Wireless power transfer by high frequency resonating coils

Wireless power transfer by
High frequency resonating
coils

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Wireless power transfer by High
frequency resonating coils
Introduction
 The project is designed to develop a concept of wireless power transfer
for several applications such as wireless powered electric vehicle in stores,
airports, departmental stores etc. It can also charge a rechargeable
battery or a cell phone wirelessly suitably modified for the purpose. AC
230V ,50 Hz mains is stepped down to low voltage ac by conventional 50
Hz iron cored transformer which is then rectified by a bridge rectifier to
develop around 14 volt DC.

Block Diagram

Hardware Requirements
 HF-Transformer
 HF-diodes
 rectifier
 Bridge-MOSFETs drive
 Two air filled inductor coils
 Voltage regulator
 BULB
 MOSFET driver
 PWM inverter IC

Software Requirements
 Keil compiler
 Languages: Embedded C or Assembly

Wireless power transmission
 The transmission of energy from one place to another without using
wires which is also known as “WiTricity”.
 Generally conventional energy is transferred using copper wires which
results in large Copper loss.
 But now-a-days this wireless transmission is made possible in using
various technologies based on Resonant frequency ,Inductive coupling
etc.

Need of Wireless power transmission
 As per studies, most electrical energy transfer is through wires.
 Most of the energy loss is during transmission as copper losses
 On an average, more than 30%
 In India, it exceeds 40%
 Billions, trillions of $ is spend on wires and in their installation.
 Waste management a challenge in 21 century.
 40 billion disposal batteries added to e-waste every year.
 PVC is non-biodegradable.

Electro magnetic Inductive coupling
 It is based on the FARADAY’S LAW OF ELECTROMAGNETIC
INDUCTION
 Make use of coils. The coils are not connected through
wire or any other kind of material.
 Transfer of energy is due to mutual induction.
 Its based on the concept : that an oscillating electric field
produces magnetic field and an oscillating magnetic field
produces oscillating electric field

RESONANT INDUCTIVE COUPLING
 Same inductive coupling(EMI) concept but the coils here
operate at their resonating frequency.
 Inductance induces current.
 Resonance makes both the coil to operate at same
frequency.
 Fields are non-radiative in nature.

Types and Technologies
 Near-field techniques
• Inductive Coupling
• Resonant Inductive Coupling
• Air Ionization
 Far-field techniques
• Microwave Power Transmission
(MPT)
• LASER power transmission

RIC VS INDUCTIVE
COUPLING
 RIC is highly efficient
 RIC has much greater range than inductive coupling
 RIC is directional when compared to inductive coupling
 RIC can be one-to-many. but usually inductive coupling is one-to-one
 Devices using RIC technique are highly portable

HF
transformers
 Electric power transmission over long distances.
 High-voltage direct-current HVDC power transmission systems.
 Large, specially constructed power transformers are used for electric arc
furnaces used in steelmaking.
 Rotating transformers are designed so that one winding turns while the
other remains stationary.

HF
transformers

HF
transformers
 A common use was the video head system as used in VHS and Beta video
tape players.
 These can pass power or radio signals from a stationary mounting to a
rotating mechanism, or radar antenna.

Rectifier
Rectifiers are used in various devices, including:
• DC power supplies
• Radio signals or detectors
• A source of power instead of generating current
• As flame rectification to detect the presence of flame
• High-voltage direct current power transmission systems

Rectifier

Voltage Regulator
 A voltage regulator generates a fixed output voltage of a preset magnitude
that remains constant regardless of changes to its input voltage or load
conditions.
 There are two types of voltage regulators: linear and switching.
 A linear regulator employs an active (BJT or MOSFET) pass device (series or
shunt) controlled by a high gain differential amplifier.

Voltage Regulator
 It compares the output voltage with a precise reference voltage and adjusts
the pass device to maintain a constant output voltage.

Description of HF
transformers
 Electric power transmission over long distances.
 High-voltage direct-current HVDC power transmission systems
 Large, specially constructed power transformers are used for electric arc
furnaces used in steelmaking.
 Rotating transformers are designed so that one winding turns while the
other remains stationary.

Description of HF
transformers
 A common use was the video head system as used in VHS and Beta video
tape players.
 These can pass power or radio signals from a stationary mounting to a
rotating mechanism, or radar antenna.

Working Principle
 AC 230V ,50 Hz mains is stepped down to low voltage ac by conventional 50
Hz iron cored transformer.
 Which is then rectified by a bridge rectifier to develop around 14 volt DC.
 This DC is again made to ac by a PWM inverter using half bridge concept
comprising of 2 MOSFETs.
 And 2 capacitors being switched at 40 KHz which is then fed to a
resonating high frequency coil acting as primary of an air core transformer.

Working Principle
 Another matching resonating coil formed as secondary drives a lamp load
of 10 watts spaced at an air distance of 20 CMs.
 The overall efficiency of the power transfer in this case is more than 90%
for perfectly coupled and matched series resonators.
 However, practically resonators with a Q of 1,000 should be able to
send power over a distance 9 times the radius of the devices with an
efficiency of 10%.

Working Principle
 The secondary coil develops a voltage of 40 KHz at 12volt while it is kept
spaced from the primary coil where air is used as the core.
 The output of the secondary can also be given to a high frequency bridge
rectifier that can deliver DC which could then be regulated to maintain a
constant voltage to a DC motor or current to feed to rechargeable battery
or a cell phone.
 However, the overall efficiency of the power transfer shall be less than 50%
for all such weakly coupled series resonators.

Air Ionization
 Toughest technique under near-field energy transfer techniques
 Air ionizes only when there is a high field
 Needed field is 2.11MV/m
 Natural example: Lightening
 Not feasible for practical implementation

APPLICATIONS
 Provides charging stations for handheld devices like phones ex: powermat,
removes the need for multiple power sockets
 Can operate appliances like tv
 Electric car manufacturers consider it for charging electric cars, currently
using wires for this purpose is not entirely practical

ADVANTAGES
 Non-radiative energy transfer is safe for people and animals.
 Wastage of power is less.
 Highly resonant strong coupling provides high efficiency over distance.
 Does not interfere with radio waves.

Conclusion
 Wireless power transfer by High frequency resonating coils was designed and
implemented. The project can be enhanced in future up to 1 meter distance in
space using resonators with a Q factor of 1,000 enabling it to send power over a
distance 9 times the radius of the coil of 11 CMs .

Wireless power transfer by high frequency resonating coils

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