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OSU Solar Vehicle Team
SVT
Solar Vehicle TeamOregon State University
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
Pout = small, maximized
Fdrag minimized
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 Li-Ion/LiFePO4 for charging and discharging.
• Concentrators used on Univ. of Michigan car
U of M solar car evening charging with concentrator sub-array
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