Making electrical devices of the future more efficient
Small electric motors – found in everything from conveyor belts to electric toothbrushes – help to drive our modern world. Given their prevalence, achieving even small energy efficiencies in how these operate can make a difference. As a result, a great deal of research has focused on a phenomenon known as ‘iron loss’. This refers to the electrical energy wasted as heat in the magnetic core of these devices. As electric motors rely on changing magnetic fields to function, energy is continuously lost.
Amorphous glass-like alloys
The AM2SoftMag(opens in new window) project, which was funded by the European Innovation Council(opens in new window), sought to address this by improving the materials used in electric motors. “In today’s motors, the stator and rotor components are made from conventional soft magnetic, coarse-grained iron alloys,” explains AM2SoftMag project coordinator Ralf Busch, a professor at Saarland University(opens in new window) in Germany. “We wanted to replace these conventional crystalline alloys with amorphous, glass-like alloys, which lose hardly any energy during remagnetisation.” Despite the name, metallic glass is far from brittle, and is in fact significantly stronger than steel. The term ‘glass’ refers to the material’s inner structure, which is amorphous – meaning it lacks a crystal lattice. “In conventional metals, atoms are arranged in ordered crystal lattices,” adds Busch. “In metallic glasses, the atoms are in a disordered, amorphous arrangement.”
3D-printed electric motors
To create devices from these materials, the project team employed additive manufacturing, commonly known as 3D printing. Powdered amorphous soft magnetic alloys were used to build highly efficient, 3D-printed electric motors for small components. Hundreds of potential alloys were selected and tested for their resistance to crystallisation. The ideal alloy not only had to vitrify (i.e. form a glass) – it also had to be compatible with 3D printing. Eventually, three suitable alloys were identified. The manufacturing process started by melting the powdered material with a laser and then controlling cooling. This enabled layers with a thickness of 50 micrometres to be built up layer by layer into motor parts made entirely of amorphous metallic glass with no disruptive crystallites. This is because by ‘freezing’ these atoms in place, they become locked into position before a crystal lattice can form – resulting in a metallic glass. Without a crystal lattice, the process of remagnetisation is easier to achieve, significantly reducing ‘iron loss’.
Lowering energy consumption
The AM2SoftMag project represents an important step forward in making electrical devices of the future more efficient. Another positive contribution of the work is that by using amorphous metals, producers will no longer have to deal with critical alloying elements such as cobalt. The extraction of this mineral is concentrated in areas of the world with geopolitical tensions and unsafe working practices. Next steps will include scaling up the process so that it works reliably at industrial scale. The list of potential end users is significant, given the demand for electric motors. As Busch points out, there are likely to be hundreds of such motors for example to control the positioning of a seat in a luxury car. “Simply by changing the material, we can lower energy consumption in a whole range of everyday electric motors and, ultimately, extend the range of things such as e-scooters or drones,” he says.
