Voltage levels between 48 and 800 V and power classes from 15 to over 300 kW are possible. Series production for various customer projects worldwide is scheduled to start in 2021. Schaeffler's global network of production plants, special machine and tool manufacturing facilities will be used to set up and operate the production lines. At the IAA, Schaeffler will be presenting its self-developed, production-ready electric motors as complete systems to the public for the first time.

Industrialization without gaps

After the last technology gap in the production of stators was closed with the acquisition of Elmotec-Statomat at the end of 2018, the entire industrialization of electric motors can now be seamlessly mapped within the company. Comprehensive expertise in mechanical components, manufacturing processes and winding technologies, as well as an in-depth understanding of the entire vehicle system, guarantee short development times and ensure smooth processes in the production of technologically sophisticated electric motors, according to the company. "Understanding and mastering transmissions, electric motors and power electronics is an art in itself," says Dr. Jochen Schröder, Head of the E-Mobility division at Schaeffler. "Combining the whole thing into a functioning overall system and powertrain is another. We have mastered both."

Solutions for both hybrid drives and electric axle drives

E-motors for P2 hybrid modules are subject to special requirements, as they run at the speed of the combustion engine due to their design principle. Minimal axial length and plenty of free space within the rotor for integrating the clutch and release system guarantee the high packing density required for this application. The single-tooth winding is available for extremely short axial installation spaces. 48 V and high-voltage motors with outputs from 15 to 120 kW can be offered. If the hybrid module is designed as a dry system, the stator is actively cooled via a cooling jacket. In systems with a wet clutch, the available oil can also be used to cool the electric motor, which leads to significantly better heat dissipation and therefore higher continuous output. However, the best power loss is the one that does not occur in the first place. The motors are therefore optimized for high efficiency across a wide range of characteristics.

Depending on the installation space conditions, the same can apply to electric motors in dedicated hybrid transmissions. In most cases, these transmissions are designed so that the electric motors have slightly more axial installation space and the electric motors rotate faster. Outputs between 80 kW and 140 kW are common. Depending on the operating mode of the transmission or drivetrain, these motors work in combination with the combustion engine in generator or motor mode and their efficiency is optimized according to the usage profile. Due to the purely electric driving modes of plug-in hybrids, the acoustic behavior clearly comes to the fore. In many cases, the use of a distributed winding is expedient. Schaeffler has defined a second standard winding for this purpose, for which the production machines are also developed in-house. This is the approach of bar shaft technology, which is being consistently advanced by Elmotec-Statomat in Karben. A traction machine was developed for a specific application, which delivers an output of 125 kW and a torque of 310 Nm with an overall axial length of 137 mm.

The portfolio is rounded off by a series of electric motors for driving electric axles. The high-voltage 2 (400 V) and high-voltage 3 (800 V) voltage levels are covered here. The power range extends from 100 kW to over 300 kW. If the system design allows, these motors are designed for high final speeds (up to 20,000 rpm). This allows the advantages of the bar shaft winding to be optimally utilized. Many stator slots result in good heat dissipation and a rotating field with few harmonics. High power density and excellent efficiency are the resulting advantages.

"By expanding our expertise in the development and production of our own electric motors, we are not only expanding our portfolio, but also consistently pursuing our e-mobility strategy. Thanks to our extensive system knowledge and the solutions correctly derived from it, we are at our customers' side as a recognized and trusted system and component manufacturer that supplies the ideal products depending on customer requirements and mobility needs," says Matthias Zink, Member of the Executive Board Automotive OEM at Schaeffler.