Audi
will be upgrading part of its vehicle electrical system from 12 to 48 volts. This
is being done to eventually facilitate the integration of new automotive
technologies while increasing the power and efficiency of its cars.
Prof.
Dr. Ulrich Hackenberg, Member of the Board of Management for Technical
Development at Audi pointed out that the company is using the full bandwidth of
electrification in its drive principles strategy. Running part of the vehicle
electrical system at 48 volts plays a central role in this, he said, adding
that it enables the company to make more energy available. All this in turn paves
the way for new technologies with which the company can make its cars more
sporty, more efficient and more convenient to use.
The
German car maker recently showcased the scope of the 48-volt
electrical system with the technology demonstrators Audi A6 TDI concept and RS
5 TDI concept. Both these models are fitted with an electrically powered
compressor. This operates independently of the engine load and therefore fundamentally
improves the acceleration performance. The 48-volt
technology is moreover ideal for realising convenience systems for dynamic
chassis control. Audi will shortly be unveiling a variety of applications in
this field, said a press note issued by Audi.
Currently
the 12-volt electrical system has reached it best effective limit. At low temperatures, all the various static-load consumers can account for the entire power generated by the
alternator, which can deliver up to three kilowatts, the release said. The
battery power is no longer capable of meeting the demands of new,
dynamic-load consumers such as high-performance
electric compressors, among other things.
The
solution lies in a second subsidiary electrical system running at 48 volts, to
complement the existing 12-volt power supply. The higher voltage
means smaller cable cross-sections are needed; this translates into lighter
cable harnesses with lower power dissipation. The 48-volt
electrical system features new storage technologies and delivers much more
power than the 12-volt system with lead batteries,
Audi has informed. Thus, it makes it an
important element of the Audi strategy of electrifying various stages of the
drivetrain. The Group’s developers have already come up with a scalable
platform concept, including a version that incorporates the electrically
powered compressor.
In
the present development version, a compact lithium-ion battery
supplies 48 volts as the energy source during engine-off phases, while a DC/DC converter integrates the 12-volt electrical system. The lithium-ion battery
operates in conjunction with a new, efficiency-optimised alternator that
qualifies the drivetrain as a mild hybrid. Within this concept there are
diverse ways of starting, controlling and deactivating the combustion engine as
needed. The powerful alternator achieves an energy recovery output of 10
kilowatts, far more than is possible at present. The savings areobvious as it
adds up to ten grams of CO2 per kilometre which is equivalent to around 0.4 litres
of fuel per 100km.
Picture explaining 48-volt technology,
courtesy Audi