Wireless power transfer (WPT) allows the transmission of electrical energy without physical connections, primarily through electromagnetic induction. It includes techniques like near-field methods (inductive and capacitive coupling) and far-field methods (microwave and laser transmission), each having unique advantages, applications, and challenges. Ongoing advancements in WPT promise enhanced convenience for powering devices, particularly in consumer electronics, electric vehicles, and medical applications.

1. Guided by –
“ Wireless Power Transfer ”

2. CONTENT
⮚ What Is It ?
⮚ History
⮚ Necessity Of WPT
⮚ Types Of WPT
⮚ Near Field Techniques
⮚ Far Field Techniques
⮚ Conclusion

3. WHAT IS IT?
► Wireless power transfer (WPT), wireless energy transmission (WET),
or electromagnetic power transfer is the transmission of electrical
energy without wires as a physical link.
► In this system a transmitter device, transmits power to a receiver device,
through the phenomenon of electromagnetic induction.

4. HISTORY
► In 1890, Nikola Tesla concluded that power could be transferred between two
objects wirelessly via an electromagnetic field.
► He demonstrated wireless transmission by "electrostatic induction" during an
1891 lecture at Columbia College.
► He had a vision for “world wireless system”
► Wardenclyffe Tower- Tower built to achieve this
purpose

5. NECCESSITY OF WPT
▪ Environmental protection and economical
▪ Reduction of transmission losses
▪ Charging of multiple devices
▪ Prevents corrosion and sparking
▪ Maintenance cost is reduced
▪ Eliminating charging cords - provision for compact and portable
devices
▪ Reduced power failures

6. TYPES OF WPT
❑NEAR FIELD TECHNIQUES
▪ Inductive Coupling
▪ Resonant Inductive Coupling
▪ Capacitive Coupling
❑FAR FIELD TECHNIQUES
▪ Microwave Power Transmission
▪ Laser Power Transmission

7. NEAR FIELD TECHNIQUES
❑INDUCTIVE COUPLING
► In this system there is a transmitter coil and a receiver coil which represent the model of a
transformer and power transfer is through electromagnetic induction
► The power transferred depends on frequency and mutual inductance M of the circuit.
► The coefficient of coupling is given by k=M/sqrt(L1*L2).
► If the two coils are aligned and close together
then all the flux passes from L1 to L2 and efficiency
approaches 100%

8. ❑ INDUCTIVE COUPLING
APPLICATIONS
► Electric tooth brushes, shavers, cardiac pacemakers, insulin pumps etc..
► Wireless charging pads to charge electronic devices
► To charge electric vehicles
MERITS
► Reduction in copper losses and heat generation
► Shock proof
DEMERITS
► The coils must be very close to each other (within centimeters)
► It is usually one to one
► Flux confinement cores have to be used

9. ❑ RESONANT INDUCTIVE COUPLING

10. ❑ RESONANT INDUCTIVE COUPLING
▪ It is the wireless transmission of electrical energy between two magnetically coupled
coils that are part of a resonant circuit (also called LC Circuit or tank circuit)
▪ Resonance is a phenomenon in which a material naturally oscillates at a specific
frequency, called “resonant frequency”
▪ The transmitter coil’s frequency is called antiresonant frequency (parallel resonant
frequency), and that of receiver’s is called the resonant frequency (serial resonant
frequency).
▪ When the transmitter is driven with resonant frequency, the circuit starts resonating and
the energy of the primary coil oscillates and is picked up by the receiver coil before it
dies out & since the phases of the magnetic fields of both the coils are now synchronized
,maximum voltage is generated on the receiver coil due to the increase of the mutual
flux.

11. ❑RESONANT INDUCTIVE COUPLING
MERITS
▪ Better charging range
▪ Ability to charge multiple devices at the same time.
▪ Higher efficiency when compared to inductive coupling
DEMERITS
▪ Relatively low efficiency due to flux leakage
▪ Greater circuit complexity
▪ Because of the high operating frequencies, potential electromagnetic interference (EMI) challenges.
APPLICATIONS
▪ Charging portable devices , biomedical implants, electric vehicles, powering buses, trains,
MAGLEV, RFID, smartcards.

12. ❑ CAPACITIVE COUPLING
► It is also referred to as electric coupling.
► Power is transferred by electrostatic induction between two electrodes forming
a capacitance with the intervening space as the dielectric
► The amount of power transferred increases with the frequency and
the capacitance between the plates, which is proportional to the area of the smaller
plate and inversely proportional to the separation.

13. ❑ CAPACITIVE COUPLING
MERITS
► Reduced interference
► Alignment requirements between the source and load are less critical.
DEMERITS
► Used in a low power applications only
► Electric fields interact strongly with most materials, including the human body causing excessive
electromagnetic field exposure
APPLICATIONS
► Charging battery powered portable devices
► Wireless power transfer in biomedical implants
► Means of transferring power between substrate layers in integrated circuits.

14. FAR-FIELD (RADIATIVE) TECHNIQUES
❑MICROWAVE POWER TRANSMISSION(MPT)
► AC is converted to DC
► DC is converted to microwaves using a magnetron
► Microwaves are received by a rectenna which converts them back to DC
► DC is converted to AC to be fed to the load

15. ❑MICROWAVE POWER TRANSMISSION(MPT)
MERITS
► Long distance power transmission
► High conversion efficiencies (rectenna efficiency is >95%)
DEMERITS
► High frequency rays- Injurious to health
► Expensive as compared to other methods
APPLICATIONS
► Aiding renewable energy , by means of satellites collecting sunlight and sending power back to Earth.
► In 1964, a miniature helicopter propelled by microwave power had been demonstrated
► Battery-free cameras and temperature sensors were powered using transmissions from Wi-Fi routers

16. ❑ LASERS
► The laser beam of high intensity is thrown from some specific distance to the load end.
► At the load end highly efficient photo voltaic cells convert light energy of the laser into electrical
energy.

17. ❑ LASERS
MERITS
► Compact size
► No radio-frequency interference
► Access control
DEMERITS
► Laser radiation is hazardous
► PV cells have limited efficiency - 40-50% only
► Atmospheric absorption and scattering -up to 100% losses.
► Direct line of sight with the target is a must
APPLICATIONS
► Lightweight unmanned model plane powered by a laser beam.
► Used in military and aerospace works (space elevator)

18. IMPLEMENTATION
▪ PowerLight Technologies - American engineering firm transmitting power via lasers.
- Primary products are power-over-fiber
▪ New Zealand- Powerco signed a deal with Emrod
- Uses MPT-2KW, 70%efficiency
▪ Aglaya, an Indian Defence Company's Research and Development unit has used WET
to charge devices in the range of 3 -12 Volts under any weather conditions.
▪ Inductive coupling WPT was adopted by the Hitachi Maxell and Murata companies to
charge an iPad.
▪ WPT was used to charge an electric bus by Hino Motors Ltd. and Showa Aircraft
Industry
▪ Toyota Inc. and Toyohashi University of Technology proposed WET for electric vehicles

19. Conclusion
► In conclusion, wireless power transfer (WPT) represents a significant
advancement in energy transmission technology. Its potential to enhance
convenience and efficiency in powering devices without the limitations of
traditional wired connections is profound. As we explored various methods,
such as inductive, capacitive, and resonant coupling, it’s clear that each has
unique applications and benefits.
► The ongoing research and development in WPT are paving the way for
innovative solutions in consumer electronics, electric vehicles, and medical
devices. While challenges such as efficiency, distance limitations, and safety
remain, the future of wireless power holds great promise. By continuing to
advance this technology, we can create a more connected and energy-
efficient world.

20. THANK YOU