2. * A hybrid electric vehicle (HEV) augments an electric vehicle
(EV) with a second source of power referred to as the
alternative power unit (APU).
* A hybrid can achieve the cruising range and performance
advantages of conventional vehicles with the low-noise, low-
exhaust emissions, and energy independence benefits of
* Accordingly, the hybrid concept, where the alternative power
unit is used as a second source of energy, is gaining
acceptance and is overcoming some of the problems of pure
3. * Any vehicle that combines 2 or more sources of power
is said to be hybrid. For example, a moped (a
motorized pedal bike), diesel-electric hybrid
* Relies not only on batteries but also on an internal
combustion engine which drives a generator to provide
electricity and may also drive a wheel.
* Alternative power unit to supply the power required by
the vehicle, to recharge the batteries, and to power
accessories like the air conditioner and heater.
5. In a series hybrid system, the combustion engine drives an electric
generator instead of directly driving the wheels.
The electric motor is the only means of providing power to the
The generator charges a battery.
Series hybrids can be assisted by ultracaps (or a flywheel), which
can improve the efficiency by minimizing the losses in the battery.
Utracaps deliver peak energy during acceleration and take
regenerative energy during braking.
Therefore, the ulracaps are kept charged at low speed and almost
empty at top speed. Deep cycling of the battery is reduced, the stress
factor of the battery is lowered.
9. There is no mechanical link between the combustion engine
and the wheels. The engine generator group can be located
There are no conventional mechanical transmission elements
(gearbox, transmission shafts). Separate electric wheel motors
can be implemented easily.
The combustion engine can operate in a narrow rpm range (its
most efficient range), even as the car changes speed.
Series hybrids are relatively the most efficient during stop-
and-go city driving.
10. The ICE, the generator and the electric motor are
dimensioned to handle the full power of the
vehicle. Therefore, the total weight, cost and size
of the powertrain can be excessive.
The power from the combustion engine has to run
through both the generator and electric motor.
During long-distance highway driving, the total
efficiency is inferior to a conventional transmission,
due to the several energy conversions.
11. Fuel tank supplies gasoline to the engine.
Set of batteries supplies power to the electric motors.
Both the engine and electric motor can turn the
transmission at the same time, and the transmission
turns the wheels.
When the APU is off, the parallel hybrid runs like an
When the APU is on controller drives the energy
between drive train and batteries
Under acceleration more power is allocated to drive
train than to the batteries and during periods of
idle,more power goes to the batteries than the drive
15. Flexible in configurations and gives room for
optimization of fuel economy and emissions.
Reduced engine size.
Possible plug-in hybrid for further improved
fuel economy and emission reduction.
17. 1. Electric motor:
Converts electric energy to mechanical energy.
It is powered by DC sources such as batteries or by AC sources
such as generators.
2. Auxiliary power unit(APU):
It is a device that provides energy for functions other than
APUs use spark and combustion engines as a source of power.
However in recent years fuel cell APUs that nearly eliminate
all emissions are used.
APU in HEVs supplies baseline power required by vehicles,
recharges batteries and power accessories such as air
conditioners and heaters.
18. 3. Generator:
The combustion engine in serial hybrid drives electric
The generator both charges battery and powers motor that
In parallel hybrid there’s no separate generator, motor
functions as generator when needed.
4. Energy storage systems:
Batteries, flywheels or ultra capacitors are used for energy
storage in HEVs
Flywheels store energy mechanically by turning heavy rotor to
store kinetic energy.
19. Lithium ion batteries are used for their efficiency and high
power to weight ratio for energy storage.
Ultra capacitors store energy in polarized liquid between an
electrode and electrolyte, provides additional power during
5. Regenerative breaking:
Vehicles relay on friction breaks to slow down, dissipating
kinetic energy as heat. Regenerating breaks turns this energy
into electricity and stores in batteries.
This electricity can later be used to run motors and accelerate
20. * Using the concept of Hybridization of cars
results in better efficiency and also saves
a lot of fuel in today’s fuel deficit world.
* A hybrid gives a solution to all the problems
to some extent.
* If proper research and development is
done in this field, hybrid vehicle promises
a practical, efficient, low pollution vehicle
for the coming era.
* One can surely conclude that this concept
and the similar ones to follow with even
better efficiency & conservation rate are very
much on the anvil in today’s energy deficit