22 Jul 2024


€36m European project develops rare-earth-free EV motor

A consortium of 30 organisations from nine European countries have built a prototype of a compact electric vehicle motor that needs no rare-earth materials, yet is smaller, lighter and more powerful than conventional EV motors. The motor has been developed as part of the €36m MotorBrain project which aims to improve the efficiency of EV drivetrains by up to 20%.

The prototype motor, shown at the recent Hannover Fair, integrates a gear drive and inverter, cutting the powertrain weight by around 15%, from the 90kg that was typical when the project started in 2011, to less than 77kg. The researchers say that a vehicle with a 60kW MotorBrain motor would be able to drive 30–40km further than the typical current EV range of around 150km per battery charge.

The motor was built by four German partners in the project: Infineon (the project leader); Siemens; Dresden Technical University; and ZF Friedrichshafen. Other organisations involved in the MotorBrain project include Fiat, Volkswagen, STMicroelectronics and Robox. There are two UK-based partners – the University of Sheffield and Qinetiq.

A key driver when developing the motor has been to eliminate costly rare-earth materials which are needed for most current EV motors. The MotorBrain motor uses less expensive ferrite magnets. To compensate for their lower performance, it uses a specially developed high-speed rotor.

The overarching goal of the MotorBrain project has been to increase the range and safety of electric vehicles, while reducing their dependency on rare-earth metals. Specific aims include:

•  to design and simulate multiphase powertrain systems with an emphasis on efficiency, economy and safety;

•  to develop and assess novel smart and fault-tolerant motor topologies that use multi-phase designs to achieve higher efficiencies, advanced integration and enhanced safety;

•  to exploit innovative magnetic materials – such as soft magnetic compounds (SMCs) – to minimise the reliance on rare-earth magnets;

•  to incorporate fault-detection and mitigation techniques, fault-tolerant power conversion topologies, and failsafe control strategies;

•  to improve the performance and integration abilities of fast switching inverters, as well as passive components, for highly-integrated EV powertrains;

•  to study advanced control approaches for distributed and centralised motor topologies; and

•  to investigate new processes and technologies to cut manufacturing costs and simplify recycling.

SMC components offer the possibility of directing magnetic flux in three dimensions, rather than the 2D of conventional sheet-steel materials. In addition, they could help to raise motor efficiencies through reduced losses at higher frequencies and higher pole-pair counts. Their more complex flux distributions and concentrations could help to substitute for rare-earth magnets. Another potential attraction is that they open up new design possibilities for a higher degree of integration and automation during production.

Members of the consortium are looking at various technologies that could be applied to future EV drivetrains, including synchronous reluctance motors, motors with moulded rotors and integrated sensors, advanced batteries, bidirectional chargers, and current, angle and torque sensors.

The MotorBrain project is due to end in October 2014. The researchers will use the remaining time to validate their research results.

Funding has come from commercial businesses and from organisations including the UK’s Technology Strategy Board, Germany’s Federal Ministry of Education and Research (BMBF) and the European ENIAC Joint Undertaking.