DEVELOPMENT OF A HYBRID ELECTRIC HEAVY DUTY TRUCK

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DEVELOPMENT OF A HYBRID ELECTRIC HEAVY DUTY TRUCK

• Kemal Çaliskan
• Prof. Dr. Y. Samim Ünlüsoy
• Varlik Kiliç
• Dr. Murat Yildirim

Middle East Technical University
FORD OTOSAN
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HYBRID TRUCKS

• In recent years, heavy commercial vehicles are
  equipped with engines of ever increasing power.
• As an alternative of replacing the engine with a
  larger one, vehicle performance can also be
  improved by hybridization.

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HYBRID TRUCKS

• Heavy commercial vehicles are driven for very
  long distances during their operational lives and
  account for a significant portion of the overall
  fuel consumption.
• Possible reduction of fuel consumption and
  emissions for these vehicles by the application
  of hybrid electric propulsion systems will be
  significant .

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HYBRID TRUCKS

• As opposed to the common objective of reduced
  fuel consumption and emissions by hybridization
  this study presents an application in which
  performance improvement is the main objective,
  with the associated improvement in fuel
  consumption and emissions as a secondary benefit.

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HYBRID TRUCKS

• Some of the main truck manufacturer companies
  have already developed medium sized hybrid trucks
  and they are working on the development of heavy
  duty hybrid trucks.

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HYBRID TRUCKS
VOLVO
MACK

• Class 8
• 2005 US AirForce
• Prototype
• 80kW EM

• Class 8
• Job1 2009
• 120kW EM
• NiMH

DAF / EATON
PACCAR/AZURE

• Class 8
• 44kW EM
• Release 2009
• Li-Ion Battery
• System

• Class 7
• 2 prototypes
• 7.2L diesel
• 90kW EM
• UCAP

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OBJECTIVES

• Main objective
• to obtain the performance of a heavy truck
  equipped with a
• - 12.5 liter diesel engine of 500 PS rated
• power,
• from a hybrid configuration of a
• - 9 liter diesel engine with 400 PS rated
• power and a suitably sized electric motor.
• Secondary objectives
• Reduced fuel consumption and emissions.

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TARGET VEHICLE

• 4x2 Tractor
• 40 ton Loaded
• 9 liter 400 PS Diesel Engine
• 16 Gear Manual Transmission

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PRELIMINARY ANALYSIS

• Examine and compare the performance of basic
  hybrid configurations.
• Determine the basic specifications of the
  electric motor and the battery for the different
  hybrid configurations to satisfy the performance
  objectives.
• Determine the performance and fuel consumption
  for different configurations using standard truck
  driving cycles.

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PRELIMINARY ANALYSIS

• For the preliminary simulations of hybrid
  configurations, NRELs publicly available vehicle
  simulation tool, ADVISOR software is used, after
  being corrected and modified for heavy commercial
  vehicle analysis
• - Converted to rear wheel drive. - Trailer
  hinge loads are included. - Different hybrid
  configurations. - Some errors were discovered
  and corrected.
• Component data were confined to those available
  in the data files of ADVISOR.

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PRELIMINARY ANALYSIS

• Simulation studies indicated that an EM which is
  capable of producing of at least
• 400 Nm torque _at_ 1600 rpm,
• and 70-80 kW power in the speed range from 1000
  to 2200 rpm
• must be specified.
• The EM is to be a shaft motor with a shaft torque
  capacity of at least 2000 Nm.

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PRELIMINARY ANALYSIS

• It was found that a battery group of
• - 90Ah capacity at 360V
• - operated within 20 state of
• charge (SOC) level (e.g. max
• 70 - min 50)
• can feed the electric motor at full power for
  five minutes.

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PRELIMINARY ANALYSIS

• Fuel consumptions of the conventional and hybrid
  configurations on a number of drive cycles showed
  that 10-50 reduction in fuel consumption,
  compared to 12.5 liter, can be realized depending
  on the cycle of interest.
• The highest reduction in fuel consumption is
  obtained in the cycles which represent low speed
  profile with considerable idling periods.

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SELECTION OF HYBRID COMPONENTS

• The required electric motor specifications are
  satisfied by a 100 kW rated power (continuous) EM
  .
• The required battery specifications are satisfied
  by the custom designed battery pack containing
  200 units (100 Series 2 Parallel) of 45Ah Li-Ion
  cells. The total capacity 32.4 kWh and nominal
  operating voltage is 360V.

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PossibleHybridConfigurations
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Selection of Configuration

• Operation of the hybrid vehicle should be as
  similar to the conventional vehicle as possible.
• Selection of a certain configuration may be
  dictated by the packaging requirements for the
  particular vehicle to be hybridized.
• Minimum change in the original vehicle
  configuration is desired.

