HIGHLY RESONANT WIRELESS POWER TRANSFER: SAFE,EFFICIENT,AND OVER A DISTANCE

WHAT IS WIRELESS ENERGY TRANSMISSION ?

The transmission of energy from one place to another without using wires

Conventional energy transfer is done using wires ,which has certain limitations.

NEED OF WITRICITY

To fulfil the ever increasing demand of nation.

It is efficient and reliable. Its applications are eco-friendly. Safe for humans. Low maintenance cost. Can be used for short-range and long-range

transmission.

WHY NOT WIRES ? Wired transmission of electrical energy is

lossy. Globally on an average about 30%. In India its about 40% or more. Billions, trillions of $ are spent on wires and

in their installation. Waste management is a challenge in 21st

century.. 40 billion disposable batteries added to e-

waste every year. PVC is non-biodegradable.

NETWORK OF WIRES ON ELECTRIC POLES IN

DARYAGANJ, NEW DELHI

Estimated that 40 billion of

disposable batteries and waste electric wires per year

add to the e-waste burden

Not a good sign….

WHAT IS THE SOLUTION THEN ????

WITRICITY

History The inventor Nikola Tesla dreamt of wireless power.

He built a coil,later named ‘Tesla coil’.

Tesla coils could illuminate the lamps from across the room and throw the occassional built of lightning on the nearest conductor.

His vision was different from WiTricity but helped

An unsuccessful experiment :Nikola tesla believed in wireless power with such an enthusiasm that with the financing of J.P.Morgan,he built a giant apparatus called:

“THE WARDENCLIFF TOWER”At his lab on the shore of long island,NY, in the year 1901.

THIS WAS BEFORE THE WORLD WAS WIRED.

Tesla coils remain popular today,though,often for their ability to put on a fantastic lightning show.

THE FORGOTTEN INVENTION IS REBORN IN 2007

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 frequency of 9.9MHz

Resonance inductive coupling Efficiency at that point was just approximately

43%

CURRENT WIRELESS TECHNOLOGY

Bluetooth Wi-Fi NFC (Near Field

Communication) Satellite communication Cordless mouse, keyboard,

mobiles, microphones and headphones.

Near Field Techniques Inductive Coupling (Short range) Resonant Inductive Coupling (mid

range) Far Field Techniques Laser power Transmission Microwave Power Transmission (long

range) Solar power Satellite(SPS)

WIRELESS ENERGY TRANSMISSION TECHNIQUES

NEAR FIELD TECHNIQUES

INDUCTIVE COUPLING

Uses electromagnetic induction concept-Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field.

 Two conductors are referred to as mutual-inductively coupled or magnetically coupled when they are configured such that change in current flow through one wire induces a voltage across the ends of the other wire through electromagnetic induction.

RESONANT INDUCTIVE COUPLING

Uses almost the same concept as Inductive coupling just that the coils operate at resonant frequency leading to efficient transfer of energy over a larger distance

RIC VS INDUCTIVE COUPLING

RIC is highly efficient RIC has much greater range

than inductive coupling RIC is directional when

compared to inductive coupling RIC can be one-to-many. but

usually inductive coupling is one-to-one

Devices using RIC technique are highly portable

FAR FIELD TECHNIQUES

MICROWAVE POWER TRANSMISSION (MPT)

Transfers high power from one place to another.

Two places being in line of sight usually.

Electrical energy converted to microwave energy using magnetron.

Capturing microwave using rectenna.

Conversion of microwave energy into electrical energy.

Transmission of electrical energy.

LASER POWER TRANSMISSION LASER is highly

directional and coherent But, gets attenuated

when it propagates through atmosphere

Simple receiverPhotovoltaic cell

Cost-efficient

SOLAR POWER SATELLITES

Satellites are placed in geostationary orbit

Solar energy is captured using photocells

Each SPS may have 400 million photocells

Transmitted to earth in the form of microwaves/LASER

Using rectenna/photAovoltaic cell, the energy is converted to electrical energy

Efficiency exceeds 95% if microwave is used.

Block diagram for witricity mechanism

WIRELESS ELECTRICITY IN OUR DAILY LIFE

CONSUMER ELECTRONICS

Photographs of a wirelessly powered laptop computer (left) and a D-Cell formfactorbattery with wireless charging built in (right).

