COLLEGE OF ENGINEERING, CHENGANNUR

KERALA

DEPARTMENT OF ELECTRICAL ENGINEERING

CERTIFICATE

This is to certify that the seminar entitled

Wireless driven LED semiconductor lightning system

Submitted by

MALAVIKA S( 19130661)

is a bonafidework done by her.

Head of the Department Coordinator

WIRELESS DRIVEN LED SEMICONDUCTOR LIGHTNING SYSTEM

Seminar Report

Submitted in the partial fulfillment of the requirements for the award

of the degree of

Bachelor of Technologyin

Electrical and Electronics Engineeringof

Cochin University of Science and Technology

by MALAVIKA S

19130661

October, 2015

Department of Electrical Engineering

College of Engineering, Chengannur-689121

Phone: (0479) 2454125, 2451424 Fax: (0479) 2451424

ACKNOWLEDGEMENTFirst and foremost I thank God Almighty for His grace and blessings, without

which this wouldn’t be possible.

I express my deep sense of gratitude to Prof. V P Jyothiraj, Principal,

College of Engineering Chengannur. I also express my gratitude to Dr. Deepa James, Head,

Department of Electrical and Electronics Engineering, who extended all support at her

disposal to its fullest, as always for the completion of my seminar.

I am greatly indebted to my seminar coordinator Miss. Lakshmi,

AsssociateProfessor, Department of Electrical and Electronics Engineering and Miss.

Vandana, Associate Professor, Department of Electrical and Electronics Engineering for

their scholarly assistance, kind treatment, encouragement and timely help in all possible

manners. I would also like to thank Mr. Bibin Baby John, Assistant Professor whose

timely guidance and advices have helped me in successful completion of my seminar.

ABSTRACT Wireless power transfer technology is the transmission of electrical energy from a power

source to an electrical load without man-made conductors. Traditional LED lighting system

sensitive to rigid environment such as humidity, corrosive and flammable. Combining the

advantages of wireless electrical power transfer and LED semiconductor lighting technology,

the wireless-driven LED (WD-LED) lighting system has advantages of electrical shock

protection, convenient, reliable, portable and environmentally sound. The wireless-driven

LED lighting source will gain increasing attention in the civilian consumer electronics

market, military area and special lighting areas. To achieve wireless electric power transfer in

LED lighting system, the wireless-driven LED lighting system should contain LED lighting

module, wireless electrical power transfer system, LED driving circuit and electrical energy

storage system. The LED lighting module was driven by the electrical power, which was

transferred from a contact free system. Either inductive coupling or magnetic resonance

coupling is responsible for transferred the electrical power. Wireless-driven LED lighting

system has a good market prospects, this new technology will make these innovative LED

lighting products more available, convenient and reliable.

CONTENTS

1. INTRODUCTION2. HISTORY OF POWER TRANSFER

2.1 TESLA COIL3. .GENERAL PRINCIPLES AND CLASSIFICATION OF WIRELESS

POWER TRANSMISSION SYSTEM3.1 ELECTROMAGNETIC INDUCTION3.2 CAPACITIVE COUPLIND3.3 RESONANT INDUCTIVE COUPLING3.4 MICROWAVE TRANSMISSION

