WIRELESS POWER TRANSMISSION THROUGH TESLA COILS

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OVERVIEW INTRODUCTION DEFINITION HISTORY BASICS OF WITRICITY SOLID STATE TESLA COILS PRINCIPLE COMPONENTS WORKING PROS AND CONS APPLICATIONS CONCLUSION

INTRODUCTION In this era of modernization, electricity has become the

unavoidable part of life. The major source of conventional form of electricity is

through wires. One of the major issue in power system is losses occuring

during the transmission and distribution of electrical power. The percentage of loss of power during transmission and

distribution is approximated as 26%. The main reason for power loss during transmission and

distribution is resistance of wires used in grid. According to world resource institute(WRI),India‘s

electricity grid has the highest transmission and distribution losses in the world –a whopping 27-40%.

Tesla has proposed methods of transmission of electricity using electromagnetic induction.

DEFINITION As the word wireless means “WITHOUT WIRE”. Wireless energy transfer or wireless power is the

transmission electrical energy from a power source to an electric load without interconnecting man made conductors.

Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous or impossible.

WiTricity ensures that the cell phones, laptops, iPods and other power hungry devices get charged on their own, eliminating the need of plugging them in.

Because of Witricity these devices won’t require batteries to operate.

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……..

HISTORY Sir Nicolai Tesla was the first one to propose and research

the idea of wireless transmission in 1899, since then many scholars and scientists have been working to make his dream a reality

1899: Tesla continues wireless power transmission research in Colorado springs and writes “The inferiority of the induction method would appear immense as compared with the disturbed charge of ground and air method”.

1961: William C. Brown publishes an article exploring possibilities of microwave power transmission

2009: Sony shows a wireless electrodynamics- induction powered TV set, 60 watts over 50 cm.

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Experiments performed between 1888 and 1907 by Nicolai Tesla

Started efforts on wireless transmission by 1891 in experimental station at Colorado.

He lightened a small incandescent lamp by means of Resonant circuit grounded on one end.

In 1901, Tesla began construction of a large high voltage wireless power transmission now called the Wardenclyffe tower at Shoreham, New York.

The idea of Tesla is taken research after 100 years by a team led by Marine Soljacic from MIT.

He used to lamp 200 lights from 40 km distance.

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.

Energy/Power CouplingEnergy coupling occurs whenan energy source has a means of transferring energy to another object.

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.

Resonance 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.

SOLID STATE TESLA COILS A tesla coil is basically high voltage

transformer that generates high voltage electric sparks into the air.

A Tesla Coil works much in the same way your cell phone charger works, but in reverse. Instead of reducing voltage, it increases it.

But a Tesla Coil does much more than increase in voltage, it increases frequency.

Tesla designed it this way because once we create very high voltage electricity at a very high frequency, we can create a field of energy with which there is transmission of power. 

Principle Wireless Electricity uses the principle which involves

the usage of inductively coupled objects with same resonant frequency.

The principle Electromagnetic Induction states that a coil generating magnetic field induces a current in another coil as it is being placed in the field of the former coil.

First, we employ a pre-made high voltage iron core transformer to go from 120 V wall current to roughly 10,000V.

The wire with 10,000 volts is wrapped into one very large (primary) coil with only a handful of turns. The secondary coil contains thousands of turns of thin wire. This steps up the voltage to between 100,000 and one million volts. This potential is so strong that the iron core of a normal transformer cannot contain it. Instead, there is only air between the coils.

Components 1) Inductors: 

The Tesla coil's primary and secondary coils are both inductors in electrical terms. When the current flowing through an inductor changes, it will create an opposing or reverse voltage. 

2) Spark Gaps: A sparking plug in a car is a basic spark gap, its break-down voltage dependent on the electrode gap size. Once it conducts, hot ionized air in the gap gives it the ability to carry on, so long as a current is flowing.

3) Capacitor:  A good analogy for a capacitor is to think of it as a sponge, placed on spilt water and left to slowly soak it up. If left for a minute and then given a quick, hard squeeze, one minute's worth of soaking-up is instantly released in a fraction of a second. In a Tesla coil circuit this so called 'soaking-up' stage lasts only a few milliseconds, while the 'squeezing-out' can be a thousand times quicker in a few micro (millionths) of a second.

Components Resonant Circuit :

If a capacitor is placed across an inductor and voltage applied, you will have a resonant circuit. As the capacitor discharges, it sends current into the inductor that stores this as energy in its magnetic field. But as the capacitor discharges, the current into the inductor also diminishes. This causes its magnetic field to collapse and generate an opposing voltage back into the capacitor, allowing the cycle to start all over again. The number of times that this 'back and forwards' cycle happens per second, is the circuit's resonant frequency, expressed in Hertz (Hz). 

