1. Energy-Harvesting Through Mechanical Vibration
Department of Mechanical Engineering
Motilal Nehru National Institute of Technology Allahabad
Uttar Pradesh- 211004
Reg. No- 2014DN06
India was the sixth largest motor vehicle/car manufacturer in the world in 2013.
Indian auto manufacturers produced a record 23.4 million motor vehicles in 201 41 5 (Apr Mar).
3.22 million passenger vehicles rolled out from Indian auto plants in 201 41 5.
According to “Indian Motor Vehicles knowIndia.net “ following data are given:-
“On the basis of above observation more than 19 millions vehicles (Passenger Vehicle , Commercial Vehicle , Three wheeler)
running on the road and suppose average 100 W electricity produce by each vehicle that means it is equivalent to 1900 MW
electricity will be produce , which is great energy”.
Domestic Motor Vehicle
2014-15 (In Millions)
Passenger Vehicles 2.60
Commercial Vehicles .61
Two -wheelers 16.0
Total 3.74 + 16.0 = 19.00
Year Total numbers of Vehicle
sales (In Millions )
2013-14 3 + 14.36 = 17.36
2010-11 1.49+5.016 = 6.506
2008-09 4.36+5.25 =9.61
5. Electromagnetic Harvesters
It is based on Faraday’s law of electromagnetic induction which state that “an
electrical current will be induced in any closed circuit when the magnetic flux
through a surface bonded by the conductor change”.
According to faraday law :- Emf = - (dɸ/dt) --------(1)
(ɸ=BA=Magnetic flux , B=External magnetic field , A=area of coil)
For a coil moving through a perpendicular constant magnetic field ,the
maximum open circuit voltage across the coil (Voc) is :
Voc = - NBl .(dx/dt) -------------------(2)
(N=Number of turns in the coil ,l=length of winding , x=relative velocity between
magnet and coil)
(figure - NiPS Energy Harvesting
6. Electromagnetic Harvesters
Magnetic field varies with distance apart from the magnet the induced emf
can be given by:-
e.m.f = - N .A. (dB/dx).(dx/dt)
(dB/dx = gradient magnetic flux density )
e.m.f = κ . (dx/dt)
κ = Electromagnetic coupling factor = -NBl = -NA( dB/ dx).
Applying Kirchhoff’s voltage law;-
e.m.f + i.(RL +Rc) + Lc (di /dt) = 0
Damping coefficient induced from electromagnetic transduction ,be –
be = κ2
/ (RL + Rc + j ω Lc )
For micro-generator that works at low resonant frequencies ,the inductive impedance of coil much lower than its resistive
impedance .Hence inductive impedance can be ignored and written as :-
be = κ
/ (RL + Rc ) and electrically induced damping factor given as:
ζe = κ
/ 2mω (RL + Rc )
7. Electromagnetic Harvesters
One of the most effective way of achieving this for energy
harvesting by use of permanent magnet and coil.
Well suited for micro-generator that works at resonant
Do not require smart materials .
No need external voltage source to start generating .
Output voltage is low ~0.1v .
Difficult to manufacture in micro scale.
Difficult to integrate with MEMS(Micro-Electro-Mechanical
system) fabrication process.
8. Electrostatic Harvesters
load is given it is based on varying vibration – dependent
capacitance of variable capacitor s (varacators).
Ambient vibrations induced displacement of charged plates of
varacators and mechanical energy converted into electrical energy.
According to “Roundy Model” variation in capacitance cause
either voltage or charge increases .
The electrostatic energy stored within the capacitor is given by
E=1/2 *Q*V = 1/2 * C * V
(Q= Charged stored , V= Voltage across the capacitor ,
C=Capacitance) & (c = εr εo (A/d)) (ε Permittivity)
Maximum voltage across the
Figure from NiPS Energy Harvesting Summer School
9. Electrostatic Harvesters
Parallel capacitor effectively constrained the voltage on the energy
Advantage of this principle of harvesting is ease of integration such
devices into printed circuit board of MEMS(Micro-Electro-
No need of smart materials.
High output voltage (2-10v).
Electrostatic generators require an initial polarizing voltage or charge.
High output impedance .
Low output current.
