Wireless charging

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[WIRELESS CHARGING]

A Seminar Report

Submitted to M.J.P Rohilkhand University, Bareilly

In Partial Fulfillment of

Bachelor in Computer Application BCA III Year V Semester

Submitted By: Mohammad Affan

Department of Computer Applications

IFTM, Lodhiput Rajput, Delhi Road, Moradabad


CERTIFICATE This is to certify that the Seminar Report entitle “WIRELESS CHARGING” has been submitted by “Mr. Mohammad Affan” in partial in fulfillment for the requirement of the degree of Bachelor in Computer Applications BCA III Year, V semester for the academic Session 2012-13. This seminar work is carried out under the supervision and guidance of Mr. Deepak Sharma, Asst. Professor, MCA department, I.F.T.M, Moradabad and he/ she has been undergone the indispensable work as prescribed by M.J.P Rohilkhand University, Bareilly Mr. Deepak Sharma Mr. Rahul Mishra Asst. Professor, Head of department Department Of Computer Applications Department Of Computer Applications I.F.T.M, Moradabad I.F.T.M, Moradabad Date:


INDEX

Sr. No. Name of Topic

1. Abstract

2. Introduction

3 History

4 Types of wireless charging

5. Inductive charging

6. Radio charging

7. Resonance charging

8. Recent inventions

9. Application

10. Advantage and Disadvantage

11. Conclusion


Lists of figure

Sr. No. Name of Figure

1. Wireless charger

2. Resonant copper coil

3. Inductive charger

4. Wireless charger circuit diagram

5. Power mat


ABSTRACT

Wireless charging is any of several methods of charging batteries without

the use of cables or device-specific AC adaptors. Wireless charging can be used

for a wide variety of devices including cell phones, laptop computers and MP3

players as well as larger objects, such as robots and electric cars.

There are three methods of wireless charging: inductive charging, radio

charging, and resonance charging. In inductive charging, an adapter equipped with

contact points is attached to the device's back plate. When the device requires a

charge, it is placed on a conductive charging pad, which is plugged into a socket.

Radio charging is used for charging items with small batteries and low power

requirements. Resonance charging is used for items that require large amounts of

power.

The technology provides a wide range of benefits, including better

portability; lower cost (once companies can assume everyone already has a

universal charger) and the end of having to guess which chargers go with what

gadgets. Wireless charging means the end of charging connectors that break, wear

out or become misaligned.


INTRODUCTION

Wireless charging is any of several methods of charging batteries

without the use of cables or device-specific AC adaptors. Wireless charging

can be used for a wide variety of devices including cell phones, laptop

computers and MP3 players as well as larger objects, such as robots and

electric cars. Imagine a future in which wireless power transfer is feasible:

cell phones, household robots, mp3 players, laptop computers and other

portable electronics capable of charging themselves without ever being

plugged in, freeing us from that final, ubiquitous power wire. Some of these

devices might not even need their bulky batteries to operate


THE HISTORY OF WIRELESS CHARGING

In 1901, scientific wunderkind Nikola Tesla began constructing

Wardenclyffe Tower, a facility intended to wirelessly transmit power

between America and Europe. The tower was never completed and was

dynamited by the US government in 1917, but its underlying principle — the

use of electrodynamics induction to transfer electromagnetic energy without

the need for wires — lived on. Its latest incarnation has delivered a range of

mainstream devices that allow you to recharge your Smartphone or portable

gaming console without actually plugging them in.

The principle of wireless charging has been around for over a century,

but only now are we beginning to recognize its true potential. First, we need

to be careful about how liberal we use "wireless" as a term; such a word

implies that you can just walk around the house or office and be greeted by

waves of energy beamed straight to your phone. As Space Age-ish as it

sounds, that kind of stuff actually is in the works, but it's still a long ways

from getting to market and even further from turning into a mainstream

solution. So for the universe as we see it today, the word merely refers to not

using.

