From the use of semiconductors in controllers to the development of plug-in hybrid models: Audi thinks progressively, far beyond the here and now. Audi places technical progress into an overall societal context in the Audi Urban Future Initiative, a think tank dedicated to the urban mobility of the future.
The Progressive Semi Conductor Program
Many innovations that Audi brings to the automobile are tightly linked to progress in microelectronics. Semiconductors are finding their way into virtually all areas and functions of the vehicle. Over 6,000 chips are now used in the large Audi model. This massive increase in distributed functions calls for high data rates for the data networks within the automobile and the best possible integration of the individual domain computers.
Audi places extremely stringent requirements on the chips, particularly regarding criteria such as durability, long-term quality and function over a wide temperature range. The bar is particularly high with innovations such as Nvidia's new Tegra graphic chips, which Audi chose to use in its cars shortly after the chips were launched. In light of this, Audi operates the Progressive Semi Conductor Program (PSCP), which is a key factor in future innovations.
Audi is breaking new ground with the PSCP, which was launched in late 2010. The system supplier remains an important contact, but Audi's engineers now also talk directly to the semiconductor manufacturers.
The intensive dialogue leads to higher efficiency and effectiveness as well as to compelling innovations at short intervals that are coming closer and closer to matching the high pace of the consumer electronics industry. In order to deepen its knowledge and manage development even more effectively, Audi is developing its own in-house semiconductor technology expertise.
The Audi A3 Sportback e-tron
The A3 Sportback e-tron from Audi is a latest-generation plug-in-hybrid car. The four-door premium compact, which is rolling into dealerships this year, combines sporty power with impressive efficiency and joy of driving with everyday practicality. It combines the best of both worlds: an electric range of 50 kilometers with the usual action radius of a fuel-efficient gasoline engine. The Audi A3 Sportback e-tron accelerates from zero to 100 km/h (62.14 mph) in 7.6 seconds and reaches a top speed of 222 km/h (137.94 mph). In accordance with the ECE standard for plug-in hybrid vehicles, its average CO2 emissions are a mere 35 grams per km (56.33 g/mile) – a consumption of 1.5 liters of fuel per 100 km (156.81 US mpg).
The 1.4 TFSI combustion engine is one of Audi’s most modern power units. With 100 kW (150 hp) and 250 Nm (184.39 lb-ft), it offers ample power. It supplies peak torque across the entire speed range from 1,750 through 4,000 rpm, thus harmonizing excellently with the electric motor. The maximum of 330 Nm (243.40 lb-ft) is available virtually immediately and up to about 2,200 rpm. Maximum output is 75 kW. The system output of the A3 Sportback e-tron is 150 kW (204 hp), system torque is 350 Nm (258.15 lb-ft) and total range is 940 km (584.09 miles).
The 1.4 TFSI is mounted in a special position to create space for the high-voltage components. Its crankcase is made from diecast aluminum, and total weight is just over 100 kg (220.46 lb). The four-cylinder engine is state of art in every respect. Take thermal management, for example: The exhaust manifold is integrated into the cylinder head. After a cold start, it brings the coolant swiftly up to operating temperature. At high loads, the water jacket lowers the temperature of the exhaust gas.
Thanks to the high electric range of up to 50 km (31.07 miles), many customers will only rarely experience the gasoline engine of the Audi A3 Sportback e-tron in action. Another effect of the plug-in hybrid concept is that the TFSI is often only activated in kickdown situations, i.e. it is subjected to high loads while still cold. The engine therefore is equipped with protective features such as modified cylinder linings and piston rings.
The electric motor is a liquid-cooled, permanently excited synchronous machine. It is located between the engine’s dual-mass flywheel and the newly developed separating clutch, the K0 clutch. When the TFSI starts, it is tow-started by the electric motor via the clutch. As soon as the TFSI reaches the same speed as the electric motor, the clutch closes within roughly half a second.
Together with the K0 separating clutch, the electric motor is integrated into a newly designed six-speed e-S tronic, which transfers the power to the front wheels. Like all Audi dual-clutch transmissions, it consists of two subsidiary transmissions that are served by the two multi-plate clutches K1 and K2. Gears are shifted by switching the clutches. This happens within a few hundredths of a second and with no detectable interruption of propulsive power.
The lithium-ion battery in the Audi A3 Sportback e-tron can store 8.8 kWh of energy, more than 70 percent of which is useable. Depending on the level of charge, the voltage ranges between 280 and 390 volts. The battery consists of 96 prismatic cells arranged into eight modules of twelve cells each. Including its electronic components, the battery system weights 125 kilograms (275.58 lb).
An elaborate liquid cooling system ensures that the battery is kept within a suitable temperature range during operation. Electric driving is possible regardless of the outside temperature, in summer and in winter. The cooling system represents a separate low-temperature circuit in the car and runs on a separate cooler housed in the engine compartment. It can also be coupled with the air conditioning system, if necessary.
In the event of a crash sufficiently severe to trigger the belt tensioners or airbags, the entire system is disconnected from the power supply. The flat-shaped battery is installed under the rear bench seat – an area where the high-strength and ultra-high-strength steel components of the occupant cell form an especially strong structure. Its housing and interior structure are equally of a very sturdy design. The 12-volt battery for the low-voltage consumers and the fuel tank are located above the rear axle. The two components barely impinge on the luggage compartment, which in the standard configuration measures 280 liters (9.89 cu ft) and 1,120 liters (39.55 cu ft) with the rear seat backs down.