4. LIGHT EMITTING DIODE5. ADVANTAGES OF WD-LED SYSTEM6. APPLICATION7. CONCLUSION8. REFERENCES

INTRODUCTION

When the interconnecting wires of lighting system are inconvenient, hazardous, or impossible, some special lighting systems have higher requirements on reliability and security, such as explosion- proof lamp, water-proof lamp, under-ground lamp.Owning to higher request for water-proof, explosion- proof, the new engineering design must be introduced into our lighting system. The concept of wireless power transfer can be dated back to as early as year 1890 when Nicola Tesla made the first attempt to transfer considerable amount of power without direct connection of wires, using Tesla coils designed by him. The idea of transmitting electric power without wires has been around for over a century. In our modern life, wireless communication has become an essential technology in many areas.Wireless power transmission is the transmission of electrical energy from power source to an electrical load without the use of interconnecting wires. Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous, or impossible. There are four different fundamental methods for wireless energy transfer. The electrical energy can be transferred by electromagnetism induction, capacitive coupling, magnetic resonance and microwaves transmission. Traditional LED lighting system sensitive to rigid environment such as humidity, corrosive and flammable. Combining the advantages of wireless electrical power transfer and LED semiconductor lighting technology, the wireless-driven LED lighting system is designed.The wireless-driven LED lighting system should contain LED lighting module, wireless electrical power transfer system, LED driving circuit and electrical energy storage system. The LED lighting module was driven by the electrical power, which was transferred from a contact free system. Either inductive coupling or magnetic resonance coupling is responsible for transferred the electrical power.

HISTORY OF POWER TRANSFER

TESLA COIL

A   Tesla coil   is an electrical   resonant transformer   circuit invented by Nikola Tesla   around 1891 . It is used to produce high- voltage , low- current , high   frequency   alternating-current   electricity.   Tesl a experimented with a number of different configurations consisting of two, or sometimes three, coupled   resonantelectriccircuits .

Tesla used these coils to conduct innovative experiments in electrical   lighting ,   phosphorescence ,   X-ray generation ,   high frequency   alternating current   phenomena,   electrotherapy , and the   transmission of electrical energy without wires .

Tesla used his Tesla coil circuits to perform the first experiments in   wireless power transmission   at the turn of the 20th century,In the period 1891 to 1904 he experimented with transmitting RF power between elevated metal terminals by capacitive coupling   and between coils of wire by   inductive coupling

Tesla coil in operation, showing brush discharges   from the toroid. The high   electric field   causes the air around the high voltage terminal to   ionize   and conduct electricity, producing colorful corona discharge ,   brush discharges   and   streamer arcs .

A Tesla coil is a   radio frequency   oscillator   that drives an air-core double-tuned   resonant transformer   to produce high voltages.   Tesla's original circuits as well as most modern coils use a simple   spark gap   to excite oscillations in the tuned transformer. More sophisticated designs use   transistor   or   thyristor switches or   vacuum tube   electronic oscillators  

Tesla coils can produce output voltages from a hundred kilovolts to several million volts for large coil.   The alternating current output is in the low   radio frequency   range, usually between 50   kHz and 1mHz.   Although some oscillator-driven coils generate a continuous   alternating current , most Tesla coils have a pulsed output the high voltage consists of a rapid string of pulses of radio frequency alternating current.

The common spark-excited Tesla coil circuit, consists of these components: A high voltage supply   transformer   (T) , to step the AC mains voltage up to a high

enough voltage to jump the spark gap. Typical voltages are between 5 and 30 kilovolts (kV).

A   capacitor   (C1)   that forms a tuned circuit with the   primary winding   L1   of the Tesla transformer

A   spark gap   (SG)   that acts as a switch in the primary circuit The Tesla coil   (L1, L2) , an air-core double-tuned   resonant transformer , which generates

the high output voltage. Optionally, a capacitive electrode (top load)   (E)   in the form of a smooth metal sphere

or   torus   attached to the secondary terminal of the coil. Its large surface area suppresses premature   corona discharge   and   streamer arcs , increasing the   Q factor   and output voltage.

The specialized transformer coil used in the Tesla circuit, called a   resonant transformer ,   oscillation transformer , or RF transformer, functions differently from an ordinary transformer used in AC power circuits   While an ordinary transformer is designed to   transfer   energy efficiently from primary to secondary winding, the resonant transformer is also designed to   store electrical energy. Each winding has a   capacitance   across it and functions as an   LC circuit   (resonant circuit,   tuned circuit ), storing oscillating electrical energy, analogously to a   tuning fork . The   primary winding   (L1)   consisting of a relatively few turns of heavy copper wire or tubing, is connected to a   capacitor   (C1)   through the   spark gap   (SG) . [14] [15]   The   secondary winding   (L2)   consists of many turns (hundreds to thousands) of fine wire on a hollow cylindrical form inside the primary. The secondary is not connected to an actual capacitor, but it also functions as an LC circuit, the inductance   (L2)   resonates with   (C2) , the sum of the capacitance   between the windings of the coil, and the capacitance of the   toroidal   metal electrode attached to the high voltage terminal. The primary and secondary circuits are tuned so they resonate at the same frequency, they have the

same resonant frequency . This allows them to exchange energy, so the oscillating current alternates back and forth between the primary and secondary coils.

