HYBRID ELECTRIC VEHICLES- HYBRIDIZATION OF AUTOMOBILE ( Unit- 2)

Dr.G.Nageswara Rao
Professor
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Hybrid Electric Vehicles

Hybrid Electric Vehicles Topologies
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(HEV Configurations)

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Series Hybrid Electric Vehicle

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Detailed Configuration of Series Hybrid Electric Vehicle

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Figure 1a: Mode 1, normal driving or acceleration
Figure 1b: Mode 2, light load
Figure 1c: Mode 3, braking or deceleration
Figure 1d: Mode 4, vehicle at stop
B:Battery
E: ICE
F: Fuel tank
G: Generator
M: Motor
P: Power Converter
T: Transmission
(including brakes,
clutches and gears)

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Power Flow Control in Series Hybrid In the series hybrid system
there are four operating modes based on the power flow:
Mode 1: During startup (Figure a), normal driving or acceleration of the series
HEV, both the ICE and battery deliver electric energy to the power converter which
then drives the electric motor and hence the wheels via transmission.
Mode 2: At light load (Figure b), the ICE output is greater than that required to
drive the wheels. Hence, a fraction of the generated electrical energy is used to
charge the battery. The charging of the batter takes place till the battery capacity
reaches a proper level.
Mode 3: During braking or deceleration (Figure c), the electric motor acts as a
generator, which converts the kinetic energy of the wheels into electricity and this,
is used to charge the battery.
Mode 4: The battery can also be charged by the ICE via the generator even when
the vehicle comes to a complete stop (Figure d).

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Parallel Hybrid Electric Vehicle

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Figure a: Mode 1, start up Figure b: Mode 2, normal driving
Figure c: Mode 3, braking or deceleration Figure d: Mode 4, light load
B:Battery
E: ICE
F: Fuel tank
G: Generator
M: Motor
P: Power
Converter

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Power Flow Control in Parallel Hybrid
The parallel hybrid system has four modes of operation. These four modes
of operation are
Mode 1: During start up or full throttle acceleration (Figure a); both the ICE
and the EM share the required power to propel the vehicle. Typically, the
relative distribution between the ICE and electric motor is 80-20%.
Mode 2: During normal driving (Figure b), the required traction power is
supplied by the ICE only and the EM remains in off mode.
Mode 3: During braking or deceleration (Figure c), the EM acts as a
generator to charge the battery via the power converter.
Mode 4: Under light load condition (Figure d), the traction power is
delivered by the ICE and the ICE also charges the battery via the EM.

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Series - Parallel Hybrid Electric Vehicle

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Figure a: Mode 1, start up Figure b: Mode 2, acceleration
Figure c: Mode 3, normal drive
Figure d: Mode 4,
braking or deceleration
Figure e: Mode 5,
battery charging during driving
Figure f: Mode 6,
battery charging during standstill

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The operating modes of EM dominated system are:
Mode 1: During startup (Figure a), the EM provides the traction
power and the ICE remains in the off state.
Mode 2: During full throttle (Figure b), both the ICE and EM provide
the traction power.
Mode 3: During normal driving (Figure c), both the ICE and EM
provide the traction power.
Mode 4: During braking or deceleration (Figure d), the EM acts as a
generator to charge the battery.
Mode 5: To charge the battery during driving (Figure e), the ICE
delivers the required traction power and also charges the battery. The
EM acts as a generator.
Mode 6: When the vehicle is at standstill (Figure f), the ICE can
deliver power to charge the battery via the EM

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Complex Hybrid Electric Vehicle

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Figure a: Mode 1, start up Figure b: Mode 2, acceleration Figure c: Mode 3, normal drive
Figure d: Mode 4
braking or deceleration
Figure e: Mode 5
battery charging during driving
Mode 6,
battery charging during standstill

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Power Flow Control Complex Hybrid Control
The complex hybrid vehicle configurations are of two types:
 Front hybrid rear electric
 Front electric and rear hybrid
Both the configurations have six modes of operation:
Mode 1: During startup (Figure a), the required traction power is delivered by the EMs and the engine is
in off mode.
Mode 2: During full throttle acceleration (Figure b), both the ICE and the front wheel EM deliver the
power to the front wheel and the second EM delivers power to the rear wheel.
Mode 3: During normal driving (Figure c), the ICE delivers power to propel the front wheel and to drive
the first EM as a generator to charge the battery.
Mode 4: During driving at light load (Figure d) first EM delivers the required traction power to the front
wheel. The second EM and the ICE are in off sate.
Mode 5: During braking or deceleration (Figure e), both the front and rear wheel EMs act as generators to
simultaneously charge the battery.
Mode 6: A unique operating mode of complex hybrid system is axial balancing. In this mode (Figure f)
if the front wheel slips, the front EM works as a generator to absorb the change of ICE power. Through the
battery, this power difference is then used to drive the rear wheels to achieve the axle balancing.

