The objective of the e performance project was to create a scalable systems architecture for electric vehicles. In the course of the project the scientists first designed and simulated the building blocks, than they manufactured prototypes of the parts, and finally they built a driveable specimen, the F12 which resembles a serial-built R8 sports vehicle but has an electric powertrain.
One of the focus topics of the project was the high-voltage battery. In the F12, the battery consists of two separate blocks which contain a total of 200 so-called macro cells. Their beveled walls allow them to shift relatively to one another for additional safety in the case of an accident. Cast aluminium sections in the battery system absorb most of the crash energy. The battery provides a capacity of 38 kWh.
The two batteries provide the power for the high-voltage electrical system of the vehicle. The batteries provide different output voltages of 144 volts and 216 volts, respectively. A DC/DC converter generates the unified system voltage. Under partial load, this voltage is only about 200V for efficiency considerations. If power demand and speed increases, the voltage gradually reaches a level of up to 440V.
In the drive train three different electric motors interact. Each one can be driven individually. When driving slowly, only the synchronous motor for the front axle is active. For higher speeds, the two asynchronous engines at the rear axle also come into play. The three motors achieve a total power of 150 kW at a torque of 550 Nm.
The driver controls the major functions of the vehicle such as park, reverse, and drive by means of buttons in the centre console. All other functions are implemented on a detachable tablet computer also located in the centre console. In addition, a programmable full-graphics display is used to provide the necessary status and driving information to the driver.
Also involved in the project that started three