1

WIRELESS DRIVEN LED SEMICONDUCTOR LIGHTNING SYSTEM

MALAVIKA SS7 FROLL NO-33

2

CONTENTS• Introduction• History of power transfer• Tesla coil• General principle and classification of wireless

power transfer• Electromagnetic induction• Capacitive coupling• Types of capacitive coupling• Resonant inductive coupling• Microwave transmission• LED• Application• Conclusion• Reference

3

INTRODUCTION

• Transmission of electrical energy from a power source to an electrical load without man-made conductors.

• The wireless-driven led (wd-led) -combine the advantages of wireless electrical power transfer and led semiconductor lighting technology

• Traditional led lighting system sensitive to rigid environment such as humidity, corrosive and flammable

• The wireless-driven LED lighting system should contain LED lighting module, wireless electrical power transfer system, LED driving circuit and electrical energy storage system.

 

4

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 

Tesla used his Tesla coil circuits to perform the first experiments in wireless power transmission at the turn of the 20th century

5

0PERATION

• The high electric field causes the air around the high voltage terminal to ionize and conduct electricity

• Colorful corona discharge, brush discharge• A Tesla coil is a radio frequency oscillator that drives an air-

core double-tuned resonant transformer to produce high voltages.

• Uses simple spark gap

Fig 1:tesla coil in operation

6

CONT..

 Transformer(T): to step the AC mains voltage up to a high enough voltage to jump the spark gap(5 and 30kV).

 Capacitor (C1): with the primary winding L1 forms tuned circuit of the Tesla transformer

 Spark gap(SG) that acts as a switch in the primary circuitTesla coil (L1, L2): an air-core double-tuned resonant transformer,

which generates the high output voltage. Capacitive electrode(E): in the form of a smooth metal sphere

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

Fig 2:spark excited tesla coil

7

GENERAL PRINCIPLE & CLASSIFICATION OF WPT

1.Electro magnetic induction• Known as inductive charging• The transmitter(L1) and receiver coils(L2) form

a transformer .•  AC through (L1) creates an oscillating magnetic

field (B) by Ampere's law.• The magnetic field passes through (L2), where it induces an

alternating EMF (voltage) by Faraday's law of induction,which creates an AC current in the receiver

Fig 3:electromagnetic induction

8

CONT..

• The power transferred increases with frequency and the mutual inductance M, which depends on the distance D between them

• A widely-used figure of merit is the coupling coefficient(K) ,equal to the fraction of magnetic flux through L1 that passes through L2.

• Safe way of connection, the products can be enclosed from air, water or plastic in the atmosphere.

• The transmission power and efficiency will change if the distance between the two coils become closer or farther

9

2.CAPACTIVE COUPLING

• In capacitive coupling (electrostatic induction), 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.

Fig 4 a)capacitive coupled power transfer b)simplified ckt

10

CONT..

• Voltage is applied to the transmitting plate, and the oscillating electric field induces an alternating potential on the receiver plate by electrostatic induction

• Causes an alternating current to flow in the load circuit• The amount of power transferred increases with

the frequency, capacitance between the plates, proportional to the area of the smaller plate and inversely proportional to the separation

11

CONT..

• Used for low power applications, because the very high voltages required to transmit significant power can be hazardous,cause side effects such as ozone production.

• Electric fields interact strongly with most materials, including the human body, due to dielectric polarisation.

• The field is largely confined between the capacitor plates ,reduces interferences

• Alignment requirements between the transmitter and receiver are less critical

12

TYPES

• Bipolar design:two transmitter plate two receiver plates.• Each transmitter plate is coupled to a receiver plate. • The transmitter oscillator drives the transmitter plates in opposite

phase by a high alternating voltage • The alternating electric fields induce opposite phase alternating

potentials in the receiver plates• This "push-pull" action causes current to flow back and forth

between the plates through the load.• The two plates in the receiving device must be aligned face to face

with the charger plates

13

• Unipolar design: the transmitter and receiver have only one active electrode,

• Either  ground or large inactive capacitive electrode serves as the return path for the current.

• The transmitter oscillator and the load is connected between the electrodes and a ground connection,

• Inducing an alternating potential on the nearby receiving electrode , causing alternating current to flow through the load and ground. 

14

3.RESONANT INDUCTIVE COUPLING

• Resonant inductive coupling or electro dynamic induction• Wireless transmission of electrical energy between two

magnetically coupled coils that are part of resonant circuits tuned to resonate at the same frequency.

• 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

15

CONT..• 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• Because the coil is highly resonant,energy placed in the coil dies

away relatively slowly , if a second coil is brought near it, the coil can pick up most of the energy before it is lost

• The fields used are predominately non-radiative , near field hardware is kept well within the 1/4 wavelength distance they radiate little energy from the transmitter to infinity. 

• If two coils resonate with the same frequency, a lot of energy moves from the transmitting coil to the receiving coils

16

4. MICROWAVE TRANSMISSION • Transmitting energy by the use of electromagnetic waves called

microwaves• Frequency range (1ghz to 300ghz)• Wavelength (30cm down to 1cm)• Distance covered by microwave signal depends on antenna

height.• To increase coverage each antenna has a built in repeater that

regenerates that signal before passing it on to the next antenna• Antennas are placed for each 25miles• Microwave power transmission belongs to a long-distance

power transmission technology.

17

• The 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.

It relies on three key elements: 1.Use of radio frequency to achieve transmission 2.Clear line of sight with no obstacle in path way 3.Regular relay stations required due to line of sight and cost

consideration

18

ADVANTAGE

• Multiple channel • Large bandwidth

DISADVANTAGE

• Towers are expensive to build• Signal absorption by atmosphere• Line of sight will be disrupted by obstacles

19

LED• LED is a PN junction diode which emits light when forward

biased• The amount of light output is directly proportional to forward

current.• N-type layer is formed on a P-type substrate by a diffusion

process. • Terminals from both layer make anode and cathode .• light energy is released at the junction when electrons and

holes are recombined.• After recombination the electrons in the conduction band of N-

region falls into the holes in the valance band of P-region .• The difference in energy between the conduction band and

valance band is radiated in the form of light  

20

• The semiconductor material used for manufacturing LED: Gallium arsenide-infrared radiation Gallium phosphide-red or yellow Gallium arsenide phosphide-red or green Gallium nitride-blue• Si and Ge is not used ,because they are heat producing

materials

21

ADVANTAGE• Products are more convenient by eliminating the wires in the

lighting system. • Safer and more reliable by eliminating the fire hazard and risk

of short circuit with conductive interconnections, • Waterproof and explosion proof by removing the electric

contacts and wires that connect led lighting module• More flexible by transferring electric power to LED lighting

module through air, water, glass and plastic without any electric connection.

• Improve the reliability• Electrical shock protection,• Portable and environmentally sound

22

CONCLUSION• Opportunities and challenges always go alone with the new

technologies.• 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 system

• And with the commercialization of wireless-driven LED products, more and more related applications will be found.

23

REFERENCE [1] 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

24