Seminar on

WiTricity: Future of Electricity

Submitted to:

Mr. Abhinav Bansal

Assistant Professor

Department of ECE

Submitted by:

Hina Saxena

ECE-3rd year

Roll no.: 1103331064

Department of electronics & Communication

Contents

• 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

• Limitations

• References

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 we need Witricity

• We use Wires..

And we use..

Which sometimes ends as..

Why not wires??

• As per studies, most electrical energy transfer is through wires.

• Most of the energy loss is during transmission

• On an average, more than 30%

• In India, it exceeds by 40%

Why not batteries??

Estimated that 40 billion batteries per year add to the e-waste burden.

And of course its not a good sign.

And this is possible due to

WIreless elecTRICITY

or WiTricity..

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 power loss Power theft

Health concerns

The forgotten invention is reborn in

2007

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

transfer, Resonance, inductive coupling.

Efficiency at that point was just approximately 43%.

Experimental design

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.

WiTricity Technology

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.

Basics of witricity

Fundamentals

• Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge.

• 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.

• Electromagnetic induction is the production of voltage across a conductor moving through a magnetic field.

• 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 coupling occurs 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

techniques

Short range– Inductive coupling

Mid range– Resonance Inductive coupling

Long range-Electromagnetic

Wave Power Transfer

How does Inductive Coupling work??

Inductive coupling works on the principles of electromagnetism:

“When a current (electricity) passes through a wire, it generates a magnetic field perpendicular to the wire.

When a wire is in proximity to a magnetic field, it generates a current in that wire.”

Magnetic fields decay quickly , making inductive coupling effective only at very short ranges.

• Wireless Charging Pad(WCP),electric brushes are

some examples

• On a WCP, the devices are to be kept, battery will be automatically charged.

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

applied.

WiTricity is based on Resonant Inductive coupling..

Long range: Far field power transfer

• Far-field method achieves longer ranges which is much greater than the diameter of device.

• These far-field type techniques include Radio & Microwave Power Transmission Techniques & LASER Techniques.

How WiTricity works

1) Power from mains to antenna, which is made of copper. 2) Antenna resonates at a frequency of 10MHz, emitting electromagnetic waves. 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 10MHz.

Efficiency Chart of WiTricity

It is observed that efficiency decreases with increase in 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 organisms—people and animals—and are scientifically regarded to be safe.

• WiTricity products are being designed to comply with applicable safety standards and regulations.

WiTricity Applications

Consumer Electronics

• Automatic wireless charging of mobile electronics in home, cars, offices.

• Mobile phones, Laptops, Game controllers etc.

Industrial Applications

• Direct wireless power and communication interconnections at points of use in harsh environments.

• In Drilling, Mining, Underwater etc.

Transportation

• Automatic wireless charging for existing electric vehicle classes.

• In Golf carts, Cars etc.

Other Applications( Medical devices, Military applications and Robots)

Benefits of WiTricity It will make products :

More Convenient: • -No manual recharging or changing batteries. • -Eliminate unsightly, unwieldy and costly power cords.

More Reliable: • -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 Charging.

Advantages

• Safe, fairly efficient, good range

• Boon for the devices which uses midrange power

• No need of line of sight.

• No need of power cables and batteries.

• Magnetic fields interact weakly with biological masses (humans), and energy is only transmitted between resonating objects.

Limitations

• Transmissions possible only in few meters.

• Possibility of “energy theft”.

• Efficiency decreases with distance.

• 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! ! !”

References • www.wikipedia.com

• 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 ”

• www.witricity.com • http://www.sciencedirect.com/science/journals