Started from scratch in September of 2016, CleanSpeed 3 (Updated to CleanSpeed 3.5 for 2018 competition) was AERO’s 7th generation vehicle. Its most prominent features include a newly designed suspension, an improved battery pack, a new powertrain, a new control system, an advanced telemetry system, and a new chassis to contain it all.
|Battery Chemistry||Lithium iron phosphate (LiFePO4)|
|Battery Capacity||6.14 kWh|
|Battery Voltage||102 V|
|Motors||Dual LMC 200D95B, shaft coupled|
|Peak Power||34 kW (46 HP)|
|Track Width||56.5 in|
CleanSpeed 2 performed very well last year, but if we were to make it perform better this year it would have needed a massive suspension redesign, which would have compromised the battery pack substantially. Because of this, we decided to build a new car around a new suspension. Senior member Greg Castaldi spent countless hours designing the system, with the primary design goals being adjustability and the ability to easily adapt it to a new chassis in the future. New uprights were designed to replace the old, non-optimized ones we had been using, and were machined by our sponsor Tru Form Precision Manufacturing. The suspension geometry was modelled using advanced software from our sponsor Lotus Cars UK to ensure the car would perform exactly as intended. Additionally, we brought back the beautiful OZ Racing rims used on the original CleanSpeed to make this car look and perform to its full potential.
Last year’s under-the-driver battery pack was great for keeping the center of gravity of the car low, but it was extremely difficult to access for maintenance and was susceptible to water damage. This year, senior members Jack Thomae and Alex Raff designed a new battery pack around the same lithium iron phosphate cells, but made it relatively easy to remove from the car for work to be done on it. Compared to last year, this year’s pack has 13% more charge capacity, which allows the car to drive farther and faster. Also, we upgraded the battery management system we had been using to a new, more configurable option from Elektromotus.
To boost performance from last year, we switched from an AC powertrain to a DC powertrain with dual, lightweight pancake-style permanent-magnet DC motors from Lynch Motors. Coupled with Manzanita Micro’s Zilla motor controller we used on the original CleanSpeed, these motors provide amazing torque, and accelerate much faster than last year’s AC motor. To send all that power to the wheels, a new, adjustable differential mount was designed by Junior member Moritz Thali, which provides an easy way to adjust chain tension and swap out different sized drive sprockets. Additionally, an electronic series-parallel motor switching system was implemented using contactors from our sponsor GIGAVAC. In series mode the car has greater acceleration, and in parallel the car has a higher top speed, effectively letting us “change gears” without any extra moving parts.
To fix the noise and signal problems CleanSpeed 2 had, a new control system was designed by sophomore member Cullen Jemison. This system, based on the industry standard controller area network (CAN) bus, was designed to eliminate noise and minimize analog signal runs in order to allow the car to run reliably under all conditions. It also includes new safety circuitry, which safely powers down the car within seconds of any dangerous fault being detected.
To allow for more effective analysis of the car’s performance, CleanSpeed 3 includes an advanced telemetry and datalogging system designed by sophomore member Peter Ferland. This system monitors and records wheel speed and shock travel on all four corners, accelerometer and gyroscope data, and GPS data, along with status information from the control system. With this system in place, the suspension movement can be carefully analyzed after driving, and other data can be combined to determine how to drive the car more effectively.