Cooling technology allows motors to be built from fibre-reinforced polymers

Researchers at the Fraunhofer Institute for Chemical Technology (ICT) in Pfinztal, Germany, have developed the new cooling concept, which they claim also significantly increases the power density of the motor, compared to existing state-of-the-art designs.

Although around 90 per cent of the electrical energy in a motor is converted into mechanical energy, the remaining 10 per cent is lost as heat from the copper windings within the stator.

To cool the motor down, this heat is typically conducted through metal housing to an outer sleeve containing cold water, according to Robert Maertens, a researcher at Fraunhofer ICT.

However, since plastic does not conduct heat as well as metal, such a design would not be possible with a housing made of polymer materials, he said.

So instead, working with the Karlsruhe Institute of Technology, the researchers have replaced the round wire typically used for the windings with a rectangular flat wire that can be wound more tightly around the stator. This creates space for a cooling channel next to the windings themselves, he said.