Drive System and Energy Supply
Four asynchronous motors with a total output of 230 kilowatts (313 hp) give the Audi e-tron the performance of a high-output sports car. The concept car can accelerate from 0 to 100 km/h (0 – 62.14 mph) in 4.8 seconds if necessary, and goes from 60 to 120 km/h (37.28 – 74.56 mph) in 4.1 seconds. The torque flows selectively to the wheels based on the driving situation and the condition of the road surface, resulting in outstanding traction and handling.
The top speed is limited to 200 km/h (124.27 mph), as the amount of energy required by the electric motors increases disproportionately to speed. The range in the NECD combined cycle is approximately 248 kilometers (154 miles). This good value is made possible by the integrated concept: technology specially configured for the electric drive system combined with state-of-the-art battery technology. The battery block has a total energy content of roughly 53 kilowatt hours, with the usable portion thereof restricted to 42.4 kWh in the interest of service life. Audi uses liquid cooling for the batteries.
The energy storage unit is charged with household current (230 volts, 16 amperes) via a cable and a plug. The socket is behind a cover at the back of the car. With the battery fully discharged, the charging time is between 6 and 8 hours. A high voltage (400 volts, 63 amperes) reduces this to just around 2.5 hours. The Audi engineers are working on a wireless solution to make charging more convenient. The inductive charging station, which can be placed in the garage at home or also in special parking garages, is activated automatically when the vehicle is docked. Such technology is already used today in a similar form to charge electric toothbrushes.
The battery is charged not only when the car is stationary, but also when it is in motion. The keyword here is recuperation. This form of energy recovery and return to the battery is already available today in a number of Audi production models. During braking, the alternator converts the kinetic energy into electrical energy, which it then feeds into the onboard electrical system.
The Audi e-tron, which is slowed by four lightweight ceramic brake discs, takes the next large step into the future. An electronic brake system makes it possible to tap into the recuperation potential of the electric motors. A hydraulic fixed-caliper brake is mounted on the front axle, with two novel electrically-actuated floating-caliper brakes mounted on the rear axle. These floating calipers are actuated not by any mechanical or hydraulic transfer elements, but rather by wire (“brake by wire”). In addition, this eliminates frictional losses due to residual slip when the brakes are not being applied.
This decoupling of the brake pedal enables the e-tron’s electric motors to convert all of the braking energy into electricity and recover it. The electromechanical brake system is only activated if greater deceleration is required. These control actions are unnoticeable to the driver, who feels only a predictable and constant pedal feel as with a hydraulic brake system.