General Principle and Classification of The WirelessPower Transmission System

A. Electromagnetism induction

Electromagnetism induction, also known as inductive charging is based on a few simple principles. The technology usually requires two coils: a primary transmitter and a secondary receiver. An alternating current is passed through the transmitter coil, generating a magnetic field, as shown in Fig1. Then the receiver can transfer the magnetic field to electric power. Induction usually use an induction coil to create an alternating electromagnetic field from within a charging base station, and a second induction coil in the portable device takes power from the electromagnetic field and coverts it back into electrical current to power a device or charge the battery. The electronic products which have the function of wireless power consortium require more electronics and coils in both device and emitter, increasing the complexity and cost products.

Figure 1 Electromagnetism induction by coils

In   inductive coupling   ( electromagnetic induction   or   inductive power transfer , IPT), power is transferred between   coils of wire   by a magnetic field.   The transmitter and receiver coils together form a   transformer . An   alternating current   (AC) through the transmitter coil   (L1)   creates an oscillating   magnetic field   (B)   by   Ampere's law . The magnetic field passes through the receiving coil (L2) , where it induces an alternating   EMF   ( voltage ) by   Faraday's law of induction , which creates an AC current in the receiver.   The induced

alternating current may either drive the load directly, or be   rectified   to   direct current   (DC) by a   rectifier   in the receiver, which drives the load.In most systems an   electronic oscillator   generates a higher frequency AC current which drives the coil, because transmission efficiency improves with   frequency .The power transferred increases with frequency   and the   mutual inductance   M   between the coils,   which depends on their geometry and the distance   D range  between them. A widely-used figure of merit is the   coupling coefficient   .   This dimensionless parameter is equal to the fraction of   magnetic flux   through   L1   that passes through   L2 . This technology can achieve the wireless power transfer without any electric connects. It provides a safe way of connection, the products can be all enclosed and away from air, water or plastic in the atmosphere. However, the transmission power and efficiency will change if the distance between the two coils become closer or farther.

B. Capacitive coupling

Instead of using electromagnetism field induction, an alternative way of wireless electric power transfer is to use electric field coupling to achieve capacitive power transfer. As shown in Fig. 1a, a typical capacitive coupled electric power transfer system is consisted of three parts, namely primary power transmitter, acting as a high frequency voltage source; capacitive structure, functioning as the electric energy transfer channel; and power receiver, acting as the secondary power conditioner, and supply the electric power to the load. Ignoring the harmonics generated by the inverter for simplification, a typical capacitive coupling power transfer system can be modeled with a simple linear circuit as shown in Fig. 2b.

Figure 2a the structure of capacitive coupling power transfer, 2b the simplified Capacitive power transfer circuit As an alternative way of wireless power transmission, the capacitive coupling system has some unique features. The coupling structure is very special, in the coupling part, the field is mostly confined between metal plates, and the system employs the electric field as the energy-carrying medium. Since the capacitive coupling is working under an alternative way, there is very small power loss in the coupling structure as the system is operating. Due to the capacitive structure in the coupling part, the electric field coupler functions as two capacitors connected in series during the operation of the system. According to different applications, the capacitive coupling structure can be designed to many different configurations.

In capacitive coupling (electrostatic induction), the dual of inductive coupling, power is transmitted by electric field between electrodes such as metal plates. The transmitter and receiver electrodes form a capacitor, with the intervening space as the dielectric.An alternating voltage generated by the transmitter is applied to the transmitting plate, and the oscillatingelectric field induces an alternating potential on the receiver plate by electrostatic induction which causes an alternating current to flow in the load circuit. The amount of power transferred increases with the frequency and the capacitance between the plates, which is proportional to the area of the smaller plate and (for short distances) inversely proportional to the separation.

