This document discusses different types of hybrid electric vehicles. It begins by defining a hybrid car as having two or more propulsion sources, most commonly gasoline and electric motors. The gasoline engine in hybrids is smaller and more efficient. There are several variations of hybrid configurations including mild, series, parallel, and series/parallel. Mild hybrids use electric motors only for assistance and cannot drive solely on electric. Series hybrids have the engine power an electric generator to charge the battery and power the electric motor driving the wheels. Parallel hybrids can use the engine or motor independently or together to power the wheels. Series/parallel hybrids combine both series and parallel systems to maximize efficiency and performance. The document provides diagrams to illustrate the different

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Electric & Hybrid Electric Vehicles
MESFIN AMSALU

2. Points:
Introduction about Hybrid vehicles.
Knowing Hybrid basics.
Hybrid system components.
Hybrid Variations /Configurations.
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3. I. Introduction
 A hybrid car is an automobile that has two or more major
sources of propulsion power. Most hybrid cars currently
marketed to consumers have both conventional gasoline and
electric motors, with the ability to power the vehicle by either
one independently or in tandem. These vehicles are
appropriately termed gas-electric hybrids. Other power
sources may include hydrogen, propane, CNG, and solar
energy.
 A gasoline-electric hybrid car has one or two auxiliary electric
motors that supplement the main gasoline engine. Compared
to conventional automobiles, the gasoline engine in a gas-
electric hybrid is smaller, less powerful, and more efficient.
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4. 1. HYBRIDS EMERGE
Many technologies and power trains may significantly
increase fuel efficiency in the foreseeable future,
including gasoline-electric hybrids, diesel, natural gas,
flex-fuel (bio-fuel), all-electric (battery only) and fuel-
cell vehicles. Over the next decade, however, we
expect hybrid technology to be the most important.
Hybrids offer improved fuel efficiency and
performance— measured by acceleration and
horsepower (hp)—lower emissions and greater
convenience: unlike bio-fuel vehicles, hybrids do not
require special pumps at refueling stations; unlike
all-electric vehicles, hybrids do not limit driving
range.
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5. 3. HYBRID SYSTEM COMPONENTS
 The main components of hybrid systems are
batteries and related electrical systems, electric
motors/generators, power-split device, and power
and control and other electronics.
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6.  Battery Systems and Related Electrical Systems
 The most expensive single hybrid component is the
energy storage system, which includes a battery
pack (containing 100 to 250 cells), a cooling
system and a battery control unit. Together, these
parts represent about 30% to 50% of the total cost
of a hybrid system today.
 The battery chemistry that dominates the hybrid-
vehicle market today uses nickel metal hydride
(NiMH), rather than the lead acid used in
traditional auto batteries, or the lithium batteries
used in lap-top computers and cell phones.
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8. Electric Motors and Generators
These are the primary workhorses in a hybrid vehicle.
The electric motor provides additional power to assist the
engine in accelerating, passing, or hill climbing. This
allows a smaller, more efficient engine to be used. In some
vehicles, the motor alone provides power for low-speed
driving conditions where internal combustion engines are
least efficient.
Transmission A specially modified version of the
existing 5-speed automatic transmission was specified.
This new transmission is more compact than that in a
conventional ones.
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9. It is specially designed
to work with the IMA's
(integrated motor assist)
electric motor to maximize
the motor's ability to regenerate
electricity during regenerative braking.
Power-Split Devices
Power-split devices, which are modified planetary-gear
systems, are robust ways to optimize the transmission
function in full hybrids for fuel efficiency and performance.
They replace the traditional transmission, acting as a virtual
gearbox between the engine, motor and generator. They allow
the motor and engine to power the vehicle separately or
jointly, in infinitely variable ratios.
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10.  With the use of electrical controls, the power-split device
can continuously vary the ratio of power going to the
wheels and the generator. As a result, it can change a
vehicle’s speed by either continuously varying the rpm
of the engine or the rpm of the generator and electric
motor.
 The main value of this design is that engine speed can
operate independently of vehicle speed. As a result, the
power-split device can run the gas engine very
efficiently by constantly maintaining the engine at its
optimal speed, adjusting the speed of the generator and
motor as driving conditions warrant.
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11.  Electronics (Power Control and Others)
 These components efficiently regulate the power
within a hybrid system by managing the flow of
voltage and current among components.
 By constantly monitoring driving conditions and
switching from motor to engine accordingly, the
control unit enables hybrid vehicles to optimize
power and fuel consumption. The inverter
controls and delivers electric power from the
direct-current battery to the alternating-current
motor.
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12. Converter; receives high-voltage direct current (typically
up to 300 volts) from the main hybrid battery and produces
low-voltage direct current (typically 12 volt) for the lead-
acid battery to help power headlamps and other low-
voltage equipment.
Automatic Start/Shutoff.
Automatically shuts off the engine when the vehicle comes
to a stop and restarts it when the accelerator is pressed. This
prevents wasted energy from idling.

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13. 4. Hybrid Variations /Configurations
Hybrid-vehicle components can be arranged in a variety of
ways to obtain different objectives, such as greater fuel
efficiency, increased power, lower emissions etc.
Mild
uses the electric motor and battery as an assist to the internal
combustion engine. A mild hybrid is one that cannot drive on the
electric motor alone. it always needs the internal combustion engine
to propel the vehicle while the motor acts as an assist.
A Mild Hybrid is the least electrified type of HEV. A Mild
Hybrid is a conventional internal combustion engine (ICE)
vehicle with an oversized starter motor that can also be used
as a generator,
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14. Figure : Schematic of a Mild Hybrid power train
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15.  Series hybrid
 In series hybrid the gasoline engine is not directly
connected to the drive train. Instead, the engine is used to
drive an electric generator that provides electricity for an
electric motor that moves the wheels:
 The engine can charge the battery when necessary via the
generator, enhancing fuel efficiency somewhat. However,
the series hybrid offers inferior performance, since only the
motor drives the wheels.
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16. Figure : Schematic of a Series Hybrid power train
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17.  Parallel hybrid
 In a parallel hybrid, the engine and the electric
motor theoretically can drive the wheels
independently or concurrently: In a Parallel
Hybrid, there are two parallel paths to power the
wheels of the vehicle: an engine path and an
electrical path, as shown in figure The power
flows to the wheels in parallel. While this
construction is capable of decent performance,
fuel efficiency can suffer because the battery is not
automatically recharged whenever the engine is
running.
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18.  Figure : Schematic of a parallel hybrid power train
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19.  Series/parallel hybrid
 A series/parallel hybrid combines both systems to maximize fuel
efficiency and performance. A Series-Parallel HEV has both Series
and Parallel energy paths.
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21. Questions & Discussion !!!!! 21
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