MAHLE has developed a highly efficient 48-volt electric vehicle concept for urban mobility. “MEET” (MAHLE Efficient Electric Transport) will make its world debut at IAA Cars 2017 in Frankfurt/Germany in September. The modular design could be transferred to a wide range of platforms, MAHLE said.
The technical focus of MEET is on maximum energy efficiency. The meshing of different energy-saving technologies in the areas of the powertrain and thermal management increases efficiency and significantly enhances the cruising range of the vehicle—even and especially at low external temperatures.
Optimized for city driving, the vehicle, due to its low mass and the maximum speed of around 100 km/h (62 mph), only requires a modest amount of drive power. Based on extensive test drives on a typical city route under different conditions and with different drivers, MAHLE determined that the maximum power requirement was around 20 kW.
To support journeys at higher speeds, MAHLE—in its first step—selected a systems power output of 28 kW for its demonstrator vehicle. This enables using a voltage level of just 48 V. As the voltage level is below the threshold of 60 V, there is no need for cost-intensive protective measures against electrical hazards. Consequently, systems costs are considerably lower than for high-voltage applications with the same driving performance.
Furthermore, MAHLE is systematically exploiting areas of synergy. According to the company, all of the technologies employed can be carried over into large-scale production—thus generating further cost benefits through economies of scale.
The MAHLE IPM (Interior Permanent Magnet Synchronous Motor) traction drive is an extremely efficient combination of a synchronous motor with permanent magnets and integrated 48-volt electronics. The motor provides maximum efficiency and dynamics in a wide speed range. To begin with, the MEET demonstrator vehicle was equipped with a MAHLE drive unit consisting of two motors each with 14 kW of mechanical continuous output and 36 N·m of torque.
At IAA the next evolutionary stage with 20 kW and 80 N·m per motor will be presented. The motors drive the rear wheels via a central transmission.
This solution combines several advantages:
The structure is modular and can be easily modified according to the application, for example for other performance levels.
The existing 48-volt architecture of hybrid vehicles allows for an easy and cost-effective integration, for example as a drive unit/electric axis or for an electric all-wheel system.
The functional safety is increased by means of redundancy in the electric powertrain.
Maneuverability and agility can be improved with torque vectoring functionality.
As a result of the wide speed range of the motors, a gearbox is not necessary; systems efficiency is increased through the elimination of switching losses.