Fraunhofer develops new polymer-based electric motor cooling concept

Researchers at the Fraunhofer Institute for Structural Durability and System Reliability (LBF) have developed a new cooling concept for electric motors that allows for the use of lighter polymer materials. This advancement is significant for the development of electric mobility, where reducing motor weight and improving efficiency are key goals.

The new approach, dubbed DEmiL (directly-cooled electric motor with integrated lightweight housing), focuses on direct cooling of both the stator and rotor. Traditional electric motors dissipate heat through a metal housing to a cooling sleeve. The Fraunhofer LBF team replaced the conventional round wire with a rectangular flat wire, allowing for tighter winding and the integration of a more efficient cooling channel directly within the stator.

"The core innovation lies in the stator design, where heat losses can be dissipated directly through the cooling channel," explained researcher Robert Maertens. This eliminates the need for a separate cooling sleeve, reduces the motor's thermal inertia, and enables higher continuous power output.

By effectively removing heat close to its source, the entire motor and its housing can be constructed from polymer materials. These polymer housings are considerably lighter than traditional aluminum ones and can be more easily molded into complex shapes. The Fraunhofer researchers are utilizing fiber-reinforced, thermosetting plastics that offer high temperature and chemical resistance.

The production of the polymer housings is carried out through automated injection molding, making the process suitable for large-scale manufacturing. The new concept not only reduces motor weight and production costs but also enhances its efficiency and power density, contributing to more sustainable transportation solutions.