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Plug-In Hybrid Electric Vehicles (PHEV)

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Plug-In Hybrid Electric Vehicles (PHEV)
A plug-in hybrid electric vehicle (PHEV) uses a battery to power an electric
motor and uses another fuel, such as gasoline or diesel, to power an internal
combustion engine. The battery pack in a PHEV is generally larger than in a
standard hybrid electric vehicle.
The larger battery pack allows the vehicle to operate predominantly on
electricity during short trips. For longer trips, a PHEV can draw liquid fuel from
its on-board tank to provide a driving range similar to that of a conventional
vehicle. An on-board computer decides when to use which fuel according to
which mode allows the vehicle to operate most efficiently.
The battery can be charged by plugging into an electric power source, through
regenerative braking, and by the internal combustion engine. In regenerative
braking, kinetic energy normally lost during braking is captured and stored in
the battery

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Plug-in Hybrid Electric Vehicles, or PHEVs, are the next generation of hybrid
electric vehicles that are fairly new to the scene but are quick to gain traction
because of their increased efficiency. They are also called range-extended electric
vehicles for the obvious reason that the vehicles always have gasoline as a
potential back-up that can extend the driving range. They are equipped with a
larger and a powerful battery compared to HEVs, which can be recharged at the
electricity grid.
PHEVs operate in two different modes based on the charge of the battery. It mostly
uses electric motor to propel the engine which automatically reduces the fossil fuel
consumption, and it will only switch to ICE if the battery level drops below the set
limit.

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Why plug-in hybrid?
Many car owner do not use the car for business travel, and they do not drive daily
more than 50km. for such distance it is not necessary to spend any petrol, because
this distance can be easily realized by energy from battery, but great disadvantage
of electric drive is, that the “empty” battery cannot be recharged in minutes and in
the case of longer trip, the safety return is not sure. Also in some rare trips during
holidays etc. cannot be realized by electric vehicle that means you must have or
purchase another car. All these problems are solved by serial hybrid with greater
battery, which can be driven first 50km from battery only and in the case of longer
trip; the engine is started and operated in the optimal efficiency work point with
constant power and speed. The generated electricity is either used for motors supply
or in case of low load is simultaneously stored in empty battery.
The PHEV must be able to work in electric mode only at any speed, during the short
trips under the daily limit. Therefore it must have strong enough electric motor EM
and this condition results in serial concept hybrid, when the ICE is not mechanically
connected with wheels, because its help is not necessary

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Components of a
Plug-In Hybrid Electric Vehicle
1. Battery (auxiliary)
2. Charge port
3. DC/DC converter
4. Electric generator
5. Electric traction motor
6. Exhaust system.
7. Fuel filler
8. Fuel tank (gasoline)
9. Internal combustion engine
(spark-ignited)
10. On-board charger
11. Power electronics controller
12. Thermal system (cooling)
13. Traction battery pack
14. Transmission

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How Do Plug-In Hybrid Electric Cars Work?
Plug-in hybrid electric vehicles (PHEVs) use batteries to power an electric motor and another fuel,
such as gasoline, to power an internal combustion engine (ICE). PHEV batteries can be charged
using a wall outlet or charging equipment, by the ICE, or through regenerative braking. The vehicle
typically runs on electric power until the battery is nearly depleted, and then the car automatically
switches over to use the ICE
Components of a Plug-In Hybrid Electric Vehicle
Battery (auxiliary): In an electric drive vehicle, the low-voltage auxiliary battery provides electricity
to start the car before the traction battery is engaged; it also powers vehicle accessories.
Charge port: The charge port allows the vehicle to connect to an external power supply in order to
charge the traction battery pack.
DC/DC converter: This device converts higher-voltage DC power from the traction battery pack to
the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.
Electric generator: Generates electricity from the rotating wheels while braking, transferring that
energy back to the traction battery pack. Some vehicles use motor generators that perform both the
drive and regeneration functions.
Electric traction motor: Using power from the traction battery pack, this motor drives the vehicle's
wheels. Some vehicles use motor generators that perform both the drive and regeneration
functions.

