1

THE INTRIGUING CONCEPTS OFWIRELESS ELECTRICITY

AND POWER TRANSMISSION

PRESENTATION BY:-ASHISH RAJ SAHUROLL NO-1112232015

2

Why do we need wireless electricity???

The need of electricity in every nook and corner of the world

The demand of eco-friendly power

Requirement of efficient and reliable power

To reduce dependence on wires and batteries

The ever increasing power demand

3

Hate wires………..We have a solution!

Do u love wires now………

We humans love electricity ……..

Trillions of dollars spent on wires and installation of electric poles……..

4

Estimated that 40 billion of disposable batteries per year

add to the e-waste burden

Not a good sign….

5

Wireless electricity wayback in the 1800s……..

In the year 1893,Nikola Tesla proposed the method of wireless transmission of electric power

One of the greatest breakthroughs of science at that time

6

Built the wardenclyffe tower which could broadcast power wirelessly using far-field techniques. Called off as it radiated power into surroundings raising issues of power lossPower theftHealth concerns

The Wardenclyffe Tower

A dream crashes……

7

Types of wireless energy transfer techniques are:-

Short range– Inductive coupling

Mid range– Resonance Inductive coupling

Long range-Microwave Transmission

8

Inducti ve coupling

Uses electromagnetic induction concept-A term for the interdependence of time-varying electric and magnetic fields

Wireless electricity makes use of the concept-“Oscillating electric field produces magnetic field and oscillating magnetic field produces electric field”.

9

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

10

11D i ff e r e n t F r e q u e n c y

ResonanceProperty of systems to operate at higher amplitudes at purticular frequencies known as resonant frequencies than at others.

When 2 objects operate at same resonant frequency they transfer energy efficiently between them without interfering with the off resonant objects.

12D i ff e r e n t F r e q u e n c y

The glass which was having the resonant frequency as of the singer’s voice accumulated sufficient energy to explode eventually

13

14

The Witricity Team

In 2007,6 MIT membersheaded by Marin Soljacic were able to successfully transmit power to a bulb within a distance of 2m at a freq of 9.9MHz using concepts of non radiative mid range energy transferResonanceinductive couplingEfficiency at that point was just approximately 43%

15

Block diagram for witricity mechanism

16

Circuit diagram for witricity demonstration

17

Coupled mode theory for range & rate of coupling

In the coupled mode theory system with 2 resonators follow the below 2 equations:-

18

The solution of the equation show that at exact resonance at: ω1=ω2 and Γ1=Γ2

the normal modes of the combined system are split by 2κ.

The energy exchange between the two objects takes place in time Pi/κ and is nearly perfect, apart for losses, which are minimal when the coupling rate is much faster than all loss rates (κ>> Γ1, 2).

The desired optimal regime {κ/sqrt (Γ1,2)>>1} is called “Strong-Coupling” regime. There is No change in Energy, unless κ/Γ>>1 is true.

The solution of the equation show that at exact resonance at: ωd= ωs and Γs=Γd

ad(t) depends on only geometry and distance between them provided k/Γ>>1.

The energy exchange between the two objects takes place in time Pi/κ and is nearly perfect, apart for losses, which are minimal when the coupling rate is much faster than all loss rates (κ>> Γs, d).

The desired optimal regime {κ/sqrt (Γs,d)>>1} is called “Strong-Coupling” regime. There is No exchange of Energy, unless κ/Γ>>1 is true.

19

Wireless electricity in our daily life

20

Efficiency chart of witricity

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

21

Applications of Witricity(short range and mid range)

1.DIRECT WIRELESS POWERNo device would need wires For TVs, toasters or any form of immobile electronic devices.2. AUTOMATIC WIRELESS CHARGINGDevice with rechargeable batteries charges itself.For any form of mobile devices .3.INDUSTRIALwould be free of heavy installation of wires and devoid of any hazardous electric shock incidents.4.TRANSPORTATIONCould charge an electric car or automobile.

22

Types of Long range/Far field transmission techniques

Radio frequency Transmission extracts small quantities of energy in the range 902 and 928 MHzDisadvantage—interference caused by metal surfaces

Laser Transmission Highly directional and coherent Inefficient for wireless power transmission

23

Microwave Transmission

Aims at higher power transfer over longer distances practically in the range of some miles

Requires a microwave source, antenna and rectenna

operates in the frequency range of 1-40GHzoperates at the highest efficiency at 2.45GHzSteps: 1.conversion of electrical to microwave energy 2.Capturing of microwave beams by Rectenna 3.conversion of microwave to electrical energy

24

Block diagram for microwave power transmission model

25

Major components of the model

Microwave generator:Microwave power sources used like Klystron, magnetron, TWT or GaAs MESFETs Output power is controlled by electronic circuits.Magnetron is most preferred at 2.45 GHzTransmitting antenna:Has the responsibility of transmitting power. Patch, Microstrip, parabolic dish or slotted waveguide antenna may be used. Rectenna:Consists of a antenna ,rectifying diodes and low pass filter.Rectenna area has to be large.Important for receiving microwave power

26

Ontroller Rectenna block diagram

Matching circuit matches receiver load to antennaSchottky diode generally used as rectifying diode to provide DC powerLow pass filter ensures no RF is input to the power management systemwhere electrical energy is stored.Power management circuit enables storage of received power.Controller ensures delivery of DC power in time when required.

27

SOLAR POWER SATELLITES:The most imp. Application or advancement:absorb light energy from sun.

converted to electric energy and beamed to earth stations in form of microwave beams

so it can power satellites,aircrafts,even supply electricity to places where wired connections are not possible at lower prices.

SPACE POWER TRANSMISSION AND LUNAR BASED PROJECTS:satellites in space can receive microwave signals from earth and beam it to any place on earth.

in future it encourages power projects on the moon

Applications of long range transmission

28

29

Image of a Rectenna in US with diameter of about half a mile which is important as 95% of the microwave power is received by rectennas.US receives about 5000MW of power as a result.

30

Wireless power transmission and reception using microwaves

31

Advantages:

Disadvantages:

1. Efficient and reliable power.2. Creation of a shock free environment devoid of any chances of power thefts.3. Provides solution to the ever increasing demand for power.4. A solution to reduce e-waste- a more safe environment.5. A more cost effective methodology for getting electricity to your houses which includes paying less for use of power.6. SPS are not affected by the day and night cycle leads to lesser limitations on power harvesting.

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.

32

Prospects & Issues:

Conclusion:

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 puts 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 no can deny that it is here to stay.

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.

33

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.WiTricitypower.com

•www.techjournal.com

•www.wikipedia.org

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

34

THANK U A

LL