The laptop PC is being powered directly by a wireless power source deployed behind the cork board, delivering over 20 watts of power over a 40 cm distance.

the D cell form factor battery shown charging is enabled for wireless energy capture, and can charge at a distance of over 10 cm from the wireless charging source. Analysts expect that the benefits of charging over distance and with spatial freedom will result in highly resonant wireless power transfer capturing over 80% market share of all wireless charging systems by 2020.

MEDICAL DEVICES

Pictures showing two examples of HR-WPT charging applications in medicaldevices: Left ventricular assist device (LVAD) (left) and pacemakers (right).

Wireless charging systems are being developed for implanted medical devices including LVAD heart assist pumps, pacemakers, and infusion pumps

The HR-WPT technique eliminates the need for drive lines that penetrate the human body, and for surgical replacement of primary batteries.

ELECTRIC VEHICLES

Photograph showing an application of HR-WPT for charging full electric and hybrid vehicles.

Wireless charging systems are being developed for rechargeable hybrid and battery electricvehicles. These systems already deliver 3.3 kW at high efficiency over a distance of 10 cm -20cm (typical vehicle ground clearances).

FIGURE shows the Audi Urban Concept Vehicle, demonstrated by Audi in April, 2012.

It is expected that wireless charging will vastly improve the charging experience for EV owners, making such vehicles even more attractive to consumers.

LED LIGHTING

Photographs showing LED lights directly powered by highly resonant wirelessenergy transfer systems.

LED (light emitting diode) lights can be directly powered with wireless electricity.

The LED fixture shown in the left photo in Figure is powered by a 10 W source mounted above the ceiling.

DEFENCE SYSTEMS

Photographs showing several military applications for highly resonant wirelesscharging systems: military robots (left) and soldier electronics (right).

The Talon tele-operated robot shown in Figure is being equipped with wireless charging so that it can be recharged while it is being transported by truck from site to site.

Efficiency chart of witricity

It is observed that efficiency decreases with increase in distance between source coil and load coil

WITRICITY CONCERNS

Will it harm me? Will it harm the environment? Will it interfere with important communication?

NO05/02/2023WiTricity40

Advantages:1.Make devices more convenient and thus more desirable to purchasers, by eliminating the need for a power cord or battery replacement.

2.Make devices more reliable by eliminating the most failure prone component in most electronic systems—the cords and connectors.

3.Make devices more environmentally sound by eliminating the need for disposable batteries.

4.Make devices safer by eliminating the sparking hazard associated with conductive interconnections, and by making them watertight and explosion proof by eliminatingconnector headers and wires that run through roofs, walls or other barriers (even skin tissue).

5. Reduce system cost by leveraging the ability to power multiple devices from a single source resonator.

Disadvantages:1.For short and mid range transfer system has to be set at the right frequency or there would be no power transfer.2.For long range the installation cost is high while EMI is also a concern.

A THOUGHT :Wireless electricity is not just a great idea but an urgent measurethat has to be taken to deal with the current energy crisis.

Even the smallest entity can lead to one of the most mindboggling dilemmas of the world. Electrons the source of electricity put us in a similar fix. It is on us to decide how to tap these electrons to be useful in our lives.

Wireless electricity comes with its baggage but none can deny that it is here to stay. Prospects & Issues:From the discussion its clear that this idea needs awareness to remove doubts from minds of the people about safety issues.

It requires both support from government and the people financially and psychologically.

CONCLUSION :

The applications of wireless power in a wired world are endless and rethinking of the infrastructure is a decades away.

With such a wide-ranging application space, I feel that the use of resonance to enhance wireless power transfer will be prevalent in many areas of life in the coming years.

At the end of the day,if you can find something that is convinient to the people and saves energy,that’s the killer app……….

References:• An article published in the Science Magazine as “Wireless Power Transfer via Strongly coupled magnetic fields ”

•“Efficient Non-Radiative Midrange Energy Transfer” by Aristeidies karalis, Marlin Soljacic,2006.

• http://ieeexplore.ieee.org/Xplore/• www.WiTricity.com

• www.techjournal.com

• www.wikipedia.org

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