Download ELECTRIC VEHICLE TECHNOLOGY

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)?
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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
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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
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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:
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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
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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
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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 purposebuilt 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)
CO2
CO
NOx+SO2
Hydrocarbons
Particulates
Diesel
Electric Savings
1331
1058
21%
7.64
0.18
98%
19.96
11.52
42%
2.74
0.18
93%
5.1
0.2
96%