About the project KOHANA

Sustainable decarbonization of road freight transport can only be achieved through electrification of the powertrain. The main focus here is therefore on the electric motor. Not only must it be particularly reliable and have a long service life, it must also be installed in a comparatively small space within the vehicle despite its power-related size, i.e. it must itself be correspondingly compact. This requires elaborate and often complex cooling concepts.

In addition, in the commercial vehicle sector, the various weight classes mean that many motor variants can be expected in comparatively small numbers. In addition, there is little budget available for the development of new motor models, and the investment budgets for tools for the economical production of such motors are also limited.

The KOHANA funding project addresses all these challenges through a two-part solution approach. First, a more automated design process is being created that combines different engineeringengineering disciplines as well as addressing functional and manufacturing requirements. The automated drive design is combined with 3D printing of the hairpin winding. This innovative manufacturing process makes it possible to produce a wide range of variants without high initial investment.

Hairpin technology for optimizing the electric drive axle

There are already various approaches to electrifying heavy-duty vehicles. Some approaches focus on optimizing the vehicle's electric drive axle by using hairpin technology. This is a winding technology for stators, i.e. the immovable part in electric motors and generators, which makes it possible to pack the copper conductors in the stator more tightly and thus get more copper into the electric motors. The result: increased performance with the same volume of stator. In addition, hairpin stators can be cooled better.

The problem with this approach so far has been that the technology is very complex to manufacture, especially with regard to the necessary bending and welding processes. In addition, special tools are needed for manufacturing.

The integrated approach pursued in KOHANA can reduce production costs and also accelerate the development of different variants. In addition, only the automatable development process enables the degrees of freedom of 3D printing to be optimally utilized.

Our approach to solving the problems of electric drive systems in commercial vehicles

As part of the project, the KOHANA project partners are developing an electric motor equipped with a 3D-printed winding. The development is based on an automatable development process that combines various engineering disciplines. In this way, the KOHANA project solves several typical problems of electric drive systems in commercial vehicles, such as a large number of variants in relatively small quantities, budget limits in the area of motor development and very limited space inside the motor of electric commercial vehicles.

Our goals

In the development and testing of the KOHANA motor model, the overarching goal is to optimize the powertrain of electrified commercial vehicles in order to drive the market ramp-up of electrified commercial vehicles.

Sub-goals within the project are the step-by-step testing of the demonstrator and the associated knowledge gain in several areas. These include additive manufacturing through industrialization of 3D printing of copper conductor materials (hairpin stator) and automated design of electric drives.

The project KOHANA relies on close cooperation and interaction in terms of content between the three partners involved. As an axle manufacturer, the BPW Group is contributing the application perspective to the project in the form of specifications and installation spaces, while at the same time assuming the role of the system integrator. Specific issues relating to the design of the E-axle in commercial vehicles, particularly with regard to the thermal design of the overall system, have to be resolved.

As a specialist in the additive manufacturing of components for electrical machines, Additive|Drives Gmbh is taking on the task of further developing and designing the manufacturing processes for the additive production of the copper winding heads of commercial vehicle electric drives with hairpin windings. Additive Drives thus focuses on the manufacturing technology perspective in the project.

At Fraunhofer IFAM, the work is focused on the optimum design of automated designs of the winding head geometry, taking into account both electrical and electromagnetic influences as well as manufacturing influences. Fraunhofer IFAM takes the perspective of the layout and design of the e-machine and hairpin stator.

More about our project partners

Duration of the project:

01.07.2022 until 30.06.2025