Audi supplies the A3 Sportback e-tron with a universal charging cable suitable for use with both domestic and industrial power sockets. The connecting plugs are country-specific in design. For use in a home garage, the cable can be clipped into a wall-mounted holder. It takes slightly more than two hours to charge the battery fully from an industrial power socket and about three hours and 45 minutes from a European domestic power socket.
Audi has partnered with a supplier of renewable energy, as electric driving only makes ecological sense with electricity generated from renewables. Another of the brand's medium-term projects is automatic charging without physical contacts, referred to as Audi wireless charging. In this case, charging is performed inductively via an alternating magnetic field between a stationary charging pad on the ground and a charging pad in the car, similar to the principle used by an electric toothbrush.
When the cable is used for charging, the electricity flows to the charging connection located behind the four rings in the Singleframe grille. In addition to a status LED, there are also two pushbuttons that allow the user to choose between timer-controlled charging and immediate charging. The charger in the car converts the incoming alternating current into direct current for the battery.
Components for electric driving
The power electronics, located in the engine compartment, then convert the battery's direct current into three-phase current for the electric motor via six high-performance transistors. With a volume of eight liters (0.28 cu ft) and a weight of 10 kilograms (22.05 lb), the power electronics, which include a DC/DC converter for connecting up the vehicle’s 12-volt electrical system, are compact and light in weight. Together with the charger, it is incorporated into the same cooling circuit as the traction battery.
There are yet more special components for electric driving. The air conditioning compressor has an electric drive integrated into the high-voltage network. A thermoelectric heating element and a gasoline-powered auxiliary heater round off the interior heating system.
The vacuum brake servo is also electronically controlled. The hybrid management system ensures that it functions in harmony with the electric motor. At up to medium braking loads, most of the braking work is performed by the electric motor, which is now functioning as a generator. The energy that it recovers is fed into the traction battery. The wheel brakes only become active if the driver presses the pedal more forcefully.
Braking recuperation is one of several operating modes of the Audi A3 Sportback e-tron. The car is almost always driven electrically, except in extreme cold or heat or when battery charge is very low. The electric motor's high torque accelerates the sporty compact in 4.9 secondsfrom 0 to 60 km/h (37.28 mph) with quiet but forceful propulsion.
In electric mode, the Audi A3 Sportback e-tron can travel at up to 130 km/h (80.78 mph). When driving at a constant 100 km/h (62.14 mph), generally only the electric motor is active provided that there is sufficient energy in the battery. As soon as the driver steps hard on the accelerator, for instance to pass, the TFSI cuts in and both drive systems provide boost. When the driver releases the accelerator at high speed, the hybrid management system switches into gliding mode. Now both drives are completely deactivated and are no longer generating braking torque. When stepping off the accelerator at medium and low speeds, the system recovers energy through coasting recuperation.
The driver has several ways of actively managing the vehicle’s response. They can choose from three programs using a button in the cockpit or the e-S tronic selector lever. The EV characteristic map gives priority to electric drive; in the S program, the Audi A3 Sportback e-tron is very sport. The “Charge” button is used to charge the battery as quickly as possible.
The hybrid hold mode can be selected via a menu in the MMI. This mode preserves the electrical energy stored in the battery for later use, such as urban driving in the destination city. The driver can also influence hybrid operation via the Audi drive select system. Different levels of coasting recuperation are assigned to the four modes available there.
The Audi A3 Sportback e-tron supplies information about the driveline status. The powermeter in the instrument cluster shows the system’s overall output, as well as the status of the driveline and the battery charge. The monitor for the MMI navigation plus shows the energy flows in the hybrid system. In addition, the driver information system displays the operating ranges and consumption figures for electricity and gasoline.
Under the Audi connect umbrella, Audi is currently developing an entire portfolio of innovative online services for the A3 e-tron. Drivers can use these to monitor and manage a wide range of functions via their iOS or Android smartphone.
For instance, they can call up the car’s status – such as the battery’s momentary charge status, the electric range or even its parked location. Drivers can control the charging planner remotely from their cell phone. They can start and stop the charging process or set the charging timer for the desired departure time. They specify in detail at what time on what days they want to drive off with the battery fully charged.
The climate control planner works similarly. The owner can, for instance, program a desired departure time. The car's cabin temperature is then brought to the preset temperature automatically during the charging process, thus there is no reduction in range for the trip itself. Finally, the web portal gives the owner the chance to review their trip data, e.g. power consumption, distance driven and speed.
Thanks to Audi’s ultra lightweight construction philosophy, the Audi A3 Sportback e-tron complete with all electrical components has a curb weight of less than 1,580 kilograms (3,483.30 lb) while offering space for five occupants and plenty of cargo. It comes complete with all the brand’s strengths – elegant design, sporty chassis, top-notch ergonomics, excellent build quality and an extensive choice of high-end assistance and infotainment systems. The Internet connection is via the high-speed LTE standard. Audi is the first carmaker to completely integrate this standard into the automobile.
The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.