Wireless power transfer,tYPES OF wpt,comparison,How to pick one technology to meet your demands,Waveform selection,Basic principles

1. Wireless Power Transmission
VISHNU V M

2. Overview
 What is wireless power transmission(WPT)?
 Why is WPT?
 History of WPT
 Types of WPT
 Techniques to transfer energy wirelessly
 Prediction
 Surprise

3. What is WPT?
• Wireless energy transfer or wireless power is the
transmission of electrical energy from a power source to
an electric load with the use os time varying electric field
,magnetic field electromagnetic field ,Radio waves or
visible light

4. Distribution loss
• Corona
• Heat loss
• Skin effect
INDIA 's electricity grid has the
highest transmission and
distribution losses up to
40%(World Resources Institute)
Maintenace
Shock

5. Why WPT?????????????
• SAFE
• Need for grids and substatioins eliminated
• Low maintenance cost
• Accesibility to remote area
• Reducing E waste

6. HISTORY
• Nikola Tesla in late 1890s
• His vision for “World Wireless
System”
• The 187 feet tall tower to broadcast
energy
• All people can have access to free
energy

7. Wardenclyffe Tower

8. HISTORY
• The idea of Tesla is taken in to research after 100 years
by a team led by Marin Soljačić from MIT. The project is
named as ‘WiTricity’.

9. Types and Technologies of WPT
• Near-field techniques
Inductive Coupling
Capacitive Coupling
Resonant Inductive Coupling
• Far-field techniques
Microwave Power Transmission (MPT)
LASER power transmission

10. Near-field techniques(Non radiative)
• Operates at distance less than a wavelength of the
transmitted signal.
• For short-range charging the receiver distance is less
than the diameter of the transmitting coil.
• Inductive and capacitive coupling are two types
• In mid-range the receiver distance varies from one to ten
times the diameter of the transmitting coil , Resonant
inductive or capacitive coupling power transfer method fall
into this type

11. Inductive Coupling (Short Range)
• A source driving the varying magnetic field is connected to
a primary coil which will induce a voltage across the
receiver secondary coil, and transfer the power transfer to
load accordingly.
• Frequency varies between the range of 20-40kHz for a
distance around of 10cm.
• Inductive coupling can be classified into two groups depending on
the direction of the flux flow relative to the charging surface
– Horizontal approach
– Vertical approach

12. –Horizontal approach
–Vertical approach

13. Inductive Coupling
(Short Range)
APPLICATION
Electric tooth brush and
Razor battery charging
induction stovetops
industrial heaters.
Medical field--
pacemaker,insulin pumb
Gadgets running battery---
Mobile,laptops,game controlls

14. Capacitive coupling (Short Range)
• In capacitive coupling energy is transferred through
electric field between two electrodes.
• The amount of transferred energy is increased with
frequency increase.
• It has advantage of capability of transferring power
through metal.
• This method has only been used for low power devices,
due to hazardous issues when high voltage is applied to
electrodes.
• Additionally, many materials are strongly affected by high
power electric fields, including human body

15. CAPACITOR COUPLING
• Bipolar
• Unipolar

16. Resonant inductive (Medium Range )
• Distances around 0.5m to 5m (d < r < 10d).
• Reciver has a tuning circuit which tuned exact to
transmitter frequncy
• The operating frequency usually ranges between 10kHz-
200MHz
• This method can be used to energize and transfer power
at home and offices.

17. Resonant inductive Power Transfer

18. Far Field (Radiative)
• Radiative or far-field power transfer operate at distance
more than twice of the wavelength of transmitted signal.
• Radiative power transfer, or far-field power transfer
technique, uses the propagation of electromagnetic
waves in long distance (kilometers range) where r >2λ. (r :
receiver distance)
• Two types of radiative power transfer are directive and
non-directive. Microwaves with frequencies 300MHz –
300GHz and laser (ten of micrometer to nanometer
wavelength) are used to transmit far-field power.

