Cost-effective Passenger Car Hybridization With ZF

ZF Friedrichshafen AG works on an integrated solution for hybrid components together with partners from business and research: This aims at installing the complete power electronics directly at the transmission. In future, this simplifies production and maintenance of hybrid passenger cars.

The space-neutral integration of the electric machine into the driveline is already a reality in ZF's parallel hybrid transmissions: The hybrid module with all full hybrid functions such as electric driving and recuperation of braking energy substitutes the standard torque converter. The thus originating hybrid transmission can be integrated into the driveline of current passenger car model platforms without any construction-related additional expenses.

The power electronics, as central connecting and controlling unit between electric machine and energy accumulator, is however, up to now, situated at different places in the vehicle depending on the manufacturer. In order to develop an integrated solution, ZF and BMW launched the research project Electric components for active power transmissions (EfA). On the basis of an 8-speed full hybrid transmission from ZF, the project partners Infineon, Kemet, and Liebherr, are developing a power electronics unit, which can be mounted to the transmission without requiring any additional installation space. This however requires an reduction of all components and a modified cooling concept due to high operating temperatures. The University of Technology of Chemnitz proofs the service life of the reengineering process.

The direct installation of power electronics at the transmission holds many advantages: On the one hand, spatial proximity to the electric machine reduces the number of system interfaces and wiring effort. On the other hand, this provides ZF with the possibility to pre-assemble power electronics independently of manufacturer and platform. The vehicle manufacturers can then install the hybrid transmission independently of the model - power electronics is always already on board. At the same time, ease of service increases because the newly developed power electronics unit can be plugged into the transmission from below.