Capacitive coupling has only been used practically in a few low power applications, because the very high voltages on the electrodes required to transmit significant power can be hazardous and can cause unpleasant side effects such as noxious ozone production. In addition, in contrast to magnetic fields, electric fields interact strongly with most materials, including the human body, due to dielectric polarization. Intervening materials between or near the electrodes can absorb the

energy, in the case of humans possibly causing excessive electromagnetic field exposure. however capacitive coupling has a few advantages over inductive. The field is largely confined between the capacitor plates, reducing interference, which in inductive coupling requires heavy ferrite "flux confinement" cores. Also, alignment requirements

between the transmitter and receiver are less critical. Capacitive coupling has recently been applied to charging battery powered portable devices and is being considered as a means of transferring power between substrate layers in integrated circuits

Capacitive wireless power systems

Bipolar

Unipolar

Two types of circuit have been used:

Bipolar design: In this type of circuit, there are two transmitter plates and two receiver plates. Each transmitter plate is coupled to a receiver plate. The transmitter oscillator drives the transmitter plates in opposite phase (180° phase difference) by a high alternating voltage, and the load is connected between the two receiver plates. The alternating electric fields induce opposite phase alternating potentials in the receiver plates, and this "push-pull" action causes current to flow back and forth between the plates through the load. A disadvantage of this configuration for wireless charging is that the two plates in the receiving device must be aligned face to face with the charger plates for the device to work.

Unipolar design: In this type of circuit, the transmitter and receiver have only one active electrode, and either the ground or a large inactive capacitive electrode serves as the return path for the current. The transmitter oscillator and the load is connected between the electrodes and aground connection, inducing an alternating potential on the nearby receiving electrode with respect to ground, causing alternating current to flow through the load connected between it and ground.

C. Resonant inductive coupling

Resonant inductive coupling   or   electro dynamic induction   is the   near field   wireless transmission of electrical energy   between two magnetically coupled coils that are part of   resonant circuits   tuned to   resonate   at the same frequency. This process occurs in a   resonant transformer , an electrical component which consists of two coils wound on the same core with capacitors   connected across the windings to make two coupled   LC circuits . Resonant inductive coupling is also being used in   wireless power   systems. Here the two   LC circuits   are in different devices; a transmitter coil in one device transmits electric power across an intervening space to a resonant receiver coil in another device. This technology is being developed for powering and charging portable devices. Resonant transfer works by making a coil ring with an oscillating current. This generates an oscillating magnetic field. Because the coil is highly resonant, any energy placed in the coil dies away relatively slowly over very many cycles; but if a second coil is brought near it, the coil can pick up most of the energy before it is lost, even if it is some distance away. The fields used are predominately non-radiative, near fields, hardware is kept well within the 1/4 wavelength distance they radiate little energy from the transmitter to infinity.

The coupling coefficient is the fraction of the flux of the primary that cuts the secondary coil, and is a function of the geometry of the system.

The coupling coefficient, k, is between 0 and1.

Household devices produce relatively small magnetic fields. For this reason, chargers should hold devices at the distance necessary to induce a current, which can only happen if the coils are close together. A larger and stronger field could induce current from farther away, but the process would be extremely inefficient. Meanwhile, a lot of power will be lost as the transmission distance become larger, because the magnetic field spreads in all directions. Resonant inductive coupling is the near field wireless transmission of electrical energy between two coils that are tuned to resonate at the same frequency. An efficient way to transfer power between coils separated by a few meters is that we could extend the distance between the coils by adding resonance to the equation. Both systems should have the same resonant frequency, the induction of electric power can be different.