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Exhaust system: The exhaust system channels the exhaust gases from the engine out through
the tailpipe. A three-way catalyst is designed to reduce engine-out emissions within the exhaust
system.
Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank.
Fuel tank (gasoline): This tank stores gasoline on board the vehicle until it's needed by the engine
Internal combustion engine (spark-ignited): In this configuration, fuel is injected into either the
intake manifold or the combustion chamber, where it is combined with air, and the air/fuel mixture is
ignited by the spark from a spark plug.
On-board charger: Takes the incoming AC electricity supplied via the charge port and converts it
to DC power for charging the traction battery. It also communicates with the charging equipment
and monitors battery characteristics such as voltage, current, temperature, and state of charge
while charging the pack.
Power electronics controller: This unit manages the flow of electrical energy delivered by the
traction battery, controlling the speed of the electric traction motor and the torque it produces.
Thermal system (cooling): This system maintains a proper operating temperature range of the
engine, electric motor, power electronics, and other components.
Traction battery pack: Stores electricity for use by the electric traction motor.
Transmission: The transmission transfers mechanical power from the engine and/or electric
traction motor to drive the wheels.

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Full hybrid cars Plug-in hybrid
cars
Electric power
Can power the car at
slower speeds
Can power the car in
all uses
Battery size and cost
Smaller, less
expensive
Larger, more
expensive
Recharging Regenerative braking External power source
Gasoline power
(ICE)
Used in most driving
conditions
Used simultaneously
or only when electric
power runs low

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Companies of BEV, PHEV and HEV
BEV PHEV HEV
Tesla Model S BMW i3 REX PHEV Audi Q5
Nissan Leaf BEV BMW i8 PHEV Acura ILX Hybrid
Mitsubishi iMiEV BEV Cadillac ELR PHEV Cadillac Escalade Hybrid
BMW i3 BEV GM Chevy Volt PHEV BMW Active Hybrid
Smart EV BEV Porsche Panamera S E PHEV BMW Active Hybrid 5
Ford Focus EV BEV Ford Fusion Energi PHEV BMW Active Hybrid 7
- Ford Cmax Energi PHEV Honda Civic Hybrid
- Toyota Prius Plugin PHEV Honda CR-Z Hybrid
- - Hyundai Sonata Hybrid
- - Infiniti Q50 Hybrid
- - Infiniti Q70 Hybrid

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Fuel cell vehicle Components

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FCEVs use a propulsion system similar to that of electric vehicles, where energy
stored as hydrogen is converted to electricity by the fuel cell. Unlike
conventional internal combustion engine vehicles, these vehicles produce no
harmful emissions.
FCEVs are fuelled with pure hydrogen gas stored in a tank on the vehicle. Similar
to conventional internal combustion engine vehicles, they can fuel in less than
four minutes and have a driving range of over 300 miles. FCEVs are equipped
with other advanced technologies to increase efficiency, such as regenerative
braking systems that capture the energy lost during braking and store it in a
battery. Major automobile manufacturers are offering a limited but growing
number of production fcev to the public in certain markets, in sync with what the
developing infrastructure can support.

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 The gas (H2), along with dioxygen (O2) from the surrounding air, are supplied to
the fuel cell. These two gases then undergo an electrochemical reaction inside the
cell, in turn producing electricity, heat and water vapor (H2O), which is released in
the form of a gas via a small tube located underneath the vehicle.
 A fuel cell is composed of two electrodes, an electrolyte, fuel (hydrogen), and a
power supply. The reduction and oxidation reaction happens through a multi-step
process involving the anode, the cathode, and the electrolyte membrane.
 At the negatively-charged anode site, hydrogen molecules are split into electrons
and protons. The electrons are then forced through a circuit where they generate
an electric current and excess heat. The protons go on to the electrolyte
membrane. At the cathode, the protons, electrons, and oxygen combine to
produce water molecules. Flow plates facilitate the transfer between the anode
and cathode. Because an individual fuel cell only produces less than 1.16 volts of
electricity, fuel cell stacks are needed to increase the amount of electricity
generated.

