Wireless Mobile

Charger
REVIEW-3

-Aditya Mahajan (16BEE008)

-Dhruvil Patwa (16BEE054)
AS PREVIOUSLY
DISCUSSED
 HISTORY

• In 1902 Tesla filed a patent titled “Apparatus for Transmitting Electrical

Energy” in which he describes a device that he believed could transmit electrical
power from one conductor to another without the need for wires.
• An early example of inductive power transfer is the crystal radio which used the
power of the radio signal itself to power headphones.
• In 2006, researchers at the MIT reported that they had discovered an efficient
way to transfer power between coils separated by a few meters.
• In August 2009, a consortium of interested companies called the Wireless
Power Consortium announced they were nearing completion for a new industry
standard for lowpower Inductive charging called Qi.
• More than 180 members of WPC include industry leaders in mobile phones,
consumer electronics, batteries, semiconductors, components, wireless power
technology and infrastructure.
● On November 21, 2012 HTC launched the droid DNA, which also supports the Qi
standard.
● October 31, 2013 Google and LG launched the Nexus 5 which also supports inductive
charging with Qi,.
● April 14,2014 Samsung launched the Galaxy S5 that supports Qi wireless charging with
either a wireless charging back or receiver.
 FUTURE TECHNOLOGIES

● The Silicon Valley startup Pi says they have found a way to charge phones and tablets by
simply placing the devices near its cone-like charger. If the company’s claims are true, the
Pi charger would be the world’s first contactless charger.
● The Pi charger emanates a magnetic fields which the company says can efficiently charge
a phone or tablet up to a foot away from your device.
● Apple introduced Airpower, it’s wireless charging mat in it’s WWDC 2018 event. It
basically is a wireless charger that can charge multiple apple products at the same time.
● Airpower uses induction, where an electromagnetic field is used to r=transfer over from
the airpower to a device. When you place your device on the Airpower, it receives a signal
from the pad to basically ‘handshake’ with the device lie compatibility, charge capacity
etc. If everything checks out, charging proceeds.
 PROCESS OF WIRELESS CHARGING

● ELECTROMAGNETIC INDUCTION

Electromagnetic Induction is a process where a conductor placed in a changing magnetic field (or
a conductor moving through a stationary magnetic field) causes the production of a voltage
across the conductor. This process of electromagnetic induction, in turn, causes an electrical
current-it is said to induce the current.

Faraday explained electromagnetic induction using a concept he called lines of force. Coils of
wire in the base station (the charging plate) create a magnetic field as the current passes
through. This field can induce an electrical current in an adjacent coil of wire without actually
touching it.
TECHNIQUES FOR WIRELESS CHARGING

● MAGNETIC INDUCTIVE COUPLING

● MAGNETIC RESONANCE COUPLING
● MICROWAVE RADIATION
MAGNETIC INDUCTIVE COUPLING

Magnetic inductive coupling happens when a

primary coil of an energy transmitter
generates predominant varying magnetic
field across the secondary coil of the energy
receiver within the field, generally less than
the wavelength.

The near-field power then induces

voltage/current across the secondary coil of the
energy receiver within the field. This voltage can
be used by a wireless device.
MAGNETIC RESONANCE COUPLING

Magnetic resonance coupling , as shown in

Fig., is based one vane scent wave coupling
which generates and transfers electrical
energy between two resonant coils through
varying or oscillating magnetic fields.

As the resonant coils, operating at the same

resonant frequency, are strongly coupled,
high energy transfer efficiency can be
achieved with small leakage to non-resonant
externalities.
MICROWAVE RADIATION

Microwave radiation utilizes microwave as a

medium to carry radiant energy. Microwaves
propagate over space at the speed of light,
normally in line-of-sight.

The power transmission starts with the AC to

DC conversion, followed by a DC-to-RF
conversion through magnetron at the
transmitter side. After propagated through the
air, the microwaves captured by the receiver
rectenna are rectified into electricity again.
MAGNETIC INDUCTIVE MAGNETIC RESONANCE MICROWAVE RADIATION
COUPLING COUPLING
Operational in close Operational in distance range of Long transmission distance
distance ( approx 30 cm). upto a metre.
Most used wireless Technology under development. Usually avoided due to safety
technology. conncerns.
Based on the principle of Based on the principle of EMI. Based on microwave radiation.
EMI.
Can charge only one Can charge multiple devices Can charge multiple devices.
device.
BLOCK DIAGRAM
WORKING

● It is clear that it requires a wireless power transmitter & a wireless power receiver.

