Electric powertrain does away with rare earth metals

April 08, 2014 // By Christoph Hammerschmidt
A research consortium of Infineon, Siemens, transmission company ZF Friedrichshafen and the Dresden Technical University has developed a motor for electric vehicles that has the potential to boost electric mobility: Though it does not contain any expensive rare earth metals, it is 15% lighter and significantly smaller than conventional electric motors.

The prototype, demonstrated at the ongoing Hanover industry fair, is the result of the European research project MotorBrain. The highly integrated design contains the most important building blocks of an electric powertrain, that is, the transmission and the power inverter are integrated. Compared to typical designs in 2011 when the MotorBrain was started, the researchers succeeded in shrinking the device by 25% - small enough to fit in a typical backpack. The latter could be an evocation to a similar motor introduced by Bosch about a year ago - with the slogan that this engine would fit into a normal school backpack.

While not all technical details were disclosed, the MotorBrain engine is still significantly heavier than its Bosch counterpart and probably more powerful. The unit weighs 77 kilograms - more than twice the weight of the Bosch motor which however comes without integrated inverters and, first of all, without transmission. In a medium-sized vehicle with 60 kilowatts (about 80 horsepowers), the MotorBrain powertrain would increase the driving range by 20 to 25 percent, the researchers say.

At least as important as the relatively low weight is the fact that the motor does not utilize any rare earth material. This does not only help to keep the price down in times these materials carry a price tag that basically makes them unaffordable. It also reduces dependencies from suppliers in difficult geographies such as central Africa or China. Rare earth materials provide a strong magnetic field even at high temperatures and thus enable motor designers to keep their motors small. The MotorBrain research team uses ferrite-based magnets instead of rare earths; their lower performance is compensated by a high-rpm rotor.

The MotorBrain project continues until October 2014. During the remaining time, the research partners now have the opportunity to validate their results, the group said.

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