Figure 3 Resonant induction coupling

As shown in Fig.3, each electronic device has a coupling receiver which consists of a cured coil of wires as an inductor and a capacitance plate. As electricity travels through the receiver, the coil begins to resonate. Its resonant frequency is a product of the inductance of the coil and the capacitance of the capacitor. In the room, the emitter is the source of electric energy. According to the theory, one coil can even send electricity to several receiving coils, as long as they all resonate at the same frequency. Electricity, traveling along an electromagnetic wave, can tunnel from one coil to the other as long as they both have the same resonant frequency. As long as coils are out of the frequency range, resonant coupling will not happen, since the magnetic fields around the coils aren’t strong enough to affect much around them. Similarly, if the two coils resonate at different frequencies, nothing will happen. But if two resonating coils with the same frequency get within a few meters of each other, a lot of energy moves from the transmitting coil to the receiving coils, since they resonate at the same frequency.

D Microwave power transmission

The above three power transmission methods belong to near-field techniques. Microwave transmission refers to the technology of transmitting energy by the use of electromagnetic waves whose wavelengths are conveniently measured in small numbers of centimeter (30cm down to 1cm), these are called microwaves (1GHz to 300GHz). Microwave power transmission is the use of microwaves to transmit power through outer space or the atmosphere without the need for wires.The distance covered by microwave signal depends upon height of antenna.in inorder to increase coverage each antenna has a built in reperater that regenerates that signal before passing it on to the next antenna in line.the placement of antenna to do this is approximately 25miles. It is a sub-type of the more general wireless energy transfer methods. Microwaves power transmission is the most commonly proposed method for transferring energy to the surface of the earth from solar power satellites or other in-orbit power sources, or sending power to the earth from space. Microwave power transmission belongs to a long-distance power transmission technology. It has more freedom of choice of both receiver and transmitters, even mobile transmitters and receivers can be chosen for the power transfer system. However, the total cost for the practical installation of microwaves power transmission system is very high. Due to the working frequency or wavelengths, the power in the transmission will interfere with present communication systems.the main drawback of microwave sgnal is that they can be affected y weather ,especially rain.

It relies on three key elements: Use of radio frequency to achieve transmission(1GHz to 170GHz) Clear line of sight with no obstacle in path way Regular relay stations required due to line of sight and cost consideration

One of its major advantage is availability of multiple channel ,large bandwidth.It also have some disadvantages like towers are expensive to build,signal absorption by atmosphere(,microwave suffers from attenuation due to atmosphere),line of sight will be disrupted if any obstacles such as new buildings are there in way.

LIGHT EMITTING DIODE

A PN junction diode which emits light when forward biased,is known as light emitting diode(LED).The emitted light may be visible or invisible.The amount of light output is directly proportional to forward current.Thus higher the forward current higher is the light output. The arrow pointing on the symbol represent the light which is being transmitted away from the junction.

Fig B shows the basic structure of a LED .here an N-type layer is formed on a P-type substrate by a diffusion process.Then a thin P-type layer is grown on N-type layer.The metal connection to both the layers make anode and cathode terminals are indicated.The light energy is released at the junction when electrons and holes are recombined.The recombination of holes and electrons takes place at the junction.After recombination the electrons lying in the conduction band of N-region falls into the holes lying in the valance band of P-region .The difference in energy between the conduction band and valance bandis radiated in the form of light , in ordinary diodes this energy is radiated in the form of heat.

The semiconductor material used for manufacturing LED are gallium arsenide,gallium arsenide phosphide,.The silicon and germanium is not used for manufacturing LED because they are heat producing materials moreover they are very poor in emitting light radiations.

The LED’s radiate light in ifferent colour such as red ,green,yellow,blue,orange etc.some LED’s emit infrared(invisible ) light also.the colour of emitted light depends upon type of semiconductor used.Thus gallium arsenide emits infrared radiations,gallium arsenide phosphide produces either red or yellow light,gallium phosphide emits red or green lightband gallium nitride produces blue light.

