Hitting the electric race track with Atmel MCUs

Written by Stuart Cording

Motorsport: the smell of fuel and oil, permanently in the air; highly-tuned, multi-cylinder engines radiating heat; and the incessant drone and whine, earsplitting at times, as cars come tearing around the track.

None of which you will experience at a race where municHMotorsport e.v. is competing with the PWe4.13, its latest high-performance, all-electric Formula Student Car. The team, comprised of students from the Fachhochschule München, Germany, has many successes behind them and grand plans for the upcoming season which kicks-off summer 2014. The vehicle has an impressive array of specifications, including: acceleration 0-100km/h of <4 seconds; top speed of 110km/h; single-piece monocoque body; and two 60kW electric motors.

The team competes in “Formula Student Germany” which defines the rules and provides the infrastructure for the racing events. Other countries have similar organizations allowing teams to compete all across the world. Electric vehicles have been included as a category for the last four years, perhaps reflecting not only the raised level of interest in “green technologies” but also the maturity and low price-of-entry for the technology needed to build an all-electric racing vehicle.

Racing against one-another is considered too dangerous for self-built vehicles and amateur drivers selected from the available teams. Thus, the competition focuses on areas such as vehicle acceleration, maneuverability and endurance. In 2012 the team suffered a bitter blow in the 22km (13.6 miles) endurance test as the vehicle rolled to a halt just 100m (330 feet) from the finish line. In 2013, however, they bounced back delivering a first place in the Spanish competition in Barcelona. The season ended with the team ranked number 5 worldwide in the electric vehicles category.

PCBs

Atmel has provided the Control/Electrical System department with ATmega32M1 automotive microcontrollers to support them in their efforts this year. The MCU was selected to fulfill two applications in the vehicle. One MCU sits snugly in the carbon-fiber steering wheel, where control switches and LEDs provide the driver interface, controlled by the on-chip CAN interface. Meanwhile, the second MCU functions as an aggregator for many of the analogue sensors built into the vehicle. Information, such as wheel rotation and tire temperature, are collected and forwarded to one of the vehicle’s four CAN networks.

steering-wheel

Like any racing team, telemetry data during testing and racing is essential for the team to understand how and where to improve the vehicle.

Talking to Maximilian Werner (Sponsoring) and Christian Schenk (Teamleader Control & Electrical Systems), the two described the project as a never ending search toward the perfect solution. As this year’s vehicle sits on the starting grid, a new group of students will join the team and the graduates will leave, meaning that valuable knowledge and know-how will have to be passed on if the team is to remain successful.

bordnetz gesamt_sml

The team is also made up of cross-discipline students, with electronics and mechanical engineers focusing mainly on design and construction and business studies students undertaking marketing, sponsoring and cost analysis roles.

As I leave the electronics development team behind, we cast an eye over what the mechanical design group is doing.

cars

The smell of glue and epoxy wafts over me as students fill moulds with carbon-fiber matting, sand surfaces to perfection and let finished parts cure. Six crushed nose cones hang on the wall. Maximilian explains that they are proof positive that the car is not only fast, but safe – the result of the mandatory crash testing required before participating.

team

From left to right: Maximilian Werner (Sponsoring); Andreas Welzmiller (Team Leader High-Voltage System); Tanja Elischer (Media/PR); Fabian Sengl (Braking Lights/TSAL); Manfred Brandstetter (Energy Recuperation); Christian Schenk (Team Leader Control & Electrical Systems)

I am left feeling amazed at the immense focus, drive and passion of a group of people, determined to do their best and deliver at every event. We wish them all the best for the coming season and hope they are first to cross the finish line at every event.

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