The McLaren powertrain that will drive the Spark-Renault Formula E racing car weighs just 26kg, yet delivers near-instant torque and revs to 17,500rpm, states technical journal The Engineer.
The article goes on to say that the biggest challenges in developing the system, based on that in the P1 as we reported here, are the high voltages involved – up to 800V – and managing heat.
The motor and power electronics began development four years ago and have been the focus of intensive research and testing ever since. The electric motor drives the rear wheels of the racing car via a four-speed sequential gearbox. The motor is much smaller than an internal combustion engine at only 26kg and provides more than 250hp. Torque delivery is almost instant, giving the powertrain extremely fast acceleration.
According to McLaren, the electric system has the highest power-to-weight ratio of any automotive motor in the world. When the driver takes his foot off the pedal, the electric motor acts as a generator, providing engine braking and charging the battery at the same time. The motor turns at speeds up to 17,500rpm, which is similar to that of the V8 Formula One engines.