Schaeffler's electric powertrain primed for FIA Formula E racing

  • 09-Sep-2015 12:02 EDT
ABT Schaeffler   Formula E car.jpg

As was the case in the inaugural season, all 40 FIA Formula E cars use the same Dallara chassis, Williams Advanced Engineering battery pack, 18-in wheels, and Michelin tires. But unlike the 2014/2015 season, teams are free to use a unique all-electric powertrain for the 2015/2016 season. The ABT Schaeffler Audi Sport car is shown during preseason two testing in England. (For additional images, click the arrow in the upper right corner of this image.)

The second season of FIA Formula E begins in Beijing, China on October 17, 2015, with the ABT Schaeffler Audi Sport team’s exclusive technology partner ready to demonstrate its novel all-electric powertrain.

“We did a lot of calculations because we needed to decide on one or two electric motors and the number of transmission gears. A single electric motor and a three-speed transmission in combination with the [rules-required] central differential is what we determined would be the best package for achieving optimal results,” said Prof. Dr.-Ing Peter Gutzmer, Deputy CEO and Chief Technology Officer for Schaeffler AG.

Gutzmer and others involved in the world’s first all-electric racing circuit spoke with Automotive Engineering during preseason two testing at the renowned Donington Park Racing Circuit in Castle Donington, England.

In the 2014/2015 inaugural season, all 40 carbon-fiber/aluminum monocoque chassis single-seat cars ran a standardized McLaren Applied Technologies powertrain on street courses in Europe, Asia, and the Americas. Although each Formula E racecar still uses a Williams Advanced Engineering-supplied battery with 28 kW·h of stored energy, each team could elect to run a unique powertrain in the 2015/2016 season.

Andrew Van De Burgt, FIA Formula E communications specialist, said eight of the 10 race teams chose not to stay with the season-one powertrain package that featured a Hewland Engineering five-speed paddle shift sequential gearbox. The eight teams opting to develop and homologate a new powertrain did so via partnering with technology specialists.

“We literally have everything from a single-speed to a five-speed transmission. Last year, the [race] starts were pretty uniform because everyone had the same transmission. Now with this vast difference in transmission technology, we could see a really big difference in the way they start,” Van De Burgt said.

From a noise perspective, there’s been a sonic sound shift from the first season because of the transmission and motor changes. “You can instantly tell the Abt/Schaeffler car because it’s much louder than the other cars. And you can tell the Mahindra, Dragon, and Venturi [team] cars because they’re really quiet. So there’s an audible difference this year,” said Van De Burgt.

The ABT Schaeffler Audi Sport team hopes to top last season’s nine podium finishes with the switch to a new powertrain that spotlights an electric motor that is more efficient and provides more torque than the predecessor.

Schaeffler’s electric motor drops double-digits in weight compared to the 57-lb (26-kg) McLaren Electronic Systems-supplied motor that propelled a 2014/2015 season racecar from 0 to 62 mph (100 km/h) in 3 seconds, according to Gutzmer. “It is a really significant weight savings. The whole system is new. But the components that we are using, including the rotor, have been approved already in other applications, [namely] commercial vehicles and motorsports,” said Gutzmer.

The three-speed transmission is being produced by Hewland to Schaeffler specifications. This new manual transmission is stiffer and more compact. “We were really focused on efficiency and maximum torque, and the three-speed transmission allows much more than last season’s five-speed transmission,” said Gutzmer. “We think the three-speed transmission is a success factor for this powertrain.”

Another focal point of the Schaeffler-developed powertrain was thermal efficiency.

“If you are taking energy out of the battery and using it just for resistance in the wirings, in the motor, and in other areas, that means a loss of power in terms of what you’re unable to use while driving the car. We improved the powertrain’s thermal efficiency in the 3% range, and it could be up to 8% better in certain driving situations. That’s a big step because it’s really important to be smart about battery usage,” Gutzmer emphasized.

Team ABT Schaeffler Audi Sport driver Lucas di Grassi said power management is vital. Last season each driver had 200 kW of power for qualifying and 150 kW of maximum power during a race from the Li-ion battery with maximum usable energy of 28 kW·h.

“The energy for qualifying remains the same, but we’re now allowed to use 170 kW in the race, so that’s a 20-kW increase over last season from the same amount of energy. So basically apart from making a motor that delivers more power, it has to be more efficient because when you accelerate, you’re using more energy,” said di Grassi.

Technical specialists from Schaeffler, ABT, and Audi Sport were involved in rewriting software code, according to Gutzmer. “It was done to alter the complete driving behavior of the car, and also was done to address the tuning of the transmission and the electric motor,” Gutzmer said.

Di Grassi’s teammate said a revised rear suspension rounds out the racecar alterations. “It starts with having a different motor and gearbox, so the connection points from the suspension change. We have different springs, different dampers, so the rear-end is all-new components,” said Daniel Abt.

All the modifications equal a better racecar, according to Jacky Eeckelaert, race engineer for driver Daniel Abt. “When we compare the data from this year to the data from last year, it’s clear the car is more competitive in terms of the powertrain and also in terms of the chassis/vehicle dynamics,” said Eeckelaert, who was the race engineer for di Grassi in the 2014/2015 season.

According to Van De Burgt, even though teams are hesitant to divulge in-depth technical details in advance of 2015/2016 racing, more information on the different all-electric powertrains is likely to be revealed as the second season progresses. “It’s very, very important for us to show a trickle-down effect from the technology that’s being used in Formula E to the technology that’s going to be used on the road cars of the future,” said Van De Burgt.

The various powertrain solutions featured in Formula E shine a bright light on what’s possible with future electrified vehicles, according to team owner Hans-Jurgen Abt. “All the good things come from motorsports normally. And now in season two it starts with Formula E and the participating manufacturers, like Schaeffler, who want to show the potential of what they can do.”

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