We're referring, largely, to inductive charging the ability to

manipulate an electromagnetic field in order to transfer energy a very short

distance between two objects (a transmitter and receiver). It's limited to

distances of just a few millimeters for the moment, but even with this

limitation, such a concept will allow us to power up phones, laptops,

keyboards, kitchen appliances, and power tools from a large number of

places: in our homes, our cars, and even the mall. And that's just for starters.


WIRELESS BATTERY CHARGING BASICS Wireless battery charging uses an inductive or magnetic field between two objects which are typically coils to transfer the energy from one to another. The energy is transferred from the energy source to the receiver where it is typically used to charge the battery in the device. This makes wireless charging or inductive charging ideal for use with many portable devices such as mobile phones and other wireless applications. However they have also found widespread use in products such as electric toothbrushes where cordless operation is needed and where connections would be very unwise and short-lived. The system is essentially a flat form of transformer - flat because this makes it easier to fit into the equipment in which it is to be used. Many wireless battery charging systems are used in consumer items where small form factors are essential.

Wireless battery charging concept

The primary side of the transformer is connected to the energy supply that will typically be a mains power source, and the secondary side will be within the equipment where the charge is required. In many applications the wireless battery charging system will consist of two flat coils. The power source is often contained within a pad or mat on which the appliance to be charged is placed.


There are three types of wireless charging.

1. Inductive charging

2. Radio charging

3. Resonance charging

1) Inductive charging

Inductive charging charges electrical batteries using electromagnetic

induction. A charging station sends energy through inductive coupling to an

electrical device, which stores the energy in the batteries. Because there is a

small gap between the two coils, inductive charging is one kind of short-

distance wireless energy transfer.

Wireless energy transfer or wireless power transmission is the process

that takes place in any system where electrical energy is transmitted from a

power source to an electrical load, without interconnecting wires. Wireless

transmission is useful in cases where instantaneous or continuous energy

transfer is needed, but interconnecting wires are inconvenient, hazardous, or

impossible.

While the physics are identical, wireless energy transfer is slightly

different from wireless transmission for the purpose of telecommunications

(the transferring of information), such as radio, where the signal-to-noise

ratio, or the percentage of power received, becomes critical if it is too low to


recover the signal successfully. With wireless energy transfer efficiency is

the more important parameter.

The most common form of wireless power is carried out using induction,

followed by electrodynamics induction. Other technologies for wireless

power include those based upon microwaves and lasers. Induction The

action of an electrical transformer is the simplest instance of wireless energy

transfer. The primary and secondary circuits of a transformer are not directly

connected. The transfer of energy takes place by electromagnetic coupling

through a process known as mutual induction. (An added benefit is the

capability to step the primary voltage either up or down.) The battery

chargers of a mobile phone or the transformers in the street are examples of

how this principle can be used. Induction cookers and many electric


toothbrushes are also powered by this technique. The main drawback to

induction, however, is the short range. The receiver must be very close to the

transmitter or induction unit in order to inductively couple with it.

Induction chargers typically 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 converts it back into electrical current to charge

electrical transformer.


2) Radio charging

Various methods of transmitting power wirelessly have been known for

centuries. Perhaps the best known example is electromagnetic radiation,

such as radio waves. While such radiation is excellent for wireless

transmission of information, it is not feasible to use it for power

transmission. Since radiation spreads in all directions, a vast majority of

power would end up being wasted into free space.

One can envision using directed electromagnetic radiation, such as

lasers, but this is not very practical and can even be dangerous. It requires an

uninterrupted line of sight between the source and the device, as well as a

sophisticated tracking mechanism when the device is mobile. Radio

charging is a wireless charging method used to charge items with small

batteries and low power requirements, such as watches, hearing aids,

medical implants, cell phones and wireless keyboards and mice. Radio

waves are already in use to transmit and receive cellular telephone,

television, radio and Wi-Fi signals. They work similarly for electrical

transmission. A radio wave, once transmitted, propagates in all directions

until it reaches an antenna tuned to the proper frequency to receive it. Here's

one example of how that capacity is used for radio charging.


