Wireless charging

TEAM-F

What is Wireless charger??

A mobile charger works on the simple principal of conversion to DC.to acquire 5V output that is what exactly needed by the smartphone.

• Inverting(DC to AC)
• Magnetic Inductance
• Rectifying
• Filtration
• Voltage regulation(LM7805)

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What does wireless charger consists??

Wireless charger consists of:

1. Transmitter circuit
2. Receiver circuit

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Transmitter circuit

Transmitter circuit consists of

1. An inductor coil
2. 1kilo ohm resistors(2)
3. LED
4. Switch
5. DC Power supply(18V)
6. Z44 MOSFET

Receiver circuit

Receiver circuit consists of

1. An inductor coil
2. Rectifier
3. Capacitor(25V)
4. LM7805 Voltage regulator
5. Micro USB charging port

Inverting Z44-mosfet

• Basically the Z44 MOSFET is used here as an oscillator. The basic principle of oscillator is to convert unidirectional current flow from a DC source into an alternating waveform which is of the desired frequency, as decided by its circuit components.

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Inductor coil

• As the current carrying coil produces some magnetic field around it, if another coil is brought near this coil, such that it is in the magnetic flux region of the primary, then the varying magnetic flux induces an EMF in the second coil. If this first coil is called as Primary coil, the second one can be called as a Secondary coil. When the EMF is induced in the secondary coil due to the varying magnetic field of the primary coil, then such phenomenon is called as the Mutual Inductance. The flux represents the magnetic flux created around the coil.

Rectifier

• The full-wave rectifier converts both halves of the AC sine wave to positive-voltage direct current. The result is DC voltage that pulses at twice the frequency of the input AC voltage.

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• A full wave rectifier is defined as a type of rectifier that converts both halves of each cycle of an alternating wave (AC signal) into a pulsating DC signal. Full-wave rectifiers are used to convert AC voltage to DC voltage, requiring multiple diodes to construct.

capacitor

• Capacitor is a device that is used to store charges in an electrical circuit. A capacitor works on the principle that the capacitance of a conductor increases appreciably when an earthed conductor is brought near it. Hence, a capacitor has two plates separated by a distance having equal and opposite charges.
• Here in this experiment we use 1000uf/25V electrolytic capacitor.
• The job of the capacitor in the output filter of a DC power supply is to maintain a constant DC value by removing as much power ripple as possible. Because these capacitors have a DC value, they are actually storing a lot of energy that never gets used.

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Voltage Regulator

• The LM7805 is a voltage regulator that outputs +5 volts. A voltage regulator is a circuit that creates and maintains a fixed output voltage, irrespective of changes to the input voltage or load conditions. Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical components.
• Output Current up to 1.5A.
• High Power-Dissipation Capability.
• The LM7805 is a linear voltage regulator which uses linear, non-switching techniques for regulation of output voltage from power supply.
• Input voltage (7V-35V).
• Regulated output : 5V (4.8V-5.2V)

Light emitting diode

• A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it. When current passes through an LED, the electrons recombine with holes emitting light in the process. LEDs allow the current to flow in the forward direction and blocks the current in the reverse direction.
• Light-emitting diodes are heavily doped p-n junctions. Based on the semiconductor material used and the amount of doping, an LED will emit a coloured light at a particular spectral wavelength when forward biased.
• The colour of an LED is determined by the material used in the semiconducting element. The two primary materials used in LEDs are aluminium gallium indium phosphide alloys and indium gallium nitride alloys. Aluminium alloys are used to obtain red, orange and yellow light, and indium alloys are used to get green, blue and white light.�

• When the diode is forward biased, the minority electrons are sent from p → n while the minority holes are sent from n → p. At the junction boundary, the concentration of minority carriers increases. The excess minority carriers at the junction recombine with the majority charges carriers.
• The energy is released in the form of photons on recombination. In standard diodes, the energy is released in the form of heat. But in light-emitting diodes, the energy is released in the form of photons. We call this phenomenon electroluminescence. Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it. As the forward voltage increases, the intensity of the light increases and reaches a maximum.

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Brief overview

• This project demonstrates the concept of wireless charging. It works on the principle of transmission of power wirelessly from transmitter to receiver circuit. Z44 Inverting MOSFET converts DC signal into AC and then through the mutual induction, power is transmitted wirelessly from coil-1 in transmitter circuit to coil-2 in receiver circuit. The AC signal is then rectified to positive DC voltage and with the help of LM7805 voltage regulator, output is constantly maintained at +5V DC which is what exactly required by electronic devices for charging.