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 electric vehicles
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 electric vehicles.
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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 locomotives
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.
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4. Two types of hybrid vehicle configurations
Parallel Hybrids
Series Hybrids
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5. Fuel tank, which supplies gasoline to the
engine.
Set of batteries that supplies power to an
electric motor.
Both the engine and the electric motor can
turn the transmission at the same time, and
the transmission then turns the wheels.
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6. When the APU is off, the parallel hybrid runs like
an electric vehicle
When the APU is on, the controller divides
energy between the drive train (propulsion) and
the batteries (energy storage).
Under acceleration, more power is allocated to
the drive train than to the batteries. During
periods of idle or low speeds, more power goes
to the batteries than the drive train.
The batteries also provide additional power to
the drive train when the APU is not producing
enough and also to power auxiliary systems such
as the air conditioner and heater.
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7. Similar to an electric vehicle with an on-
board generator
The vehicle runs on battery power like a pure
electric vehicle until the batteries reach a
predetermined discharged level.
At that point the APU turns on and begins
recharging the battery.
The APU operates until the batteries are
charged to a predetermined level.
APU never directly powers the vehicle
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8. The length of time the APU is on depends on
the size of the batteries and the APU itself.
Since the APU is not directly connected to
the drive train, it can be run at its optimal
operating condition; hence, fuel economy is
increased and emissions are reduced relative
to a pure IC engine vehicle.
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9. Electric drive motors
to provide the power for propulsion
converts electric energy to mechanical energy
(motion) to drive the hybrid vehicle.
Direct Current Motors, Alternating Current Motors
The two possible configurations of electric drive
motors in a hybrid vehicle
single electric motor connected to the wheels through a
drive train and multiple electric motors, one located at
each wheel.
Auxiliary Power Units
Supplies the baseline power required to the vehicle,
recharges the batteries and powers accessories such
as the air conditioner and heater.
The APU can consist of a mechanical type engine or a
fuel cell.
Spark Ignition Engine, Compression Ignition Engines, Fuel
Cells
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10. Generators
to convert the mechanical power into
electrical power when used in a series
hybrid.
Energy Storage Systems
Peak power required in hybrid vehicles is met
by devices like batteries, capacitors or a
flywheel.
store energy and readily release it when
needed.
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11. Regenerative Braking
some of the energy is converted into
electrical energy and stored.
rotational energy of the braking mechanism
generates electrical power and stores it in
the batteries.
Control Systems
contains two main components-command and
power components.
command component manages and processes the
driver’s instructions.
power component chops power flows to control
the motor’s power intake.
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14. Electric vehicle equipped with a fuel cell
Use hydrogen as a fuel and power the electric battery
when it is depleted
In the 21 century, the auto fuel will be replaced by
such regenerative resources as hydrogen and the
power system with traditional internal combustion
engine will be replaced by hybrid system and finally
be replaced by fuel cell power system to realize
multi-resources, electric driving and zero emission.
For the fuel cell hybrid electric bus developed, high-
pressure PEMFC and high-power NiMH battery pack
forms the hybrid system.
In order to obtain the higher fuel efficiency and avoid
the frequent charge & discharge of battery pack, the
active control for the fuel cell pack to follow the
driver’s pedal and the surplus peak power from NiMH
battery pack passively is used.
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15. Fuel cell Hybrid Power Train Structure
Fuel Cell Indirect Power System
FCE is connected with ESS in parallel after DC/DC
converter
better for the optimization and control of the FCE and is
an economic selection for the fuel cell vehicle nowadays.
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16. Fuel Cell Direct Power System
FCE’s output is directly inputted to DC/AC and the ESS is
connected with the FCE’s output in parallel after a
bidirectional DC/DC.
FCE outputs power directly into DC/AC, the FCE must
have good dynamic response to output enough power
quickly to meet the vehicle’s driving performance
requirement and good voltage maintained performance to
avoid the large voltage drop of bus line and the large
torque drop of electric motor. On the other side, the FCE
must be overlarge to avoid the possible damage.
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18. The main controller receives the pedal signals
from the driver. With the values of pedal,
speed, the driving power required is calculated
by look-up table of motor performance map.
The target power of fuel cell engine is the sum
of the driving power and the SOC-regulated
power of battery pack.
The target current of the DC-DC converter is
real-time calculated by the target driving power
divided by the bus voltage. The air compressor’s
speed control is based on the target power of
fuel cell engine.
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19. In order to properly determine the target power of Fuel cell
and at the same time to realize the active control of fuel cell
engine, it becomes very important to design a suitable and
reasonable system control strategy.
Two kinds of control strategies
Conventional fuel cell output power oriented
control strategy
Setting the FCE as the main power sources and
controlling the FCE’s output power to follow
the vehicle’s driving power requirement at
some extent. The FCE is working on nearly for
all of the driving time expect for the first cold
start and small driving power requirement
while battery pack is at high SOC.
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20. Fuel cell output power oriented control strategy
based on FCE loading and unloading equations
similar to the fuel cell output power oriented control
strategy as just mentioned above, but there has some new
control characteristics as follows:
If cSOC > cSOC.t, the battery regulation power is zero and
the battery actual output power is the power difference
between Pd and Pf;
If cSOC ≤ cSOC.t, the battery regulation charging power is
considered and the target fuel cell power is the sum of
driving power and charging power;
When the vehicle is braking, the fuel cell works at the
minimum power and charges the battery pack with the
regenerative braking;
The fuel cell engine works on nearly all of the driving
time expect for the over high SOC battery pack and
small driving power requirement at the first cold
starting.
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21. to transport and store hydrogen fuel in the
vehicle.
the cost of producing a powerful fuel cell is
high.
the size and weight issue as fuel cells
powerful enough to power a car or truck
are still rather bulky and heavy.
However technology is maturing fast, so fuel
cells may well prove to be a viable option in
automotive technology in the not so distant
future.
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22. Drive slower - The aerodynamic drag on the car
increases dramatically the faster you drive. For
example, the drag force at 70 mph (113 kph) is about
double that at 50 mph (81 kph). So, keeping your speed
down can increase your mileage significantly.
Maintain a constant speed - Each time you speed up the
car you use energy, some of which is wasted when you
slow the car down again. By maintaining a constant
speed, you will make the most efficient use of your fuel.
Avoid abrupt stops - When you stop your car, the electric
motor in the hybrid acts like a generator and take some
of the energy out of the car while slowing it down. If
you give the electric motor more time to slow the
vehicle, it can recover more of the energy. If you stop
quickly, the brakes on the car will do most of the work
of slowing the car down, and that energy will be wasted
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23. 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 world.
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