Download Develop a formula SAE electric racecar capable of passing technical

FSAE-Electric 2016
Problem Statement
Develop a formula SAE electric racecar capable of passing
technical inspection and obtain data for future generations of
the EV car design.
Overall Vehicle Goals
• Incorporate an all-electric drivetrain into a competitive race
design.
• Redesign the EV1 electrical systems for increased reliability
and serviceability.
• Gather data to build profile for battery characteristics
• Systems design approach that emphasizes safety.
Concept Selection
• Formula SAE rules and guidelines used to drive product
requirements.
• Functional requirements derived from competition scoring.
• Concepts evaluated using decision matrices.
Component Goals
Electrical
Suspension
• Design safety circuits and
reliable battery which meet
specs given in rules and
passes Technical inspection
• Integrate a Automotive grade
Microcontroller
• Integrate motor controller
and motor with battery and
Microcontroller to pass
technical inspection
• Obtain battery performance
data for next iteration
• Redesign rockers and Antiroll
• Improve ride height
Cooling
• Design an accumulator case
that cools battery cells and
can withstand impact forces
• Design sidepods that
effectively increase air flow
to the battery cells
Drivetrain
• Mount the Emrax 208 motor
• Utilize Ford Quaife Differential
• Chain Drive with interchangeable
sprockets for varied gear ratio
Low Voltage Controls
•
Driver Controls
– Brake sensor
– Torque Encoders
– Voted Encoder System (MCU
Driven)
– Driver Profiles
•
Safety
– Shutdown Circuitry
•
•
•
•
•
Insulation Monitoring Device
Crash Sensor
E-Stop Buttons
Brake plausibility device
Brake-Over-Travel
Tractive System
• Battery Pack
– Melasta Cell 10Ah
•
•
•
•
•
Max Voltage,
300 VDC
Nominal Voltage,
266 VDC
LiCoO2 cell
chemistry
72 Series
Configuration
Motor Controller
– RMS PM100DX
•
•
•
•
•
•
Max power, 100
kW
Max output
current, 300 ARMS
Pre-charge/
Discharge Circuit
Rpm limiting
Temp, Current
and Voltage
monitoring
Full motor profile
•
Suspension
Designed to
Accommodate Hoosier
20.5x7.0 - 13 FSAE Race
Tires
–
–
•
Carbon Fiber Unequal
Length Double A-Arm
–
–
–
•
Kinematics designed in
Optimum K based on
characteristics derived
from tire data
Roll and pitch rates
designed to accommodate
mass of electric drivetrain
Unsprung mass: 27kg per
corner
Mathematical Modeling
–
–
•
Low degree of camber
change through
suspension travel.
Adjustable Ackermann: +2
to -2 deg at average steer
angle
Iterative design process
sought simultaneous
compromises between many
parameters
Load transfer, steering, tire,
and damper properties
tracked through various
cornering conditions
RockShox Coil-Over
Spring/Dampers
– Tuned to damper force/speed
curves obtained from dyno
testing
– Vehicle static ride height: 1”
– Vehicle natural frequency: 3.1
Hz
•
CNC Machined Rockers
–
–
Two piece rockers for easy
manufacture and integrated
spacers
1.1:1 and 1.4:1 motion ratio
in front and rear respectively
allows for full range of travel
damper travel
Cooling
•
Accumulator Case
–
Steel Case
• Resists an impact
load of 20 G’s
– 72 battery cells
– Large air vents to
keep batteries
below 60 C (140 F)
•
Aerodynamics
– Nosecone
– Aero fabric
• Diverts air back
into the sidepod
– Sidepod
• Airflow to the
battery case
• Fiberglass
•
Water Cooling
– Radiator
– Water Pump
• Directs water to
the Emrax 208
motor and HV
Controller
Drivetrain
• Electric Motor
– Emrax 208
Motor
• Max power =
80 kW @
300V
• 140 Nm (103
ft-lb) peak
torque
• Chain Drive to
Quaife Limited
Slip Differential
– Mid-engine rear
wheel drive
– 1 to 5 final drive
ratio
• Max Torque at
wheels = 700
Nm (515 ft-lb)
• Custom aluminum
mount
– Added support
bearing
– Built in chain
adjustment
Sponsors:
G&N Construction Ault, Co.
Special Thanks To:
Dr. Mitchell Stansloski
Dr. Troy Holland
Dr. Donald Radford
JR Garza
Stephanie Rosso
Bryan and Virginia Christensen
The Houser family