FEV will showcase some of its 48-Volt technology capabilities at the 2016 SAE World Congress next week in Detroit. FEV says it believes that 48V technology will be the next evolution in in-vehicle power.
The proliferation of components and systems that require electrical power in today’s vehicle are pushing the standard 12-Volt battery to its limits. Under idle conditions and especially under low-temperature conditions, current 12V electrical systems can account for the entire power output of a conventional alternator, FEV notes.
Increasing the vehicle’s power network (or portions thereof) to a higher voltage reduces losses in the vehicles distribution system. At higher voltages (over about 60V) safety regulations make this a much more challenging effort.
Industry OEM’s are also facing significant challenges in terms of meeting fleet consumption thresholds in nearly all of their production vehicle segments. Vehicle electrification will play a significant role in finding a solution path.
However, the plug-in hybrid that offers so much benefit in this regard also necessitates massive intervention into the design of the transmission which generates additional cost. These costs then need to be amortized over what, at least for the moment, are relatively small production volumes.
FEV engineers are working on a mild hybrid approach that has promise, in this regard, since accommodating a 48-Volt architecture does not require a complete redevelopment of the entire powertrain.
FEV engineers used the AMG45 as a technology carrier to demonstrate how a production-compatible solution might look by advantageously integrating an additional 48V E-Charger.
The AMG A45—the smallest AMG with a 2-liter, 4-cylinder turbocharged engine—features a specific performance of 133 kW/l (181 HP). FEV engineers installed an additional E-Charger. The electronically operated unit supports the twin-scroll turbocharger, optimized for maximum performance at low speed and highly dynamic load changes. The maximum torque of 450 N·m becomes available early in the speed range at 1,750 rpm—500 rpm earlier than in the series version.
|Torque curves with and without the E-Charger. Source: FEV. Click to enlarge.|
The result is that the elasticity and the responsiveness of the AMG A45 considerably increase and the number of gear changes can be minimized.
The E-Charger, incorporated into the AMG technology demonstration vehicle, was a way for FEV to showcase its capabilities to support this upcoming technology. The E-Charger combined with a high power vehicle electrical system supports downsized engines with high specific power by improving transient response and low-end torque.
A 48-Volt system also enables new vehicle features with high power demand such as active damping, electric power steering, and off-engine climatization. In combination with a 48-Volt battery and 12-Volt DC/DC converter, mild hybridization is also possible.
The system’s capabilities can be used to obtain a reduction in fuel consumption of up to 15% via down-speeding or, alternatively, used to increase performance and provide even better responsiveness.
FEV engineers performed the mechanical integration of e-Booster hardware and modified the charging system, integrated the 48V electric system, and performed all the Rapid Control Prototyping (RCP), functional development and calibration for the e-Booster operating strategy. Also contributing to its environmental advantage is the fact that raw engine emissions can be reduced by supplying transient boost more rapidly.