|Components of the 48 Volt Eco Drive system and the demonstrator. Click to enlarge.|
Continental presented its new “48 Volt Eco Drive” system at the Frankfurt Motor Show. The new system supplements the traditional 12V electrical network with a 48V electrical system and components, bridging the gap between low-end hybridization based on present-day 12V start/stop systems and more sophisticated high-voltage hybrid solutions.
Installed in a demonstrator vehicle, the 48 Volt Eco Drive system offers NEDC fuel savings of around 13%. First orders have been received, and production will begin in 2016, according to José Avila, Head of the Powertrain Division and Member of the Continental Executive Board.
The fuel-saving potential of the 48 Volt Eco Drive system is based chiefly on more efficient energy recuperation and extension of the start/stop functionality to cover both constant-speed cruising and sailing or coasting. The powertrain and energy management is implemented using modules from Continental’s Engine Management System (EMS) platform.
The new 48V voltage level has multiple advantages, Continental suggests: first of all no special electric shock safeguards are required, since the relevant statutory requirements only apply to system voltages of more than 60V. At the same time a 48V system already offers much more efficient braking energy recovery than a 12V system. A further advantage is that electrical consumers with higher power requirements operate more efficiently at 48V.
These are important benefits given that 12V networks are increasingly being pushed to their limits by the growing number of electrical functions in the vehicle.
A 48V starter-alternator also provides fast and quiet restarting after an engine stop, even at sub-zero temperatures. And a 48V system requires no modifications to the engine and transmission configuration.
In principle, the system architecture, from the belt system, electric motor, DC/DC converter and lithium-ion battery through to the powertrain and energy management modules can be integrated in any vehicle. In the demonstrator vehicle’s 48V system, a belt-driven alternator starter (BAS) replaces the conventional alternator.
“Alternatively, the BAS electric motor can be directly mounted on the transmission. This sort of flexibility is a big strength of our “Eco Drive” concept. For example it is also possible to vary the length and diameter of the electric motor, depending on the available installation space and power requirements.—Xavier Pujol, Head of the Hybrid Electric Vehicles Business Unit within the Powertrain Division
The demonstrator’s lithium-ion battery, supplied by SK Continental E-motion (venture of SK Innovation and Continental), is also relatively easy to integrate. Its dimensions are virtually identical to those of a 12V lead-acid battery.
The “48V Eco Drive” system also allows electrification of further vehicle functions. This is particularly relevant in larger vehicles, where conventional 12V electrical systems are nearing the limits of their capacity.
Here, without an additional voltage level, electric functions such as windshield heating, power steering or anti-roll stabilization (active reduction of body roll when cornering) would be very difficult to implement.
At the same time, if more functions are handled by a higher-voltage system, this also has benefits for vehicle weight, since the greater efficiency of 48V electrical consumers facilitates lighter-weight design.