Figure-Tom J.Kazimiersiki.steve Beeby energy .
10. Piezoelectric Harvesters
The piezoelectric effect was discovered by Pierre and Jacques Curie
Piezoelectric materials are generating electric charge when a
mechanical load is applied . Mechanical energy is in the form of
pressure or force into electric energy and vice versa.
The constitutive equation for a piezoelectric material is given by-
D = ε . E + d . σ -------------------------------------(Direct effect)
€ = (σ/Y) + d . E --------------------------------------(Converse effect)
(D=Electrical displacement (charge density) , ε=Dielectric constant
,d=Piezoelectric strain coefficient , E =Electric field, σ =Mechanical
stress , € =Mechanical strain)
The voltage source (Voc ) open circuit voltage when electrical
displacement is zero is given by :-
Voc = -(d/ ε ) .t. σ
t=Thickness of piezoelectric material .Figure-Energy harvesting system by Tom.J.Kazmie.
11. Piezoelectric Harvesters
Energy harvesting device employing piezoelectric conversion mechanism typically consist of cantilever beam coated
with piezoelectric material and mass placed on the tip of beam.
Piezoelectric require no external voltage source.
Compact dimension allow for MEMS integration.
Voltage relatively high (2-10V).
Poor mechanical properties .
poor coupling in piezo thin film.
Piezoelectric materials -
a.) Naturally occurring crystal –Berlinite(AlPO4 ), Cane sugar , Quartz ,Rochelle salt
b.)Man made ceramics - Barium titanate(BaTiO3),Lead titanate (PbTiO3) ,Lead zirconium titanate(PZT) ,
c.) Polymer - Polyvinyledene fluoride (PVDF)
12. Magnetostrictive Harvesters
Magnetostrictive energy harvesters use the “ Villari effect of
Magnetostrictive materials” such as Metglas 2605SC,
TerfenolD /PZT/ Terfenol-D composite.
These materials deform when placed in a magnetic field and it
can induce charges in magnetic field when it is strained.
Magnetostrictive materials are generally used in piezoelectric-
magnetostrictive composites. Such composites were originally
used in magnetic field sensors and have recently been adopted
in energy harvesting .
B = dm .σ + μ . H --------------(Villari effect)
S = (σ/E) + dm .H --------------(Joule effect)
The magnetic field strength , H, could calculate-
H = IN
(B=Magnetic displacement /flux density , dm-Magnetostrictive
constant , σ – Stress , Permeability , H – Magnetic field
,S – Strain ,E-Young’s modulus, I= Current ,N=Number of coil
Fig - http://dx.doi.org/10.5772/50892
13. Magnetostrictive Harvesters
Magnetostrictive materials to be used in actuator and sensor application
Ultra-high coupling coefficient >.9
No depolarization problem .
Suited to high frequency vibration.
Difficult to integrate with MEMS fabrication process.
Need of pick-up coil.
14. MMR is energy harvesting shock absorber which is able recover the
energy otherwise dissipated in suspension vibration while simultaneously
suppress the vibration induced by road roughness .
It can work as a controllable damper as well as an energy generator.
A mechanical motion rectifier (MMR) is a device which convert the
oscillatory vibration into unidirectional rotation of the generator .
Prototype MMR is to achieve more than 60% efficiency at high
frequency ,which is much more better than conventional regenerative
shock observer in oscillatory motion.
The model is capable of analyzing electrical and mechanical components
at the same time.
15. Shock absorber are installed between chassis and wheels to suppress the vibration.
16. The road test are done to demonstrate the feasibility of the MMR shock observer and it is observe that more than 15
watts of electricity which harvested while driving at 15 mph on a smooth road.
Scientist Zuo and Zhang ,They observe that 100 to 400 watts of energy harvesting potential exist in the suspension of
typical passenger vehicle travelling 60 mph on the good roads and more energy available for trucks or on the rough roads .
The motion rectifier based design can also be used for other application of vibration energy harvesting such as from tall
building ,long bridge or ocean vehicles.
It can significantly improve the reliability by reducing impact forces and increase efficiency by decreasing the
influence of friction.
17. It is working on “motion rectifier” with two working mode : positive mode and
negative mode .
