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DRIVES, CONTROLS & MOTORS
FEATURE
How rArE EArtH dEpEndEncE is rEsHAping Motor dEsign
R
are earth mining and permanent magnet production are heavily concentrated in a small number of geographies, a situation
that caused price volatility and supply disruption. As a result, vehicle manufacturers are beginning to reassess a supply chain dependency that many viewed as unavoidable. Increasingly, manufacturers are asking:
Are there other motor technologies capable of delivering comparable performance without the supply chain vulnerabilities associated with rare earth materials? The answer, yes – but not all alternatives are equal.
underStanding the motor landScape Electric motors may appear similar from the outside, but the technologies behind them vary significantly in design, performance and material requirements. Interior Permanent Magnet (IPM) motors
remain the dominant option across the EV market today. Used extensively, IPM motors embed rare earth magnets into the rotor to create high torque density and strong efficiency characteristics. IPM motors are compact, powerful and suited
to passenger vehicle applications. However, the supply chain vulnerabilities they expose are creating huge challenges for producers. It has often been thought that rare-earth free
motor technologies come with compromises, but this is no longer the case. Induction motors, popularised in earlier EV programmes, remove the need for permanent magnets entirely. Instead, they generate magnetic fields electrically within the rotor. Though proven, induction motors can suffer from lower efficiency under certain operating conditions, lower power density and often generate higher thermal loads. Electrically Excited Synchronous Motors
(EESMs) are another rare earth-free option. They replace permanent magnets with electrically powered rotor windings. Several OEMs have adopted this approach, but the added mechanical complexity introduces new
The company’s technologies are gaining serious traction with OEMs and Tier 1 suppliers
Historically, the electric vehicle industry has
largely agreed on one assumption: that rare earth permanent magnet motors represent the best possible solution for EV performance. But, that assumption is now under increasing scrutiny and, in many cases, being proven incorrect. Advanced Electric Machines (AEM) explains
engineering challenges. Ferrite magnet motors reduce
reliance on rare earths by using ferrite materials, but they typically struggle to match the torque density and compact packaging of high-performance permanent magnet systems.
a different approach There is one rare-earth free electric motor that has been proven to match and exceed the performance characteristics of interior magnet motors, developed by Advanced Electric Machines (AEM), a UK-based manufacturer headquartered in Washington. While much of the industry spent the last
decade refining permanent magnet systems, AEM focused on developing an optimised reluctance motor architecture capable of eliminating not just rare earth magnets, but permanent magnets entirely. The company’s technologies are now gaining
serious traction with OEMs and Tier 1 suppliers looking for ways to future-proof electrification strategies. AEM’s latest designs prove the performance gap between rare earth and rare earth-free motors no longer applies. Using benchmarking data from
automotive engineering consultancy, FEV, AEM compared its SSRD passenger car motor against production motors from three key OEMs. After adjusting for differences in size, speed and power output, the results showed AEM’s motor produces more torque across its operating range than other systems – including the permanent magnet motor it was designed to replace. Crucially, it achieved this without using any rare earth materials. SSRD matches the torque and power
density of IPM motors at speeds up to 17,000rpm, which is typical for the current market. It can deliver 180kW from active motor components weighing
www.designsolutionsmag.co.uk
AEM’s rare-earth free electric motor
around 20kg. In applications that allow higher speeds, SSRD technology can operate up to 30,000rpm, enabling even greater power density than most other motor technologies. This performance does not come at the expense of efficiency: peak efficiency reaches around 97%, with strong efficiency maintained across a wide operating range.
Supply chain reSilience and circularity The International Energy Agency has already warned that rare earth demand could outpace supply during the 2030s, increasing pressure on manufacturers reliant on permanent magnet systems. AEM believes that dependence on those
materials was always a weakness in the EV supply chain. Its motor designs instead use steel and aluminium, materials with broad global supply chains and established recycling infrastructures. They shut down completely when not in use, reducing safety challenges, enabling coasting and improving overall system efficiency. Unstable supply chains are forcing the
automotive industry to recognise something it perhaps overlooked during the first wave of EV adoption: not all electric motors are equal and magnets are not always the best possible solution.
Advanced Electric Machines (AEM)
https://advancedelectricmachines.com/
JUNE 2026 dEsign soLUtions 43
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