CleanSpeed 4 (CS4) is AERO’s eigth generation vehicle, and fourth generation electric vehicle. Going into the design of CleanSpeed 4, AERO has two primary goals. The first goal is to improve on the performance of CleanSpeed 3 by decreasing weight and increasing power output. This will be done by using lighter, more power-dense Lithium-Ion batteries instead of Lithium Iron Phosphate batteries. To handle the extra power, CleanSpeed 4 will use a new motor and motor controller. The second goal is to implement a robust data acquisition and telemetry system, which should improve the design of future cars, as well as increasing performance at competition. This data acquisition project will be conducted as a Senior Capstone Project for the senior members of the team.
Early CleanSpeed 4 frame design. Due to the smaller and lighter components, this frame is much lighter than CleanSpeed 3’s frame.
|Battery Chemistry||Lithium ion|
|Motor||Emrax 228 MV|
|Battery Capacity||5.76 kWh|
|Battery Voltage||288 V|
|Peak Power||63 kW (85 HP)|
|Track Width||54 (front)
|Weight||600 lbs (estimate)|
CleanSpeed 4’s battery pack is the largest improvement over CleanSpeed 3. It uses Samsung 18650 cylindrical cells for a much higher power-to-weight ratio. These cells are assembled into 8-cell parallel modules by Energus for rules compliance and ease of assembly. The car will have two sidepod-style battery packs on either side of it, next to the driver, each with 40 battery modules in it, for a total of 80 modules. The total weight of the pack (with both side-pods) is 60kg (130lbs), which is less than half of CleanSpeed 3’s pack. Even with this 50% weight reduction, the new packs have only 10% less capacity and can deliver twice the power with higher efficiency.
CleanSpeed 3’s suspension was its biggest improvement over any vehicle AERO had made in the past. Because of this, CleanSpeed 4 will use the same general suspension design with limited geometry modifications. The major changes will include raising roll centers, lowering steering weight, and adapting the rear geometry to fit the smaller rear of the car. These changes, along with brake biasing improvements, should allow CleanSpeed 4 to perform even better in autocross events.
CleanSpeed 4’s powertrain has been redesigned to handle the full power of the new battery packs. It uses an Emrax 228 medium-voltage, combination-cooled PMAC motor controlled by a Rinehart PM100DX 3-phase motor controller. These components have a minimum efficiency of around 85% at full power draw, which is higher than CleanSpeed 3. This means the motor is less prone to overheating, even with a higher power output. This configuration also allows for regenerative braking, which will help maximize performance in the endurance event.