Four years ago, researchers from nine European countries launched the MotorBrain project, which aimed to develop an EV drivetrain that didn’t need costly rare earth metals in the motor. Now they’re ready to present a prototype of a fully-integrated drivetrain with a rare-earth-free permanent magnet synchronous motor at this year’s CWIEME Berlin exhibition.
“Rare earth metals produce powerful and reliable permanent magnets, which is why they are used by almost every major hybrid and electric vehicle manufacturer today,” says Dr. Yves Burkhardt, an engineer at Siemens and a MotorBrain researcher. “Yet their availability is limited – around 90% of the world’s supply is controlled by China – and they can be difficult and potentially hazardous to mine, making them a key cost driver for electric motors.”
The researchers discounted induction motors due to limitations in their design, and set about investigating alternatives to rare earth permanent magnets in synchronous motors. “Our results showed that ferrite-based magnets, although inferior to rare earth magnets, could still achieve the same or even better power density than in induction motors but with the other benefits that synchronous motors can offer,” Dr. Burkhart says. “We can use fewer components and make the manufacturing process quicker and easier. For the end user this means a lighter, cheaper, more efficient motor,” he says.
The project team also sought to reduce the cost and number of components using an integration approach. “In earlier generations of electric vehicle powertrains, the steering and power electronics are separate, but we integrated the electric motor, the gear box and the control of the system into a single housing,” Dr. Burkhardt says. “With no plugs and cables and fewer external interfaces that need sealing, we created a common system that saves on space and parts and is cheaper and more robust.”
Dr. Yves Burkhardt, R&D engineer at Siemens, and his MotorBrain colleague Dr. Michael Lambeck, director of R&D at Egston System Electronics, will present a prototype drivetrain at CWIEME Central (hall 3.1) on Tuesday 5th May, 16:20-17:00.