Evolution instead of revolution: Audi looked at every single detail in the development of the Audi e-tron FE06. The results: even higher efficiency, less weight, optimized packaging and enhanced operability of the software. In addition, tests and perfected simulations are important elements on the way to a perfect race day.
The tight regulations of Formula E are both a blessing and a curse: a blessing because they are conducive to the utmost competitiveness of the teams and the car concepts, which guarantees gripping racing, and a curse because new developments entail meticulous and detailed work for the engineers: the perfect challenge for Tristan Summerscale and his team. The Formula E Project Leader at Audi says: “If we optimize each of the 2,000 pieces of the puzzle just a little bit, we may be gaining the crucial tenth of a second in the end.”
Besides the software, the powertrain is the only area of the Formula E car that the manufacturers are allowed to freely develop. It consists of the motor, inverter, transmission and parts of the rear suspension. As in the previous years, the motor generator unit, named the Audi Schaeffler MGU04, has been jointly developed by Audi and technology partner Schaeffler. “With energy conversion efficiency in the range of more than 90 percent, we’re already at the limit in terms of efficiency. Even so, just like with the dynamics of the MGU and the inverter, small steps were still possible,” says Tristan Summerscale.
The engineers achieved a further weight reduction of the powertrain and the optimization of the packaging, which refers to the arrangement and accessibility of the individual components. “The schedule on a Formula E race day is extremely tight: there’s not much time for driving and the breaks between the various sessions are usually short,” says Summerscale. “So the speed at which the mechanics are able to make changes, for instance to kinematics or dampers, or repairs in the event of damage, may be decisive. We’ve made good progress in this area.”
In the sixth season of Formula E, the motor may deliver a maximum power output of 250 kW (340 hp) in qualifying. In the races, output is limited to 200 kW (272 hp). The attack mode has proven successful: when a driver passes the activation zone on the race track, the power output of his car is briefly boosted to 235 kW (320 hp). Formula E fans will be able to support their favorite drivers again by voting online this season: “FanBoost” provides a short-term boost to 250 kW (340 hp) in the race.
All of the Formula E teams draw their power from identical 385-kilogram batteries supplied by McLaren. The lithium-ion battery sits between the driver’s seat and the powertrain, has an available capacity of 52 kWh and is recharged within 45 minutes. New since the fifth season has been the brake-by-wire system, in which brake actuation and transfer to the rear axle are isolated from each other and electronically controlled. As a result, brake force distribution is always optimally adjusted and recuperation even more efficient.