Download Solar Powered Cars - Classes

SVT
Oregon State University
Solar Vehicle Team
OSU Solar Vehicle Team
Background Information – Solar Cars
• Solar panels directly on car
• Completely enclosed system
– No external energy input
• Aux. battery pack to store excess energy
for later usage
• Solar cars mainly seen in two events
– North American Solar Challenge (NASC)
– World Solar Challenge (WSC)
Solar Car Races: NASC and WSC
• World Solar Challenge
– 3000 km race from Darwin
to Adelaide
– 10 day race
• North American Solar
Challenge
– 2400 mile race from Dallas,
TX to Calgary, Canada
• Highway format
– Highway speeds, traffic
– Must be street legal (auto
insurance, plates, VIN, etc)
WSC
Solar Car Races: NASC and WSC
• Fastest cars in
World Solar
Challenge can go
faster than 142 kph
• Top 2 to 3 vehicles
can sustain posted
speeds throughout
race
NASC 2008
Solar Array and Batteries
• 6 m2 or 9 m2 solar array
surface area allowed
• Generates around
1800W (2.4 HP) peak
with triple junction GaAs
• Batteries only store 5
kWH (1.34 HP for 5 hrs)
• How is propulsion
possible?
Triple junction GaAs cell [2]
Forces and Power Balance
Pin = small, maximized
Fdrag
minimized
Pout = small,
maximized
Design Goals
•
•
•
•
Efficient power input
Efficient power usage
Low aerodynamic drag
Low mass
Efficient Power Input – Best Cars
• > 26% efficient, triple
junction GaAs array on
fastest cars
• > 98% efficiency
electronics
• High efficiency LiIon/LiFePO4 for
charging and
discharging.
U of M solar car evening charging with
• Concentrators used on
concentrator sub-array
Univ. of Michigan car
Lowering drag
• Reduced weight
– Carbon fiber
– Aluminum/Titanium chassis
– Most cars weigh 200 to
300kg
• Better areo
– Cd of .21
– .741 m2 cross sectional
area
– Cd * A = .156
– CFD/wind tunnel testing
– Attention to detail – fillets,
ridges
2010 OSU Solar Car in wind tunnel
OSU Solar Vehicle Team
• OSU’s first solar vehicle
– First car in Northwest
– $50,000 budget vs. $2.4
million of U. of Mich.
– 16.4% efficient cells
– Brushed DC motor, 94%
efficient peak (linearly
decreasing to 0 as RPMs
drop)
– Fiberglass body
– First titanium chassis in
NASC history
– LiFePO4 battery pack
– 15th out of 24 entrants
OSU Solar Vehicle Team (cont’d)
• 2010 OSU Solar Car: Odyssey
– 17.4% minimum efficiency
mono-crystalline SolarWorld
solar array
– Optimized prepreg carbon fiber
body
– Ti-425 titanium chassis and
suspension
– 95% efficient NGM PMAC wheel
motor
– 0.21 Cd drag, 0.74 m2 frontal
area
– Goal for top 5 cars in 2010
NASC
– Anticipated speeds
• 45-50 mph cruising
• 85 mph top speed
Odyssey Solidworks Schematics
Case Study: Body Design Process
• Customer need:
– Maximum solar
surface area with
minimum drag
• Problem definition &
specifications
– Body must fit within a
box that’s 1.8m x
1.6m x 5 meters and
hold solar array
Body Design Continued
• Data and information collection
– Looked at over 30 vehicles from 1989 to
now
– Consulted books and experts
• Evaluation of design and selection of
optimal design
– Ran computational fluid dynamics on more
than 100 separate designs
– Tested two best designs by 3D printing at
EECS and using wind tunnel in Rogers
Body CFD
Body Wind Tunnel Testing
Implementation of Design
• Implementation of design
– Carbon fiber composite fabrication
Making the Car
• Phase 1: Making the chassis, suspension,
steering, body, wheels
• Phase 2: Making the power electronics,
attaching motor, batteries
• Phase 3: Attach solar cells
How You Can Help
• Help out with design and construction
• Attend construction meetings
– Meeting times will go out in emails, but will
typically be Tuesday, Thursday, Friday and
Saturdays.
– Sign up by emailing [email protected]
• Visit our website at:
http://oregonstate.edu/groups/solar