Wireless charging

[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
1

www.ithubpage.blogspot.com

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
Asst. Professor,
Department Of Computer Applications
I.F.T.M, Moradabad

Mr. Rahul Mishra
Head of department
Department Of Computer Applications
I.F.T.M, Moradabad

Date:

2


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

3


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

4


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.

5


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

6

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.
7


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.

8


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 shortdistance 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
9


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
10


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.

11


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.

12


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.

13


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 socalled "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
14


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 omnidirectionally and efficiently, irrespective of the geometry of the surrounding
space, even when environmental objects completely obstruct the line-ofsight 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
15


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.

16


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.

17


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.

18


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.

19


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.

20


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.

21


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-soobvious 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.

22


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