Hybrid electric vehicles

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Hybrid electric vehicles

• An extra credit presentation by Harry
  Papacharissiou
• With supplementation by Andrew Nafalski

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Hybrid electric vehicles

• What is a HEV?
• Why HEVs
• Advantages of using HEVs
• Types of HEVs
• HEV components
• The future of HEVs

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What is a HEV?

• Hybrid electric vehicles (HEVs) combine the
  internal combustion engine of a normal vehicle
  with the battery and electric motor of an
  electric vehicle.
• This results in twice the fuel economy of
  conventional vehicles.
• Also offers the extended range and rapid
  refuelling that consumers expect from a normal
  vehicle, with all the energy and environmental
  benefits of an electric vehicle.
• Can be used in a wide range of applications, from
  personal transportation to commercial hauling.

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Hybrid Electric Vehicle

• Combination of petrol engine and electric motor
• Energy density
• Petrol - 12,500 Wh/kg
• Lead Acid battery - 25 Wh/kg
• Nickel-metal hydride battery 44 Wh/kg
• Series hybrids petrol engine drives alternator
  to store energy in batteries or sent to electric
  motor which powers the wheels. Petrol engine
  never supplies the wheels directly.

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Why HEVs?

• Hybrid power systems were designed as a way to
  compensate for the shortfall in battery
  technology.
• Because batteries could supply only enough energy
  for short trips, an onboard generator, powered by
  an internal combustion engine, could be installed
  and used for longer trips. This is the concept of
  the HEV.
• Electric vehicles are only being used in selected
  market applications where fewer kilometres are
  travelled.
• Conventional motor vehicles powered by
  internal-combustion engines (ICE) pose
  substantial economic, environmental and energy
  security issues for the planet.

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Why HEVs?

• More efficient cars can make a big difference to
  society in terms of environmental benefits, and
  the state of the urban air has motivated buyers
  to purchase cleaner cars.
• Use of production HEVs will reduce smog-forming
  pollutants over the current national average.

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Why HEVs?

• Hybrids will never be true zero-emission
  vehicles, however, because of their internal
  combustion engine.
• But the first hybrids on the market will cut
  emissions of global-warming pollutants by a third
  to a half, and later models may cut emissions by
  even more.

• The Honda Insight

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HEV Advantages

• One of the most important differences between a
  HEV and a normal vehicle is the HEV's ability to
  reclaim a portion of the energy lost to braking.
• In a HEV, when the driver brakes, the motor
  becomes a generator, using the kinetic energy of
  the vehicle to generate electricity that can be
  stored in the battery for later use.
• Traditional brakes are necessary, as well as a
  consistent strategy for smoothly blending the two
  braking systems.
• Regenerative and friction brakes need to be
  controlled electronically so that stopping
  ability is maximized to make the dual brake
  operation not noticeable to the driver.

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HEV Advantages

• Regenerative braking (explained above) capability
  helps minimize energy loss and recover the energy
  used to slow down or stop a vehicle.
• Engines can be sized to accommodate average load,
  not peak load, which reduces the engine's weight.
  
• Fuel efficiency is greatly increased (hybrids
  consume significantly less fuel than vehicles
  powered by gasoline alone).
• Emissions are greatly decreased.
• HEVs can reduce dependency on fossil fuels
  because they can run on alternative fuels.
• Special lightweight materials are used to reduce
  the overall vehicle weight of HEVs.

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Types of HEVs

• Many configurations are possible for HEVs.
• Essentially, a hybrid combines an energy storage
  system, a power unit, and a vehicle propulsion
  system.
• The primary options for energy storage include
  batteries, ultra capacitors, and flywheels.
• Although batteries are by far the most common
  energy storage choice, research is still being
  done in other energy storage areas. Hybrid power
  unit options are spark ignition engines,
  compression ignition direct injection engines,
  gas turbines, and fuel cells.

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Practical realisations

• Parallel hybrid two power paths either engine or
  motor, or both power the wheels directly.
• Series hybrid is more efficient but parallel
  hybrid has higher power output needed in
  practical conditions
• Honda Insight vs Toyota Prius
• Insight is pure parallel Prius uses combination
  of both (engine power split along two paths
  wheels and alternator which drives the electric
  motor and also charges the batteries)

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Types of HEVs

• Propulsion can come entirely from an electric
  motor, such as in a in line (series)
  configuration, or the engine might provide direct
  mechanical input to the vehicle propulsion system
  in a V(parallel) system.
• There are several transmission options when it
  comes to HEVs as wellthe driver determines which
  transmission will be most efficient.
• A hybrid's efficiency and emissions depend on the
  particular combination of subsystems, how these
  subsystems are integrated into a complete system,
  and the control strategy that integrates the
  subsystems.
• A hydrogen fuel cell hybrid, for example, would
  produce only water as a by-product and run at
  greater overall efficiency than a
  battery-electric vehicle that uses wall-plug
  electricity.

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HEV Components
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HEV Components

• A HEV is an optimised mix of many components. The
  vehicle drive train consists of
• Electric traction motors/controllers
• Electric energy storage systems, such as
  batteries, ultra capacitors, and flywheels
• Hybrid power units such as spark ignition
  engines, compression ignition direct injection
  (diesel) engines, gas turbines, and fuel cells
• Fuel systems for hybrid power units
• Transmissions

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HEV Components

• There are other key developments being made to
  help
• reduce emissions and improve the efficiency of
  HEVs
• Emission control systems
• Energy management and systems control
• Thermal management of components
• Light-weight and aerodynamic body/chassis
• Low rolling resistance (including tires)
• Reduction of accessory loads in the vehicle

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The future of HEVs

• HEVs are now at the forefront of transportation
  technology development. They are reducing
  critical resource consumption, dependence on
  foreign oil, air pollution, and traffic
  congestion.
• Their widespread penetration into the automotive
  market depends mainly on the economics of
  producing a complex hybrid power system, rather
  than the inherent capabilities of the technology
  itself.

• The Toyota Prius

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The future of HEVs

• As with any new technology, there may be
  obstructions to its acceptance by consumers, But
  time will soon tell.
• The Honda Insight is available to United States
  consumers now, and so far its been getting a lot
  of attention.
• The Toyota Prius has been available for sale in
  Japan since December 1997 and has been a hot
  seller.
• To help with market acceptance, federal and state
  incentives are in place to off-set some of the
  HEV purchase costs when they come to Australia
  for retail sale.

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Comparison
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Insight

• Substantial fuel saving costs
• Ultra low emissions and fuel economy
• HEV technology (65)
• Weight reduction Aerodynamics Reduction in
  rolling resistance (35)
• Source IEE Review, January 2001

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THE END

• References

http//www.altfuels.com/evp.html - Electric
vehicle progress http//www.escapehev.com/index.as
p - Ford HEV