When a person walks, pressure is exerted on the ground and this pressure can be converted into electrical energy and it can be used to power electronic devices. In this paper a Mobile charging system is designed. A piezo electric generator is placed in the shoe. The power that is generated by piezo electric generator when a person walks is transferred to the device by using a mid-range wireless power transfer (WPT) which is a Resonance coupling technique.

1. Project Power Shoe: Piezoelectric Wireless
Power Transfer - A Mobile Charging Technique
Made by- Shayan Pervez
USN- 1CR14EC172

2. ABSTRACT
 When a person walks, pressure is exerted on the
ground and this pressure can be converted into
electrical energy and it can be used to power
electronic devices. In this presentation a Mobile
charging system is discussed. A piezo electric
generator is placed in the shoe. The power that is
generated by piezo electric generator when a
person walks is transferred to the device by using a
mid-range wireless power transfer (WPT) which is a
Resonance coupling technique.

3. INTRODUCTION
 Imagine your phone getting charged where ever you go. This is possible by
Piezo electric wireless power transfer mobile charging technique. The keys to
this technique are the piezoelectricity and Wireless power transfer (WTP).
 Harvesting mechanical energy from human motion is an attractive approach
for obtaining clean and sustainable electric energy.
 Piezoelectricity is electrical energy produced from mechanical pressure (such
as walking, running). When pressure is applied to an object, a negative
charge is produced on the expanded side and a positive charge on the
compressed side of the piezoelectric crystal.
 Once the pressure is relieved, electrical current flows across the material.
Wireless power or wireless energy transmission is the transmission of
electrical energy from a Power source (piezoelectric Power) to a load (such
as any electrical device) without any physical connector such as wires or
conductors.
 Energy is harvested from the human movements and is transmitted wirelessly
thorough wireless power transfer technique and is used to charge the mobile
battery.

5. Piezoelectric sensor
A piezoelectric sensor is a device that
uses the Piezoelectric effect to measure
pressure, acceleration, force by
converting them to an electrical signal.
The sensor uses quartz crystal material.

6. PIEZOELECTRIC SENSORS DATASHEETS

7. PIEZOELECTRIC SENSORS SPECIFICATIONS
 The high modulus of elasticity of many piezoelectric materials
is comparable to that of many metals and goes up to 106
N/m².
 Even though piezoelectric sensors are electromechanical
systems that react to compression, the sensing elements
show almost zero deflection.
 Additionally, piezoelectric technology is insensitive to
electromagnetic fields and radiation, enabling measurements
under harsh conditions.
 Some materials used (especially gallium phosphate or
tourmaline) are extremely stable at high temperatures,
enabling sensors to have a working range of up to 1000 °C.
 Piezoelectric sensors produces AC output voltage.

8. SIMPLE MOLECULAR MODEL

9. SIMPLE MOLECULAR MODEL

10. SIMPLE MOLECULAR MODEL

11. OUTPUT VOLTAGE OF PIEZOELECTRIC
SENSORS

12. DESIGN:
Design consists of two units:
Design
a)Generation- A
transmission unit
b)Receiver – A
charging unit

13. Fig.1

14. A)GENERATION – A TRANSMISSION
UNIT
 The Generation - Transmission unit side consists of
the Piezo electric generator, capacitance bank,
oscillator, and transmitter Tx unit. This unit is
integrated inside the shoe. Fig. 1 shows the design
of the system.

15. B)RECEIVER – A CHARGING UNIT
 Receiver and charging unit consists of capacitance
bank, rectification circuit and charging circuit. This
can be either designed mobile independent or
embedded inside the mobile. The receiver receives
the power and this power is converted to DC supply
using a rectification process and the output is fed to
a battery of a device (mobile) through the charging
circuit.

16. DESIGN:
 The Piezo electric generator is placed inside a Shoe.
 A shoe has two points where the pressure exerted in maximum and they are the heel and the toe,
and this is the exact place where the piezo electric unit is placed figure below shows the
arrangement of the piezoelectric generator inside a shoe.
 The design consists of a pair of array of piezo electric generator units connected in series.
 The Font panel has the array of piezo electric generator in a linear arrangement and the rear
panel with a circular arrangement.

Fig:Arrangement of piezoelectric inside a shoe

17. WIRELESS POWER TRANSFER(WPT)
 In the early 20th century, before the electrical- wire grid, Nikola Tesla
devoted much effort towards transferring power wirelessly. However,
typical embodiments (e.g., Tesla coils) involved undesirably large
electric fields.
 In recent years, there has been increasing interest in research and
development of wireless power technology to eliminate the “last
cable” after Wi-Fi becoming widely accepted.
 Wireless electricity technique used here is based on strong coupling
between electromagnetic resonant coils to transfer energy wirelessly
between them. [5] This differs from other methods like simple
induction, microwaves, or air ionization.
 The system consists of transmitters and receivers that contain
magnetic loop antennas critically tuned to the same frequency.

