Inductive coupling and resonant coupling are two methods for wirelessly transferring energy between coils. Inductive coupling uses electromagnetic induction to transfer power between transmitter and receiver coils that form a transformer, with the transmitter coil generating a magnetic field that induces a voltage in the secondary receiver coil. Resonant coupling uses coils tuned to the same resonance frequency, where an oscillating current in the transmitter coil creates a strong magnetic field that is converted into electric current in any coupled receiver coil within that magnetic field region. The efficiency of wireless power transfer is affected by factors like the air gap between coils and matching their resonance frequencies, as greater coupling occurs with smaller gaps and matched frequencies.

1. Inductive coupling
&
resonance coupling
BY: TAYYAB SADAQAT
ROLL#2K19-ELE-03

2. How energy transfer from one coil to
another in wireless systems?
In the wireless power transmission one coils works as transmitter while the
other works as a receiver. Whenever they will be placed together then these
coils will start transferring energy.

3. Inductive coupling
In inductive coupling (electromagnetic induction or inductive power transfer)
power is transferred between coils of wire by a magnetic field. The transmitter
and receiver coils together forms a transformer.

4. Inductive coupling
The primary and secondary couple circuits are in the form of coils to increase
the magnetic field of the circuits. In this ways the transmitter coil has current to
pass through it that generates a magnetic field.
This is coupled to the secondary coil and when there is a change in transmitter
primary current. This induces a voltage in the secondary receiver coil.

5. Resonant Coupling:
When we give electricity to the coil(magnetic resonator) the rapidly oscillating
current applied to the coil at a specific resonance frequency. It will create strong
magnetic field in a region of coil.
When we placed the second resonant coil of the same frequency, it will be
coupled. And it will convert that magnetic field into the electric current
anywhere in that magnetic field region.
This response is called highly coupled magnetic resonance.

6. Frequency Characteristics
As the air gap between the coils increase the coupling between the coils will be weakens.
Therefore, the impedance of the circuit changes as the air gap changes affecting the power
transfer efficiency and the resonance frequency.
When the gap is smaller, the coupling is strong, two resonance frequencies that permit power
transfer at maximum efficiency exists. Which means that the gap between coils and resonance
frequency directly affects the efficiency of power transfer.