When it comes to electric motors, efficiency is key, especially in racing. Every manufacturer can develop electric powertrains with gobs of power but how much of the battery’s energy can they actually convert into forward thrust? In Formula E, that’s an extremely important question because it could be the difference between finishing a race flat-out or having to limp to finish to conserve battery power. According to the folks in Ingolstadt, the Audi e-tron FE07 Formula E car is 95-percent efficient.
“The Audi e-tron FE07 has an all-new electric powertrain that was developed in-house for the first time,” says Stefan Aicher, Head of Development e-Drive at Audi Sport. “We went to the limits in all areas of this project,” he said.
This new electric powertrain is called the Audi MGU05 and it’s been developed by Audi Sport to be as absolutely as powerful and efficient as possible. It’s a one-speed electric powertrain with an internal rotor concept, external magnets, a highly-efficient cooling system and six electrical phases. Aicher’s team also focused hard on weight savings, to make sure the MGU05 was as light as possible.
“We were able to directly reinvest these savings in the new MGU for the benefit of enhanced efficiency. Even so, the new MGU inverter unit weighs less than 35 kilograms. This was an exceptional achievement by the whole team,”
Still, above all, efficiency is key for Formula E. Squeezing as much energy out of the battery and putting it to the tarmac is one of the most important aspects of Formula E powertrain development.
“That is why we are leaving no stone unturned to reduce the energy loss within the system to an absolute minimum,” says Tristan Summerscale, Formula E Project Leader at Audi Sport. “We have achieved an overall efficiency of more than 95 percent for our powertrain. The new MGU inverter unit has an efficiency of even more than 97 percent in all relevant driving conditions.”
That becomes even more impressive when you compare it to internal combustion engines. One area where EV-proponents will criticize internal combustion is efficiency. While gasoline has a higher specific energy output, internal combustion engines aren’t very good at maximizing that energy output to the road. So even inefficient EVs are far more efficient than gasoline-powered cars. With the Audi e-tron FE07, it’s an ever greater disparity.
“If you compare our MGU with an internal combustion engine delivering a comparable power output of 250 kW (335 hp), our efficiency is not only twice as high, but our weight of less than 35 kilograms is also much lighter,” says Tristan Summerscale. “This clearly shows what an efficient solution an electric powertrain is.”
The Audi e-tron FE07 will make its debut in Valencia this Saturday, November 28. So we’ll be able to see it in action soon enough.