800 Volts: Racing Technology for Long Distances

Sports prototypes with 400-volt technology can also deliver the maximum permitted recuperation power of 300 kilowatts as indicated in endurance regulations. However, their on-board network requires wire diameters that are twice as thick, resulting in an extra weight of about 30 kilograms. In the end, the overall efficiency counts. Less weight and less refueling stops meant that the lead for the winning 800-volt bolides grew ever wider. The motto of success on the racetrack was "Smart braking wins."

What leads to triumphs in motorsports is now helping electromobility to achieve a breakthrough for everyday

vehicles, especially in those segments where long-distance capability is high on the list of requirements. Weight does not matter as much here as it does in motor sports. However, for a good average travel time from Hamburg to Munich, it is not only the capacity of the batteries that is decisive, but also how quickly the batteries can be recharged at charging stations. And here a luxury car benefits just as much as a race car does from the enormous energy currents that an 800-volt electrical system can handle when braking quickly from the high speed of more than 320 km/h to less than 90 km/h at the finish. The 800-volt formula in everyday use is "ten minutes for 100 kilometers of range," which is possible with a charging power of up to 350 kW. With a usual break time of 20 to 30 minutes, enough energy flows into the drive battery for the next 300 kilometers – a feat of strength that cannot be achieved with a 400-volt vehicle electrical system. Because the power loss increases quadratically with the transmitted current, the standard plugs would quickly glow. With 800 volts, on the other hand, the electrical load is cut in half.

"It is becoming apparent that the 800-volt architecture will establish itself in future premium vehicles or sporty electric vehicles, whereas the 400-volt architecture will remain the standard in the volume market," says Dr. Otmar Scharrer, who is responsible for System Development of Electric Drives at ZF. "For 400-volt applications, we have already been supplying series technology for years. For 800-volt applications, we are now preparing to start series production this year." This means that 800-volt technology could help electric drives achieve a similar technological leap, as turbocharging once did for combustion engines.

ZF has already gained experience with 800-volt technology in the Formula E racing series. There, 800 volts are set, but not because of the fast recharging. In the increasingly popular racing series, which has FIA World Championship status, the aim is to get the electrical energy from the batteries to the drive wheels as efficiently as possible as kinetic energy. However, this cannot be achieved with 800 volts alone. To win in Formula E – and achieve maximum ranges in everyday life – silicon carbide power electronics are needed that can process an 800-volt voltage and ensure better efficiency.