Resonance : It is the tendency of a
system to oscillate with larger
amplitude at some frequencies than at
others. These are known as the system's
resonant frequencies (or resonance
frequencies). At these frequencies, even
small periodic driving forces can
produce large amplitude oscillations.
• Resonant Magnetic Coupling: Magnetic
coupling occurs when two objects
exchange energy through their varying
or oscillating magnetic fields. Resonant
coupling occurs when the natural
frequencies of the two objects are
approximately the same.
Types of wireless energy transfer
How does Inductive Coupling work??
Inductive coupling works on the principles of
“When a current(electricity) passes through a
wire, it generates a magneticfieldperpendicular to
Whena wire is in proximity to a magnetic field, it
generates a current in that wire.”
Magneticfields decay quickly , making inductive
coupling effective only at very short ranges.
• Wireless ChargingPad(WCP),electric brushes are
• On a WCP, the devices are to be kept, batterywill
How does Resonant Induction work??
• Resonant induction still uses the
same principles as magnetic
induction (magnetic fields to
transfer current) , but it uses
resonance to increase the range
at which the transfer can
efficiently take place.
• “Resonance", a phenomenon that
causes an object to vibrate when
energy of a certain frequency is
WiTricity is based on Resonant Inductive coupling..
Long range: Far field power transfer
• Far-fieldmethodachieves longer ranges which is much
greater than the diameter of device.
• These far-field type techniques include Radio &
Microwave Power Transmission Techniques & LASER
How WiTricity works
1) Power from mains to antenna, which is made of copper.
2) Antenna resonates at a frequency of 10MHz, emitting
3) 'Tails' of energy from antenna 'tunnel' up to 2.5m (8.2ft).
4) Electricity picked up by laptop's antenna, which must also be
resonating at 10MHz. Energy used to re-charge device.
5)Energy not transferred to laptop re-absorbed by source
antenna. People/other objects not affected as not resonating at
Efficiency Chart of WiTricity
It is observedthat efficiency decreases with increasein distance between
source coil and load coil.
Is WiTricity Technology safe?
• WiTricity’s technology is a non-
radiative mode of energy
transfer, relying instead on the
magnetic near field.
• Magnetic fields interact very
weakly with biological
animals—and are scientifically
regarded to be safe.
• WiTricity products are being
designed to comply with
applicable safety standards and
• Automatic wireless charging of mobile electronics in home, cars, offices.
• Mobile phones, Laptops, Game controllers etc.
• Direct wireless power and communication interconnections at points of use in
• In Drilling, Mining, Underwater etc.
• Automatic wireless charging for existing electric vehicle classes.
• In Golf carts, Cars etc.
Other Applications( Medical devices, Military applications
Benefits of WiTricity
It will make products :
• -No manual recharging or changing batteries.
• -Eliminate unsightly, unwieldy and costly power cords.
• -Never run out of battery power.
• -Reduce product failure rates by fixing the ‘weakest link’: flexing wiring
and mechanical interconnects.
More Environmentally Friendly:
• -Reduce use of disposable batteries.
• -Use efficient electric ‘grid power’ directly instead of inefficient battery
• Safe, fairly efficient, goodrange
• Boon for the devices which uses midrange power
• No needof line of sight.
• No needof power cables and batteries.
• Magnetic fields interact weakly with biological masses
(humans), and energy is only transmitted between
• Transmissions possible only in few meters.
• Possibility of “energy theft”.
• Efficiency decreases withdistance.
• The resonance condition should be satisfied and if any
error exists, there is no possibility of power transfer.
Future of Witricity
If we apply this idea to the whole city, we might not have to use
any wired cable. Moreover, in the future, it would save the
material cost, and
“WE CAN SAVE THE WORLD, YEAH!!!”
• S. Sheik Mohammed, K. Ramasamy, T. Shanmuganantham,”
Wireless power transmission – a next generation power
transmission system”, International Journal of Computer
Applications (0975 – 8887)
• An article published in the Science Magazine as “Wireless
Power Transfer via Strongly coupled magnetic fields ”