Working The circuit of the coil contains a

capacitor and a small hole called a spark gap.

When the coil is turned on, electricity flows through the circuit and fills the capacitor with electrons, like a battery. This charge creates its own electric potential in the circuit, which tries to bridge across the spark gap.

The capacitor ('C') is charged up by a high voltage source, like example of the sponge soaking up water.

Working Once the capacitor attains a high enough

voltage the spark gap fires and conducts (Fig 2 ). The spark gap is now a short-circuit that completes the resonant circuit (shown in red) of the primary inductor and capacitor.

The spark gap firing is virtually an instantaneous discharge of the capacitor energy into the inductor.

The inductor (the primary) stores this energy in its magnetic field with its lines of force cutting into the secondary coil (another inductor) and induces a voltage into it. Once the capacitor is empty, the current flow into the inductor stops, and its magnetic field collapses causing a reverse current (now fairly reduced) to flow back into the capacitor again.

Working This means that the secondary

coil (an inductor) along with the capacitance of the toroid also forms a resonant circuit, behaving much like the primary circuit. The secondary's energy is therefore also resonating back and forth between the coil and the toroid. However it does not dampen down the same as the primary does, in fact it is steadily increasing.

In a perfect Tesla coil once breakout has occurred this would be the end of the matter, allowing a fresh charging cycle to start all over again. What usually occurs though is that as the secondary's field starts collapsing it starts to transfer its energy back into the primary again.

Pros and cons PROS Allows a wide range of firing

rates to be investigated with a variable speed rotary spark gap, without encountering beating and surging.

Allows power throughput to be controlled by altering the rotary speed.

Charging is slow immediately after the spark gap fires.

Provides excellent load sharing if a 3 phase rectifier is used at higher powers.

CONS

More complex circuit is required.

Greater cost.

Large DC smoothing capacitor is needed unless 3-phase power is used. Such a capacitor is expensive, and stores lethal energy.

High voltage, high inductance charging inductor is needed. This is a specialised part and may be difficult to obtain.

Requires a 3-phase supply to be most effective.

Applications Tesla coil circuits were used commercially in spark gap radio

transmitters for wireless telegraphy telegraphy until the 1920s,and in electrotherapy and pseudomedical devices such as violet ray.

Today, although small Tesla coils are used as leak detectors in scientific high vacuum systems and igniters in arc welders, their main use is entertainment and educational displays.

Tesla coils are built by many high-voltage enthusiasts, research institutions, science museums, and independent experimenters.

Although electronic circuit controllers have been developed, Tesla's original spark gap design is less expensive and has proven extremely reliable.

TESLA COILS IN ENTERTAINMENT Tesla coils can also be used to generate sounds,

including music, by modulating the system's effective "break rate" (i.e., the rate and duration of high power RF bursts)

Tesla coils are very popular devices among certain electrical engineers and electronics enthusiasts. Builders of Tesla coils as a hobby are called “Coilers". A very large Tesla coil, designed and built by Syd Klinge, is shown every year at the Coachella Valley Music and Arts Festival, in Coachella, Indio, California, USA.

People attend "coiling" conventions where they display their home-made Tesla coils and other electrical devices of interest.

CONCLUSION The main objective was to demonstrate wireless

power transmission using solid state tesla coils. Tesla coils are remarkable devices able to

generate high voltage, high frequency waveforms with little control circuitry.

Most of the builders of Tesla coils are interested in producing electric arcs and visible effects suitable for displays and general amusement, not in producing power supplies and power effects units which may have significant practical importance.

It has demonstrated that tesla coils can be designed for wireless power transmission.

REFERENCES Basharat Nizam, “Inductive Charging Technique,”

International Journal of Engineering Trends and Technology (IJETT), Volume4, Issue4- April 2013

A.K. RamRakhyani, S. Mirabbasi, and M. Chiao, “Design and Optimization of Resonance Based Efficient Wireless Power Delivery Systems for Biomedical Implants,” IEEE Transactions on, Volume5, No1:48–63,February 2011.

David W Baarman, “Understanding wireless power”, Director of Advanced Technologies, Fulton Innovation Joshua Schwannecke, Research Scientist, Fulton Innovation December 2009

Shawon Senjuti, “Design and optimization of efficient wireless power transfer links for implantable biotelemetry systems,” A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering Science

Dr. Morris Kesler, “Highly resonant wireless power transfer”.

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