Eliminating Rare Earth Minerals from Motors

Rare earth minerals are one of the most contentious issues in the technology industry today. While the vast majority of companies are trying to push their green credentials, much of the technology we use relies on rare earth materials, such as neodymium and dysprosium, which are required for a lot of the components and applications found in engineering.

However, the process to extract rare earth materials is anything but environmentally friendly. Rare earth materials are often found in ores alongside radioactive materials such as thorium and uranium, and the rare earths are extracted using acid. The process produces radioactive waste, acid-containing sewage water, and waste gas that contains hydrochloric acid in much larger quantities than the useful materials extracted.

More and more research is going into finding ways of producing components and products that do not need rare-earths to function properly, and now some of that research is bearing fruit. AEM, a spin-off from Newcastle University, based in the north-east of England, has recently announced its HDSRM and SSRD ranges of electric motors that do not require any rare earth materials.

To make the motors even more sustainable, they don’t use copper for windings either. Copper windings need to be removed before recycling at the end of the motor’s useful lifetime. This process is difficult and costly. The AEM solution only uses steel and aluminium and the new motors can be recycled quickly and cheaply.

In contrast to the permanent magnet motors normally used in motor vehicles, the new AEM motors are based on switched reluctance (SRM). This kind of motor is not usually used for automotive designs as they usually have problems with both noise and torque ripple. AEM claims to have eliminated noise and torque through the use of clever design and patented technologies. The company also says that HDSRM series motors are capable of the performance and efficiency benefits of a conventional permanent magnet motor, while remaining environmentally friendly. They are able to make use of the standard power electronics found in most EV drivetrains. Other benefits offered by the new SRM design include robust construction, no risk of demagnetisation due to overheating, and the ability to freewheel without any electromagnetic losses. Customers have reported that those combined attributes provide a longer range and lower costs for the overall drivetrain system. The HDSRM motor was specifically developed for use in commercial vehicle applications, which require very high levels of continuous performance and a long service life.

AEM’s other new release is designed for the passenger car market. The company claims the SSRD motor can provide 50% more power for 35% less weight than a leading permanent magnet passenger car motor - 125kW as a single motor up to 600kW as a lightweight e-axle. The SSRD motor also has a lower BoM and is easier to recycle that the conventional motors it is intended to replace.

It definitely looks like an interesting technology. The HDSRM motor has already been deployed in the new generation of Tevva Motors trucks, so it will be interesting to keep an eye on the results.

Advanced Electric Machines