● Transmitter coil converts the DC signal from oscillator to high frequency AC power
signal.

● This high frequency alternating current, which is linked with the wireless power
transmitting coil, would create an alternating magnetic field in the coil due to induction,
to transmit energy.

● In the wireless power receiver power section, the receiver coils receives that energy as an
induced alternating voltage (due to induction) in its coil and a rectifier in the wireless
power receiver section converts that AC voltage to DC voltage.

● Finally this rectified DC voltage would be feed to the load through a voltage controller
section.
DC POWER SOURCE

● It consists of a step down transformer that step downs the supply voltage to a desired
level , and a rectifier circuit to convert that AC signal to DC signal.

● AC supply of 220V is supplied to the circuit, then transformer is connected which

converts this 220V to 18V supply.
OSCILLATOR CIRCUIT

● An oscillator is an electronic device

for generating am AC signal voltage.
● The frequency of the generated signal
depends on the circuit constants.
● An oscillator is a back and forth
motion.
TRANSMITTER COIL

For this Wireless power transmission

mobile charger circuit using inductive
coupling project, we use 6mm
enamelled wire (Magnet wire) for
constructing the transmitter coils.
Actually this enamelled wire is a
copper wire, which has a thin layer of
insulation coatings on it. Here the
transmitter coil is constructed with a
diameter of 16.5cm or 6.5 inches and
8.5 cm of length
WIRELESS POWER RECIEVER SECTION

● The receiver section consists of

receiver coil, rectifier circuit and a
voltage regulator IC. The AC current
flowing through the transmitter coil
creates a magnetic field.
WIRELESS POWER RECIEVER SECTION

● The receiver section consists of receiver coil, rectifier circuit and a voltage regulator IC.
The AC current flowing through the transmitter coil creates a magnetic field.
● When we place the receiver coil with in a specific distance from this transmitter coil, the
magnetic field in the transmitter coil extends to this receiver coil, and it induces an AC
voltage and generates a current flow in the receiver coil of the wireless charger.
● The rectifier circuit in the receiver section converts this AC voltage in to DC and the
voltage regulator IC helps to provide a constant limited regulated output voltage to the
load for charging the low power devices. LM 7805 voltage regulator IC is used because
the IC gives a regulated 5V as its output and it don’t allow more than 5V to the output.
REVIEW - 3
TRANSMITTER COIL CIRCUIT
MODEL

In the transmitter circuit section, we use-

● 2 enhancement power MOSFET (IRF540 – Q1, Q2)
● 2 choke coils (L1 & L2)
● Capacitor C
● Diode D1, D2
● Transmitter coil L
● Resistors R1,R2,R3 & R4
WORKING

● When power is given to the oscillator circuit, the DC current starts flowing through the
two sides of the coil (L1&L2) and also to the Drain terminals of the MOSFET.
● During the same instant, voltage appears on gate terminal of both the transistors and
tries to turn ON the transistors.
● Any one of the transistor will be faster than the other and it will turn ON first.
● Assume that Q1 will be turning on first, and then Q1’s drain voltage will be clamped to
near ground.
● At the same time, Q2 will be in less conductive state or in off state, then Q2’s drain
voltage will rise to peak and starts to fall due to the tank circuit formed by the capacitor C
and the primary coil of oscillator through one half cycle. The operating frequency of the
oscillator is determined by the resonance formula given below

F = ½ × π × √ (LC)
RECIEVER CIRCUIT DIAGRAM
MODEL

● Diode, D1, D2, D3, D4: D4007

● Resistor, R 1k ohm
● Voltage Regulator IC: IC LM 7805
● Receiver coil, L: 1 .235 μH

Capacitors:
● C1: 6.8 nF
● C2: 220 μF
WORKING

● The AC current flowing through the transmitter coil creates a magnetic field.
● When we place the receiver coil with in a specific distance from this transmitter coil, the
magnetic field in the transmitter coil extends to this receiver coil, and it induces an AC
voltage and generates a current flow in the receiver coil of the wireless charger.
● The rectifier circuit in the receiver section converts this AC voltage in to DC and
the voltage regulator IC helps to provide a constant limited regulated output voltage to
the load for charging the low power devices.
THANK
YOU