lncreased System Efficiency by an 800 Volt Axle Drive Concept

Authors

Dr. G. Rösel, P. Moenius, N. Daun, Dr.-Ing. S. Spas, Dr.-Ing. W. Hackmann,B. Schmitt, A. Reich, Vitesco Technologies, Regensburg / Nuremberg / Berlin

Year

2020

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 813

Summary

The worldwide electrification of the transport sector requires the development of highly efficient and cost-effective electrified powertrain solutions. A voltage level of 800 V in the traction system enables the advantages of fast charging and makes it possible to reduce the cross sections of the conductors. Since the battery still causes most of the costs of an electric drive, it is important for range considerations to use the energy supplied by the battery in the most efficient way for powering the drivetrain. The efficiency of the transformation from electrical to mechanical energy is therefore relevant for the development. To increase the efficiency the power losses must be reduced. The power losses of the inverter have to be kept on a low level, while the harmonic losses of the electric motor have to be reduced. The 800 V system voltage level offers the possibility to achieve both goals, if the silicon carbide (SiC) technology is used in the inverter. Due to better electrical properties of the semiconductor material, a SiC inverter is basically more effective than a silicon (Si) inverter due to lower conduction losses. The SiC technology enables furthermore higher switching frequencies which increase the efficiency of the electric motor by reducing the harmonic losses. The combination of the silicon carbide semiconductor material properties, a module design which  is optimized on efficiency and the improved operation point control with additional free parameters leads to a highly efficient traction system consisting of inverter and electric motor. For an optimized design the system efficiency of the drivetrain can be increased up to  4 – 8% in the WLTP cycle. In order to optimize and predict the lifetime of the drivetrain accurately, the increasing electrical loads of the motor must be analyzed. Vitesco Technologies will contribute to the efficiency increase of electrical powertrains by developing an extended modular concept for an 800 V axle drive.