Audi A1 e-tron Concept, 2010

Audi A1 e-tron Concept, 2010

 

 

 The new e-tron model series from Audi will gain another new member at the 2010 Geneva Motor Show: The Audi A1 e-tron Concept is a Mega City Vehicle (MCV) with an innovative drive technology. It comes equipped with a powerful electric motor for zero-emission driving in the city. There is also an internal combustion engine on board that recharges the battery in exceptional circumstances. The Audi A1 e-tron Concept is very agile thanks to the 75 kW (102 hp) peak power of its electric motor.

The technology of the Audi A1 e-tron
The e-tron model family from Audi is just a few months old, but it already has a number of members, for each of which Audi has chosen a different drive technology. The first e-tron, which debuted at the 2009 IAA in Frankfurt/Main, is a near-series high-performance sports car with electric motors for all four wheels. The study shown at the Detroit Motor Show in 2010 is a lightweight, compact two-seater with two electric motors on the rear axle.

The Audi A1 e-tron Concept now presents another approach - a compact electric car in the premium class. The four-passenger, two-door MCV city car was designed specifically for use in the metropolitan areas of Europe and North America and in the rapidly growing megacities of Asia and South America. The Audi A1 e-tron always drives on electric power; its internal combustion engine is only used to recharge the battery in isolated cases.

The integration of the new technologies shows the holistic approach that Audi is pursuing with electric mobility. The objective is to use the energy with the lowest possible losses. The precise interaction of the components, their intelligent packaging, and the efficient management of the current flows are the product of the expertise that the company has developed in this area.

Audi has developed a proprietary thermal management system to keep the battery, the electric motor, and the power electronics within their respective ideal temperature windows.

Behind the three e-tron models is a broadly diverse and modular technology platform that continues to grow very rapidly as Audi drives development forward.

The electric motor: 75 kW (102 hp) peak power
The synchronous electric motor of the Audi A1 e-tron is mounted transversely at the front of the car. Its low mounting position has a positive effect on the vehicle's center of gravity. Continuous output is rated at 45 kW (61 hp), with peak power of 75 kW (102 hp) available in short bursts. 150 Nm (110.63 lb-ft) of torque is continuously available, and peak torque is 240 Nm (177.01 lb-ft).

The electric motor sends its power to the front wheels via a single-speed transmission. The elegant, retractable selector lever on the console of the center tunnel used to choose between "Drive," "Reverse," and "Neutral" was taken from the first Audi e-tron.

The power electronics are mounted in the engine compartment above the electric motor. The most important components are the pulse-controlled inverter, which serves as the controller between the electric motor and the battery; the DC converter, which connects the high-voltage network with the 14 volt electrical system; a breaker unit to protect the high-voltage components; and the charging module. The socket for the standard charging plug is located behind the rings in the single-frame grille of the Audi A1 e-tron. A fully depleted battery can be recharged in approximately three hours from the 380 volt grid. A display immediately adjacent to the plug-in connection shows the current charge status and the charging time remaining.

The concept of the innovative Mega City Vehicle requires the electrification of key auxiliaries. The refrigerant compressor of the climate control system, for example, is electrically powered by a high-voltage electric motor that supplies only the amount of power needed at the time.

This increases system efficiency substantially compared to conventional concepts. Thanks to a special circuit, the climate control loop also functions as a heat pump that regulates the temperature of the cabin and the battery.

The power steering of the Audi A1 e-tron is electro-mechanical and thus particularly energy-efficient. 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. In addition, the servo unit received a new, demand-controlled electric vacuum pump.

The large electric motor powering the Audi A1 e-tron Concept can convert braking energy into electric current and feed it back into the electrical system. The high degree of recuperation benefits overall efficiency. The electric control actions are imperceptible to the driver, who notices only the familiar, precise, and perfectly controllable pedal feel.

Audi e-tron Concept, 2009

Audi e-tron Concept, 2009

 The Audi presents the highlight of the IAA 2009: the Audi e-tron Concept, 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 230 kW (313 hp) and 4,500 Nm (3,319.03 lb-ft) of torque, the two-seater accelerates from 0 to 100 km/h (0 - 62.14 mph) in 4.8 seconds, and from 60 to 120 km/h (37.28 - 74.56 mph) 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 Audi e-tron Concept 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 Audi e-tron Concept 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 has taken a new and in some cases revolutionary approach to many of the technical modules. A heat pump is used to efficiently warm up and heat the interior. The drive system, the power electronics and the battery are controlled by an innovative thermal management system that is a crucial component for achieving the car's range without compromising its high level of interior comfort. Networking the vehicle electronics with the surroundings, which is referred to as car-to-x communication, opens new dimensions for the optimization of efficiency, safety and convenience.

The Concept
Electric drive systems are still very much outsiders. The first vehicles of this type took to the roads around 1900, yet in 2009 no volume car manufacturer has a car powered exclusively by batteries in its lineup. Fewer than 1,500 electric vehicles are currently registered in Germany, corresponding to only 0.035 percent of all registered vehicles.

Yet electric driving potentially offers numerous advantages. Electric cars reduce the dependence of transportation and the economy on the raw material petroleum. They produce no direct exhaust emissions and thus ease the local burden on the environment. Electric drive systems are also significantly more efficient than combustion engines, consequently making them easier on the customers' wallets. Other strengths include sportiness and the fun they bring to driving. All of the torque is essentially available the moment the driver steps on the accelerator, allowing for breathtaking acceleration.

There is still a lot of work to do before electric cars are ready for volume production, however. The greatest challenge is the integration of the energy storage system. Acceptable range and performance requires a traction battery that is heavy and takes up a lot of space. Audi is taking a new approach to offset these disadvantages - a holistic approach with a specific vehicle package, a systematic lightweight construction concept and an optimal configuration of all components for the electric drive.

Audi e-tron Concept - The Holistic Approach
The most important development related to batteries for electric drives are lithium-ion cells. Numerous experts throughout the world are working on their further development for use in cars, with the primary objectives being to reduce weight and increase capacity and performance. 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.

The Audi team therefore focused its attention on the total vehicle, which is reflected in the comprehensive requirement specification.

    * The reduction of road resistances and the resulting increase in range plays a major role with electric vehicles. Lightweight construction was therefore a top priority for the Audi e-tron Concept car. The body, in particular, combines low weight with supreme strength and rigidity. An intelligent aerodynamics concept with active elements helps to reduce consumption.
    * The package ensures the safe integration of the electric drive system and the battery. Placing the battery in front of the rear axle ensures an optimal axle load distribution without compromising the compact overall design and the generous amount of interior space.
    * Advanced battery technology enables a practical range. The battery system is water-cooled for optimal performance and service life.
    * A needs-based energy management system controls all functions for the chassis, convenience equipment and other auxiliary consumers.
    * The innovative thermal management system with optimally matched cooling and heating components considers the cooling requirements of the battery and the drive system in addition to the interior temperature.
    * Driving dynamics and road comfort are what Audi customers have come to expect in the sports car segment.
    * Vehicle safety is on par with the best of today's production vehicles.
    * The driver is provided with clear and comprehensive information.
    * The Audi e-tron Concept car uses car-to-x communication technology developed by Audi to improve the efficiency of conventionally powered vehicles. For example, information about traffic light cycle times and the flow of traffic - provided by the infrastructure and other vehicles - is used to compute an optimal driving strategy. Audi has already modeled such a solution in Ingolstadt as part of its "travolution" project.