A company called Powercast has devised two units used to transmit and

receive radio waves for energy. The transmitter, called the "Power caster,"

sends a low-power radio wave at a fixed frequency. The receiver, called the

"Power harvester" can be affixed to any low-power device. When the Power

harvester is set to the same frequency as the Power caster, it will power the

device and will charge the unit's battery.

Radio charging is only effective for small devices. The battery of a laptop

computer, for example, requires more power than radio waves can deliver.

The range also limits the effectiveness of radio charging, which works on the

same principle as an AM/FM radio does: The closer the receiver is to the

transmitter, the better reception will be. In the case of wireless radio

charging, better reception translates to a stronger charge for the item.


3) Resonance charging .

Two resonant objects of the same resonant frequency tend to exchange

energy efficiently, while interacting weakly with extraneous off-resonant

objects. A child on a swing is a good example of this. A swing is a type of

mechanical resonance, so only when the child pumps her legs at the natural

frequency of the swing is she able to impart substantial energy.

Another example involves acoustic resonances: Imagine a room with 100

identical wine glasses, each filled with wine up to a different level, so they

all have different resonant frequencies. If an opera singer sings a sufficiently

loud single note inside the room, a glass of the corresponding frequency

might accumulate sufficient energy to even explode, while not influencing

the other glasses. In any system of coupled resonators there often exists a so-

called "strongly coupled" regime of operation. If one ensures to operate in

that regime in a given system, the energy transfer can be very efficient.

Magnetic coupling is particularly suitable for everyday applications

because most common materials interact only very weakly with magnetic

fields, so interactions with extraneous environmental objects are suppressed

even further. "The fact that magnetic fields interact so weakly with

biological organisms is also important for safety considerations."

The design consists of two copper coils, each a self-resonant system. One

of the coils, attached to the power source, is the sending unit. Instead of

irradiating the environment with electromagnetic waves, it fills the space

around it with a non-radioactive magnetic field oscillating at MHz


frequencies. The non-radioactive field mediates the power

exchange with the other coil (the receiving unit), which is specially designed

to resonate with the field. The resonant nature of the process ensures the

strong interaction between the sending unit and the receiving unit, while the

interaction with the rest of the environment is weak.

The crucial advantage of using the non-radioactive field lies in the fact

that most of the power not picked up by the receiving coil remains bound to

the vicinity of the sending unit, instead of being radiated into the

environment and lost. With such a design, power transfer has a limited

range, and the range would be shorter for smaller-size receivers.

Still, for laptop-sized coils, power levels more than sufficient to run a

laptop can be transferred over room-sized distances nearly omni-

directionally and efficiently, irrespective of the geometry of the surrounding

space, even when environmental objects completely obstruct the line-of-

sight between the two coils. As long as the laptop is in a room equipped with

a source of such wireless power, it would charge automatically, without

having to be plugged in. In fact, it would not even need a battery to operate

inside of such a room. In the long run, this could reduce our society's

dependence on batteries, which are currently heavy and expensive.

At first glance, such a power transfer is reminiscent of relatively

commonplace magnetic induction, such as is used in power transformers,

which contain coils that transmit power to each other over very short

distances. An electric current running in a sending coil induces another


current in a receiving coil. The two coils are very close, but they do not

touch. However, this behavior changes dramatically when the distance

between the coils is increased, "Here is where the magic of the resonant

coupling comes about. The usual non-resonant magnetic induction would be

almost 1 million times less efficient in this particular system.


Recent inventions

Powermat

The mat, available in both a Portable and a more elegant Home model,

will include a universal Powercube in the box, including 8 power tips for

compatibility with popular handheld devices. Unlike other "wireless"

charging devices, such as the Wild charge Touch Charge, which requires

direct contact with a conductive surface, the Powermat uses inductive

technology, which does not require a physical connection.

