Wireless Power Transfer and Inductive Charging

Wireless Power Transfer

• Wireless power transfer (WPT) efficiently transmits electricity without wires.
• WPT can be used for charging various devices simultaneously with a single power outlet.
• Inductive coupling is a simple and effective method for WPT, transferring power through magnetic fields.

Inductive Coupling

• Inductive coupling works on the principle of electromagnetism.
• When a wire is near a magnetic field, a magnetic field forms in that wire; transferring energy via magnetic fields.
• Two circuits are magnetically coupled if a portion of one circuit's magnetic flux interlinks with another circuit.
• Mutual inductance measures the inductive coupling between two conductors.

Inductive Charging

• Inductive charging uses electromagnetic fields to transfer energy between coils.
• A charging station's induction coil creates an alternating electromagnetic field.
• The portable device's induction coil captures the power, converting it back into electrical current to charge the battery.
• Resonant inductive coupling is used for longer distances.

Inductance of Coil and Coil Design

• Real inductors contain resistance and capacitance values.
• Losses in core material and parasitic capacitance values of the wire influence the inductor's behavior at high frequencies.

Circuit Diagrams

• Diagrams of the transmitter and receiver circuits are provided, along with component details and values.

Components Used in Transmitter

• A list of components used in the transmitter circuit with their corresponding values or codes.

Components Used in Receiver

• A list of components used in the receiver circuit with their corresponding values or codes.

Components Specification (Capacitor)

• Capacitors store electrical energy; consisting of two conductors, insulated from each other.
• A parallel plate capacitor is a simple example.
• If equal positive and negative charges are deposited on the plates, the capacitor is charged.

Resistors

• Resistors are components that resist the flow of electrons, causing energy loss in the form of heat.
• Resistors' values are measured in ohms.

Diodes

• Diodes allow current flow in one direction but block it in the opposite direction.
• A P-N junction diode, consisting of p- and n-type materials, is a common type.
• Diodes' direction of current flow depends on whether they are forward or reverse biased.

MOSFET

• MOSFETs are more advanced field-effect transistors (FETs).
• MOSFETs are designed to solve the disadvantages of other FETs. These include high drain resistance, moderate input impedance, and slow operation.
• MOSFET usage is suitable owing to their lightly doped substrate which is diffused with a heavily doped region.

Radio Frequency Choke

• Inductors and RF chokes are similar.
• Inductors/RF chokes' design varies to either choke off or transmit high/low-frequency alternating current (AC) signals.
• If high-frequency impedance is needed, a larger inductance is needed.

Working of Transmitter

• The transmitter module is comprised of a DC power source, oscillator circuit, and transmitter coil.
• This arrangement converts a DC supply to high-frequency AC supply, which produces an alternating magnetic field.

Working of Oscillator

• The oscillator circuit (crucial for WPT) utilizes components (chokes, MOSFETs, capacitors) to generate specific oscillating current flows for efficiency.
• Oscillator runs at a frequency that depends on inductance values and capacitive values of components.

Working of Receiver

• The receiver module consists of a receiver coil, rectifier circuit, and voltage regulator IC.
• An AC voltage is induced in the receiver coil; rectified to DC by a rectifier.
• A voltage regulator circuit controls the output voltage.

Operation of Bridge Rectifier

• During a positive AC half-cycle (input), diodes D1 and D3 are forward biased and conduct.
• During a negative AC half-cycle, diodes D2 and D4 are forward biased.

Voltage Regulator IC

• A voltage regulator IC automatically maintains a constant voltage level.
• Used for controlling the output voltage for the receiver.

Buck Converter

• A buck converter converts a higher DC voltage to a lower one with low power loss.
• This is an optional component but necessary when you need to increase current at the output.

Conclusion

• The project successfully designed and implemented a wireless charging system.
• Resonant inductive coupling is effective for wireless power transfer.

Possible Applications

• Wireless chargers for various devices (phones, tablets, etc.)
• Public charging stations
• Usage with various items such as TV remotes, cordless tools, hearing aids

Advantages

• Removes wires, making use more user friendly. Simplifies and is more convenient.

Disadvantages

• Higher power loss with greater distances. Increase in distances correlates with loss.

Appendix

• Datasheets for specific electronic components (MOSFET, diodes, voltage regulators).

This quiz explores the concepts of wireless power transfer (WPT) and inductive coupling. Learn how these technologies use electromagnetic fields to charge devices without the need for wires. Test your understanding of mutual inductance and the principles behind efficient energy transmission.