Key components of “motion rectifier” are two one way roller clutch that transmit
rotation only in one direction and dive the motion in two different routes. As a result
,shaft of the motor and planetary gear will always move in one direction.
It converts the irregular reciprocating vibration into the unidirectional rotation.
MMR with two roller clutch can be analogy to full-wave voltage rectifier using a
centre tapped transformer and two diodes.
The system inertia is equivalent to the electrical smoothing capacitor in series with
When the direction of the motion changes , the relative velocity between the driving
part and driven part , which caused by backlash , would be much smaller so that the
impact forces would be much smaller ,in this way reliability would be improved.
19. Design of MMR is very compact in comparison of existing other design.
In this design they using pair of rack and pinion ,one shaft and three bevel gears .
Two roller clutches are mounted between the shaft and the two larger bevel gears , which
are always engaged with the small bevel gear .
When rack moves up and down ,the pinion and shaft rotate clock wise and counterclockwise
directions . Due to the engagement of one-way roller clutches at instant time only one large
bevel gear will be engaged and be driven by the shaft ; another large bevel gear disengaged
with from the shaft by the roller clutch.
The assembly of the pinion, shaft, and bevel gears will be mounted to one cylinder, and
another cylinder covers outside and to guide the linear motion. Similar as roller bearings,
the roller clutches can’t hold large thrust in the axial direction, so two thrust bearings are
designed to support the thrust forces on the two larger bevel gears.
In order to reduce the friction between the inner and outer cylinders, we insert Teflon rings
between the two cylinders. The rack is preloaded and guided by a roller in the place
opposite to the pinion . The enclosed construction of the shock absorber prevents dirt from
hurting gears inside.
20. The prototype was tested with the MTS 858 Mini Bionix II testing system and a dynamic signal analyzer (Hewlett Packard
21. Triboelectric effect – “The triboelectric effect is phenomenon that material becomes
electric charged after it contacts a different material through friction .”
It is based on triple-cantilever TENG harvesting vibration energy with the assistance
of nanowire arrays fabricated onto the surface of beryllium-copper alloy foils.
TENG produces an open-circuit voltage up to 101 V and short circuit current
reached up to 55.7 μA with peak power density of 252.3 mW/m2 .
Output power of single device with a size of 3.2 cm by 2.8 cm is high enough to
simultaneously light up more than 40 commercial LED .
Unambiguously demonstrating its feasibility of power portable electronics.
Using as sensor for environmental and infrastructure monitoring security.
22. The basic structure of the triple-cantilever based TENG in which three metal plate of beryllium-copper alloy foils are the three
The bottom surface of top cantilever and top surface of bottom cantilever are coated with polydimethylsiloxane(PDMS) films
and middle cantilever are covered by ZnO nanowire array which layer copper will deposited.
A mass is attached at end of its effectiveness of vibration.
Middle cantilever has two chances the contact the top and bottom cantilever in
each cycle of vibration.
PDMS film can easily deformed to increase the effectiveness contact area and
nanowire array can deeply inserted into PDMS to increase the effective contact area
and thus leading to substantially higher electric output.
A cycle of electricity generation process illustrating mechanism of the TENG can be explained by coupling between
triboelectric effect and electrostatic effect.
23. Fig : A cycle of electricity generation process for illustrating the mechanism of the triple-cantilever based TENG .
BCAL(65x28x.2)With tip mass
2 BCAFs(45x28x.2)With spin coated
Aqueous solution of
hexamethylenetetramine and zinc
nitrate hexahydrate with equal
Concentrated used to growth of ZnO
nanowire on BCAFs .
PDMS elastomer and cross-linker
mixed in ratio 10:1(w/w) then cast on
BCAF substrates . Uniform PDMS
obtained by heating in a mechanical
convection at 850c for 2 hours.
25. Fig . - Open-circuit voltage (VOC) at vibration frequencies of 3.5 Hz (a), 3.7 Hz (b), and 4.0 Hz (c) and rectified
short-circuit current (ISC) at vibration frequencies of 3.5 Hz (d), 3.7 Hz (e), and 4.0 Hz (f). The insets of (c) and (f) are
enlarged views of half cycles of the VOC and ISC at 4.0 Hz, respectively.