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.

Concept Selection

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.

• Formula SAE rules and guidelines used to drive product requirements.

• Functional requirements derived from competition scoring.

• Concepts evaluated using decision matrices.

Electrical• 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

Suspension• Redesign rockers and Antiroll• Improve ride height

Drivetrain• Mount the Emrax 208 motor• Utilize Ford Quaife Differential• Chain Drive with interchangeable

sprockets for varied gear ratio

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

Component Goals

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– Low degree of camber

change through suspension travel.

– Adjustable Ackermann: +2 to -2 deg at average steer angle

• 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– 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:

Special Thanks To:

Dr. Mitchell StansloskiDr. Troy HollandDr. Donald RadfordJR Garza

Stephanie RossoBryan and Virginia ChristensenThe Houser family

G&N Construction Ault, Co.