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Fuel cells are a type of energy conversion technology which take the chemical energy contained within a
fuel and transform it into electricity along with certain by-products (depending on the fuel used). [1] It's
important to note that fuel cells are not heat engines, so they can have incredibly high efficiencies. However,
when a heat engine is used to power a fuel cell, the heat engine still has a limiting thermal efficiency.
Fuel cells can be seen as an energy storage device, as energy can be input to create hydrogen and oxygen,
which can remain in the cell until its use is needed at a later time. In this sense they work much like a
battery. There are multiple types of fuel cells, but two common types are the solid oxide fuel cell (SOFC)
and the polymer electrolyte membrane fuel cell (PEMFC).
To produce electricity in a solid oxide fuel cell, oxygen in the air combines with free electrons to form
oxide ions. The oxide ions travel through a ceramic electrolyte and react with molecular hydrogen to form
water. The reaction that makes water also releases electrons which travel through an external
electrical circuit, producing electricity.[4] This process can be seen in figure 1.
To produce electricity in a polymer electrolyte membrane fuel cell, a gaseous fuel is input and reacts with a
catalyst made of platinum nanoparticles. When molecular hydrogen comes into contact with this, it splits
into two H+ ions and two electrons. The electrons are conducted through an electromotive force and
electricity is produced. The hydrogen ions pass through a proton exchange membrane (also known as a
polymer electrolyte) where it reaches the cathode and combines with oxygen to form water. This process
can continue as long as there is hydrogen and oxygen supplied to the cell.[1] Figure 2 shows this process in a
PEMFC.
Fuel Cell

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Solid oxide fuel cell (SOFC). Molecular
oxygen becomes oxide ions (O2-) and
combines with hydrogen to form water,
while simultaneously producing electricity
Polymer electrolyte membrane fuel cell (PEMFC).
Molecular hydrogen fuel becomes hydrogen ions
(H+) that travel through a polymer electrolyte. The
hydrogen ions combine with oxygen to form
water, while simultaneously producing electricity

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In contrast to conventional battery electric vehicles, hydrogen fuel cell electric vehicles
generate their energy using a fuel cell powered by hydrogen, as opposed to relying
completely on batteries. As a main energy source, hydrogen is used for fuel cell electric
vehicles. They generate no pollutants from the exhaust and emit no greenhouse gases into
the atmosphere, making them more energy efficient than internal combustion engines.
As depicted in Figure, the propulsion technique is comparable to that of a battery electric
vehicle, with hydrogen being transformed into electricity. The hydrogen gas is stored in the
hydrogen tank until it is required by the fuel cell stack, which is located inside the vehicle. A
fuel cell stack is a device of separate membrane electrodes that combine hydrogen and
oxygen to generate electricity. DC-DC converter transforms higher-voltage DC power
coming from the fuel cell stack into the lower-voltage DC power required to operate the
electronics and recharge the battery of the vehicle. The DC-AC converter controls the
motor's speed and torque by regulating the flow of electrical energy generated by the fuel
cell stack and the battery. As a result, the rotation of the wheels is performed and the vehicle
is driven by the electric motor.
Working Principle of a Hydrogen Fuel Cell Electric Vehicle

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The polymer electrolyte membrane (PEM) fuel cell where an electrolyte membrane is
positioned between the cathode and anode, is the most popular kind of fuel cell used in
hydrogen fuel cell electric vehicles. The cathode receives oxygen from the air, whereas the
anode receives hydrogen from the hydrogen tank. An electrochemical process takes place in
the fuel cell stack, causing the hydrogen molecules to split into protons and electrons. After
that, the protons pass through the membrane and are transported to the cathode and the
electric vehicle is powered by electrons being pushed through an external circuit, with the
electrons eventually recombining the protons on the cathode side to generate an H2O
molecule.
As a result of the interaction between the protons, electrons, and oxygen molecules, only heat
and water vapor are released into the atmosphere from this process. Several catalysts that are
nano-sized particles can be used with various hydrogen fuel cell designs. Fuel cells are very
effective since chemical energy does not have to be transformed into thermal energy and
mechanical energy. Fuel cells reduce pollution in two ways, they produce fewer carbon
emissions than conventional internal combustion engines and they waste less energy in the
form of heat. Due to many positive aspects, fuel cells can be used in a broad variety of
applications, from huge facilities like power plants to transportation.

