Audi presents the highlight of the IAA 2009: the e-tron, a high-performance sports car with a purely electric drive system.
Four motors - two each at the front and rear axles - drive the wheels, making the concept car a true quattro.
Producing 313 hp and 4,500 Nm (yes, that's 4,500)of torque, the two-seater accelerates from 0 to 100 km/h in 4.8 seconds, and from 60 to 120 km/h in 4.1 seconds. The lithium-ion battery provides a truly useable energy content of 42.4 kilowatt hours to enable a range of approximately 248 kilometers.
The performance figures are by no means the only evidence of the consistent and holistic strategy. The design makes it clear that the e-tron belongs in the major leagues of sports cars, and the package takes into account the specific realities of an electric vehicle. The battery is directly behind the passenger cabin for an optimal center of gravity and axle load distribution.
The e-tron is able to freely distribute the powerful torque of its four electric motors to the wheels as required. This so-called torque vectoring allows for dazzling dynamics and an undreamed-of level of agility and precision when cornering.
Audi e-tron - The Holistic Approach
The most important development related to batteries for electric drives are lithium-ion cells. Audi has also opted for this technology, both for use in a hybrid production vehicle, such as the upcoming Q5 hybrid, and in the e-tron test platform.
The requirement specification for the concept vehicle goes far beyond battery technology and the replacement of the combustion engine with an electric drive system, however.
The Audi development engineers decided back in the concept phase to design practically every component and technology based on the new requirements of electric mobility. The interaction of all elements has a decisive influence on the factors efficiency, range and practicality.
Design and Package
The Audi e-tron has a wide, powerful stance on the road. The car body seems almost monolithic; the closed rear end appears powerful and muscular. The trapeze of the single-frame grille dominates the front end and is flanked by two large air intakes.
The top of the grille merges into the flat strips of the adaptive matrix beam headlamp modules with their clear glass covers. High-efficiency LED technology is used for all lighting units - a matter of honor for Audi as the worldwide pioneer in this field.
The headlamps are the core of a fully automatic light assistance system that reacts flexibly to any situation. The new technology recognizes weather conditions and adapts the illumination to rain or fog. The technology at the heart of the light assistance system is a camera that works together with a fast computer to detect oncoming traffic, recognize lanes and measure visibilities, such as in the event of fog.
The body structure is based on Audi Space Frame (ASF) technology and was realized as a hybrid construction. All add-on parts - doors, covers, sidewalls and roof - are made of a fiber-reinforced plastic.
The combination of aluminum and carbon fiber-reinforced composite material guarantees supreme rigidity coupled with low weight. Audi will soon use this technology in a similar form for production vehicles. Despite the complex drive system layout with four electric motors and a high-capacity battery system, the total weight of the Audi e-tron is only around 1,600 kilograms
Energy Supply
The top speed is limited to 200 km/h, 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.
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 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. During braking, the alternator converts the kinetic energy into electrical energy, which it then feeds into the onboard electrical system.
source: One Shift
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