ELECTRIC VEHICLE

Vilje

Vilje is the second electric car by Revolve NTNU, and is a complete redesign from the KOG Arctos R. Even after the extensive weight reduction last year, the weight of Vilje was reduced by another 10 kg to just 175 kg. The drivetrain is based on the Emrax 228 electric motor with an in-house developed inverter and accumulator. All electronics were developed in-house, including the battery management system, motor control and inertia measurement unit. The aerodynamics package went through a complete redesign and features an undertray and rear diffusers in addition to the front and rear wings. A two-piece monocoque design was made for the chassis and a hydrophobic nano technology paint job weighing just 260 grams was applied. For 2015 our telemetry software Revolve Analyze was completely reworked from the ground up to enable more efficient and systematic testing and driver feedback.

Gnist

Gnist is the first four-wheel drive electric car designed and manufactured in Scandinavia. Four hub-mounted AMK DD5-14-10 motors with individual compound planetary gearboxes provide a combined power output of 190 bhp. A total redesign from Vilje was necessary to accommodate this powertrain system. A new monocoque design, aerodynamics package, electrical systems, and more make way for an advanced torque vectoring system: By controlling the power output for each wheel individually, Gnist’s cornering and acceleration capabilities are further improved.

Gnist’s drivetrain and powertrain design was acknowledged with two special awards:
– Jaguar Land Rover Award For Innovation in Propulsion Systems.
– Class 1 Best High Voltage Powertrain Implementation by Mercedes AMG High Performance Powertrains.

Other improvements include two-piece full carbon fiber rims, topology optimized titanium 3D-printed uprights, and a pushrod actuated, double un-even a-arm, suspension system.

Eld

Eld is our second four-wheel drive electric race car. The car is based on many of the same features as our previous race car, Gnist, but designed to be even better than its predecessor. By focusing on reducing weight, we managed to shave off 7 kg. We used the same mould for our monocoque, but the aero package was revamped, resulting in a downforce of 610N at 60 km/h. Both the monocoque and the aero package are made of carbon fiber and produced in-house. We also changed the upright design to get an even stiffer and lighter upright for maximum performance. Eld consists of 66 in-house designed and produced circuit boards and 325 sensors. Our program Revolve Analyze is used to receive and use data from the sensors. Revolve Analyze is an in-house data solution for visualizing and interpreting sensor data through telemetry from the car. Furthermore, we made significant changes to our torque vectoring system to help the car stick to the track during dynamic events.

Atmos

Atmos is the third generation four-wheel driven, electrical race car developed, and produced by Revolve NTNU. A new monocoque design with a rearwards inclination in the floor has opened for an aerodynamic undertray and diffuser, achieving a 30% increase in downforce. To compensate for an increase in downforce, the suspension is fitted with a 3rd spring, to stabilize the chassis in heave/pitch movement.

In addition to the 325 sensors used in last years vehicle, Atmos is equipped with hub-mounted accelerometers, IR temperature sensors and a new inertial navigation system. One of the focus areas of the year have been to provide more information about the vehicle and information of higher quality. It is used in the advanced torque vectoring algorithm, and to validate the performance of Atmos. We have also upgraded our telemetry to include driver communication, and live transmission of HD-video. This is used as a visual aid for driver-training.

Nova

Nova is our sixth electrical race car, and the fourth that is four wheels driven with an electrical motor in each wheel. The car has a top speed of 115 km/h, and it weighs only 162.5 kg which is a reduction of 20 kg from last year.

This year, we will for the first time ever drive with self developed, electrical motors! This has led to more flexibility in how we make the parts in the wheel interact, and of course learning a lot along the way. This has enabled us to make an even more compact gearbox, and we were able to reduce the weight by 15% which is 3 kg. We have also increased power with 22% and increased the top speed from 110 km/h to 115 km/h.

Revolve NTNU has a long history of developing our own inverters. The alternative is to buy commercially available inverters, but these are bigger, heavier and harder to troubleshoot. At full speed, the inverters and the motors are able to produce a force equivalent of lifting 500 kg straight up in the air, and the driver experiences to be pushed back in the seat with double his own weight. To make this happen, the inverter has to convert the direct current from the battery to alternating current. We use 24 SiCMOS transistors to make this work, and they each open and close 12 000 times per second. If only one of them miss with less than 700 billion parts of a second, then the consequences are catastrophical. This tells about the precision required to control the inverters without even mentioning the heavy theory behind. The inverter project has lasted for over four years, eight students have dedicated a year of their life in which three of them have written a master thesis on the matter. This is without even mentioning all the competance and funds we have gotten from external partners. We are proud to say that this year we have a working self-built inverter.