Institute for Drive Systems and Power Electronics Research Research Projects
Innovative Ultra High-Speed Multistage Concept for Electrified Power Trains in Vehicles for Highest Efficiency and Comfort (ATEM Speed2E)

Innovative Ultra High-Speed Multistage Concept for Electrified Power Trains in Vehicles for Highest Efficiency and Comfort (ATEM Speed2E)

Led by:  Prof. Dr.-Ing. Bernd Ponick, Prof. Dr.-Ing. Axel Mertens
Team:  Gerrit Narjes, Bastian Weber
Year:  2014
Funding:  BMWi, DLR
Duration:  01.01.2014 - 31.12.2016

The overall goal of Speed2E is the development, optimisation and construction of a high-speed power train for use in electrified vehicles. Increasing the speed of an electric drive bears the potential for increasing the electrical machine's power density and the vehicle's overall efficiency considerably.  In today's drive topologies, speeds of 15,000 rpm maximum are common practice.  But in most cases, only up to 10,000 rpm are used, since vehicle drives with higher speeds are not yet safely manageable concerning  their operational stability, suspension, efficiency and acoustics.  Compared to today's standard, a triplicate motor speed of 30,000 rpm  is able to reduce motor volume and mass approximately by half and motor cost by about 30%, thus leading to an increase in power density, efficiency and profitability of electrified power trains in vehicles.

Within the scope of the project Speed2E, research is done on the novel drive train concept  of the project "double e-drive“ of the research initiative "DriveTechnologies for Electric Mobility" announced by BMWi  that is based on two electric drive units and a transmission with two parallel sub gearboxes, one of which is a shift gearbox.

In case of ultra high-speed drives (30,000 rpm), special measures  are necessary to optimise the overall efficiency and the acoustic behaviour of the power train appropriately:

  • Losses of the air flow, in seal contacts and in semiconductors of the power electronics play more and more an important role and must be limited by a proper selection and design of the mechanical and electrical systems.

  • Running through critical speed of the gear stages can practically not be avoided. Vibrations excited by the tooth engagement in the gearbox together with possible high-frequency excitations caused by electromagnetic forces of the e-machine or the power electronics can form an obstacle that is not to be neglected. These problems shall be solved based on the investigations made within the project Speed2E.

  • It has to be found out in how far induction motors, due to their favourable properties at high speeds, can be an alternative to permanent magnet synchronous motors commonly used.

  • Due to the multi-phase topology and the overload withstand capability of electric traction drives, an investigation of gear changes with uninterrupted traction force is possible based on geared switching elements.

  • Thanks to the innovative gearbox management including the respective control strategies, the components' potential concerning acoustics and efficiency is implemented in an optimum way.

The results can directly be verified and compared to existing drive systems by practical experiments carried out on the components developed.