Wireless charging
Transcript of Wireless charging
WIRELESS CHARGING OF MOBILE PHONES USING
MICROWAVES
SARATH.S.KUMAR
BY
INTRODUCTIONCharging of mobile phones are becoming a problem
while travelling
This new technology of wireless charging will be a great relief for this
Here mobile phones can be charged from any where ,any time
We can charge our mobile phones by just making a call
Charging is done by converting the microwaves reaching the mobile phones to dc
MICROWAVESMicrowaves are emitted from objects such as cars and
planes, and from the atmosphere.
These microwaves can be detected to give information, such as the temperature of the object that emitted the microwaves.
Shorter microwaves are used in remote sensing.. Microwaves, used for radar, are just a few inches
long. Because microwaves can penetrate haze, light rain and snow, clouds and smoke.
Micro wave spectrum containing different band such as L band, S band etc
Here we have selected the license free 2.45 GHz ISM band for our purpose
The Industrial, Scientific and Medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes
SCHEMATIC DIAGRAM
TRANSMITTER DESIGN
• A magnetron is a main part of transmitter
magnetron
Magnetron
The MAGNETRON is a self-contained microwave oscillator.
There's a heated cathode (coloured yellow)
A ring-shaped anode surrounds the cathode (colored red).
When the electrons try to zip from cathode to anode, , they feel a force and follow a curved path (blue circle)
As the electrons nip past the cavities, the cavities resonate and emit microwave radiation
MAGNETRON OPERATION PHASE 1Cathode centre at high negative volts
Anode at zero volts
No magnetic field
Electrons move in straight line
Magnet added
North pole on top
South pole at bottom
Electrons curve to the right
Electrons curve more when the magnetic field is increased
MAGNETRON OPERATION PHASE 1
Green path Weak magnet. All cathode electrons reach anode
Red path Magnetic field increased to “critical” value. Anode current decreases to a small value.
yellow path Magnetic field increased further. Anode current drops to zero
Magnetic field adjusted to where electrons just fail to reach the anode, the magnetron can oscillate
MAGNETRON OPERATION PHASE 2
Interaction space between cathode and cavities
2 electric fields, ac & dc in interaction space
Polarity is one instant of ac (µ-wave) field
The dc field extends radially from cavities to cathode
Electrons near cavities move tangentially to cavities
Electrons approaching the positive sides are speeded up
Electrons departing the positive side and approaching the negative side are slowed down.
MAGNETRON OPERATION PHASE 3
12 cavity magnetron
Rotating 6 spoke space charge
Space charge gives µ-wave energy to the cavity keeping it oscillating
8 cavity magnetron
4 spoke wheel
MAGNETRON OPERATION PHASE 4
Assume dc field & rf fields on cavities (magnetron oscillating
Electron approaching cavity gives up energy to cavity
Electron slows down accordingly
Then electron speeds up gaining energy from dc field
Electron eventually reaches cavity (anode current)
RECIEVER DESIGNThe reciever consists ofA RECTIFYING PART The basic addition to the mobile phone is going to
be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity.
With the advent NANOTECHNOLOGY and MEMS the size of these devices can be brought down to molecular level.
SENSOR PART Another important part of our receiver circuitry is
a simple sensor. This is simply used to identify when the mobile phone user is talking.
Process of rectificationAN RECTIFYING ANTENNA rectifies received
microwaves into DC current
A rectenna comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converting it into electric power
Rectenna are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity
.A simple rectenna can be constructed from a
Schottky diode placed between antenna dipoles.
The diode rectifies the current induced in the antenna by the microwaves.
RECTIFYING ANTENNA CIRCUITARY
Sensor circuitryDetects if the mobile phone receives any message signal.
This is required, as the phone has to be charged as long as the user is talking.
A simple F to V converter would serve our purpose.
Thus the usage of simple F to V converters (LM2907.)would act as switches to trigger the rectenna circuit to on.
It acts as a switch for triggering the rectenna circuitry.
Thus on the reception of the signal the sensor circuitry directs the rectenna circuit to ON and the mobile phone begins to charge using the microwave power.
ADVANTAGESHas wide application..Can charge our mobile phones any where any
time even if the place is devoid of facilities for charging.
Wired chargers can be eliminated…Have a wide future scope…Could provide a new dimension in the
revelation of mobile phone.
CONCLUSION It have great advantage of mobile phone
users they cannot carry their chargersRectenna and sensors gives new dimension in
mobile phone Initial cost large
BATTERY FULL
QUESTIONS