19. Microwave Power Transmission (MPT)
• Power transmission via radio waves can be made more
directional, allowing longer-distance power beaming, with
shorter wavelengths of electromagnetic radiation
• Technology gain popularity after the invention of Rectenna
1. Steps involved
• Converting electrical power into microwave
• Receiving transmitted wave by rectenna
• Regeneration of power from microwave
Application:solar power satalite to earth

20. LASER power transmission
• At transmitter power converted into laser
• At receiver laser falls on photovoltaic cells and produce
voltage
• Advantages 1.compact 2.No RF interference
• Drawback
– Laser radiation is hazardous
– Conversion between electricity and light is limited
– Requires a direct line of sight with the target

21. STANDARDS
• When designing the wireless power transfer system,
safety standard should be taken into account.
• Electromagnetic interference and human exposure to
radiation should be studied.
• Lots of standards identify the safety of radiated emission
• Few are: CISPR 11 or EN55011 class B group 2, CISPR
22 or EN55022 class B, FCC part 15 class B, CISPR 14.2
and EN62233:2008.

22. STANDARDS
• Over 130 companies formed a wireless power consortium
and launched the first standard.
• "Qi" was announced in 2010 for portable electronic
devices up to 5W, and then part-1 of the standard was
updated.
•

23. STANDARDS
• Full Spatial Freedom for the placement of devices anywhere on a
charging pad
• The ability to charge Multiple Device simultaneously
• Interoperability – the ability to charge different brands and models
of devices on the same transmitter
• Integrated receivers in the device to eradicate the need for added
charging covers and sleeves
• Efficiency levels from the plug to the device that meet or exceed
the performance of existing cable based power solutions
• Consumer safety by keeping to the lowest effective transmission
frequency.

24. STANDARDS

25. Decay curve of efficiency

26. Comparison

27. Inductive and Resonant
inductive coupling

28. Back to the basics

29. Back to the basics
Inductor--An inductor, also called a coil or reactor, is a passive two-terminal
electrical component that stores electrical energy in a magnetic field when
electric current is flowing through it.
Inductive reactance
an inductors electrical resistance when used in an AC circuit is called
Inductive Reactance.
• What is inductance ?
• If a changing flux is linked with a coil of a conductor there would be an emf
induced in it. The property of the coil of inducing emf due to the changing flux
linked with it is known as inductance of the coil.

30. • Self Induction
• Mutual induction

31. Inductors
• Application of inductors
• Inductors in Tuned Circuits(Oscilators)
• Inductive sensors
• Used in power supply's(Buck&boost converter)
• Filters
• Chokes
• Relays
• Ferrite beds

32. Faraday's Law's
• Any change in the magnetic field of a coil of wire will cause an
emf to be induced in the coil. This emf induced is called induced
emf and if the conductor circuit is closed, the current will also
circulate through the circuit and this current is called induced
current.
• It states that the magnitude of emf induced in the coil is equal to
the rate of change of flux that linkages with the coil. The flux
linkage of the coil is the product of number of turns in the coil and
flux associated with the coil.
e = N dϕ/dt

33. Lenz's Law
• The polarity (direction) of the induced voltage is given by Lenz's
law, which states that it will be such as to oppose the change in
current.
• e = -N dϕ/dt

37. Transformer
• Transformer is a static device (and doesn’t contain on rotating parts, hence no friction
losses), which convert electrical power from one circuit to another without changing its
frequency. it Step up (or Step down) the level of AC Voltage and Current.
• Transformer works on the principle of mutual induction of two coils or Faraday Law’s Of
Electromagnetic induction. When current in the primary coil is changed the flux linked to the
secondary coil also changes. Consequently an EMF is induced in the secondary coil due to
Faraday law’s of electromagnetic induction.
• The transformer is based on two principles: first, that an electric current can produce a
magnetic field (electromagnetism), and, second that a changing magnetic field within a coil of
wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the
current in the primary coil changes the magnetic flux that is developed. The changing
magnetic flux induces a voltage in the secondary coil.Operation & Working Principle of a
Transformer

39. Transformer Losses
• Core losses
• Copper losses
• How to reduce losses?

40. Explanation in terms of circuit

41. Explanation in terms of circuit
• Equivalent circuit of transformer with secondary parameters referred to the
primary.

42. WPT – Inductive coupling

43. WPT – Inductive coupling

44. Wave selection