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Selection of Configuration

• In view of the above criteria, it is decided to
  carry out detailed acceleration, gradeability and
  fuel consumption simulations for the three
  candidate hybrid configurations.
• Parallel hybrid driveline with electric motor
  located
• - after clutch,
• - before clutch, and
• - after transmission.

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Selection of Configuration

• After the results of the simulation studies are
  obtained, the simulated performance of each
  hybrid driveline configuration is compared with
  those of
• - conventional with 9 lt, and
• - conventional 12.5 lt engines.

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ACCELERATION PERFORMANCE
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GRADEABILITY
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FUEL CONSUMPTION lt/100km
Reference
NYGTC
WUINTER
UDDSFDV
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Comparison of the Hybrid Configurations
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Selection of Configuration

• The two choices, after-clutch and pre-clutch, do
  not have any clear advantages over each other
  with respect to performance, fuel consumption,
  and required driveline modifications.
• Before clutch configuration lacks the ability of
  pure electric drive while the after clutch
  configuration have problems with idle charging
  and using EM as the starter.

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Selection of Configuration

• It is decided to employ the Double Clutch
  Parallel Hybrid configuration. This
  configuration will include both the before clutch
  and after clutch configurations.
• It will thus be possible to observe advantages
  and disadvantages of both configurations by
  disabling one of the clutches at a time.

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PACKAGING
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CHASIS MODIFICATIONS

• Engine mounts and locations
• Fuel tank position and mounts
• Li-Ion battery pack mounts
• Electric motor housing and mounts
• Propeller shaft
• Rear splash shield brackets

• Brake Pedal Sensor
• Electric motor cooling pump, radiator and hoses
• Clutch control system pipes
• HV Cabling
• Gear shifting cables
• Brake pipes
• Fuel pipes

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BRAKING SYTEM

• To satisfy the legal requirements for braking of
  commercial vehicles a secondary braking system is
  necessary.
• The large and heavy retarder of the vehicle is to
  be replaced with a smaller and lighter intarder
  coupled to the transmission.

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BRAKING SYTEM

• However, if
• - EM size is doubled, and
• - power resistors are used to
• dissipate the energy when the
• batteries are full
• there will be no need for the intarder !

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CONTROL SYSTEM DEVELOPMENT

• A forward looking simulation model is developed
  in Matlab/Simulink, including external and
  internal motion resistances, load transfer due to
  trailer loads, detailed clutch and tire models.

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CONTROL SYSTEM DEVELOPMENT

• The forward looking simulation model for the
  vehicle performance accepts the following
  commands
• - gas pedal position,
• - brake pedal position,
• - intarder level,
• - pure electric drive switch state,
• - idle charging switch state.
• These commands can be directly input or may be
  determined by a driver model to let the vehicle
  trace a cycle velocity profile.

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CONTROL SYSTEM DEVELOPMENT

• Modes of the rule based control algorithm
• EM only drive (engine disengaged)
• - engine runs inefficiently at very low power,
• - launch up to a certain speed.
• Engine only drive (EM freewheeling)
• - engine runs efficiently.
• EngineEM drive (power summation)
• - power demand is more than engine capacity.
• EngineEM drive (power split)
• - engine runs inefficiently at high power.

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CONTROL SYSTEM DEVELOPMENT

• Modes of the rule based control algorithm
• Engine drive EM charging
• - engine runs inefficiently at low power.
• Regeneration
• - friction and intarder braking,
• - engine braking for zero throttle.
• Pure electric drive (if requested by the driver)
• Idle charging (if requested by the driver)
• ! The selection and application of the control
  rules depend on the battery state of charge (SOC).

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CONTROL SYSTEM DEVELOPMENT
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CONCLUSIONS

• Difficulty in finding suitably sized hybrid
  components.
• Difficulty (in terms of time and cost) in
  purchasing these components.
• The current battery technology is still the most
  challenging obstacle for the development of heavy
  duty hybrid vehicles due to their weight, volume,
  and cost.

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CONCLUSIONS

• With the conclusion of the project study, a
  prototype hybrid truck will be available for
  further development by road tests and studies on
  the control strategies.
• The study may be extended for
• - engine shutdown capability.
• - removal of intarder, starter and alternator.
• - adaptation to the anti-idling and reduced
  emission laws.
• - application to trucks of different
• classes.

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THE END
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HYBRID TRUCKS
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PRELIMINARY ANALYSIS

• It was found that a battery group of 90Ah
  capacity at 360V operated within 20 state of
  charge (SOC) level (e.g. max 70 - min 50 SOC)
  can feed the electric motor at full power for
  five minutes.

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BRAKING SYTEM

• Legal requirement for braking of commercial
  vehicles is stated as maintaining the speed of
  30 km/h on a 7 down gradient for a distance of 6
  km without using the friction brakes.

• Therefore, a secondary system is necessary to
  fulfill the legal requirement.