Urbanization, traffic chaos, and air pollution are acute problems of this decade which call for alternative drive solutions that are integral to zero-emission mobility concepts.

Bühler Motor is making its contribution to micro-mobility by developing a direct drive in the form of a hub motor while also developing the necessary electronics.

Every development project involves certain technical hurdles that must first be identified and then overcome. The development is based on the standards DIN EN 15194 and DIN EN 13849-2 for safety-related functions. In addition to requirements based on standards, there are also customer-specific requirements that are derived from a use case analysis.

Drive

The drive concept builds on a BLDC motor with a nominal voltage supply of 48 volts. Customer interfaces such as brake disk, wheel rim, and driveshaft can be implemented as an integrated solution within the housing design. Since a platform concept is consistently applied, the product is readily adaptable to different diameters and customer-specific interfaces. The drive is distinguished by very high efficiency, high torque density, low torque ripple, and very good acoustic properties. Other noteworthy characteristics are integrated temperature monitoring and high vibration strength, which is necessary due to the external excitation caused by road bumps.

ECU with software

The electronics – which can be custom-adjusted for every application – implement many different functions. The ECU constantly communicates the status of the drive to the vehicle over the integrated interface. Protective and diagnostic functions ensure smooth operation. An ingenious system architecture also enables conformance to legally required safety targets. Depending on the specific use case, a sophisticated control strategy enables switching between sensor-based and sensor-free operation. Rotor position detection and sensor-based commutation enable gentle and clean motor startup. As was the case for the drive, customer-specific interfaces are also easy to implement for the ECU.

Next steps

The first prototypes have already been built and installed in a vehicle for driving test purposes. The project is still in the development phase and will go into production in 2021. Industrial Drive Solutions continues to track and analyze the micro-mobility market and views it as a strategically important future market.