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ELECTRIC VEHICLE TECHNOLOGY.ppt

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ELECTRIC VEHICLE TECHNOLOGY.ppt Powered By Docstoc
					ELECTRIC VEHICLE TECHNOLOGY



David Brandt, P.E.
The Basics:
• EV: electric vehicle
• Are EV’s practical? Golf courses and
  airports have thought so for many years.
• But what about on the road? Are there EV’s
  among us? Yes, and not just in California!
• Is there actually technology available to
  you and me to allow us to operate a
  practical EV? Yes!
OEM EV’s (you may have heard of
some of these):
• GM EV1
OEM EV’s:
• Solectria Force
OEM EV’s
• Corbin Sparrow PTV
Hobbyists?
• The hobbyist says “If I can’t buy one, I’ll
  build my own…
• Honda Civic
More Hobbyist EV’s
• My Escort
More hobbyist EV’s
• Ford Ranger
Components
• What is out there that you need to have to
  build an EV (besides batteries)?
  –   Motor
  –   Controller
  –   Charger
  –   DC/DC Converter
  –   Heater
  –   Instrumentation
  –   Contactor(s)
  –   Safety Equipment
Motors
• OEM’s: typically AC drive
  – Fail-safe design
  – Low initial torque, higher at speed
  – requires complicated electronics package
     •   AC speed control (similar to industrial)
     •   Inverter (convert DC to AC)
     •   High voltage (240-350 VDC)
     •   Bearings only mechanical maintenance item
Motors
• Hobbyist: typically brushed DC series
  wound
  –   Motors are available and inexpensive
  –   100% torque at 0 RPM
  –   Controllers are dirt cheap compared to AC
  –   No inverter stage required
  –   Lower voltage system (72-156 VDC)
  –   Bearings and brushes are potential
      maintenance items (change brushes every
      100,000 hours or so)
Motors
• “Advanced DC” 9” diameter motor
• Others include GE, Prestolite
Controllers
• In General, Volts = Speed, Amps = Torque
  – Curtis
     • to 144 VDC, 500 Amps
  – Auburn Scientific
     • to 192 VDC, 1200 Amps
  – DCP
     • to 336 VDC, 600/1200 Amps
  – EVCL
     • “GODZILLA” to 336 VDC, 1200 Amps
Controllers
• All use PWM technology.
Chargers
• OEM: uses weird connectors like inductive
  “paddle” or AVCON “gas pump” nozzle.
• Hobbyist: How about something everyone
  already has, like 120 VAC household outlets
  and 240 VAC dryer outlets?
• Simple (voltage regulated) to complicated
  (computer controlled charging algorithms)
• More advanced charging required for
  advanced batteries (AGM)
DC/DC Converters
• Uses PWM to step traction pack voltage
  down to 12V to run car accessories.
• Common in electronics use
• Not widely available in the voltages
  required
Heater
• Ceramic - Self-regulating temperature of
  about 180° F.
• As temp. increases, resistance increases,
  decreasing power and stabilizing temp.
• Therefore, more air across the element =
  more heat.
• Typically 1500W. Can be stacked for more
  heat.
Heater
• The right type can be “harvested” from an
  AC ceramic heater.
Instrumentation
• Instrumentation can be as simple as an
  expanded scale voltmeter, but can be
  sophisticated, and include:
  –   Traction Pack Voltmeter
  –   Battery Current Ammeter
  –   Motor Current Ammeter
  –   Amp-hour/kWh meter (“E-Meter”)
Contactors
• BIG relays for switching traction pack
    Safety
• Inertia switch to deactivate contactor(s)
    – same as is used to shut off fuel pumps in ICE
      cars
• AGM batteries - no spillage
• Service disconnects - BIG circuit breakers
• Fuses, of course
• Traction pack is electrically isolated from
  frame
• 8 G crash load rating recommended for
  battery boxes
Performance
• Acceleration and speed
  –   About the same as ICE
  –   Ranges from “economy car” to “muscle car”.
  –   DC motors great for drag racing
  –   Current NEDRA record 8.801 seconds in the 1/4
      mile by “Current Eliminator”
Performance
• tZero by AC Propulsion
Performance - tZero
• AC Propulsion's tzero out-accelerated a
  Ferrari F355, a new Corvette, and a Porsche
  Carrera 4 in a series of impromptu 1/8 mile
  drag races held on January 22, 2000 at
  Moffett Field in Mountain View, California,
  and at Calstart's northern facility at the
  former Alameda Naval Air Station.
Performance - tZero
• tZero mfg. By AC Propulsion versus Corvette
Performance
• Range - typically 30-60 miles
  – somewhat dependent on if you have a lead foot
  – great for commuting, which is where people
    use the most gas anyway.
  – Use an ice vehicle for long trips - the right tool
    for the right job.
• Over 100 miles attainable with purpose-
  built EV’s or using advanced batteries
Performance
• John Wayland’s 120 mile range “Red
  Beastie”
Performance
• “Red Beastie’s” battery pack
Emissions
• Common claim is EV’s just move the
  pollution
• Point taken, but power plant emissions are
  scrubbed to a point not possible on a
  vehicle.
Emissions
• Belfast electric bus project (4 year
  duration of monitoring)
Fuel Consumed (kWh/mile)
                           Diesel       Electric Savings
                                    4.9        2.2    55%
Pollutants (gms/mile)
                           Diesel     Electric Savings
CO2                             1331       1058     21%
CO                              7.64        0.18    98%
NOx+SO2                        19.96      11.52     42%
Hydrocarbons                    2.74        0.18    93%
Particulates                      5.1        0.2    96%

				
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