18. WIRELESS POWER TRANSFER(WPT)
 The principle of Evanescent Wave Coupling extends the
principle of Electromagnetic induction
 Electromagnetic induction works on the principle of a primary
coil generating a predominant magnetic field and a secondary
coil being within that field so a current is induced within its
coils.
 This causes a relatively shorter range due to the amount of
power required to produce an electromagnetic field.
 Theoretical analysis shows that by sending electromagnetic
waves around in a highly angular waveguide, evanescent
waves are produced which carry no energy. If a proper
resonant waveguide is brought near the transmitter, the
evanescent waves can allow the energy to tunnel to the power
drawing waveguide, where they can be rectified into DC
power. Since the electromagnetic waves would tunnel, they
would not propagate through the air to be absorbed or be
dissipated, and would not disrupt electronic devices or cause
physical injury.

19. SYSTEM DESIGN AND CIRCUIT
(GENERATOR CIRCUIT)
 The schematic design of Generator and transmission side of
the Piezo electric wireless power transfer mobile charging
technique is given in Fig below.
 piezo electric generator is the source which powers the whole
circuit and the power is transmitted wirelessly using wireless
power transfer technique.
Fig : generation and transmission
circuit

20. SYSTEM DESIGN AND CIRCUIT
(RECEIVER CIRCUIT)
 The schematic design and circuit of the receiver and charging side is
shown in figure below. It can be seen that the receiver RX and the
capacitance bank are connected in parallel and a rectification circuit
is also connected. This circuit converts the supply into DC form, and
the charging circuit is powered which in turn charges the battery in
the device. A regulator can also be connected between the rectifier
and charging circuit if necessary.
Fig : receiver and charging
circuit

21. PROTOTYPE:
The above pictures shows how the final prototype looks like.

22. PROTOTYPE CIRCUIT DESIGN

23. PROTOTYPE CIRCUIT DESIGN
 The prototype circuit design is shown in the Fig in previous slide. The
circuit consists of Piezo generator which is the source for the system.
 This energy which is generated is rectified and regulator and is sent
to a high frequency inverting circuit, this power is then transferred
using wireless power transfer technique.
 Then the received power is rectified, regulated and boosted and sent
to the charging module. The LM5035 which is PWM Controller with
Integrated HalfBridge is used here.

24. SIMULATION DIAGRAM

25. Fig1 : simulation circuit (matlab simulation link)

26. Fig2 : interleaved boost converter simulation

27. Output and Results
Fig1 : output from piezo after rectification

28. Fig.2. Input at Coil Tx (Wireless Power Transfer) after high frequency inverter.

29. Fig.3. Output at Coil Rx (Wireless Power Transfer)

30. Fig4 : final output

31. CONCLUSION
• In this project we have illustrated the design of system
which can harness the power generated by the human
movements and transfer the power to a device
wirelessly
• We believe that this research holds the key to an
uninterrupted way of using smart phones.
• Harvesting energy from human motions is an attractive
approach for obtaining clean and sustainable energy.
• This project has its root in all the areas of consumer
electronics.
• This project also extends Future work includes
designing authentication and monitoring systems for this
project.

32. REFERENCES
1. A Shoe-Embedded Piezoelectric Energy Harvester for Wearable
Sensors by Jingjing Zhao and Zheng.
2. Piezoelectric generator Datasheet: www.piezo.com/prodproto4EHkit
3. Wireless Power Transfer via Strongly Coupled Magnetic Resonances
by AndréKurs, AristeidisKaralis RobertMoffatt, J.D.Joannopoulos,
PeterFisher, MarinSoljac.
4. Design and Test of a High Power High Efficiency Loosely Coupled
Planar Wireless Power Transfer System by Zhen Ning Low, IEEE
transactions on industrial electronics, vol. 56, no. 5, May 2009.
5. Wireless Power Transfer via Strongly Coupled Magnetic Resonances
by Andre Kurs, Aristeidis Karalis, Robert Moffatt, J. D. Joannopoulos,
Peter Fisher, Marin Soljacic. 2008.
6. Wireless Power Transmission Using Magnetic Resonance by Mandip
Jung Sibakoti and Joey Hambleton Cornell College PHY312,
December 2011, Professor Derin Sherman.
7. www.google.com

33. END OF PRESENTATION