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Pros of Hydrogen Cars:
Faster refueling: It will take only a few minutes to refill/refuel the hydrogen
gas tank due to its time-effective and instantaneous process.
Distant range: Hydrogen cars are not only faster but also offer a distant
range with just a single tank of fuel.
Zero emissions: The only thing that a hydrogen car emits is water vapor,
making it a zero-emission vehicle.
Cons of Hydrogen Cars:
Lack of infrastructure: With the limited refueling stations or lack of
infrastructure, hydrogen cars would not be a viable option.
Quite expensive: Hydrogen-powered cars are not cheap, and the refueling
charge differs considerably among different countries.
Production challenges: When it comes to the production of hydrogen, it
can be energy-intensive and may rely on various non-renewable sources.

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Pros of Electric Cars:
Advanced infrastructure: Compared to hydrogen cars, electric cars have advanced
infrastructure and charging stations in which governments worldwide are investing.
Emissionless and cheaper: Electric cars run silently and produce no pollution or
emissions. Also, electric cars are more affordable, and the cost of recharging the
batteries is convenient.
Lower maintenance: Due to the lack of moving parts, battery-powered electric cars
are reliable and require less maintenance, resulting in less cost.
Cons of Electric Cars:
Limited range: One of the most considerable drawbacks of electric cars is the
limited range compared to the time it takes to recharge the batteries.
Battery lifespan: The lifespan of the batteries is limited, and it becomes difficult to
dispose of them properly. It will be essential to replace the old batteries with new
ones at a regular period.
Limited charging stations: The charging or refueling stations are currently in the
development phase, having around 1000 charging stations.

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Advantages and Disadvantages of Battery and Hydrogen Fuel Cell Technologies

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Fuel cells are a type of energy conversion technology which take the chemical
energy contained within a fuel and transform it into electricity along with certain
by-products (depending on the fuel used). [1] It's important to note that fuel cells
are not heat engines, so they can have incredibly high efficiencies. However, when
a heat engine is used to power a fuel cell, the heat engine still has a limiting
thermal efficiency.
Fuel cells can be seen as an energy storage device, as energy can be input to create
hydrogen and oxygen, which can remain in the cell until its use is needed at a later
time. In this sense they work much like a battery. There are multiple types of fuel
cells, but two common types are the solid oxide fuel cell (SOFC) and the polymer
electrolyte membrane fuel cell (PEMFC).

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Fuel Cell Working Principle and
Schematic Diagram:
Fuel Cell Working Principle explains that it is an
electrochemical device that converts chemical
energy of a conventional fuel directly into low
voltage D.C. electrical energy. It is then described
as a primary battery in which fuel and oxidizer are
stored external to the battery and fed to it when
needed. A schematic diagram of fuel cell is shown
in Fig. The fuel gas is diffused through the anode
and is oxidized, thus releases electrons to the
external circuit. The oxidizer is diffused through
the cathode and is reduced by the electrons
coming from the anode through the external
circuit. The fuel cell keeps permitting the fuel
molecule to mix with the oxidizer molecules, and
allow the transfer of electron by a metallic path
that contains a load.

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The gases diffuse through the electrodes by undergoing the following reaction.
When the temperature is high, the electrolyte material acts as a sieve and the hydrogen
ions migrates through the material. An electrical load is connected between the anode and
the cathode. The chemical reaction in the cathode, the energy representing the enthalpy of
combustion of fuel is released and a part of it is available for conversion into electrical
energy. The water formed is drawn off from the side
This fuel cell uses hydrogen as fuel and oxygen as an oxidiser. A typical hydrogen-oxygen
fuel cell is shown in the Fig. There are three chambers separated by two porous electrodes,
the anode and cathode. The middle chamber between the two electrodes is filled with
electrolyte (strong solution of potassium hydroxide). The electrodes surfaces are chemically
treated to repel the electrolyte in order to restrict the flow of potassium hydroxide to the outer
chambers.

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Advantages of fuel cells:
1.Conversion efficiency is high.
2.Easy and simple construction.
3.Require very little attention and maintenance.
4.High power to weight ratio.
5.Fuel cell does not make any noise.
6.Less space required.
7.Quick operation.
8.Can be installed at the use point.
Disadvantage of fuel cell:
1. It is very costly.
2. Short service life.
3. Low voltage output.
4. Proper attention is needed while selection of materials.
Application of fuel cell:
1. Domestic use
2. Automotive vehicle
3. Central power station

Thanks!
Any questions?
You can find me at: gnrgudipudi@gmail.com
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HYBRID ELECTRIC VEHICLES- HYBRIDIZATION OF AUTOMOBILE ( Unit- 2)

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