Ben Palmer asks: how feasible is green magnetic EV engine power?
Developing the next generation of EV powertrains that use permanent magnet motors free of rare earth elements, would seem a great idea in theory. But how feasible is this technology and what challenges must be overcome?
Strong permanent magnets suitable for use in high-performance applications, such as EV motors, typically contain rare earth elements, such as neodymium and samarium. Most of the world’s supply of rare earth elements is controlled by Chinese companies, which also means it is becoming more costly to source, and rising geopolitical tensions and potential supply oligopolies have brought an increased risk of supply chain disruption. Furthermore, the extraction and processing of rare earth elements requires a considerable amount of energy and generates by-products that can be harmful to the environment.
Reducing reliance on rare earth elements, whilst also finding a way to eliminate the use of lithium and cobalt, which are typically used in EV batteries, has become a key area of focus for the EV industry globally. Achieving these goals, whilst maintaining or improving the overall efficiency and performance of EV powertrains and bringing the resulting benefits for the motorist, has become an important engineering challenge.
Tesla announced earlier this year that it is developing a next generation electric drive unit that uses a permanent magnet motor with no rare earth materials. The EV maker already produces permanent magnet motors, but the focus now appears to be on eliminating the use of rare earth elements without impacting the motor’s power output. The technology behind it is not yet known, although the company has filed a patent application for rotor lamination technology that reduces magnetic flux leakage, which could be part of the solution by boosting power output.
Elsewhere, engineers are developing solutions that could support the EV industry in greening powertrains. For example, Gaussion, a company founded by two former PhD students at the University College London (UCL) has developed a patented technology, known as MagLiB, which uses a dynamic magnetic field to facilitate the ultra-rapid charging of lithium-ion battery cells at higher average electrical currents. The technology can reduce battery charging time by 68%, which speeds up manufacturing and means motorists could charge the average EV in just eight minutes rather than 20, without reducing battery lifetime. The ability to charge batteries more quickly could also help to offset the loss of torque that can result if motor efficiency is reduced due to the absence of rare earth elements.
Japan’s IHI has recently announced that it has developed a ‘high-flux plastic magnet rotor prototype’, which is efficient, light and compact. Made from a composite of plastic and magnetic powder with a magnetic orientation similar to that of a Halbach array, the prototype has a magnetic field strong enough to power a high-speed motor suitable for use in an aircraft or EV. As it is 50% plastic, the magnet also uses half the amount of rare earth elements required for the same output.
Another way to reduce the impact of rare earth elements is to find a more efficient way of extracting them from waste electronics, enabling their reuse. With this goal in mind, Bentley Motors is nearing the end of a three-year study, known as the RaRE (Rare-earth Recycling for E-Machines) project, which is aiming to deliver a breakthrough in rare earth element recycling. The project is developing a means of extracting magnetic material from waste electronics and HyProMag is re-processing it back into new magnetic materials for use in ancillary motors. With an abundance of waste electronics containing rare earth elements, recycling could become an increasingly important source of materials for EV motors.
In the longer term, recent hype surrounding LK-99 has reinforced the game-changing potential for the EV industry of superconductor materials capable of operating at room temperature. Such a material could completely redefine EV battery and motor architectures, eliminating the use of rare earth metals altogether. However, for now at least, this technology remains a distant dream.
With so many strands of innovation activity underway, it seems inevitable that the promise of greener electric powertrains will be realised in the next few years. Those companies that own patents directed to the core elements of these breakthrough technologies will be at a significant commercial advantage to those who follow.
Ben Palmer is a partner and patent attorney, specialising in the automotive industry, at European intellectual property firm, Withers & Rogers