The Powermat can charge up to three devices at a time and requires only

one cord--to receive power from an AC outlet. You simply drop your device

(with attached Powermat receiver) at designated points on the Powermat's

surface to charge, with an indicator light and tone confirming a connection.

The company claims that the Powermat, unlike many third-party charging

products, is able to charge mobile devices just as quickly as with its

packaged chargers, and often more efficiently--the Powermat stops powering

a device once it's fully charged, "checking in" to top off the juice at

designated intervals.


The first two Powermat products, demonstrated at CES 2009, are the

company's first to come to market; but their wireless charging technology

has the potential to completely transform the way we power and charge

devices around the home. Powermat says that future products will also

include support for data transmission, and will be integrated in mobile

devices--as demonstrated by the Palm Pre and Touchstone accessory.


Application

Wireless charging can be used for a wide variety of devices including cell

phones, laptop computers and MP3 players as well as larger objects, such as

robots and electric cars. There are three methods of wireless charging:

inductive charging, radio charging and resonance charging.

Inductive charging is used for charging mid-sized items such as cell

phones, MP3 players and PDAs. In inductive charging, an adapter equipped

with contact points is attached to the device's back plate. When the device

requires a charge, it is placed on a conductive charging pad, which is

plugged into a socket.

Radio charging is used for charging items with small batteries and low

power requirements, such as watches, hearing aids, medical implants, cell

phones, MP3 players and wireless keyboard and mice. Radio waves are

already in use to transmit and receive cellular telephone, television, radio

and Wi-Fi signals. Wireless radio charging works similarly. A transmitter,

plugged into a socket, generates radio waves. When the receiver attached to

the device is set to the same frequency as the transmitter, it will charge the

device's battery.


Resonance charging is used for items that require large amounts of

power, such as an electric car, robot, vacuum cleaner or laptop computer. In

resonance charging, a copper coil attached to a power source is the sending

unit. Another coil, attached to the device to be charged, is the receiver. Both

coils are tuned to the same electromagnetic frequency, which makes it

possible for energy to be transferred from one to the other.The method

works over short distances (3-5 meters).

The idea of wireless power transmission is not new. In 1899, Nikola

Tesla wirelessly transmitted 100 million volts of electricity 26 miles to light

200 bulbs and run an electric motor. However, at that time direct current

(DC, which is the wired method) and alternating current (AC) were

competing technologies. DC, backed strenuously by Thomas Edison,

emerged the winner.


Advantages and disadvantages:

The major advantage of the inductive approach over conductive charging is

that there is no possibility of electrocution as there are no exposed

conductors. This advantage also makes the approach attractive for implanted

medical devices that require periodic or even constant external power.

Prior technologies for inductive charging have used lower frequencies

and older drive technologies, and generally charge slowly and generate heat

for most portable electronics,[citation needed] though the technology is used

in some electric toothbrushes and wet/dry electric shavers, partly for the

advantage that the battery contacts can be completely sealed to prevent

exposure to water.

Newer approaches with ultra thin coils, higher frequencies and

optimized drive electronics provide chargers and receivers that are compact,

efficient and can be integrated into mobile devices or batteries with minimal

change. These technologies provide charging time that are the same as wired

approaches and are finding their way into mobile devices rapidly.


Conclusion

Wireless charging means the end of charging connectors that break, wear out

or become misaligned.

A single charging pad will be able to juice all your gadgets, so you

won't have to match this charger with that gadget, or replace an overpriced

charger when you lose it.

It also makes it easier to build mobile devices that - like your toothbrush

- are waterproof, dustproof and more rugged.

The technology provides a wide range of other obvious and not-so-

obvious benefits, including better portability, lower cost (once companies

can assume everyone already has a universal charger) and best of all the end

of having to guess which chargers go with what gadgets.

Wireless charging

Education

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