ELECTRIC VEHICLE TECHNOLOGY

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ELECTRIC VEHICLE TECHNOLOGY

• David Brandt, P.E.

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The Basics

• EV electric vehicle
• Are EVs practical? Golf courses and airports
  have thought so for many years.
• But what about on the road? Are there EVs 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!

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OEM EVs (you may have heard of some of these)

• GM EV1

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OEM EVs

• Solectria Force

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OEM EVs

• Corbin Sparrow PTV

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Hobbyists?

• The hobbyist says If I cant buy one, Ill build
  my own
• Honda Civic

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More Hobbyist EVs

• My Escort

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More hobbyist EVs

• Ford Ranger

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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

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Motors

• OEMs 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

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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)

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Motors

• Advanced DC 9 diameter motor
• Others include GE, Prestolite

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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

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Controllers

• All use PWM technology.

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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)

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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

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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.

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Heater

• The right type can be harvested from an AC
  ceramic heater.

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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)

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Contactors

• BIG relays for switching traction pack

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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

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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

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Performance

• tZero by AC Propulsion

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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.

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Performance - tZero

• tZero mfg. By AC Propulsion versus Corvette

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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 EVs
  or using advanced batteries

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Performance

• John Waylands 120 mile range Red Beastie

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Performance

• Red Beasties battery pack

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Emissions

• Common claim is EVs just move the pollution
• Point taken, but power plant emissions are
  scrubbed to a point not possible on a vehicle.

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Emissions

• Belfast electric bus project (4 year duration of
  monitoring)