OEM&Lieferant Ausgabe 1/2019

98 Drive Technology The future of electrically assisted supercharging By Dr. Hermann Breitbach, Vice President Global Engineering and Innovation, BorgWarner Turbo Systems Electrically assisted supercharging is becoming more and more important. BorgWarner shows crucial challenges and differences with the help of eBooster ® and eTurbo TM . Images: © Borg Warner Status quo A historical look back shows that electrically assisted supercharging was introduced as early as 1915. The approach is up to date again today, as engine outputs of more than 10 kW can be achieved using 48-V electrical systems, modern battery technology and highly effi- cient electric motors. Thus, the BorgWarner eBooster – an electrically driven compressor – is combined with a conventional turbocharger. The eBooster carries out supercharging at low speeds and ensures an excellent response of the internal combustion engine, whereas the turbocharger takes over for supercharging at high loads. In the BorgWarner eTurbo, the conventional turbocharger already includes the electric motor, and this compact design is one of its advantages. In comparison, the eBooster is an additional element that can be positioned flexibly but takes up more installation space. In contrast to the eTurbo, the eBooster cannot recuperate energy, but its compressor wheel can be selected independently of that of the turbocharger. As the eTurbo covers the entire operating range of the engine from idle to full load, the compressor has to be dimensioned accordingly. The eTurbo works most econom- ically at medium speeds and relatively high loads. In contrast, the eBooster compressor is optimized for lowengine speeds such as those occurring when starting up. As a result, the eBooster can be recommended in particular for downsizing concepts with optimized con- sumption, whereas the eTurbo is especially suitable for engines that focus on the driving experience. Basis For the purposes of compari- son, Fig. 1 shows the eBooster with integrated power elec- tronics, whereas Fig. 2 shows the eTurbo with power elec- Fig. 1: The compact BorgWarner eBooster with integrated power electronics.