Technology in Focus: Audi's forthcoming mild hybrid systems
The next big step in efficiency will be in electrical systems and mild hybrids that help to make cars more economical and offer lower running costs. In the next few years, every Audi on sale will be a mild hybrid in some form or other, using high voltage electrical systems to power faster and earlier-acting start-stop systems, make turbochargers work more efficiently and quickly, and take the pressure off the engine of running air conditioning units.
The 48-volt electrical system
It might sound a fairly dry subject but cars running 48-volt electrical systems, rather than the current 12-volt setup, will transform the way they operate, without overtly changing the character of the car.
Mild hybrids using small lithium ion batteries and a 48-volt set-up will be seen first on a new Audi model next year. This allows technology such as electrically driven compressors and the electromechanical active roll stabilisations. Compressors can be used to remove turbo lag by feeding air into the system earlier, helping performance but also making the turbo work more efficiently to improve economy.
Electromechanical active roll stabilisation uses an electric motor to decouple two halves of the stabiliser, meaning in a straight line the car rides more comfortably. In bends, the motors stiffen the stabilizer for roll-free bends. When on a bumpy road and opposing wheels are moving independently of each other, the system can recuperate energy too.
Audi also intends to convert auxiliaries such as pumps and superchargers for the engine, transmission and air conditioning system to 48 volts. Currently they are driven hydraulically or by the combustion engine, but if operated electrically, they can be controlled even more effectively according to demand; they would also be lighter and more compact. The same applies to large static convenience consumers such as window heating or sound systems.
Audi is hoping to launch wireless charging for its e-tron cars in 2017. The driver approaches a plate on the floor connected to the electricity grid, when radio contact between the car and plate is made. They can they see a display in order to park precisely over the top, although in future iterations this will be done remotely.
An electromagnetic field created by the plate induces the charging in the car, making the system completely safe for nearby humans or animals, allowing quick and easy charging of hybrids or EVs.
Shock absorbers that create electricity
Engineers at Audi are developing a system whereby each movement of the suspension is transferred through an arm which absorbs the force and transfers it through gears into an electric motor.
The energy created by this movement can then be fed into the system to help power various functions on the car, saving fuel. According to early estimates (the application could make it onto production models in around five years’ time) it could save up to 5g/km of CO2 on a bumpy country road.