Potential Applications of Wireless- driven LED Lighting System

Due to its unique features, WD-LED lighting system can be used in the following lightingapplications:

a) Wireless-driven/charging LED lighting systems

Schematic diagram of LED lights powered by wireless power transmission

LED lighting system can be directly powered with wireless electric power, eliminating the electric connections compared to the traditional lighting products. Combining the advantages of wireless electrical power transfer and LED semiconductor lighting technology, the wireless-driven LED lighting system has advantages of electrical shock protection, convenient, reliable, portable and environmentally sound. As shown in Fig, to achieve wireless electric power transfer in LED lighting system, the wireless-driven LED lighting system contain LED lighting module, wireless electrical power transfer system, LED driving circuit and electrical energy storage system. The LED lighting module was driven by the electrical power, which was transferred from a contact free system. Either inductive coupling or magnetic resonance coupling is responsible for transferred the electrical power. Wireless-driven LED lighting system has a good market prospects, this new technology will make these innovative LED lighting products more available, convenient and reliable. In the movable light source field, the wireless- driven/charging LED lighting systems with rechargeable battery have a good market prospect. The movable LED lighting products are more convenient and safety with wireless power technique. And in the plant lighting cultivation field, the WD-LED lighting systems may float in the air or water without power cord, it is beneficial for designers to design more novel lighting products.

b.Contact less driven led integrated chip or module

In this section, we mainly research in wireless electrical energy transmission tech, LED integrated package tech, LED driver circuit tech.In recent years, many researchers are working on the monolithic GaN optoelectronic system. In the future research, the LED chips will be designed to be smaller to meet different application requirements. However, as we all know, the traditional LED chips must have positive and negative electrodes for electric connection and carrier injection. But the electrodes take a part of area on chips, determining the chip can’t be too small.This situation will be changed if wireless power technique is applied in the design of monolithic LED optoelectronic devices. the monolithic GaN optoelectronic device with wireless power technique include optoelectronic technology, TSV technology, multilayer metal interconnection technology, LED drive circuit technology. The monolithic LED chip can be powered without any electric connect, since a wireless power receiver is integrated in the chip. If this integrated technology can be achieved, it will be used in LED lighting field, decoration field, high resolution LED TV.

ADVANTAGES

There are several motivations or advantages for apply this technology to the design of LED lighting products, such as the following:

Advantages

Make LED lighting products more convenient and novel to consumers, by eliminating the wires as drive the lighting system.

Make LED lighting products safer and more reliable by eliminating the fire hazard and risk of short circuit with conductive interconnections, making the LED lighting system waterproof and explosion proof by removing the electric contacts and wires that connect LED lighting module with drive circuit or grid.

Make the design of LED lighting products more flexible by using wireless power technique, transferring electric power to LED lighting module through air, water, glass and plastic without any electric connection.

Improve the reliability by using wireless-driven method to separate the drive circuit from lightning chips.

electrical shock protection portable and environmentally sound.

CONCLUSION

Opportunities and challenges always go alone with the new technologies. As the wireless-driven LED system, different products will have different problems in the design and fabrication of new system. According to the design of different products and application field, suitable wireless power transmission should be chose. A new technology always finds its value only in that it can be applied in practical and commercial products. In many areas, the wireless power technique can be integrated with LED lighting or display system, which can make LED products more convenient or reliable compared to the traditional form or design method. And with the commercialization of wireless-driven LED products, more and more related applications will be found.

REFERENCE

1. Wikipedia.(2012,August7).Teslacoil[Online]Avaliable:http://en.wikipedia.org/wiki/Tesla coil

2. Liang Huang and Aiguo Patrick Hu, “An overview of capacitively coupled power transfer—a new contactless power transfer solution”, 2013 IEEE 8th Conference on Industrial Electronics and Applications(ICIEA), pp 461- 464. 3. http://en.wikipedia.org/wiki/Microwave_transmission 4. Vikash Choudhary and Satendar Pal Singh, “Wireless Power Transmission: An Innovative Idea”, International Journal of Educational Planning & Administration. ISSN 2249-3093 Volume 1, Number 3 (2011), pp. 203-210